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PubMed1987

Analysis of acetone-hexane artifacts produced in the Soxhlet extraction of solid environmental samples.

A study was performed to examine the artifact formation during the acetone-hexane Soxhlet extraction of suspended materials collected on glass fiber filters. Capillary gas chromatographic analysis showed a great number of artifacts of significant concentration in the Soxhlet extractions of the filters after cleaning, the acetone solvent blank and the acetone-hexane Soxhlet blank. Gas chromatographic-mass spectrometric analysis indicated that the compounds are primarily condensation products of acetone produced during the Soxhlet extraction process and solvent impurities. Acetone and hexane washes of the glass fiber filters showed a large variety of compounds to be present on the filters as received from the manufacturer. A reaction scheme is proposed to explain the formation of some of the acetone condensation products identified in this study. A comparison study using methylene chloride to clean and extract the filters showed considerably less artifact formation and solvent impurities. The development of an appropriate quality assured extraction method, which minimizes artifact formation, is needed for the broad spectrum analysis of non-polar trace organics associated with suspended materials in aquatic samples.

Acetone↗
PubMed1989

[How can one recognize a velum snorer?].

In ten habitually snoring subjects and ten patients with obstructive sleep apnea syndrome, preoperative snoring sounds above a preset sound pressure level were recorded and a frequency spectrum analysis by means of time series Fast Fourier Transformation was performed. All patients underwent uvulopalato-pharyngoplasty after which the snoring sounds were recorded again and analysed under the same conditions. Preoperative frequency spectra in heavy snorers were dominated by a component which results from the movement of the soft palate and uvula and which presents as a low-frequency vibration of 25 to 50 c/s and its harmonics up to several hundred c/s. After UPPP the sound pressure level of the snoring noise in heavy snorers was reduced by 20 to 30 decibels and could not be recorded any more. The frequency spectrum of snoring noises in patients with obstructive sleep apnea syndrome differed from those of heavy snorers. In apnea patients the snoring noise usually consisted of other and higher frequency components which masked the vibration of the soft palate and uvula to a more or less high degree. An extreme degree of masking is reached in snoring noises following apneic episodes when identification of the movement of the soft palate is impossible. After performing UPPP in an apneic patient the low-frequency content of the spectrum below about 400 Hz was reduced dramatically but higher frequency parts were still present. This resulted in only minor reduction of snoring noise sound pressure level. Our results are in agreement with other authors in showing that UPPP is not successful when the site of obstruction is not in the velo-pharyngeal plane.(ABSTRACT TRUNCATED AT 250 WORDS)

Airway Obstruction↗
PubMed2005

Improving feature detection and analysis of surface-enhanced laser desorption/ionization-time of flight mass spectra.

Discovering valid biological information from surface-enhanced laser desorption/ionization-time of flight mass spectrometry (SELDI-TOF MS) depends on clear experimental design, meticulous sample handling, and sophisticated data processing. Most published literature deals with the biological aspects of these experiments, or with computer-learning algorithms to locate sets of classifying biomarkers. The process of locating and measuring proteins across spectra has received less attention. This process should be tunable between sensitivity and false-discovery, and should guarantee that features are biologically meaningful in that they represent chemical species that can be identified and investigated. Existing feature detection in SELDI-TOF MS is not optimal for acquiring biologically relevant data. Most methods have so many user-defined settings that reproducibility and comparability among studies suffer considerably. To address these issues, we have developed an approach, called simultaneous spectrum analysis (SSA), which (i) locates proteins across spectra, (ii) measures their abundance, (iii) subtracts baseline, (iv) excludes irreproducible measurements, and (v) computes normalization factors for comparing spectra. SSA uses only two key parameters for feature detection and one parameter each for quality thresholds on spectra and peaks. The effectiveness of SSA is demonstrated by identifying proteins differentially expressed in SELDI-TOF spectra from plasma of wild-type and knockout mice for plasma glutathione peroxidase. Comparing analyses by SSA and CiphergenExpress Data Manager 2.1 finds similar results for large signal peaks, but SSA improves the number and quality of differences betweens groups among lower signal peaks. SSA is also less likely to introduce systematic bias when normalizing spectra.

Algorithms↗
PubMed1999

Relationship between acuity for gratings and for tumbling-E letters in peripheral vision.

Earlier studies have reported that grating resolution is sampling-limited in peripheral vision but that letter acuity is generally poorer than grating acuity. These results suggest that peripheral resolution of objects with rich Fourier spectra may be limited by some factor other than neural sampling. To examine this suggestion we formulated and tested the hypothesis that letter acuity in the periphery is sampling-limited, just as it is for extended and truncated gratings. We tested this hypothesis with improved methodology to avoid the confounding factors of target similarity, alphabet size, individual variation, peripheral refractive error, and stimulus size. Acuity was measured for an orientation-discrimination task (horizontal versus vertical) for a three-bar resolution target and for a block-E letter in which all strokes have the same length. We confirmed previous reports in the literature that acuity for these targets is worse than for extended sinusoidal gratings. To account for these results quantitatively, we used difference-spectrum analysis to identify those frequency components of the targets that might form a basis for performing the visual discrimination task. We find that discrimination performance for the three-bar targets and the block-E letters can be accounted for by a sampling-limited model, provided that the limited number of cycles that are present in the characteristic frequency of the stimulus is taken into account. Quantitative differences in acuity for discriminating other letter pairs (e.g., right versus left letters E or characters with short central strokes) could not be attributed to undersampling of either the characteristic frequency or the frequency of maximum energy in the difference spectrum. These results suggest additional tests of the sampling theory of visual resolution, which are the subject of a companion paper.

Discrimination, Psychological↗
PubMed1981

[The use of electrophysiological techniques to project typical psychotropic drug effects: some examples (author's transl)].

A long existing hypothesis, i.e. that the EEG effects, in lead O2A2, of typical psychotropic drugs are substance class specific, when given as single oral dosages to healthy volunteers, is discussed. Using the technique of pharmacoelectroencephalograhpy, five typical representatives of neuroleptics, anxiolytics, antidepressives, psychostimulants (Fig. 2) as well as placebo were investigated in 75 volunteers, each receiving one representative of each substance class in a double blind 5-fach change over latin square design (Fig. 3). A five minute EEG record for lead O2A2 was obtained pre, 1 h and 3 hrs post drug intake unter RR (Relaxed Recording) conditions. Typical samples of th EEG records are shown in Figs. 4--7. Parametrisation was done using power spectrum analysis. Then 3 x 7 target variables were formed--six relative power values in predetermined frequency bands and the total power between 1.5 and 30.0 Hz for 3 occasions of measurement (Fig. 4--7). Using a (five-group) linear discriminant analysis the substance effects on the EEG were transformed into 5 probability measures for the five substance classes (Fig. 4--7). The present paper should provide a demonstration of some typical examples, using single subjects, of the projection of substance effects onto an electrophysiological level using a vector of 21 components (7 target variables for 3 occasions of measurement) as can be seen from Table 1. Furthermore, the transformation into probability measures of the five substance classes are shown in Table 2. Table 3 shows five examples of projections of substance effects, which do not fit into the classifications to which they belong. An attempt is made to explain, whether single target variables from the power spectrum can contribute differently to the discrimination between single substances of different substance classes. Within the accepted system of 4 psychotropic drug classes, the following variables seem to be of importance: a) The benzodiazepine anxiolytics show a marked increase in beta F1 (12.0--18.0 Hz) power and activity and, related to sedation, an increase in delta F-power and a decrease in alpha-power; b) The psychostimulants of the amphetamine type show an increase in total power and alpha-power, an increase in the power of the frequency ranges near to the alpha-band (slow beta, fast theta) and a decrease in delta F (1.5--5.5 Hz)-power, when delta F-power is high in the pre-values, indicating a stabilization in vigilance; c) The neuroleptics show a marked increase in theta F (5.5--8.5 Hz)-power, some increase in the delta F--and a decrease in the beta F1-and beta F3-power; d) Tricyclic antidepressants show an interaction between delta F-theta F-, alpha- and beta-power, in the sense of a dissociative shift in vigilance.

Adult↗
PubMed2005

Analyzing genes using closing and replicating circles.

During the past two years, significant breakthroughs have been achieved in genetic analyses through the application of technologies based on analytical DNA-circularization reactions. Padlock probes and molecular inversion probes have enabled parallel, high-throughput single nucleotide polymorphism (SNP) genotyping at increased scales, whereas, at the other end of the analysis spectrum, DNA molecules in individual cells have been genotyped, in situ, using padlock probes and rolling-circle amplification (RCA). This review describes the recent developments in the technologies that use specific DNA circularization, coupled to DNA amplification through PCR or rolling-circle amplification, and addresses the great potential of these tools.

Animals↗
PubMed1977

Quantitative electromyographic studies of back muscle activity relatated to posture and loading.

The myoelectric activity of some of the posterior muscles of the back was studied quantitatively using signal amplitude estimation and power spectrum analysis. Surface electrodes were placed on both sides of the trunk at T4, T8, L1, L3, and L5 levels. Four different angles of forward flexion were studied during external loading of the spine with 200 N. At 30 degrees of forward flexion studies were made when the load was increased from 0 to 300 N. Asymmetric loading was studied with the trunk erect, in lateral flexion, and in rotation. The myoelectric activity increased when the angle of flexion increased and when the external load was increaed at a fixed angle of flexion. During asymmetric loading, comparatively higher activity was found on the contralateral side in the lumbar region and on the ipsilateral side in the thoracic region. The magnitude of the power spectrum changes correlated well with the amplitude of the myoelectric signal. Spectral changes increased when the signal amplitude increased, indicating localized muscle fatigue.

Adult↗
PubMed1993

Effects of the cold pressor test on short-term fluctuations of finger arterial blood pressure and heart rate in normal subjects.

The effect of the cold pressor test on autonomic cardiovascular control was studied non-invasively by means of spectrum analysis of periodic heart rate and blood pressure fluctuations in ten normal subjects. Fast Fourier Transform algorithm based on a 256-point time series (sampling rate 2 Hz, i.e. 2-min and 8-s) was used to estimate the amplitude spectra of heart rate and blood pressure rhythmicity at the low frequency (70-140 mHz) and respiration related frequency (230-270 mHz) band. Respiration rate was controlled at 250 mHz. Auto- and cross-spectral techniques were used to determine the complex relationship between systolic blood pressure and heart rate fluctuations in the frequency domain. The spectral pattern of systolic and diastolic blood pressure showed a marked increment of the absolute and relative (100 multiplied with absolute value/total area under the curve of the amplitude spectrum from 15-500 mHz) low frequency component: control vs. cold pressor test--systolic blood pressure--absolute values (in [mmHg/Hz1/2]): 634.4 +/- 48.9 vs. 827.4 +/- 69.9*; relative values (in [%]): 26 +/- 2 vs. 32 +/- 2*; diastolic blood pressure--absolute values: 433.2 +/- 42.3 vs. 537.2 +/- 45.8*; relative values: 35 +/- 3 vs. 40 +/- 2*, (average +/- SEM, *P < 0.05). The cold pressor test induced no change in average heart rate; the absolute low frequency component in heart rate spectra increased clearly during the test: low frequency component (in [bpm/Hz1/2]): 586.9 +/- 89.9 vs. 712.0 +/- 91.4*, while the relative low frequency component did not change: 29 +/- 3 vs. 30 +/- 3.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

Comparison of evoked potentials and high-frequency (gamma-band) oscillating potentials in rat auditory cortex.

1. Transient and steady-state (40 Hz) evoked potentials, as well as spontaneous and click-evoked gamma-band oscillations, were recorded from 15 lightly anesthetized rats using an 8 x 8 electrode epipial array covering auditory cortex and adjacent areas to determine and compare the spatiotemporal distributions of these four phenomena. 2. The transient evoked response replicated earlier findings in our laboratory, consisting of an initial biphasic sharp wave in area 41, a similar but delayed biphasic sharp wave in area 36, and more widely distributed slow-wave components. Spatiotemporal analysis supported a model of parallel and asynchronous activation of distinct groups of thalamocortical projections underlying the neurogenesis of these temporal components of the middle-latency auditory evoked potential (MAEP) complex. 3. The 40-Hz response to click trains was superimposed on a steady potential shift (SP), both of which were localized within primary auditory cortex. Epipial distributions of the SP were similar to those of the shortest-latency negative peak in area 41 recorded in the same animals, suggesting similar neural generators. The 40-Hz response was more focal and dissimilar from the SP and any other temporal components of the MAEP complex, suggesting that a unique subpopulation of cells underlies its neurogenesis. 4. Spontaneous gamma-band activity, as assessed by power spectrum analysis, was localized to primary and secondary auditory cortex but had a variable distribution between rats that did not conform to the cytoarchitectonic boundaries within subdivisions of this region. Digital movies computed for individual bursts of gamma-activity indicated a high degree of spatiotemporal variability within and between bursts. 5. Single-trial spectral analysis of click responses indicated an inhibition of gamma-band oscillations during most of the MAEP complex, with subsequent enhanced gamma-activity during the 300- to 350-ms slow-wave component that outlasted the MAEP by approximately 500 ms. The epipial distributions of prestimulus and enhanced poststimulus gamma-oscillations were the same. In contrast to the 40-Hz response to click trains, phase-locking of gamma-oscillations by the single click stimulus was not observed. 6. These results suggest that both the MAEP complex and the steady-state 40-Hz response with its associated SP are highly stereotyped in lightly anesthetized rodent cortex. Their spatiotemporal distributions are probably determined in large part by asynchronous activation of parallel thalamocortical projection systems. Our data suggest no direct link between either the MAEP or the steady-state 40-Hz response to spontaneous or evoked gamma-band oscillations in auditory cortex.(ABSTRACT TRUNCATED AT 400 WORDS)

Acoustic Stimulation↗
PubMed1992

Cellularity and fibrin mesh properties as a basis for ultrasonic tissue characterization of blood clots and thrombi.

This in vitro study was designed to evaluate the ability of ultrasonic tissue characterization (UTC) based on power spectrum analysis of backscattered radio-frequency echo signals to distinguish two prominent variables of thrombi: cellularity (primarily red cell content) and fibrin-mesh density. Six types of clots simulating thrombus components were prepared by varying red-cell and platelet concentrations and shear forces during clotting. Data were acquired with a linear-array transducer, digitized, and analyzed in terms of slope and intercept parameters obtained from normalized power spectra of radio-frequency echo signals. Increased cellularity and fibrin-mesh density both produced lower slope and higher intercept values, which permitted statistically significant discrimination of cellularity and mesh density in the six types of clots analyzed. Shearing forces and (to a lesser degree) platelet concentrations increased fibrin-mesh density. This study suggests that UTC based upon the power spectrum of echo signals may be used to detect and follow compositional differences that have clinical relevance in the diagnosis and follow-up of thrombi.

Blood Coagulation↗
PubMed1983

Contraction-related, low-frequency components in canine electrogastrographic signals.

Interdigestive gastric contraction-related phenomena were studied in four healthy conscious dogs by running-spectrum analysis of signals derived from the abdominal surface. When groups of contractions occur irregularly spaced in time, low frequencies (in the range below 0.085 Hz) show up in the power spectra of the electrogastrograms. It has been hypothesized that prolonged electrical control activity (ECA) intervals shown to coincide with irregular contractions are related in some way to these low frequencies. This hypothesis was investigated in detail. Whereas a certain degree of correlation was demonstrated between ECA interval variations, contractile activity, and the presence of low frequencies in the spectra obtained from electrogastrograms recorded during interdigestive migrating complexes, a more pronounced correlation between these phenomena was found during "minute rhythms." It was concluded that the presence of lower frequencies ranging from the normal gastric one to about 0.01 Hz in the running-spectrum representation of electrogastrograms recorded in fasting dogs is indicative of strong antral contractions and that the mechanism through which this is brought about involves prolongation of ECA intervals associated with these contractions.

Animals↗
PubMed2000

The correlation between intron length and recombination in drosophila. Dynamic equilibrium between mutational and selective forces.

Intron length is negatively correlated with recombination in both Drosophila melanogaster and humans. This correlation is not likely to be the result of mutational processes alone: evolutionary analysis of intron length polymorphism in D. melanogaster reveals equivalent ratios of deletion to insertion in regions of high and low recombination. The polymorphism data do reveal, however, an excess of deletions relative to insertions (i.e., a deletion bias), with an overall deletion-to-insertion events ratio of 1.35. We propose two types of selection favoring longer intron lengths. First, the natural mutational bias toward deletion must be opposed by strong selection in very short introns to maintain the minimum intron length needed for the intron splicing reaction. Second, selection will favor insertions in introns that increase recombination between mutations under the influence of selection in adjacent exons. Mutations that increase recombination, even slightly, will be selectively favored because they reduce interference among selected mutations. Interference selection acting on intron length mutations must be very weak, as indicated by frequency spectrum analysis of Drosophila intron length polymorphism, making the equilibrium for intron length sensitive to changes in the recombinational environment and population size. One consequence of this sensitivity is that the advantage of longer introns is expected to decrease inversely with the rate of recombination, thus leading to a negative correlation between intron length and recombination rate. Also in accord with this model, intron length differs between closely related Drosophila species, with the longest variant present more often in D. melanogaster than in D. simulans. We suggest that the study of the proposed dynamic model, taking into account interference among selected sites, might shed light on many aspects of the comparative biology of genome sizes including the C value paradox.

Animals↗
PubMed1990

Mutagenesis of the gene encoding cytochrome c550 of Paracoccus denitrificans and analysis of the resultant physiological effects.

By using synthetic oligonucleotides, the gene encoding soluble cytochrome c550 was isolated from a genomic bank of Paracoccus denitrificans. The nucleotide sequence of the gene was determined, and the deduced amino acid sequence of the mature protein was found to be similar to the primary structure of purified cytochrome c550 except for the presence of seven additional amino acid residues at the C terminus. At the N terminus of the primary structure was found an additional stretch of 19 amino acid residues that had the typical features of the signal sequence of the cytochrome. Comparison of the nucleotide sequences of the upstream regions of the P. denitrificans cytochrome c550 gene and bc1 operon revealed three regions with a distinct organization that showed strong similarity. Downstream of the c550 gene was found part of another gene, the deduced amino acid sequence of which showed strong homology with subunit 1 of the cytochrome aa3 oxidase. For gene replacement experiments, the suicide vector pGRPd1 was constructed. The cytochrome c550 gene was inactivated by insertion of a kanamycin resistance gene, and the mutated gene was cloned into this vector. Recombination with the wild-type gene resulted in a mutant strain with an inactivated cytochrome gene. Isolated mutant strains were unable to synthesize the soluble cytochrome, as judged by spectrum analysis and analysis of periplasmic proteins by gel electrophoresis and heme staining. The mutation resulted in a 14% decrease in the growth yield during aerobic heterotrophic growth and in a 40% decrease in the maximum specific growth rate during growth on methylamine. Furthermore, a longer lag phase was observed under both growth conditions. The mutation had no effect on growth yield, maximum specific growth rate, and duration of the lag phase during anaerobic growth in the presence of nitrate. In addition, there was no accumulation of nitrite and nitrous oxide.

Amino Acid Sequence↗
PubMed2003

Atmospheric pressure matrix-assisted laser desorption/ionisation ion trap mass spectrometry of synthetic polymers: a comparison with vacuum matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry.

Atmospheric pressure matrix-assisted laser desorption/ionisation quadrupole ion trap (AP-MALDI/QIT) mass spectrometry has been investigated for the analysis of polyethylene glycol (PEG 1500) and a hyperbranched polymer (polyglycidol) in the presence of alkali-metal salts. Mass spectra of PEG 1500 obtained at atmospheric pressure showed dimetallated matrix/analyte adducts, in addition to the expected alkali-metal/PEG ions, for all matrix/alkali-metal salt combinations. The relative intensities of the desorbed ions were dependent on the matrix, the alkali-metal salt added to aid cationisation and the ion trap interface conditions [capillary temperature, in-source collisionally-induced dissociation (CID)]. These data indicate that the adducts are rapidly stabilised by collisional cooling enabling them to be transferred into the ion trap. Experiments using identical sample preparation conditions were carried out on a vacuum MALDI time-of-flight (ToF) mass spectrometer. In all cases, vacuum MALDI-ToF spectra showed only alkali-metal/PEG ions and no matrix/analyte adducts. The tandem mass spectrometry (MS/MS) capability of the ion trap has been demonstrated for a lithiated polyglycol yielding a rich fragment-ion spectrum. Analysis of the hyperbranched polymer polyglycidol by AP-MALDI/QIT reveals the characteristic ion series for these polymers as also observed under vacuum MALDI-ToF conditions.

Journal Article↗
PubMed1998

Smooth muscle electromyography of the urinary bladder.

To elucidate smooth muscle activity of the urinary bladder, we utilized an optimized animal model and a specially developed, computer-aided data acquisition and analysis system for bioelectrical signals. Twenty-five Wistar rats were pharmacologically paralyzed and artificially respirated. The urinary bladder was exposed by a suprapubic midabdominal incision, and both ureters were ligated to prevent physiological filling of the bladder. The bladder was initially emptied by slight manual pressure and was then filled via a transurethral catheter in 0.1-ml steps to a maximum of 0.45 ml with physiological saline. A custom-made, gold-plated needle electrode was tangentially guided by a micromanipulator to the smooth muscle of the bladder dome, and the recordings commenced. Furthermore, smooth muscle EMG recordings of the bladder were performed after pharmaco-stimulation of the detrusor with carbachol. Initial results demonstrate that, with the animal model presented here, it is possible to record reproducible and almost artifact-free smooth muscle activity from the urinary bladder. All experiments displayed a stochastic distribution of similar electrical events, increasing in appearance and amplitude with increased bladder volume and after pharmacostimulation with carbachol. Two-dimensional power spectrum analysis revealed a main signal frequency below 1 Hz.

Animals↗
PubMed2003

[The analysis of formant characteristics of vowels in the speech of patient with cleft palate].

OBJECTIVE: To analyze the formant frequency of vowels in the sequence therapy of patient with cleft palate. METHODS: The formant frequency of vowels [a], [e], [i], [u] of normal children and postoperative patients with and without speech therapy was measured and analyzed by VS-99. RESULTS: 1. The mean value of F1, F2, F3 of [a] did not show significant difference among the three groups (P > 0.05). 2. The difference of mean value of [e] was significant between control group and pre-speech-therapy group, and between pre-speech-therapy and post-speech-therapy group (P < 0.05), but no significant difference was found between post-speech-therapy and control group(P > 0.05). The mean value of the formant in post-speech-therapy was higher than that of pre-speech-therapy. 3. The difference of mean value of [i] was significant between pre-speech-therapy and post-speech-therapy (P < 0.05), the mean value of F2, F3 in post-speech-therapy group decreased significantly compared with control (P < 0.05). 4. The difference of mean value of [u] showed significance between pre-speech-therapy and post-speech-therapy (P < 0.05), while the differences among other groups were insignificant (P > 0.05). CONCLUSION: Surgical repair of cleft palate cannot make all patients obtain perfect Velopharyngeal competence (VPC), while speech therapy can improve patient's pronunciation. Speech spectrum analysis can judge the effect of cleft palate therapy objectively.

Adolescent↗
PubMed1995

Murine models of neoplasia: functional analysis of the tumour suppressor genes Rb-1 and p53.

Loss of function of one or both of the two tumour suppressor genes p53 and RB-1 has been recognised as an important step in the development of a variety of human neoplasias for some time. By virtue of the ability to manipulate the genome of murine embryonic stem cells in culture, it has become possible to generate strains of mice which bear inactivations of the murine counterparts of these genes. This article attempts to bring together some of the many results obtained from these murine strains which are shedding light both on the normal role played by both of these genes and the consequences of their dysfunction. Surprisingly neither gene product is revealed to have an indispensable role at the level of the single cell. Hence, even though the Rb-1 gene product clearly has an important role in cell cycle regulation animals constitutively deficient in this gene develop relatively normally for the first 10 days of embryogenesis. It is only at and beyond this stage of development that a requirement for Rb-1 becomes clear, in the regulation of certain cell populations through control of both proliferation and apoptosis. That loss of function of Rb-1 is associated with tumorigenesis is confirmed by the development of tumours of the pituitary gland within heterozygotes. The retinas of these animals, the target organ for tumorigenesis in human RB-1 heterozygotes, remain unaffected. The majority of mice homozygous for an inactivating p53 mutation survive to birth, but then rapidly succumb to tumorigenesis. Heterozygotes also develop tumours, but with a delayed time course and altered spectrum. Analysis of several tissue types from the mutant animals has shown p53 to be crucial for the normal induction of apoptosis following DNA damage, and it is thought that failure of this process is a key predisposing step towards tumorigenesis within the mutant animals. Finally, studies on these and other transgenic strains have revealed interactions between pathways governed by these two genes. For example, the fate of Rb-1 deficient cells has been shown, in some tissues at least, to be dependent upon the functional status of p53.

Animals↗
PubMed1985

[Studies on the tocogram with bearing-down efforts during labor--analysis of the waveform and its clinical significance].

Together with a recording of external tocogram (Ex. toc.), intra-uterine pressure (IUP) and pressure between fetus and birth canal (PFB) were measured simultaneously and continuously, in 77 women during labor who were showing uterine contraction (UC) with bearing-down efforts (BDE). UC curves with BDE were analyzed to detect characteristic features and the sequence of their change in the second stage of labor. The following results were obtained. IUP curves were able to be classified into three types (Type A, B and C) according to the characteristics of the BDE waveform. This means of categorization was also able to be applied to the waveforms of PFB and Ex. toc., because those two pressure curves were essentially the same as that of IUP. Most of the type A contractions were observed early in the second stage of labor, and type B and C made their appearance successively. During the period of labor, from the first appearance of BDE on UC until the termination of the delivery, the mean frequency of UC with BDE was estimated to be 43 times in premiparae (Type A 5.8, Type B 19.7 and Type C 15.5 times) and 13 times in multiparae (Type A 2.0, Type B 2.7 and Type C 7.6 times). 3) Clinical significance from the point of view of parameters was as follows. The peak pressure of IUP increased slightly as labor progressed and the mean levels were 14.4kPa in Type A, 17.7kPa in Type B and 23.5kPa in Type C, respectively. PFB peak pressure, however, remained close to 50kPa in all cases irrespective of the type of curve. The mean BDE pressure was about a half the mean peak pressure for IUP and PFB respectively. The ratio of the levels of peak pressure of PFB and IUP (PFB/IUP ratio) were found to be approximately from 2.04 to 3.12. By a power spectrum analysis, the maximum levels of power in Type B curves were found at both 0.01 Hz and 0.2 Hz. The differential calculus curves estimated from IUP with BDE were able to be divided into three types, and the maximum value in Type B curves of IUP was 12.8kPa/sec. The IUP levels were plotted against those of PFB estimated from UC curves and the curve obtained indicated a straight line relationship. The levels of PFB were consistently two or three times higher than those of IUP.(ABSTRACT TRUNCATED AT 400 WORDS)

Cervix Uteri↗