Search PubMed⌕ Search

Biomedical subjects

W Hanke

Publications and source records attributed to W Hanke.

At least 163 records · Page 9Linked to original sources
PubMed1985

The effects of pentachlorophenol, phenol and other pollutants on the liver of carp (Cyprinus carpio L.).

Liver tissue of carp was kept in roller tubes and the basal and epinephrine-induced release of glucose after 6 or 24 hr incubation were measured. The amount of liver glycogen after incubation was also determined. The liver was taken from carp treated in vivo with pollutants, mainly PCP or phenol, or was exposed to these pollutants in vitro. Treatment of carp in vivo with 10-10(4) micrograms/l phenol reduced the basal and the epinephrine-induced release of glucose from the liver. Treatment with low doses increased the glycogen content of the liver slightly, treatment with higher doses reduced the amount. Treatment of carp with low doses of several pollutants decreased mainly the basal glucose release from the liver and reduced the glycogen content. In vitro incubation of the liver with PCP or phenol for 3 days reduced at first the basal release and later the epinephrine-stimulated release of glucose from the liver. After a few days the glycogen content of liver exposed to pollutants was more strongly reduced than that of controls. The phosphorylase activity was slightly increased in liver tissue by the pollutants.

Animals↗
PubMed1984

Reconstitution of highly purified saxitoxin-sensitive Na+-channels into planar lipid bilayers.

Highly purified Na+-channels isolated from rat brain have been reconstituted into virtually solvent-free planar lipid bilayer membranes. Two different types of electrically excitable channels were detected in the absence of any neurotoxins. The activity of both channels was blocked by saxitoxin. The first channel type is highly selective for Na+ over K+ (approximately 10:1), it shows a bursting behavior, a conductance of 25 pS in Na+-Ringer and undergoes continuous opening and closing events for periods of minutes within a defined range of negative membranes voltages. The second channel type has a conductance of 150 pS and a lower selectivity for Na+ and K+ (2.2:1); only a few opening and closing events are observed with this channel after one voltage jump. The latter type of channel is also found with highly purified Na+-channel from Electrophorus electricus electroplax. A qualitative analysis of the physicochemical and pharmacological properties of the high conductance channel has been carried out. Channel properties are affected not only by saxitoxin but also by a scorpion (Centruroides suffusus suffusus) toxin and a sea anemone (Anemonia sulcata) toxin both known to be selective for the Na+-channel. The spontaneous transformation of the large conductance channel type into the small one has been considered; the two channel types may represent the expression of activity of different conformational states of the same protein.

Animals↗
PubMed1984

The significance of cortisol for osmoregulation in carp (Cyprinus carpio) and tilapia (Sarotherodon mossambicus).

Changes in plasma cortisol and glucose concentration were studied in carp during acclimation from fresh water (FW) to 1.5% salt water and vice versa. There was an increase in cortisol and glucose concentration during acclimation from FW to salt water which lasted for several days. Reacclimation to FW did not cause clear changes in cortisol and glucose levels. One single injection of cortisol (0.2 mg/100 g or 1 mg/100 g) and additional transfer to salt water (1.5% for carp and 2.7% for tilapia) altered the changes caused by acclimation alone of cortisol, glucose, Na+ concentration, and the osmolality in plasma. Gill Na-K-ATPase activity was also influenced. The effects of cortisol on electrolyte concentrations during acclimation and on Na+-K+-ATPase activity differed in both types of fish. Cortisol clearly lowered the increase in plasma Na+ concentration of the stenohaline carp and increased the ATPase activity. The changes in plasma Na+ concentration of the euryhaline tilapia was not clearly altered and the enzyme activity was inhibited. The significance of these cortisol effects is discussed.

Acclimatization↗
PubMed1984

A comparison of physiological changes in carp, Cyprinus carpio, induced by several pollutants at sublethal concentration--II. The dependency on the temperature.

Carp were exposed to 10 different pollutants with sublethal concentrations at 12, 17 or 22 degrees C. The effects on the serum cortisol and glucose levels, the amount of liver and muscle glycogen and the concentration of protein and cholesterol in the serum were examined. The level of serum cortisol and glucose increased, the amount of liver and muscle glycogen decreased and the protein and cholesterol concentration were reduced after exposure to the pollutants. The cortisol and glucose response was similar at all temperatures, slightly reduced at 17 degrees C. The glycogen reaction was strongest at 17 degrees C and the protein and cholesterol response was low at 12 degrees C and increased with the temperature. The explanation of the different temperature dependency is difficult. Carp are stressed and have low metabolic rate at 12 degrees C. They have good conditions at 17 degrees C and have a higher energy demand at 22 degrees C. These simple differences cannot exactly explain the different dependency.

Animals↗
PubMed1984

Incorporation of ion channels from bovine rod outer segments into planar lipid bilayers.

Membranes vesicles, prepared from bovine rod outer segments were fused with planar lipid bilayers. Two different ion channels were identified by recording currents from single channels. Both types of channels were selective for sodium rather than potassium and were impermeable to chloride ions. Unit conductances were 20 and 120 pS, respectively, in 150 mM sodium chloride. The channel with the larger unit conductance was sensitive to the transmembrane potential. This channel rapidly activated within less than 10 ms after a voltage jump to a more negative membrane potential and then inactivated after several seconds. The duration of the active period and the properties of the channel depended on the amplitude of the voltage jump. The channel of smaller unit conductance did not show any voltage-dependent activation or inactivation. Both types of channels were insensitive to light in the planar bilayer system. Channels incorporated into planar bilayers on a Teflon sandwich septum or on the tip of a glass micropipette gave similar results.

Animals↗
PubMed1984

Respiratory morbidity in wollastonite workers.

Medical and environmental surveys were conducted at a wollastonite mine and mill in 1976 and in 1982. Health testing included chest radiography, spirometry, and a questionnaire. Workers at a nearby electronics plant were also examined in 1982 for a comparison of lung function and respiratory symptoms. Both wollastonite and control workers showed significant smoking effects for chronic respiratory symptoms, but differences between the groups were not detected. Pneumoconiosis was found in 3% (3/108) of the wollastonite workers in 1982, but none showed a significant progression from their 1976 radiographs. The lung function tests of the 108 wollastonite workers examined in 1982 showed dust related changes in FEV1, FEV1/FVC ratio, and peak flow rate which were independent of age, height, and smoking habit (p less than 0.01). For non-smokers alone, only the FEV1/FVC ratio declined significantly with dust-years of exposure (p less than 0.01). The comparison of lung function in 1982 between a high dust exposed subgroup of wollastonite workers and the control population showed a significantly lower FEV1/FVC ratio and peak flow rate in the study group (p less than 0.05). Analysis of 1976-82 changes in pulmonary function showed that wollastonite workers with higher dust exposure had a significantly greater decline in peak flow over the period than workers with lower exposures (p less than 0.01). These data suggest that long term cumulative exposure to wollastonite may impair ventilatory capacity as reflected by changes in the FEV1/FVC ratio and peak flow rate.

Adult↗
PubMed1984

New scorpion toxins with a very high affinity for Na+ channels. Biochemical characterization and use for the purification of Na+ channels.

Biochemical characterization of the Tityus gamma toxin receptor associated with the voltage-sensitive Na+ channel was carried out in different tissue preparations with the use of an iodinated toxin derivative. The affinity of the toxin for the receptor is high with a dissociation constant of 4 X 10(-12) M for rat synaptosomes. The density of binding sites is in the range of 0.3 to 2 pmol/mg of protein. Toxin gamma does not seem to bind to Na+ channels located on transverse-tubule membranes of skeletal muscle, but only to Na+ channels located on the sarcolemma. Both affinity labelling and radiation inactivation analysis indicate a molecular weight for the toxin receptor of 270 000 daltons. The same molecular weight is found using the tetrodotoxin. Only one single major protein component of the Na+ channel was purified from Electrophorus electroplax, rat brain membranes and chick heart membrane using the toxin gamma as a marker. The molecular weight of this component is 230 000-270 000 daltons. Reconstitution of the purified Na+ channel into planar lipid bilayers has been carried out. Two different types of electrically excitable channels with conductances of 150 and 25 pS were detected. The activity of both channels is blocked by saxitoxin.

Animals↗
PubMed1983

Melittin and a chemically modified trichotoxin form alamethicin-type multi-state pores.

The bee venom constituent, melittin, is structurally and functionally related to alamethicin. By forming solvent-free planar bilayers of small area (approx. 100 microns 2) on the tip of fire-polished glass pipettes we could observe single melittin pores in these membranes. An increase in the applied voltage induced further non-integral conductance levels. This indicates that melittin forms multi-level pores similar to those formed by alamethicin. Trichotoxin A40, an antibiotic analogue of alamethicin, also induces a voltage-dependent bilayer conductivity, but no stable pore states are resolved. However, chemical modification of the C-terminal molecule part by introduction of a dansyl group leads to a steeper voltage-dependence and pore state stabilization. Comparing structure and activity of several natural and synthetic amphiphilic polypeptides, we conclude that a lipophilic, N-terminal alpha-helical part of adequate length (dipole moment) and a large enough hydrophilic, C-terminal region are sufficient prerequisites for voltage-dependent formation of multi-state pores.

Alamethicin↗
PubMed1983

Reconstruction of full-thickness defects of the cheek.

Six patients required reconstruction of full-thickness defects of the cheek and underlying maxilla. We preferred to use a technique employing local cervicofacial rotation advancement flaps. The advantages of this technique include an excellent color match and placement of the line of closure in natural junction zones of the face. Problems that must be dealt with include correction of ectropion and revision of the lower portion of the nose. An alternative means of reconstruction consists of prosthetic management and the use of a regional pedicle flap. Careful monitoring of the soft-tissue margins, evaluation for possible cranial nerve involvement, and the use of postoperative irradiation therapy are important therapeutic considerations.

Adult↗
PubMed1983

The role of hormones in regulation of carbohydrate metabolism in the Australian lungfish Neoceratodus forsteri.

Adrenaline, arginine vasopressin, arginine vasotocin, and glucagon, all at 10(-6) M, stimulate glycogen breakdown and glucose release from hepatic tissue of Neoceratodus forsteri cultured in vitro. Adrenaline acts via a beta-adrenergic receptor in this species. Gluconeogenesis from 2 mM lactate occurred at a rate of 680 +/- 39 nmol/g liver/h. This rate of gluconeogenesis was unaffected by the addition of 10(-6) M adrenaline.

Animals↗
PubMed1983

The effect of temperature on physiological changes in carp, Cyprinus carpio L., induced by phenol.

Carp were exposed to four sublethal phenol concentrations (0.01, 0.1, 1.0, 10 mg/liter) at two temperatures (12 and 17 degrees C). Blood and tissue samples were taken after various periods (1-72 hr) of exposure. For each period controls were taken. Serum concentrations of glucose, cortisol, protein, cholesterol, and triglycerides were determined. Parallelly, the liver glycogen content and the relation of wet and dry weight of the white epaxial muscle were measured. No general significant differences were found among the phenol-treated groups exposed to concentrations of 1 mg/liter and lower. After exposure to these concentrations only serum cortisol showed a significant elevation versus control at both temperatures. In fish exposed to 10 mg/liter a temperature-dependent, significant response to the stressor was found: At the lower temperature mostly a higher stress response occurred in the measured parameters. Fish, which were exposed for 7 days to 10 mg/liter, recovered from all changes after a retransfer to unpolluted water at 17 degrees C.

Animals↗
PubMed1983

Physiological changes in carps induced by pollution.

Several pollutants like DDT, atrazine, PCP, and others induce changes of cortisol and glucose levels in serum, variations of the amount of liver glycogen and liver function, and exert changes of the activity of gill ATPase and acetylcholinesterase in brain and serum of carps. There is always a biphasic response, an increase of concentration or enzyme activity for a short time, and a decrease or inhibition of the enzymes after a longer exposure to the pollutants. The time scale, the duration of the period of increase and that of decrease, depends on the concentration and the toxicity of the pollutants. The influence of the pollutants in normal fresh water was compared with the effects occurring in carps acclimated to 1.2% salt water. This condition enables one to show that the carps are more sensitive to the pollutants under this condition. All responses are unspecific. Advice for the use of these tests as criteria for water quality are given.

Acetylcholinesterase↗
PubMed1983

Single chloride channels from Torpedo electroplax. Activation by protons.

Single-channel fluctuations of a chloride-specific channel from Torpedo californica electroplax were studied with high current and time resolution. Channels were incorporated into virtually solvent-free planar bilayer membranes formed from phospholipid monolayers, and the substructure of the open channel was analyzed. The single channel displays three well-defined substates of conductances 0, 10, and 20 pS in 200 mM Cl-. These three substates are interpreted in terms of a dimeric channel complex composed of two identical "protochannels" gating independently in parallel on a time scale of milliseconds, but coupled together by a bursting process on a time scale of seconds. The probability of forming an open protochannel is voltage dependent and is increased strongly as aqueous pH is lowered. Variations of pH are effective only on the same side of the bilayer as the addition of electroplax vesicles. The dependence of single-channel kinetics on pH and voltage lead to a minimal four-state model in which both open and closed states can be protonated on a residue that changes its pK from 6 to 9 upon opening of the protochannel.

Animals↗
PubMed1981

A new method for membrane reconstitution: fusion of protein-containing vesicles with planar bilayer membranes below lipid phase transition temperature.

A new method of membrane reconstitution was developed by fusion of channel protein containing vesicles with planar bilayer membranes. The fusion process only occurred below and near the phase transition temperature of the lipid used. We obtained the following results: 1. Our system is solvent-free and vesicles do not come into contact with the air/water interface. This obviates a possible denaturation of hydrophobic proteins. 2. Channel forming proteins and protein complexes, respectively, are active in a frozen lipid matrix. 3. We detected an unknown channel in cilia fragments. 4. Purified acetylcholine receptors form fluctuating channels in a membrane consisting of a pure synthetic lecithin (two component system).

Animals↗