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PubMed1977

[Postural drainage and breathing gymnastics--conditiones sine qua non-before lung resections for bronchiectasis (author's transl)].

Report on 150 lung resections in 143 patients with bronchiectasis in the period of 1958-1974. The intensive preparation of the patients before surgery is of highest importance for a small risk and rare complications after operation. Postural drainage and breathing gymnastics are able to increase significantly FEV1 and VC and to reduce RV in the preoperative phase. The complication rate amounted to 8%, lethality after surgery to 1.3%.

Breathing Exercises↗
PubMed2025

Recent Non-LTR Retrotransposon Activity Predicts Cancer Prevalence in Mammals.

Non-long terminal repeat retrotransposons (nLTRs), including long and short interspersed nuclear elements (L1 and SINEs), are the most abundant and active mobile elements in mammals. NLTRs play critical mutagenic and regulatory roles during oncogenesis in humans and model species. However, it is not known whether recent nLTR activity in the genome is related to the lifetime cancer risk of a species beyond humans and conventional model organisms. We examined whether recent nLTR activity predicts cancer prevalence across mammals using comparative analyses of de novo whole-genome repeat annotations from 55 species, each with over 20 published zoo pathology records. We quantified nLTR activity as the number of potentially active elements, their proximity to protein-coding genes and cancer gene orthologs (CGOs), and insertions within these genes. Across all three metrics, neoplasia prevalence was associated with both L1 and combined L1-SINE activity, while malignancy was linked exclusively to the L1-SINE predictors. This pattern suggests a complementary and escalating trajectory, where L1s contribute to early tumorigenic events, while SINE activity, driven by L1s, amplifies their impact and fuels the transition to malignancy. Moreover, genomes harboring more CGOs tended to exhibit higher neoplasia prevalence, and the number of fusion cancer genes was strongly correlated with the number of potentially active L1s across species. Our results further revealed a pattern wherein species with minimal cancer prevalence exhibit restricted activity of at least one major nLTR superfamily, suggesting that preserving genome stability through limited retrotransposition may serve as a protective mechanism against cancer.

Cancer Genes↗
PubMed1979

Adaptation effects on the apparent "squareness" of square-wave gratings.

Adaptation to a 9 cycles deg-1 sine wave makes the apparent brightness profile of a 3 cycles deg-1 square wave look less "square" even when it does not look like that of a sine wave. Adaptation to a 3 cycles deg-1 sine wave has no noticeable effect. Hypotheses based on "excitation patterns" across spatial-frequency-selective channels can account for these results; it is not clear whether variations in local light adaptation can also account for them.

Adaptation, Ocular↗
PubMed1978

The effect of contrast on the transfer properties of cat retinal ganglion cells.

1. Variation in stimulus contrast produces a marked effect on the dynamics of the cat retina. This contrast effect was investigated by measurement of the responses of X and Y ganglion cells. The stimuli were sine gratings or rectangular spots modulated by a temporal signal which was a sum of sinusoids. Fourier analysis of the neural response to such a stimulus allowed us to calculate first order and second order frequency kernels. 2. The first order frequency kernel of both X and Y ganglion cells became more sharply tuned at higher contrasts. The peak amplitude also shifted to higher temporal frequency at higher contrasts. Responses to low frequencies of modulation (less than 1 Hz) grew less than proportionally with contrast. However, response amplitudes at higher modulation frequencies (greater than 4 Hz) scaled approximately proportionally with contrast. Also, there was a marked phase advance in these latter components as contrast increased. 3. The contrast effect was significantly larger for Y cells than for X cells. 4. The first order frequency kernel was measured with single sine waves as well as with the sum of sinusoids as a modulation signal. The transfer function measured in this way was much less affected by increases in contrast. This implied that stimulus energy at one temporal frequency could affect the response amplitude and phase shift at another temporal frequency. 5. Direct proof was found that modulation at one frequency modifies the response at other frequencies. This was demonstrated by perturbation experiments in which the modulation stimulus was the sum of one strong perturbing sinusoid and seven weak test sinusoids. 6. The shape of the graph of the amplitude of the first order frequency kernel vs. temporal frequency did not depend on the amplitudes of the first order components, but rather on local retinal contrast. This was shown in an experiment with a sine grating placed at different positions in the visual field. The shape of the first order kernel did not vary with spatial phase, while the magnitudes of the first order responses varied greatly with spatial phase. 7. Models for the contrast gain control mechanism are considered in the Discussion.

Action Potentials↗
PubMed1979

Spatial and temporal properties of X and Y cells in the cat lateral geniculate nucleus.

1. Extracellular recordings were obtained from units in the dorsal lateral geniculate nucleus of anaesthetized cats. 2. Of sixty-nine units, sixty-three could be unambiguously identified as either X (n = 33) or Y (n = 30) by testing the presence of a null response to stationary sine wave gratings presented in different spatial phases. 3. In response to stationary gratings flashed on and off, Y cells exhibited bigger, more transient responses than X cells. 4. All Y cells but few X cells exhibited a shift effect (modulated periphery effect). 5. In response to drifting sine wave gratings of different spatial frequencies, X cells preferred higher spatial frequencies and showed smaller peak contrast sensitivities and somewhat narrower tuning curves than Y cells. 6. In response to a sine wave grafting of optimal spatial frequency drifting at different velocities, X and Y cells had similar temporal tuning curves. However, Y cells, largely because they preferred lower spatial frequencies, preferred higher drift velocities than X cells. 7. Our data suggest that X and Y cells can be differentiated objectively on the basis of a number of discharge parameters. These parameters are compared with similar data collected by others from neurones in the visual cortex.

Action Potentials↗
PubMed1976

Physiology of peripheral neurons innervating otolith organs of the squirrel monkey. III. Response dynamics.

1. The discharge of peripheral otolith neurons in response to sinusoidal force variations was investigated in the barbiturate-anesthetized squirrel monkey (Saimiri sciureus). The sine waves were superimposed on a background force which biased the end organ so as to excite or inhibit the unit's firing. Both regularly and irregularly discharging neurons were studied. 2. The response amplitude, measured as a peak-to-peak changes in firing rate, reached near-maximal values during the first sine-wave cycle and, for most units, remained constant as sinusoidal stimulation was prolonged. 3. In regular units, introduction of an excitatory bias increased the sensitivity to sinusoidal stimulation in a manner consistent with the static asymmetries observed in the response to constant forces. Bias effects in irregular units were usually small and, in some cases, excitatory biases resulted in a decrease in sensitivity. 4. Variation in sine-wave amplitude had no effect on the sinusoidal gains or phases of regular units. For irregular units, there was some evidence of a small gain increase as stimulus amplitude decreased. 5. Nonlinear distortion was usually 10-20% and was mainly of an asymmetric type. In regular units, the distortion could be partially related to static asymmetries. 6. The response of regular units is predominantly tonic, that of irregular units more phasic. For regular units there was usually no more than a twofold gain enhancement as frequency was increased in the spectrum from DC to 2.0 Hz; typically, small phase leads at low frequencies were replaced by similar phase lags at higher frequencies. Irregular units were characterized by a 20-fold frequency-dependent gain enhancement over the same spectrum; phase leads of 20-40% were seen. 7. Bodeplots were fit by a family of transfer functions, each consisting of three terms. The first is a velocity-sensitive operator with a fractional exponent. The second is a low-frequency adaptation operator. Only the lag operator can be related to the dynamics of otoligh motion. Most of the variations among units, including those seen between regular and irregular units, can be accounted for by suitable variations in the velocity-sensitive and adaptation operators. 8. The transfer functions, when integrated and inverted, led to reasonable approximations of the response to force trapezoids. It is concluded that the transfer functions provide an adequate representation of the dynamic behavior of most units. The only exceptions are the few neurons showing delayed adaptation.

Animals↗
PubMed1976

Quantitative studies of single-cell properties in monkey striate cortex. III. Spatial frequency.

1. The response properties of single cells in monkey striate cortex were examined using moving bars, square-wave gratings, and sine-wave gratings. 2. The moving of cells studied were not selective for bar width or for the spatial frequency of square-wave gratings. 3. Most cells responded selectively to the spatial frequency of the sine-wave gratings. 4. The spatial frequency of the sine-wave grating eliciting the optimal response could not be predicted from the organization of the receptive field of each cell as determined by stationary or moving stimuli. 5. The sharpness of spatial-frequency selectivity is only slightly more pronounced in S-type cells than in CX-type cells. 6. S-type and CX-type cells differ significantly in the temporal modulation of their discharges to gratings. S-type cells discharge in sharp bursts to each cycle which traverses the receptive field. CX-type cells discharge in a rather continuous fashion. This measure can be used reliably to classify cells as S or CS type.

Animals↗