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Biomedical subjects

M Laine

Publications and source records attributed to M Laine.

At least 91 records · Page 5Linked to original sources
PubMed1995

Virus-specific, antibody-secreting cells during upper respiratory infections.

The humoral immune response of 18 army recruits with febrile upper respiratory infection (URI) was studied by enumerating virus-specific, antibody-secreting cells in the peripheral blood. Diagnosis was based on viral antigen detection in nasopharyngeal specimens, virus isolation from throat swabs, or on antibody measurement from paired serum samples. At the time of the sample collection, three viruses, including adenovirus, influenza A, and influenza B, were found mainly to cause URIs among the recruits, and ELISPOT assay for enumeration of the specific antibody-secreting cells was selected for these viruses. Of the 36 patients with febrile URI studied, viral diagnosis was made in 18 cases, which included 11 patients with adenovirus infection, three with influenza A, and four with influenza B. The first blood sample was collected at the first signs of URI and the second and third samples at 2-week intervals. The adenovirus-positive patients developed a strong IgG class antibody-secreting cell response against the homologous virus, which peaked at the first sample and decreased steeply by the second and third samples. In the influenza A and B patients, the response was similar kinetically to that seen in adenovirus-positive patients. In those cases where also IgA and IgM class antibody-secreting cells were determined, the IgG response dominated. The ELISPOT method has potential also as a diagnostic tool for respiratory infections.

Adenovirus Infections, Human↗
PubMed1995

High concentrations of atrial natriuretic peptide and brain natriuretic peptide in rat pericardial fluid and their reduction by reserpine in vivo.

We determined concentrations and molecular sizes of natriuretic peptides in rat pericardial fluid and plasma by use of specific radioimmunoassays (RIA) and gel filtration HPLC. Our study shows that pericardial fluid forms a local extracellular storage of immunoreactive (ir) atrial natriuretic peptide (irANP) and brain natriuretic peptide (irBNP) near the heart where these peptides can be found in high concentrations in vivo. The concentrations of irANP, irBNP and NH2-terminal fragment of proANP (irNT-proANP) in pericardial fluid were 9.8 +/- 3.7, 0.49 +/- 0.47 and 28.9 +/- 11.8 nmol/l, respectively. IrBNP had the lowest (20 +/- 11) and irANP the highest (90 +/- 32) concentration ratio between pericardial fluid and plasma. The elution positions of irANP, irBNP and irNT-proANP in pericardial fluid and plasma were similar as examined by gel filtration HPLC. Furthermore, we show that the reduction of noradrenaline content of the heart muscle by reserpine reduces concentration of irANP in pericardial fluid by 39.6% and in plasma by 30.3% when compared to respective control group values. The concentration of irBNP is reduced by 44.1% in pericardial fluid but in plasma its reduction was not statistically significant. Vasoactive peptides released into the interstitial space and from there into pericardial fluid may have a more active role in the regulation of cardiac function than previously considered.

Animals↗
PubMed1995

Cortical processing of vowels and tones as measured by event-related desynchronization.

Event-Related Desynchronization (ERD) and Synchronization (ERS) were studied in 20 normal subjects during a Sternberg-type auditory memory-scanning paradigm. Half of the subjects performed the experiment with vowels and the other half with tones as stimuli. The stimuli consisted of 100 msec long synthesized vowels and 100 msec long tones produced by eight different synthesized instruments. In this paradigm each trial started with the presentation of a visual warning signal, after which a four-stimulus set was presented for memorization whether after a probe stimulus was presented and identified by the subject as belonging or not belonging to the memorized set. The ERD/ERS of the lower (8-10 Hz) and upper (10-12 Hz) alpha frequency bands differed in their reactivity to stimulus type; the differences between the two frequency bands reached statistical significance only in the case of vowels. The presentation of the memory set elicited ERS which was more pronounced in the 10-12 Hz frequency band and greater for vowels than for tones. On the other hand, the presentation of the probe elicited ERD which was greater for vowels than for tones, especially in the upper alpha frequency band. The results of this exploratory study suggest that ERD is closely related to memory process and that the ERD/ERS-technique might provide a valuable tool for future research encompassing more complex auditory stimulation like speech and music.

Acoustic Stimulation↗
PubMed1995

Lateralized free-association priming: implications for the hemispheric organization of semantic memory.

The organization of semantic memory in intact cerebral hemispheres was examined by a free-association priming task. Normal subjects studied a list of word pairs where the semantic relations were either coordinate (e.g. saw-axe) or locative (e.g. bear-forest). Priming of the word pairs was tested by presenting test cues (initial words of the pairs) to the left or to the right visual field. Results showed an interaction between visual field and word pair type, suggesting a qualitative difference in the semantic organization of the hemispheres. Specifically, the results support the view that coordinate relations are represented in both hemispheres whereas locative relations are represented mainly in the right hemisphere.

Brain↗
PubMed1995

Organic halogens in the environment: studies of environmental biodegradability and human exposure.

Organic halogens from chlorobleaching of kraft pulp were not as biorecalcitrant as has been assumed. Fifty percent were removed during biotreatment of wastewater, and 50% of the remaining organohalogens faded in fresh water ecosystems in 200 to 400 days. Molecular size seemed not to hinder biodegradation up to sizes of approximately 2000 daltons. Anoxic biodegradation was of prime importance for halomineralization of pulp bleaching organohalogens but could also lead to toxic metabolites such as vinyl chloride from tri- and tetrachloroethene in anoxic soil. Indigenous soil microbes were unable to clean old organohalogen pollution but had converted chlorophenols into polymeric substances, chlorohumus, which were found bioaccumulable by earthworms in spite of the large (up to 5000 g/mole) molecular sizes. Because of the danger of formation of toxic metabolites, the biochemistry of the xenobiotic degradation must be elucidated before active bioremediation is practiced on polluted soil or water. Groundwater pollution by chlorophenols led to increased disease among the exposed population in one well-studied case. Two further cases of potential environmental health impact are described.

Biodegradation, Environmental↗
PubMed1995

Human pericardial fluid contains the highest amount of endothelin-1 of all mammalian biologic fluids thus far tested.

Immunoreactive endothelin-1 (ET-1) levels were measured in the pericardial fluid (PF), plasma (PL), and atrial and ventricular tissues of 16 cardiac surgical patients. ET-1 was higher in the PF (73 +/- 11 pg/ml) than in the PL/3.33 +/- 0.51 pg/ml; p < 0.05/. PF/PL ratio ranged from 8 to as high as 200. An inverse relationship was found between the NYHA stage and ET-1 concentrations in PF, whereas ET-1 in PL did not have any relation to the NYHA stage of the disease. In HPLC analysis, the total immunoreactive ET-1 in PF from five different patients co-eluted with the human ET-1 standard. The results indicate that ET-1 concentrations in human PF can be several-fold those in the PL. The source and function of the ET-1 in PF requires further investigation.

Body Fluids↗
PubMed1994

Block of stretch-activated atrial natriuretic peptide secretion by gadolinium in isolated rat atrium.

1. Isolated superfused rat atrial preparations were used to study the mechanism of stretch-induced atrial natriuretic peptide (ANP) secretion. The stretch of the atrial myocytes was induced by raising the intra-atrial pressure. The secretion rates were analysed by measuring ANP concentrations from the superfusate fractions by radioimmunoassay. 2. The effect of gadolinium, a blocker of stretch-activated ion channels, on stretch-induced and basal ANP secretion was investigated by superfusing the atrial preparation with 5, 20 or 80 microM GdCl3. Gadolinium decreased stretch-induced ANP secretion in a dose-dependent manner, but did not affect basal secretion. 3. Because high concentrations of gadolinium may block voltage-gated calcium channels, we tested whether the selective blockers of L-type (diltiazem) and T-type (NiCl2) calcium channels affect the stretch-stimulated ANP release. Neither diltiazem at 3 microM nor NiCl2 at 50 microM affected stretch-induced ANP release in paced atrial preparation. 4. Gadolinium, but not diltiazem, also inhibited stretch-stimulated ANP secretion in non-paced, quiescent atria. 5. The findings that ANP release is inhibited by Gd3+, but not by diltiazem or NiCl2, and that the stretch-induced secretion in quiescent atria is also inhibited by Gd3+, suggest that stretch-activated ion channels are involved in the regulation of stretch-induced ANP release.

Animals↗
PubMed1994

Effect of ryanodine on atrial natriuretic peptide secretion by contracting and quiescent rat atrium.

To elucidate the mechanism involved in the release of atrial natriuretic peptide (ANP), we studied the importance of ryanodine-sensitive Ca2+ release in stretch-secretion coupling. The experiments were made with a left atrial preparation, where the stretch of myocytes was induced by changing the intra-atrial pressure. When external pacing was not applied, the atrial preparation was not spontaneously contracting, and it was therefore possible to investigate the secretory mechanism in the quiescent atrium. The superfusate was collected in 2-min fractions and assayed for ANP immunoreactivity. Filtration analysis revealed that the major fraction in the superfusate in all experimental situations had a similar molecular weight as the ANP 1-28. Ryanodine (1.0 microM and 0.1 microM) inhibited stretch-stimulated ANP secretion dose dependently both in paced and non-paced atrium, but did not have any effect on basal secretion. The present results support the notion that intracellular Ca2+ transients from the intracellular stores are essential for stretch-stimulated ANP secretion, independently from excitation and contraction. Basal ANP secretion is not inhibited by blocking ryanodine-sensitive Ca2+ channels, either in contracting or in non-contracting atria. In addition our results confirm that the principal stimulus for ANP secretion in response to atrial distension is the stretch of myocytes. Length shortening of myocytes is not essential for ANP release.

Animals↗
PubMed1994

Event-related desynchronization evoked by auditory stimuli.

Event-Related Desynchronization (ERD) and Synchronization (ERS) of several EEG alpha frequencies was studied in 19 subjects during the presentation of linguistic and/or melodic auditory stimuli. The stimulus length was 1300 msec (+/-100 msec) and the interstimulus interval was 2000 msec. A significant ERD was found during auditory stimulation in the 8-10 Hz and 10-12 Hz alpha frequency bands, and there were also significant differences in the spatiotemporal pattern of the ERD between these frequency bands. Significant ERD was elicited also in the 10-11 and 11-12 Hz frequency bands by auditory stimulation. There were no significant differences between these one-hertz frequency bands. The subjects were assigned to two analysis groups according to their individual alpha peak frequency (10-11 or 11-12 Hz) at rest. The ERD in these groups reached statistical significance and there were significant differences between the groups. The ERD of the two groups differed significantly also when their EEG data was studied in the 10-12 Hz frequency band. The results from this study show that ERD is not modality-specific, i.e., it can be elicited also by auditory stimuli. Moreover, they indicate that it is important to control over interindividual variation in the EEG when studying the ERD phenomenon.

Acoustic Stimulation↗
PubMed1994

Thermal properties of thermodilution catheters.

A suitability of thermodilution catheters to hypothermic conditions was investigated. Thermal properties of two types of thermodilution catheters (Edwards and Spectramed) were checked within a temperature range of 37 degrees C to 22 degrees C. The linear calibration method normally used in normothermia appeared to be inadequate because of the non-linear character of the temperature-resistance curve of the thermistor probe. The best calibration was obtained by using second order formula (ax2 + bx + c) that was fitted to measured temperature-resistance points. An exponential calibration was also tested, but the correlation of the fit was not as good than in the case of the polynome. The absolute variation of resistance of catheters at 37 degrees C was large. If the catheters are calibrated according to mean values, the error in temperature determination was about 1 degree C at normothermia. Erroneously measured temperatures in hypothermia give false cardiac output measurements, which can be dangerous in clinical practice.

Catheterization↗
PubMed1993

Identification and characterization of an anti-tyrosine kinase factor in cystic gliomas.

In view of the frequent activation of the epidermal growth factor receptor (EGF-R) in gliomas and autocrine hypothesis, we searched for 'EGF-like' factor(s) in cystic fluids (CFs) associated with gliomas. Membranes of A431 cells, which overexpress EGF-R, were used to explore such activity in 20 CFs. In all cases CFs induced inhibition of EGF-R phosphorylation. Biochemical analysis revealed an anti-tyrosine kinase activity which was identified as a 18 kDa proteic factor. Effectiveness at high dilution and anti-proliferative effect on living cells in culture suggest that this factor may be involved in the negative regulation of glial oncogenesis.

Astrocytoma↗
PubMed1993

Cortical differences in tonal versus vowel processing as revealed by an ERP component called mismatch negativity (MMN).

Event-related potentials were recorded from four aphasic subjects in order to study if discrimination of synthetic vowels is impaired by left posterior brain damage. A component called the mismatch negativity (MMN) which is assumed to reflect basic discriminatory processes of auditory stimuli was measured. In accordance with the hypothesis, two patients with posterior lesions failed to show any MMN response to synthetic vowels, whereas two patients with predominantly anterior lesions produced the response. The fact that all four patients produced an MMN response to sine wave stimuli indicates that the result does not reflect an across-the-board effect.

Acoustic Stimulation↗
PubMed1993

Immunohistochemical demonstration of androgen receptors in human salivary glands.

Androgen receptors were demonstrated in human salivary glands by immunohistochemistry using polyclonal antibodies. Fresh, clinically healthy salivary gland samples (two from minor, seven from parotid and eight from submandibular glands) of both sexes were used. Frozen tissue sections were incubated with the antibody against human androgen receptor and visualized by an indirect immunoperoxidase technique. Androgen receptors could be detected in all salivary tissues studied. Positive staining was confined to nuclei of almost all acinar cells as well as to the majority of nuclei in ductal cells. Very few of the nuclei of connective tissue and endothelial cells stained positively. The presence of androgen receptors in human salivary glands suggests possible direct effects of androgens on these tissues.

Adult↗
PubMed1993

Metabolism of progesterone and testosterone in human parotid and submandibular salivary glands in vitro.

Twenty-three parotid and twelve submandibular human salivary glands were used for analyzing in vitro metabolism of progesterone (P) and/or testosterone (T), in order to find out their possible contribution to the concentrations of salivary P or T. Glands were excised from 21 women and 14 men because of a stone, tumor or sialoadenitis, and the healthy tissue was used for incubation. The tissues were homogenized and incubated with 5 to 7 nmol/l of [14C]P or [14C]T for 2 h, extracted with methylacetate and subjected to two dimensional thin-layer chromatography. The thin-layer plates were autoradiographed, and the radioactivity of the different metabolites were counted to assess the amounts of metabolites formed. No lipoidal or conjugated steroids were formed. All of the radioactivity was associated with the free fraction of steroids. Both P and T were metabolized significantly more actively in male submandibular gland compared to male parotid gland (P < 0.05-0.01). No significant differences were found between female and male parotid glands, nor between the parotid glands of hormonally medicated (oral contraceptives or postmenopausal estrogen treatment) and non-medicated women. The submandibular glands more actively metabolized the steroids studied than the parotids (P < 0.01). The main metabolites were 20 alpha-hydroxy-4-pregnen-3-one for P, and androstenedione for T. In conclusion, the present results bring further evidence that the P or T levels in saliva may not be identical with the unbound steroid fraction in circulation, but a part of the steroids are metabolized in salivary glands. However, due to the rapid passage of steroids from blood to saliva, the metabolism demonstrated probably does not form an important source of error in salivary P and T measurements.

Adult↗
PubMed1992

Immunohistochemical detection of androgen receptors in human oral mucosa.

Oral mucosal biopsies from 11 healthy volunteers, 7 women and 4 men, were analysed for the localization of androgen, oestrogen and progesterone receptors. The samples were dissected as quickly as possible and immediately frozen in liquid nitrogen to be stored at -70 degrees C. Only androgen receptors could be detected by the methods used. These were mainly located in the nuclei of basal epithelial cells, and to some extent in the nuclei of fibroblasts and endothelial cells. Failure in the localization of oestrogen and progesterone receptors might have been due either to low numbers of receptors or to the insensitivity of antibodies used. The method is thus suitable only for detecting androgen receptors.

Adult↗