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Biomedical subjects

T Katila

Publications and source records attributed to T Katila.

126 records · Page 7Linked to original sources
PubMed1985

Magnetic fields produced by eye blinking.

Magnetic signals produced by voluntary eye blinking were recorded. The maximal signals were found over the posterior parts of the orbits. The polarity of the signal reversed over each eye and in the frontal midline. The amplitude increases with light and amplitude decreases with darkness were similar in the electrical and magnetic blink and eye movement signals. Three different simulation models were used in the interpretation of the results. It is concluded that the primary current source of the blink signal is the transretinal current density. Lid movements change the geometry of the volume conductor resulting in changes in the measured electrical and magnetic field patterns.

Adult↗
PubMed1983

Cerebral magnetic fields preceding self-paced plantar flexions of the foot.

Cerebral magnetic fields preceding self-paced plantar flexions of the feet were studied with a SQUID gradiometer in 4 subjects. A slow magnetoencephalographic (MEG) shift was observed to begin as early as 1 sec before the movement. The shift changed its polarity between frontal and parietal areas. The MEG shifts preceding right and left foot movements were similar in shape, but their polarities differed at many recording locations. Simultaneous movements of both feet were preceded by shifts approximately equal to the sum of the shifts preceding the unilateral foot movements at the same recording location. The results suggest that the EEG and MEG shifts preceding foot movements are largely generated by tangential current sources on the mesial surface of the contralateral hemisphere around the motor representation area of the foot.

Brain↗
PubMed1982

Interstimulus interval dependence of the auditory vertex response and its magnetic counterpart: implications for their neural generation.

Auditory vertex responses elicited by short tone bursts were compared with their magnetic counter parts. Special attention was paid to the behaviour of the N100 deflection of the response. Electrical responses were recorded from scalp locations Fp2, Fz, Cz, Pz, C4 and T4 and the magnetic responses half way between P4 and T6, at a point where the response has one of its amplitude extrema. Different ISIs (from 1 to 16 sec) were applied in order to differentiate specific and nonspecific evoked potential components from each other. The main results were as follows: (1) The scalp distsribution of the electical vertex response depends on the ISI used: with frequent stimulation there are no marked differences in the amplitudes of N100 between frontal and central areas but with long ISIs the amplitude maxima move to the vertex. (2) The magnetic responses also show a clear ISI dependence. The magnetic counterpart of N100 saturates at shorter ISIs than N100 recorded from the vertex. Independent of the ISI the magnetic counterpart of P200 is constantly very small. On the basis of the different sensitivities of the EEG and MEG to current sources of different orientations it is concluded that the auditory vertex response contains both modality specific and non-specific components. Experimental conditions, especially the ISI used, determine the relative contributions of these components to the potential recorded on the scalp.

Adult↗
PubMed1980

On-line quantification of fetal heart rate variability.

An on-line methods for quantification of fetal heart rate variability (FHRV) from fetal electrocardiography (FECG) is presented. A CMOS microprocessor system with a 2k read-only-memory and a 4k random-access-memory is constructed. The processor is connected to a commercial cardiotocograph, and it calculates the interval index (II) measuring the long-term variability and the differential index (DI) measuring the short-term variability of FHR. The accuracy of the system was tested by calculating the FHRV indices from simultaneously recorded direct FECG and abdominal FECG. The correlation between the results of these two methods was good. II and DI were calculated serially for 34 fetuses during normal pregnancies. The FHRV analysis succeeded in 80-100 percent of patients from the 20th until the 27th week of gestation and again from the 35th week until term. The method was less successful, 35-70 percent, between gestational weeks 28 and 34. On average, II and DI grew as the gestation advanced. II had a greater scatter than DI and it was considered to measure mainly the fetal arousal level. DI on the other hand was not below three after the 30th week of gestation. DI may become a new marker of fetal status also in antepartum fetal surveillance.

Computers↗
PubMed1976

Magnetic measurements of pulmonary contamination.

The magnitic determination of pulmonary contamination is based on the remanent magnetization of ferromagnetic contaminating particles. The remanent field of the externally magnetized particles is proportional to their amount and shows their distribution. Although only magnetizable particles are detected with this method, the amount of the inhaled ferromagnetic substance can be used when the total dust exposure of the worker is estimated. In this work five shipyard welders were studied. First the particles disposed to the lungs were externally magnetized and then their distribution was mapped with a sensitive magnetometer. The magnitudes of the remanent fields measured from the welders differed from the fields measured from controls by several orders of magnitude. The radiographic findings showed a good correlation with the magnetic measurements, and further experiments will prove whether this method can partly replace presently used radiological investigations.

Foreign Bodies↗
PubMedDate not supplied

Relationship between embryo recovery rate and uterine lavage fluid composition in postpartum mares.

The aim of the study was to determine whether neutrophil numbers (PMN), trypsin-inhibitor capacity (TIC), lysozyme, N-acetyl-beta-D-glucosaminidase (NAGase), beta-glucuronidase (B-Gase), total protein, and plasmin in uterine lavage fluid of postpartum (p.p.) mares, either at the time of foal heat insemination or around the time of arrival of the embryo in the uterus, could be used in predicting conception. Fifteen mares were inseminated within 13 h after the first p.p. ovulation. Uterine lavage fluids were successfully collected from 9 out of 12 mares before insemination and from all 15 mares before embryo recovery 7 to 8 days after insemination. The embryo recovery rate was 53% (8/15). Prior to insemination, PMN, TIC and lysozyme levels were elevated in 3/4 mares not producing embryos. However, only 1/5, 1/5 and 0/5 mares producing embryos had elevated levels of PMN, TIC, and lysozyme, respectively. None of the parameters was significantly different in mares with or without embryos, but lysozyme was the closest to significance (p = 0.07). In both groups of mares, activities of NAGase (p < 0.01) and B-Gase (p < 0.05) were significantly higher in dioestrus than immediately after ovulation. At embryo recovery, NAGase was higher in mares not producing embryos (p < 0.05). The results suggest that a long-lasting inflammation is the best explanation for low pregnancy rates during the first p.p. oestrus. Further research is needed to establish whether lysozyme, or possibly TIC, could be used in predicting conception at foal heat.

Acetylglucosaminidase↗
PubMedDate not supplied

XO syndrome in the mare.

Only one X chromosome was found in each of the lymphocyte metaphases studied in an infertile mare. Karyotype analysis was made with the CBG and GTG banding techniques. The most obvious clinical abnormality was gonadal hypoplasia.

Animals↗
PubMedDate not supplied

Treatment of cystic ovaries in dairy cattle using human chorionic gonadotropin or a compound consisting of human chorionic gonadotropin with progesterone.

The present study deals with a comparison of HCG and HCG + P (N) as to their efficiency in the treatment of the ovarian cystic syndrome in dairy cattle (263 cases). The intervals between treatment and first oestrus were the same in both groups (22 vs. 23 days), whereas the cows of the HCG-group conceived earlier (29 days) than the cows of group N (36 days), the difference was not, however, significant. The conception rate after first AI was almost significantly higher in the HCG-group (67% vs. 49%, P less than 0.05). The number of inseminations required per pregnancy was also almost significantly lower in the HCG-group (1.22 vs. 1.48, P less than 0.05). The conclusions drawn were the following: the treatment of ovarian cysts with HCG was somewhat more effective than a treatment with N, thus confirming the previous results achieved under Finnish conditions.

Animals↗