Biomedical subjects

M Ollikainen

Publications and source records attributed to M Ollikainen.

10 recordsLinked to original sources

PubMed2004

BRAF screening as a low-cost effective strategy for simplifying HNPCC genetic testing.

BACKGROUND: According to the international criteria for hereditary non-polyposis colorectal cancer (HNPCC) diagnostics, cancer patients with a family history or early onset of colorectal tumours showing high microsatellite instability (MSI-H) should receive genetic counselling and be offered testing for germline mutations in DNA repair genes, mainly MLH1 and MSH2. Recently, an oncogenic V600E hotspot mutation within BRAF, a kinase encoding gene from the RAS/RAF/MAPK pathway, has been found to be associated with sporadic MSI-H colon cancer, but its association with HNPCC remains to be further clarified. METHODS: BRAF-V600E mutations were analysed by automatic sequencing in colorectal cancers from 206 sporadic cases with MSI-H and 111 HNPCC cases with known germline mutations in MLH1 and MSH2. In addition, 45 HNPCC cases showing abnormal immunostaining for MSH2 were also analysed. RESULTS: The BRAF-V600E hotspot mutation was found in 40% (82/206) of the sporadic MSI-H tumours analysed but in none of the 111 tested HNPCC tumours or in the 45 cases showing abnormal MSH2 immunostaining. CONCLUSIONS: Detection of the V600E mutation in a colorectal MSI-H tumour argues against the presence of a germline mutation in either the MLH1 or MSH2 gene. Therefore, screening of these mismatch repair (MMR) genes can be avoided in cases positive for V600E if no other significant evidence, such as fulfilment of the strict Amsterdam criteria, suggests MMR associated HNPCC. In this context, mutation analysis of the BRAF hotspot is a reliable, fast, and low cost strategy which simplifies genetic testing for HNPCC.

Colorectal Neoplasms, Hereditary Nonpolyposis↗

PubMed2001

Ethanol modulates cortical activity: direct evidence with combined TMS and EEG.

The motor cortex of 10 healthy subjects was stimulated by transcranial magnetic stimulation (TMS) before and after ethanol challenge (0.8 g/kg resulting in blood concentration of 0.77 +/- 0.14 ml/liter). The electrical brain activity resulting from the brief electromagnetic pulse was recorded with high-resolution electroencephalography (EEG) and located using inversion algorithms. Focal magnetic pulses to the left motor cortex were delivered with a figure-of-eight coil at the random interstimulus interval of 1.5-2.5 s. The stimulation intensity was adjusted to the motor threshold of abductor digiti minimi. Two conditions before and after ethanol ingestion (30 min) were applied: (1) real TMS, with the coil pressed against the scalp; and (2) control condition, with the coil separated from the scalp by a 2-cm-thick piece of plastic. A separate EMG control recording of one subject during TMS was made with two bipolar platinum needle electrodes inserted to the left temporal muscle. In each condition, 120 pulses were delivered. The EEG was recorded from 60 scalp electrodes. A peak in the EEG signals was observed at 43 ms after the TMS pulse in the real-TMS condition but not in the control condition or in the control scalp EMG. Potential maps before and after ethanol ingestion were significantly different from each other (P = 0.01), but no differences were found in the control condition. Ethanol changed the TMS-evoked potentials over right frontal and left parietal areas, the underlying effect appearing to be largest in the right prefrontal area. Our findings suggest that ethanol may have changed the functional connectivity between prefrontal and motor cortices. This new noninvasive method provides direct evidence about the modulation of cortical connectivity after ethanol challenge.

Adult↗

PubMed2001

EEG responses to combined somatosensory and transcranial magnetic stimulation.

OBJECTIVES: To investigate a possible interaction between sensory processing and transcranial magnetic stimulation (TMS), an experimental set-up permitting multichannel EEG measurements was used. METHODS: A somatosensory stimulus was delivered to the right wrist, while single-pulse TMS was applied to the contralateral somatosensory cortex, either concurrent with the somatosensory stimulus or 10 ms after it. A control condition served to mimic the sound of TMS without actually resulting in brain stimulation. RESULTS: An enhancement of the P25 component of the somatosensory-evoked potential (SEP) was consistently observed for TMS concurrent with somatosensory stimulus. The effect was topographically specific to the EEG recording sites below the TMS coil, i.e. above the somatosensory cortex contralateral to the stimulated peripheral nerve. CONCLUSIONS: The results can be interpreted (1) as an indication of local interaction between the somatosensory-evoked cortical activity and TMS-evoked activity or (2) as support of a relationship between the background EEG and the evoked potential (EP), this relationship being 'disrupted' by TMS.

Adult↗

PubMed2001

Towards efficient pollution control in the Baltic Sea: an anatomy of current failure with suggestions for change.

We study the Baltic Sea countries' declaration to reduce nutrient loads by 50% in each country in an ecological-economic model. The model consists of country-based abatement-cost functions, and transfer coefficients describing how phosphorus and nitrogen flow from one country to another, as estimated in a hydrological model of the Baltic Sea. We show that for nitrogen in particular the overall abatement costs of the current policy are much higher and that the benefits are more uneven than under a cost-efficient policy. Consequently, one can expect that countries with high marginal abatement costs have the least incentives to follow the agreement and to invest in nitrogen abatement. This is also confirmed by our data. Therefore, we suggest and outline a joint implementation policy to promote cost efficiency and to increase incentives for investments.

Baltic States↗

PubMed2000

Coil design for real and sham transcranial magnetic stimulation.

Transcranial magnetic stimulation (TMS) can be used to excite the human cortex noninvasively. TMS also activates scalp muscles and sensory receptors; additionally, the loud sound from the stimulating coil activates auditory pathways. These side effects complicate the interpretation of the results of TMS studies. For control experiments, we have designed a coil that can produce both real and sham stimulation without moving the coil. The sham TMS is similar to the real TMS, except for the different relative direction of the currents in the two loops of the figure-of-eight coil. While the real TMS elicited activation of hand muscles, sham TMS had no such effect; however, the auditory-evoked potentials were similar.

Electroencephalography↗

PubMed1999

Separation of contamination caused by coil clicks from responses elicited by transcranial magnetic stimulation.

Transcranial magnetic stimulation (TMS) is accompanied with loud clicks that evoke auditory responses in the brain, confounding several types of TMS studies. We investigated the effects of these clicks with high-resolution EEG by applying TMS pulses at 3 magnitudes, with the coil placed either at 10 or 50 mm over the subjects' vertex and recording event-related potentials (ERPs). The clicks were found to elicit a positively displaced response at 150-250 ms post-TMS. Furthermore, clicks were found to interact with simultaneously presented auditory sinewave stimuli, resulting in an amplitude decrease in the auditory N1 response.

Adult↗

PubMed1997

Amniotic fluid U. urealyticum colonization: significance for maternal peripartal infections at term.

The aim of this study was to examine the relationship between maternal peripartal infectious morbidity and amniotic fluid colonization by U. urealyticum. Amniotic fluid specimens for bacterial and mycoplasmal cultures were obtained by aspiration at nonelective cesarean section from 98 pregnant women. Amniotic fluid cultures revealed micro-organisms in 70 (71%) parturients and U. urealyticum was the most frequently isolated species, detected in the specimens from 38 (39%) women. In the total study population, the prevalence of clinically defined infectious morbidity was 26%, including 8 (8%) patients with chorioamnionitis, 11 (11%) with endometritis, 5 (5%) with urinary tract infection, and 4 (4%) with wound infection. A significant association between the amniotic fluid U. urealyticum colonization and increased maternal peripartal infectious morbidity was observed (p < 0.0027; relative risk 4.1; 95% confidence limits 1.6 to 10.7). Amniotic fluids positive for U. urealyticum were significantly more often positive for other potentially pathogenic bacteria (p < 0.0024) and particularly for Bacteroides spp. (p < 0.0074). Our results support the existence of an association between amniotic fluid U. urealyticum invasion and maternal infectious morbidity. However, U. urealyticum was not usually isolated alone from amniotic fluids but combined with other pathogenic bacteria, the severity of infections were not enhanced when U. urealyticum was present and parturients with diagnosed infections managed well without specific antibiotic against U. urealyticum. Hence, it appears that the significance of U. urealyticum in maternal infections in this study population was mainly based on its interactions with other bacteria.

Adult↗

PubMed1997

C-reactive protein in uncomplicated parturients delivered by cesarean section.

BACKGROUND: The purpose of this study was to determine normal values and evaluate clinical variables associated with postoperative C-reactive protein serum concentration after uncomplicated abdominal delivery. METHODS: C-reactive protein serum concentrations were determined serially by a quantitative immunoturbidimetric assay in 479 clinically non-infected parturients undergoing uncomplicated Cesarean section, before operation and during the first week of puerperium. Associations between clinical variables and maximal postoperative C-reactive protein levels were examined by variance analysis. RESULTS: The preoperative values were significantly higher in parturients from whom samples were obtained after the onset of labor and/or rupture of the membranes (16 +/- 10 (s.d.) mg/l) compared with the preoperative values obtained from parturients operated with no labor and intact membranes (12 +/- 7 (s.d.) mg/l) (p < 0.0001). An overall significant increase was observed in C-reactive protein concentrations after delivery, peaking on the second postoperative day, compared with the preoperative values. In the parturients operated upon after the onset of labor or ruptured membranes, postoperative values were 24% higher up to the sixth postoperative day than in parturients operated upon with intact membranes and no labor. The onset of labor, duration of operation, the number of vaginal examinations and the duration of internal monitoring before operation were associated with the maximal postoperative C-reactive protein concentrations, but they explained only 9% of postoperative CRP level variation. CONCLUSIONS: The wide range of serum C-reactive protein concentrations during puerperium complicates its use as a simple marker in obstetric postoperative complications. However, after normal uncomplicated operative delivery, C-reactive protein concentrations rapidly decrease towards the baseline after the second to third postoperative day.

Adult↗

PubMed1997

Amniotic fluid leukocytes and leukocyte esterase activity in parturients delivered by caesarean section.

Amniotic fluid specimens from parturients undergoing caesarean delivery were examined for leukocytes and leukocyte esterase activity, as well as for amniotic fluid bacteria and mycoplasmas by cultivation. The aim of this study was to evaluate the intrauterine environment in noninfected parturients and the associations between leukocyte test results, amniotic fluid microbial colonization and postcaesarean endometritis. Samples were obtained by direct aspiration at operation from 289 parturients with no clinical intrauterine infection. Among the total study population, leukocytes were found in 41% of the amniotic fluid samples by Gram staining and in 39% of the samples by the leukocyte esterase activity test. Leukocytes and leukocyte esterase activity were observed significantly more often in the amniotic fluids of parturients undergoing operation after onset of labour or ruptured membranes compared with those operated upon with intact membranes and no labour (p < 0.0001 and p < 0.0001). Of 255 amniotic fluid cultures, microbial colonization was observed in 82 (32%) parturients. Positive results in the leukocyte tests were associated significantly with amniotic fluid microbial colonization among parturients who underwent operation with intact membranes, or who underwent operation after rupture of the membranes and had cervical dilatation of < 5 cm at the operation (Gram stain: p < 0.0001; leukocyte esterase: p < 0.003). If cervical dilatation was > or = 5 cm, no such association was observed. In the population studied, endometritis developed in 2% and 4% of the parturients with positive test results. Thus, neither the presence of leukocytes nor detected leukocyte esterase activity were predictive of subsequent postoperative endometritis. In the detection of amniotic fluid microbial colonization, the tests functioned best in non-laboring parturients with intact membranes and in those operated on at the early stage of labour.

Adult↗

PubMed1997

Cesarean delivery. Microbial colonization in amniotic fluid.

OBJECTIVE: To determine the frequency, clinical significance and causative factors behind intraamniotic microbial colonization in uninfected parturients at the time of cesarean delivery. STUDY DESIGN: Amniotic fluid specimens for bacterial and mycoplasmal cultures were obtained by direct aspiration at cesarean section from 251 pregnant women (24-43 completed weeks) who had no clinical infection at the time of the operation. The symptoms of maternal infection were followed postoperatively for the first week of the puerperium. RESULTS: The prevalence of amniotic fluid microbial invasion was 29% (72/251). In patients not in labor and with intact membranes, it was 13% (20/158); in patients in labor and with intact membranes, 23% (5/22); and in those with ruptured membranes, 66% (47/71). The most common species isolated were Ureaplasma urealyticum, Lactobacillus species and coagulase-negative staphylococci. In the total 251 patients, clinically evident postoperative endometritis was observed in 6 (2%) and wound infection in 10 (4%). In patients operated on and with intact membranes, no risk factors were found as regards amniotic fluid microbial colonization. In patients operated on after rupture of the membranes, the only significant risk factor as regards amniotic fluid microbial invasion was use of an internal monitor before the operation (P < .0003) (relative risk 10.7, 95% confidence limit 2.9-39.4). The relative risk of postoperative endometritis was 2.3 (95% confidence limit 1.3-4.3) in patients with microbial invasion of the amniotic cavity as compared to patients without invasion. The corresponding risk value for post-operative wound infection was 1.4 (95% confidence limit 0.6-3.1). CONCLUSION: Though the incidence of microbial invasion of the amniotic fluid before surgery was unexpectedly high, its clinical significance as regards maternal puerperal morbidity appeared to be low. The use of internal monitoring during labor was the only significant risk factor as regards amniotic fluid microbial colonization in patients operated on after membrane rupture.

Amniotic Fluid↗