Temporary Interference Research Articles

Repetitive transcranial magnetic stimulation. Possibilities, limits and safety aspects

Repetitive magnetic stimulation (rTMS) is a non-invasive, painless method to induce transient activation in circumscript regions of the human cortex. In contrast to TMS with single pulses rTMS allows a more effective stimulation of association cortex and temporary interference with the proper functioning of stimulated areas. Possible applications for examination of the functional anatomy of language lateralisation, memory functions and visual perception are discussed. Possible therapeutic for movement disorders and depression are discussed. On the basis of theoretical considerations and current experience rTMS induced epileptogenic effects are discussed and safety recommendations are given.

Effects of bilateral lesions of auditory cortex in mice on the acoustic startle response

The acoustic startle response (ASR) was used to investigate the effects of auditory cortical lesions on a brain stem-mediated auditory behavior. The ASRs were obtained longitudinally from young adult C57BL/6J mice before bilateral ablation of auditory cortex, 1 day after ablation, and 1 month later. Control mice received lesions of nonauditory cortex. For some mice, averaged brain stem-evoked responses (ABR) were obtained, and these indicated no effects of lesions on auditory sensitivity. One month after surgery, mice with auditory cortex ablations were statistically indistinguishable from controls on all suprathreshold measures of ASR. However, 1 day after ablation of auditory cortex, experimental animals (but not controls) exhibited a change in ASR amplitude (but not threshold or latency). When a noise burst of 80 dB SPL was used to elicit the ASR, the amplitude was diminished, but with a 110 dB stimulus, amplitude was enhanced. The findings can be interpreted in one of two ways: temporary interference with modulation of the ASR normally performed by auditory cortex; or a general effect of auditory cortex ablation on brain stem auditory circuits not specific to the ASR. In any event, if auditory cortex plays a modulatory role with regard to the ASR, it is apparently nonessential and/or readily compensated for after ablation.

Real exchange rate changes as a cause of protectionism

In this article, the various ways in which a real appreciation of the exchange rate can induce an increase in the overall or sector-specific level of protection are surveyed. In a normative framework, a real appreciation can justify temporary government interference, including trade policy, aimed at protecting (part of) the traded-goods sector. In addition, a positive approach of political decision-making on protection has been applied in order to explain actual government behaviour. After a real appreciation the balance of influence between the interest groups involved will change in such a way that an increase in the level of protection results.

Azocarcinogen-induced release of chromatin-associated RNA into liver cytoplasm: The possible role of reiterated RNA sequences in the control of RNA processing

In the liver of rats fed the azocarcinogen 3′-methyl-4-dimethylaminoazobenzene (3′MeDAB) reiterated RNA sequence transcribed from middle repetitive DNA are released into the cytoplasm. The same repetitive nucleotide sequences can be isolated from the chromatin of the liver of control animals in the form of metabolically highly active, 13 000 daltons RNA. This small, chromatin-associated RNA originates from nuclear RNA larger than 10 S. The discontinuation of the feeding of the azocarcinogen will not stop the release of the nuclear reiterated RNA sequences into the cytoplasm. The repetitive sequences of nuclear RNA which are released into the cytoplasm in animals fed the azocarcinogen can no longer be found in the chromatin in the form of small RNA molecules. The results can be explained by the assumption that the reiterated RNA sequences are involved in the upholding of RNA processing. A cell-specific processing of RNA will be maintained by the interaction of reiterated RNA fragments from already processed RNA with the reiterated complementary sequences on RNA yet to be processed. Existence of such a feed-back circuit would make it possible to explain how a temporary interference of the azocarcinogen with RNA processing will result in the disappearance of specific reiterated RNA sequences from the chromatin. It could also explain the continuation of the release of the same repeated RNA sequences into the cytoplasm as part of larger RNA molecules even after the removal of the carcinogen.

Seed harvesting by ants in forests of Eucalyptus regnans F. Muell. in central Victoria

In an unburnt, mature forest the germination of E. regnans on undisturbed bare ground is very poor in spite of adequate seed fall, and the presence of conditions suitable for germination over much of the year. No seed storage occurs in the top soil in spite of some temporary seed dormancy and the disturbance of the surface soil by earthworms and lyre birds. Seed is removed from the top soil by several ant species– Prolasius pallidus, P. brunneus, P. flavicornis and Chelaner leae –and is taken into nests. Removal of seed is more rapid and complete in summer than winter and is more vigorous in young forest than old. Observations on artificial nests in the field and laboratory indicate that seed is eaten and not stored for any length of time. The testae may be left intact, fragmented or moulded into crumbs with other material. Certain sugar-like substances, which are extractable in low concentrations from fresh seed, may be involved in the attractivity of seed to ants. The numbers of ant species in the forests vary with the micro-climate of the site, and in the mature understorey of Pomaderris aspera the activities of the three dominant species Iridomyrmex biconvexus, Prolasius pallidus and P, hrunneus are largely separated diurnally, seasonally, and spatially in the foraging areas of the litter layer. The density of the nests of seed-harvesting ants is high, particularly in bare areas of the forest floor. The total number of ants probably exceed 5–6 million/ha and is probably sufficient to effectively remove 60% of the sporadic seed fall of normal years. It is suggested that the success of germination of E. regnans after wild fires is not due to any specific stimulation but rather to a temporary interference of ant foraging activity and then to the saturation of their food requirements by a massive seed fall from canopy-stored capsules.

Brainstem lesion with coma for five years following manipulation of the cervical spine

A woman, aged 38, lost consciousness immediately after manipulation of the cervical spine and remained in coma for nearly 5 years in a combined decorticate and decerebrate state. Cerebral angiography revealed impaired circulation in the vertebrobasilar system. The EEG initially showed generalized cerebral dysrhythmia but tended, over the years, to become more normal with desynchronized fast activity of low voltage. Neuropathological examination postmortem revealed a large cystic lesion in the pressure equalization area of the carotid and basilar circulation in the upper pons, mesencephalon, posterior hypothalamus and basal thalamus. No definite stenosis or occlusion was seen in the cerebral vessels on angiography or at the postmortem examination. The mechanism of the lesion is considered to have been temporary interference with the blood flow in the vertebrobasilar system during manipulation of the cervical spine sufficient to cause ischemia and subsequent infarction of the brainstem. The pathogenesis of vascular lesions of the brain stem following manipulation of the cervical spine is discussed briefly.

Compensatory vowel characteristics resulting from the presence of different types of experimental dental prostheses

This paper describes a series of experiments in which experimental dental prostheses were worn by normal speaking subjects, causing temporary interference with habitual articulatory patterns, so that the process of speech compensation could be studied. Three different types of experimental dental prostheses were supplied in turn to six subjects. Acoustical analysis of vowel formants revealed individually distinctive patterns of formant change (or lack of change) when the protheses were worn. Jaw position and larynx height after insertion of a prosthesis likewise showed individually different patterns of articulatory adjustment. Subjects reacted differently to identical prosthodontic modifications of vocal tract contour, thus vowel characteristics could not be predicted from the type of prosthesis provided. Vowel changes were not always compensated for during a week of adaptation to prosthesis. After removal of a prosthesis, vowel formants did not immediately return to the normal range previously determined for individual subjects, indicating that a period of readjustment was necessary. Subjects were not aware of vowel changes caused either by insertion or removal of a prosthesis.

The Effect of Pharmacological Agents on Ejaculation

Infertility in a patient on pharmacological agents with sympatholytic activity was found to be caused by ejaculatory failure owing to absent contraction of the seminal vesicle, ampulla and ductus deferens, rather than the previously accepted reason of retrograde ejaculation. These findings suggest that pharmacological agents producing alpha-adrenergic blockage may produce temporary interference with ejaculation, suggesting investigation of their use as reversible male contraceptives.

Stimulation of Tissue Regeneration by Pulsed Plane-Wave Ultrasound

Plane-wave ultrasound at certain dosages can cause a statistically significant increase in the rate at which tissue re- generates to replace that lost after injury. The experimental model used in this study is the replacement of tissue in the pinna of the ear of a rabbit after the removal of tissue of area 1 cm2 through the full thickness of the ear. The regenerate consists of skin and its derivatives and elastic cartilage. The method of irradiation and the effects of a range of dosages on the rate of tissue replacement are described. Experimental evidence indicates that the growth rate increases found are not due to thermal effects caused by ultrasound; it is thought that a mechanical factor, streaming, may be involved. Electron microscopic studies show changes in the irradiated tissue that may be interpreted as indicating an increase in protein synthesis and temporary interference with the polymerization of collagen precursors. Autoradiographic investigation of 3H-thymidine uptake shows that the rate of synthesis of DNA in the regenerating tissue is increased by treatment with ultrasound. ISTROUL-CTIOX HERE have been several reports that ultrasound at certain dosages can increase enzyme activity (l), (2) and thus generally increase metabolic ac- tivity. In plants this effect stimulates seed germination and the growth rate of young seedlings (3), (4). This stimulation of plant growth suggested the use of ultra- sound as a possible stimulant of tissue growth in animals. The control of regenerative growth, i.e., the replacement of lost tissue, is clinically important in the treatment of injuries and in post-operative care. It is possible to stimulate growth by systemic means, for example, by the repeated injection of anabolic hormones (5), but such treatment affects other sites as well as the regenerate and can produce undesirable side effects. The direct

The Effect of Sublethal Doses of Parathion on Honeybee Behaviour. I. Oral Administration and the Communication Dance

SummaryThe oral sublethal dose of parathion in honeybees was determined as less than 0–03 μg per bee. Sublethal doses of parathion prevented bees from communicating the direction of a food source to other bees by dancing. The basic form of the dance of poisoned and nonpoisoned bees was similar, except that the angles at which the poisoned bees danced changed in a disjunct step-wise fashion (instead of linearly) with time. No evidence of changes in other behavioural patterns of foraging bees was observed in these tests, but there are suggestions that parathion at this level caused a temporary interference at an integrating centre outside the brain.

Reductions in size and total DNA of cerebrum and cerebellum in adult mice after corticosterone treatment in infancy

This study was designed to examine the long-term effects on the brain of intensive corticosterone treatment during the period of rapid postnatal brain growth and maturation. Mice were given a single subcutaneous implantation of a pellet of corticosterone at 2 days of age. This produced a temporary interference with growth that resulted in a 10% reduction in body weight of the adults; a slightly greater reduction in cerebral weights and a 21% reduction in cerebellar weights. Determinations of DNA, RNA and cholesterol were made, as indices of cell number and maturation. the total DNA of the normal mouse cerebrum increased 25% between 2 and 14 days of age, while cerebellar DNA increased 580%. Total cerebral DNA did not change in control mice between 14 and 350 days of age. Corticosterone given between 2 and 14 days reduced total cerebral DNA 18% at 14 days and 10% at 8 months; and reduced cerebellar DNA 25%. In the cerebrum there was a small but significant decrease in cholesterol at all ages studied. There was a transient decrease in the RNA DNA ratio. The findings indicate that corticosterone given in infancy interfered with the synthesis of DNA, RNA, and protein in the brain, and produced an irreversible reduction in brain size and cell numbers, which was particularly marked in the cerebellum, because of the high rate of postnatal mitosis characteristic of certain cerebellar neurons.

OLIGURIA FOLLOWING ORABILIX ADMINISTRATION.

Cholecystography is usually regarded as a safe investigation, but recently renal complications have been described when Orabilix has been used as the contrast medium. Orabilix, 3(3-butyrylamino-2, 4, 6-tri iodophenyl)-2 ethyl sodium acrylate, is a brand of Buniodyl (Brit. Med. J., 1964) or Bunamiodyl. It is an iodine-containing oral cholecystographic agent, rapidly absorbed from the gut and excreted by the liver in much the same way as bilirubin and bromsulphthalein. Transient effects on bromsulphthalein excretion rates have been noted to occur and are probably due to temporary competitive interference. Maximum blood concentrations are found after one to three hours and because of butyrylation of the amine group 70 per cent is excreted by the kidneys. Bickham (1960) thought it to be safer than previously employed contrast media and he noted that side effects were uniformly lower than with other media. Several reports have appeared in the American literature linking the drug with renal toxicity (Rene and M...

TEMPORARY INTERFERENCE OF INSOLVABLE DISCRIMINATION REVERSAL TRAINING UPON LEARNING SET IN THE SQUIRREL MONKEY.

TEMPORARY INTERFERENCE OF INSOLVABLE DISCRIMINATION REVERSAL TRAINING UPON LEARNING SET IN THE SQUIRREL MONKEY.

Prognosis of epiphysial separation: an experimental study.

1. The methods by which epiphyses receive their blood supply was studied by means of India ink injections in monkeys. Two types were identified depending upon whether the epiphysis was entirely or partly covered by articular cartilage. In the former, nutrient vessels enter the epiphysis by traversing the perichondrium at the periphery of the plate. In the latter they enter the epiphysis by penetrating the cortex at the side of the epiphysis at a point remote from the epiphysial plate. 2. The histological changes after separation of the second type of epiphysis were also studied. After temporary interference with endochondral ossification marked by increased thickness of the epiphysial plate, healing occurred so rapidly that within three weeks it was difficult to determine that the epiphysis had been separated at all. 3. It is concluded that when nutrient vessels enter an epiphysis at a point remote from the epiphysial plate, that epiphysis can be separated without serious disturbance to its blood supply and accordingly without interference with its capacity for growth. As it has been established that an epiphysis which is entirely covered by articular cartilage cannot be separated without destruction of its blood supply and subsequent avascular necrosis (Harris and Hobson 1956), it is concluded that the prognosis of an epiphysial separation is dependent upon the degree of damage to its blood supply rather than the mechanical disturbance of the epiphysial plate.

Single-Sideband Operation for International Telegraph

The increased demands for multiple and direct international radiotelegraph channels between the nations of the world and the shortage of usable high-frequency spectrum has greatly increased the importance of the single-sideband radio system for this purpose. The world's requirements for high frequencies, 4 mc to 30 mc, are so large that they are assigned over and over again to various services on the basis of geographical and time sharing. Single-sideband operation with multiple subcarriers and automaticfrequency control permit a high order of frequency utilization efficiency. Single-sideband operation offers a high degree of flexibility in meeting the various requirements of international communications. The number of its subcarriers can be changed to meet varying load conditions; they can be shifted to avoid temporary interference; and they can be used to operate with more than one point in the same geographical area. Codes with various numbers of signal elements either equal or unequal in length, and different types of modulation, and speeds can be carried on any or all subcarriers.

ANGINA PECTORIS

Innumerable hypotheses have been proposed to explain the mechanism of an attack of angina pectoris. Huchard 1 collected about eighty such hypotheses in his monograph. It is not within the scope of this paper to enumerate or to discuss the great majority of these. However, the two that seem to be commanding most attention at the present time merit a brief outline. 1. The hypothesis, stated first by Parry, 2 holds that the attack of angina pectoris is dependent on a temporary interference with the blood supply of a part of the heart muscle. This hypothesis is based on the following points: ( a ) the frequency with which advanced coronary disease is found post mortem in patients who have died from angina pectoris; ( b ) the similarity of the syndromes of angina pectoris and coronary occlusion in regard to the character and location of the pain; ( c ) the adequate explanation of the mechanism

Societies and Academies

LONDON. Royal Society, Jan. 24.—D. Denny-Brown: (1) On the nature of postural reflexes. Postural reflexes are all based on Liddell nd Sherrington's stretch-reflex. This basic reflex is a discharge of motor impulses at a slow rate, and no mechanical plastic or fixing mechanism is involved, except contraction caused by those impulses. The magnitude of reflex response changes by alteration of number of nerve units in discharge. This is effected by variations in excitation of units, either from changes in tension on muscle or from changes in excitatory effect relayed from higher levels of nervous system.—(2) The histological features of striped muscle in relation to its functional activity. Speed of contraction is a property of muscle fibres independent of observable histological differences, although development of rapid contraction occurs in fibre groups which are more highly differentiated for storage of lipoid substances or factors increasing fibre diameter.—W. S. Stiles: The effect of glare on the brightness difference threshold. A method is described for determining brightness-difference threshold in presence of point-source of glare. The value, for two subjects, of Fechner's fraction in absence of glare has been found for field brightness 0-001-2-2 candles/sq. ft. Threshold in presence of glare source is best expressed in terms of equivalent background brightness and a formula is developed which serves over this range.—L. J. Harris: The combination of proteins, ammo-acids, etc., with acids and alkalis. Part 2. Titration curves of amino-acids, in presence of formol. Curves are given for variation in pH value (colorimetrical) with amount of soda added when amino-acids are titrated in aqueous formaldehyde, each addition being corrected for the acidity of the ‘solvent.’ The hydrochloric acid titration curve remained virtually unchanged by addition of formaldehyde. The results are explained on the basis of the ‘zwitterion’ hypothesis, according to which the caustic soda and hydrochloric acid titrations relate not to the apparent, but to the true, basic and acidic constants.—F. W. R. Brambell and G. F. Marrian: Sex-reversal in a pigeon (Golumba livid).—J. B. Gatenby and Sylvia Wigoder: (1) The effect of X-radiation on the spermatogenesis of the guinea-pig. X-radiation prevents mitosis in those cells entering prophase. It is suggested that the X-radiation breaks up lipoids in some way essential to mitosis. Mild doses cause only temporary interference with lipoid metabolism, so that cells not already entering prophase of mitosis are able to recover. No evidence of stimulation effects by X-rays was procured.—(2) The post-nuclear body in the spermatogenesis of Oavia cobaya and other animals. In probably all flagellate sperms, the flagellum is fixed to the nucleus, not by the head centrosome, or by a protoplasmic membrane, but by a special structure called the post-nuclear body. This has often been mistaken for centrosome, middle-piece, or acrosome. It is a separate and distinct structure which (especially in molluscs) can be traced back into the spermatocyte.—J. B. Gatenby: Study of Golgi apparatus and vacuolar system of Cavia, Helix, and Abraxas, by intra-vital methods.—A. B. Macallum: Ionic mobility as a factor in influencing the distribution of potassium in living matter.

THE VALUE OF TEMPORARY COLOSTOMY

Diseased or injured limbs and joints respond to treatment most effectively when function is suspended and immobilization is effected. Physiologic rest alone is a valuable therapeutic agent because the organ involved can, so to speak, devote its entire energy to the business of getting well. Unfortunately, many organs, which would be benefited by the complete suspension of activity, are so vital to life that complete rest is an impossibility. A half a loaf is better than no bread. When one cannot secure complete cessation of functional activity, a minimum of function must suffice. Fortunately, the colon can be completely excluded from functional activity, and in the treatment of various pathologic conditions which affect it, relief and cure can often be effected by a temporary interference with its activity. Enterostomy and colostomy are both being utilized with increasing frequency for temporary purposes. The number of lives saved yearly by the employment