Über die Desorption von positiven und negativen Ionen durch starke elektrische Felder

An Hand von Beobachtungen über die Feldelektronenemission wird gezeigt, daß sich aus dünnen, auf Wolframeinkristallspitzen aufgedampften Kaliumchloridschichten, deren Schichtdicke größer ist, als dem Minimum der Elektronenaustrittsarbeit entspricht, durch positive Felder positive Kaliumionen, durch negative Felder negative Chlorionen „abreißen“ lassen; im ersten Fall erscheint die effektive Austrittsarbeit der Elektronen nach dem Abreißvorgang vergrößert, im zweiten Fall vermindert. Aus den dünnsten, vermutlich monomolekularen Kaliumchloridschichten, gelingt es dagegen mit den hier verwendeten Feldstärken nur, positive Ionen, aber keine negativen Ionen abzureißen; dies wird verständlich, wenn man beachtet, daß aus energetischen Gründen das Chlor in unmittelbarer Berührung mit der Wolframoberfläche nicht als Ion, sondern nur als neutrales Atom gebunden sein kann, weil seine Elektronenaffinität (3,79 eV) kleiner als die Austrittsarbeit des Wolframs (4,5 eV) ist.

Zur Deutung von früher untersuchten Abreißerscheinungen an gasbeladenen Wolframspitzen, die einer thermischen Nachbehandlung unterworfen waren, wird die Annahme vorgeschlagen, daß es sich bei den „Zentren“, die für die starken Intensitätsunterschiede im Feldelektronenemissionsbild solcher Schichten und für die Abreißerscheinungen verantwortlich sind, um überschüssige Metallatome handelt, die an bestimmten Stellen der Oberfläche der dünnen Oxyd- bzw. Carbidschicht eingebaut sind, mit der die gasbeladene Wolframoberfläche nach ihrer thermischen Nachbehandlung bedeckt ist.

[Importance of home care personally to individuals with advanced cancer and their families]

OBJECTIVE

The objective of the study is to evaluate the importance of home care for patients with advanced tumor diseases and for their families.

METHODS

The analysis was based on structured interviews with relatives of patients with terminal tumor diseases. They had participated in the home care of 50 consecutively treated patients 2 years previously. The value of home care was evaluated on the basis of the personal experience of those concerned.

RESULTS

The answers were largely consistent. The holistic concept of palliative therapy could be implemented by a specialized home care team at a high quality level. Under the favorable conditions of the familiar surroundings, an atmosphere of trust developed as a result of the cooperation with the family members, people close to the patients and with family doctors. It contributed to a relatively high quality of life and to alleviate the emotional stress. Most of those involved were able to accept the hand of fate. On this basis, the terminal phase could be satisfactorily arranged and preparations made for a good quality of death. During the home care, appreciation of the value of the family increased. The intensified family relations were mostly sustained after the patient's death. The results document the great personal importance of home care for patients, their caretakers and families.

CONCLUSION

The positive experience and the awareness of having contributed substantially to coping with the life crisis made it easier for the bereaved to grieve and to rearrange their life.

Acute effects of simulated microgravity on heart rate variability

Microgravity is known to stress the heart and blood vessels and to perturb the normal neural regulation of the cardiovascular system. In an effort to gain greater insight into the adjustments of neural control of the cardiovascular system in space, we have used a model of simulated microgravity, the -6 degrees head-down tilt body position (HDT). As a common method for the description of the functional state of the cardiovascular system the power spectral analysis of the heart rate can be used. The following working hypotheses were postulated: 1. HDT causes an acute activation of the parasympathetic nerve traffic to the heart, which is detectable by a reduction in heart rate and by the spectral power distribution of the heart rate variability. 2. HDT induces changes in the autonomic nervous response to upright posture which can be detected after a 45-minute period of head-down tilt.

Proliferation and collagen biosynthesis of osteoblasts and chondrocytes in short rib syndrome type beemer

We report on a case of lethal short-limbed skeletal dysplasia with extremely short ribs, median cleft upper lip and palate, malrotation of intestine, lung hypoplasia with bilateral segmentation defect, atrial septum defect, union of distal urethra and vagina, and complex brain malformations. Based on radiological criteria and the pattern of associated abnormalities a short rib syndrome without polydactyly (Type Beemer) was diagnosed. Morphologically, the growth plate showed a reduced proliferation zone and an enlarged zone of hypertrophic cartilage. In addition, islands of persistent hypertrophic cartilage were present even in the metaphysis. In monolayer cell cultures supplemented with 10% fetal calf serum proliferation was normal in articular chondrocytes, reduced in costal chondrocytes, and elevated in osteoblasts from the patient. Clonal growth of costal and articular chondrocytes in methylcellulose could be stimulated normally by insulin-like growth factor-I (IGF-I), IGF-II, and human growth hormone (hGH). However, the response to transforming growth factor beta 1 (TGF-beta 1) was markedly elevated in articular chondrocytes of the patient compared to those of 3 fetal controls. Quantitative collagen synthesis in both osteoblasts and chondrocytes from the patient did not differ significantly from that of controls. Osteoblasts synthesized predominantly collagen I and minor amounts of collagen III, chondrocytes synthesized primarily collagen II. All collagen chains including CNBr-peptides of collagen II showed normal migration in PAA gel electrophoresis.

Intact inhibition of the stretch reflex during general tetanus

Tetanus toxin at lethal doses (2-10 x 10(3) mouse minimal lethal doses per kg body weight, mMLD/kg) was injected i.v. into 10 cats under pentobarbital anaesthesia. After the appearance of the first sign of generalized tetanus the animal was anaesthetized by a mixture of urethane and chloralose. Experiments were performed several hr thereafter when the toxin action was anticipated to be optimal. The stretch reflexes were elicited manually, by the contraction of the antagonistic muscles or by a stretch device. In toxin treated animals the spontaneous electromyographic activity was inhibited by strong stretching of the tested muscle or by that of the antagonistic muscle. The stretch reflex of the extensor muscle elicited by a contraction of the flexor muscle was inhibited by electrical stimulation of the flexor afferent fibres. The stretch reflex elicited by a stretch device as well as the electrically elicited monosynaptic reflex were inhibited by conditioning stimulation of the antagonistic nerve. The inhibition curves were almost the same as those of healthy animals. It is concluded that the spinal inhibitions, such as antagonistic group Ia, autogenic group Ib, groups II and III and the presynaptic inhibitions, were kept intact in severe general tetanus.

Relation between height and the maximum conduction velocity of the ulnar motor nerve in human subjects

The maximum motor nerve conduction velocity of the right and left ulnar motor nerve was measured in more than 650 healthy medical students of both sexes. There was no side difference in the maximum conduction velocity. The shorter person has a statistically significant higher conduction velocity than the taller person. Comparison of students of both sexes showed a slightly higher conduction velocity in females. However, with regard to its relation to height, the conduction velocity was higher in males.

Blocking effects of tetanus toxin and its fragment [A-B] on the excitatory and inhibitory synapses of the spinal motoneurone of the cat

A highly purified fragment [A-B] preparation (5.5 micrograms of protein in 5 or 10 microliters which is far less than the minimal lethal dose), free from contamination with the whole toxin, was injected intraspinally into the neighbouring area of the gastrocnemius motoneurone pool (eight cats). Tetanus toxin (27 micrograms protein, about 100 LD50) in 5 or 10 microliters (four cats) and 10 microliters of Ringer's solution (four cats) were injected in the same way. Fragment [A-B] depressed both the monosynaptic reflex (MSR) of the gastrocnemius motoneurone pool and its inhibition by conditioning stimulus on the antagonistic peroneal nerve almost simultaneously in the individual cats, in contrast to the whole toxin which blocked first the inhibition of the MSR and later the MSR itself. The effects of fragment [A-B] appeared late, at about the time when the whole toxin blocked the MSR. The cats injected with fragment [A-B] did not die by intoxication. Fragment [A-B] at high doses (up to 120 micrograms) injected intramuscularly into the rat had no effect on neuromuscular transmission. The results clearly showed a blocking action of fragment [A-B] on inhibitory and excitatory synapses of the spinal motoneurones.

Presynaptic inhibition of the monosynaptic reflex during local tetanus in the cat

Tetanus toxin at doses of 2-2000 mouse MLD/kg was injected into the gastrocnemius muscle of the left hind limb of the cat. Acute experiments were performed at various times thereafter, when the intoxicated hind leg was strongly extended. Presynaptic inhibition of the monosynaptic reflex (MSR) of gastrocnemius motoneurones was tested by applying conditioning single electric stimuli to the antagonistic deep peroneal nerve. In most intoxicated animals the delayed inhibition of the MSR could still be observed at time intervals typical for presynaptic inhibition. However, the amplitude of the MSR often showed a strong toxin-induced facilitation at about 30 msec after the conditioning stimulus which could mask the presynaptic inhibition and sometimes made it difficult to observe it at all. After spinal transection at the Th1 level the inhibition could be better observed in such cases. Further evidence for the resistance of the presynaptic inhibitory system against the tetanus toxin in the given dose range was given by recordings of distinct dorsal root potentials which were abolished, together with the MSR inhibition by i.v. injection of picrotoxin. It is concluded that the mechanism of presynaptic inhibition remains intact or is even lengthened during local tetanus after i.m. injection of moderate, clinically relevant, toxin doses.

Binding of 18F by cell membranes and cell walls of Streptococcus mutans

The binding of 18F to isolated cell membranes and cell walls of Streptococcus mutans GS-5 or other bacteria was assayed. The attachment of 18F to these cell envelopes proceeded slowly and reached equilibrium within 60 min. 18F binding was stimulated by Ca2+ (1 mM). The binding of 18F to cellular components was dependent upon the pH, as well as the amount of 18F and dose of the binder employed. The binding of 18F by cell walls prepared from fluoride-sensitive and fluoride-resistant cells of S. salivarius and S. mutans did not differ significantly. The pretreatment of cell walls or cell membranes for 60 min at 30 degrees C with 1 mg of RNase, DNase, or trypsin per ml did not influence the binding of 18F by the walls and membranes of S. mutans GS-5. However, prior exposure of cell membranes to sodium dodecyl sulfate caused a significant reduction in the number of 18F atoms bound by the membranes. In saturated assay systems, cell membranes of S. mutans GS-5 bound 10(15) to 10(16) atoms of 18F per mg (dry weight), whereas cell walls from S. mutans GS-5, FA-1, and HS-6 or Actinomyces viscosus T14V and T14AV bound 10(12) to 10(13) atoms of 18F per mg (dry weight). 18F in this quantity (10(12) to 10(13) atoms) cannot be detected with the fluoride electrode. The data provide, for the first time, a demonstration of 18F binding by cell membranes and walls of oral flora.

Effect of tetanus toxin on the monosynaptic reflex

Tetanus toxin was injected at various doses (0.1-10,000 mouse MLD/kg) into the gastrocnemius muscle of the left hind leg of the cat. The relative excitability of the monosynaptic reflex (MSR) was increased in the very early period of the intoxication decreased in the later period, during which the MSR of the gastrocnemius was either partially or totally depressed at doses as low as 10 mouse MLD/kg.

Genetic and endocrine findings in a 31-year-old 45,X/46,Xdel(Y)(q12) male

This report describes genetic, endocrine, and histological findings in a 31-yr-old 45,X/46,Xdel(Y)(q12) male with gynecomastia and azoospermia. A preponderance of 45,X cells was found in all tissues studied. Endocrine data suggested an abnormal Leydig cell-pituitary gonadotroph axis, although the basal testosterone level and the response to short term administration of hCG were normal. Testicular histology showed Leydig cell hyperplasia and seminiferous tubule atrophy. These findings are compared to 17 similar cases in the literature. A characteristic of all these cases is a morphologically abnormal Y-chromosome, which probably results in the 45,X cell line. The masculinizing genes on the remaining Y-chromosomes are functionally intact and promote a male phenotype in infancy and adolescence. Azoospermia is usually present, and gynecomastia or hypogonadism occurs later in life. Comparison with other nonmasculinized 45,X/46,XY cases supports existing theories regarding the function of the various segments of the Y-chromosome.

Reversible inhibition of testicular steroidogenesis and spermatogenesis by a potent gonadotropin-releasing hormone agonist in normal men: an approach toward the development of a male contraceptive

We studied the antifertility effects of a potent gonadotropin-releasing hormone agonist, D-Trp6-Pro9-N-ethylamide-LHRH (LHRHA) in eight normal men, who received daily subcutaneous injections for six to 10 weeks. Plasma testosterone levels fell substantially in all eight. Plasma 17-hydroxyprogesterone and serum estradiol-17 beta levels decreased concordantly with plasma testosterone. Impotence developed in five men between the sixth and seventh weeks of treatment, with resolution in each case within two weeks of stopping treatment. Serum gonadotropin levels also fell during treatment, briefly rebounding above basal levels when therapy ended. Sperm density and motility fell t a nadir during the seventh to 18th week after therapy. In six subjects sperm levels fell to 6 X 10(6) sperm per milliliter or less, and in the other two they decreased 70 and 86 per cent below basal mean values. Sperm density returned to pretreatment levels in all men during the 10-to-14-week recovery period. These results are consistent with LHRHA-induced pituitary "desensitization" but do not exclude a direct inhibitory effect of LHRHA on testicular steroidogenesis and spermatogenesis.

Rhythmic activity in the cerebellum and spinal cord of rabbits receiving tetanus toxin intravenously

1. In rabbits intravenously injected with tetanus toxin (2 x 10(5) mouse LD50), a rhythmic electrical activity was recorded in the cerebellum and in the spinal cord. 2. The motor system appears to be strongly involved in this event, since the ventral roots displayed rhythmic activity correlated to the spinal cord rhythm. Extracellular recordings showed the same rhythmic discharge pattern in many alpha- and gamma-motoneurons and Renshaw cells of hindlimb flexor and extensor muscles. 3. Upon high spinalization at C1, the rhythm could be recorded in the cerebellum but no longer in the spinal cord. Cooling of the cerebellar surface suppressed the rhythm in both structures. 4. The data are discussed under the current view, that generalized tetanus is a special form of local tetanus. 5. We suggest that the rhythmic activity is of supraspinal origin and is transmitted to alpha- and gamma-motoneurons of both the flexor and extensor motor systems.

Activation and inhibition of muscle and cutaneous postganglionic neurones to hindlimb during hypothalamically induced vasoconstriction and atropine-sensitive vasodilation

1. Discharge patterns in postganglionic neurones to muscle and to hairy skin of the hindlimb of chloralose anaesthetized cats were investigated during electrical hypothalamic stimulation which induced either vasoconstriction or atropine sensitive vasodilation in the skeletal muscle. 2. Spontaneously active postganglionic neurones to muscle were activated both during hypothalamically induced vasoconstriction and active vasodilation. Stimulation of the hypothalamic vasodilator area induced mostly a sequence of activation-depression-activation in these neurones. Stimulation of cutaneous Group IV afferents elicited reflexes in these neurones; repetitive high frequency stimulation of large diameter afferents in the vago-depressor nerve produced depression of spontaneous activity followed by a post-inhibitory excitation. The characteristics of these neurones fit those that would be expected of vasoconstrictors. 3. Normally inactive postganglionic neurones to skeletal muscle could only be activated during hypothalamically induced atropine sensitive vasodilation. These neurones exhibit no reflexes on somatic stimulation. The axons of these neurones conduct faster than those of the spontaneously active postganglionic neurones. It is likely that they are cholinergic vasodilator neurones. 4. Most of the cutaneous postganglionic neurones to hairy skin were activated during stimulation of both the hypothalamic vasoconstrictor and the vasodilator areas. These neurones have the characteristics of cutaneous vasoconstrictor neurones. Part of the cutaneous not spontaneously active postganglionic neurones could neither be activated from the hypothalamus nor by somatic stimuli.

Some properties of sympathetic neuron inhibition by depressor area and intraspinal stimulation

In Nembutal anesthesized cats single shock stimulation of the depressor area of the medulla oblongata evoked inhibition of spontaneous and glutamate-evoked activity of sympathetic preganglionic units. Single shocks to the lateral funiculus of the cervical or upper thoracic spinal cord in acute spinal cats evoked inhibition of the spontaneous and glutamate-evoked activity of single units and of the segmental reflex mass discharge evoked by spinal afferent stimulation. Cats studied 4 to 6 weeks after a complete transection of the spinal cord also showed, on stimulation of the lateral funiculus below the transection, an inhibition of the segmental reflex with time course similar to that seen in the acute spinal state, but of lower threshold and greater intensity. These results suggest that the inhibitory coupling between supraspinal levels and sympathetic preganglionic units is mediated, at least in part, by propriospinal neuronal system which survive after chronic spinal section. On the assumption that the observed changes in the properties of inhibition are due to plastic changes consequent to partial denervation the results also suggest that continuous descending tracts exist, and that both the continuous and the propriospinal descending tracts may be converging onto some common neural element.