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Biomedical subjects

T Korhonen

Publications and source records attributed to T Korhonen.

At least 55 records · Page 3Linked to original sources
PubMed1996

Multiple-unit responses to pitch changes in rabbits.

Multiple-unit activity (MUA) was recorded from the hippocampus (Hc), the visual cortex (VCx) and the cerebellar cortex (CerCx) in rabbits when pitch deviant tones were presented in a series of standard tones (oddball situation) and when standard tones were absent (deviant-alone situation). Significant MMN-like responses (deviant responses minus standard responses in the oddball situation) occurred in Hc, reflecting a MUA increase to the standards and its decrease to the deviants. In accordance with parallel ERPs reported earlier, the MMN-like responses reflected responses only to different presentation frequencies of stimuli. Non-selectivity in the pitch of such responses in VCx and a lack of an effect of the different stimulus repetition frequencies on responses in CerCx resulted in absent MMN-like responses in both of these locations.

Animals↗
PubMed1996

ERPs to pitch changes: a result of reduced responses to standard tones in rabbits.

Event-related potentials (ERPs) were recorded in rabbits when pitch deviant tones occurred in a series of standard tones (oddball situation). In control recordings, the deviant tones were presented without the standard tones (deviant-alone situation). In the oddball situation, significant difference ERPs (deviant ERPs-standard ERPs) could be found in the hippocampal and cerebellar recordings but not in the visual cortex. All the ERPs to the deviant stimuli observed in the oddball situation were also present in the deviant-alone situation. The difference ERPs were therefore based on reduced responses to the standards. The results are discussed in the context of a mismatch negativity (MMN) in humans.

Acoustic Stimulation↗
PubMed1996

Family life 1 year after infantile colic.

OBJECTIVE: To determine the persistence of family psychological characteristics associated with infantile colic. DESIGN: A 1-year follow-up survey of families with colicky infants was carried out. The family interview was used to evaluate the psychological factors of colicky and control families. PARTICIPANTS: A total of 59 families with a colicky infant and 58 control families were enrolled in the initial evaluation in the population-based study. On the basis of a structured diary of the infant's crying, filled in by the parents, 3 groups of families were formed: severe colic group (n = 36), moderate colic group (n = 23), and control group (n = 58). The families were interviewed when the infants were 2 and 12 months old. The Beavers-Timberlawn Family Evaluation Scale and the Oulu Family Assessment Scale were used. Thirty-two families (89%) from the severe colic group, 17 (74%) from the moderate colic group, and 49 (84%) from the control group participated in the 1-year assessment. RESULTS: At the 1-year assessment, the structural profile of the families did not differ between the groups. However, families in the severe colic group had more difficulties in communication, more unresolved conflicts, more dissatisfaction, and greater lack of empathy than families in the other groups. Furthermore, there was less flexibility in both colic groups than in the control group. During the follow-up period, coalition between parents in the moderate colic group became stronger compared with the first assessment, and the atmosphere improved significantly in all 3 study groups. However, the amount of empathy decreased in the severe colic group. CONCLUSIONS: Our study shows that certain family characteristics associated with severe infantile colic persist. Families in the moderate colic group coped nearly as well as families in the control group. The family mood had improved a lot in all families when the infant was 1 year old.

Adaptation, Psychological↗
PubMed1996

Could Helicobacter pylori infection increase the risk of coronary heart disease by modifying serum lipid concentrations?

OBJECTIVE: To investigate the relation between Helicobacter pylori infection and coronary heart disease (CHD). DESIGN: A case-control study. SETTING: Northern Finland (about 650,000 inhabitants). PATIENTS: 116 patients with angiographically documented CHD and 116 controls matched for age and gender randomly recruited from the register of the Finnish Social Insurance Institute. MAIN OUTCOME MEASURES: The odds ratio (OR) estimates for the association of H pylori infection with CHD. RESULTS: 64% of the CHD patients and 53% of the controls were seropositive for H pylori; the OR adjusted for age and gender was 1.5 (95% confidence interval (CI) 0.9 to 2.5). An additional adjustment for the common risk factors of CHD, including lipid concentrations, in a logistic regression analysis produced an OR estimate of 1.1 (95% CI 0.6 to 2.1). Among the controls, those who were H pylori positive had significantly (P = 0.03) higher concentrations of serum triglycerides than those who were H pylori negative: the trend among the cases was similar, but non-significant. The concentrations of HDL cholesterol tended to be lower in those who were H pylori positive than in those who were H pylori negative, among both the cases and the controls. CONCLUSIONS: The impact of H pylori infection as an independent risk factor for CHD seems to be minor. On the other hand the results are consistent with the hypothesis that H pylori infection might modify the serum lipid concentrations in a way that could increase the risk of CHD.

Adult↗
PubMed1995

Hippocampal evoked potentials to pitch deviances in an auditory oddball situation in the rabbit: no human mismatch-like dependence on standard stimuli.

Hippocampal auditory evoked potentials (AEP) were recorded in 10 rabbits when pitch deviant tones occurred in a series of standard tones (oddball situation). In control recordings, deviant tones were presented without intervening standard tones (deviant-alone situation). All AEP deflections observed in the oddball situation were found also in the deviant-alone situation. Thus, it appeared that none of the AEP deflections to deviant tones in the oddball situation was specific to a memory trace of preceding standard tones. This observation was in contradiction to such a specificity of the mismatch negativity (MMN) found in humans. Instead, a connection to a neuronal orienting reaction interpretation was shown to be apparent. A need for additional control procedures revealing a contribution of neural orienting responses in animal MMN experiments is discussed.

Acoustic Stimulation↗
PubMed1995

Effect of a synthetic prostaglandin E2 analogue, RS-86505-007, on plasma lipids and lipoproteins in patients with moderate hypercholesterolaemia: efficacy and tolerance of treatment and response in different apolipoprotein polymorphism groups.

A double-blind, placebo-controlled ascending dose trial was carried out to evaluate the hypocholesterolaemic efficacy and tolerance of RS-86505-007, a prostaglandin E2 analogue, in moderately hypercholesterolaemic patients. Twenty-four patients received an oral dose of RS-86505-007 3 micrograms t.i.d. and a separate group of 26 patients 6 micrograms t.i.d. for 6 weeks. Plasma total and low-density lipoprotein (LDL) cholesterol concentrations decreased after 2 weeks of treatment, and the reductions were dose dependent. After 6 weeks of treatment (6 micrograms t.i.d.), the reductions from baseline in total and LDL cholesterol concentration were 14.6% and 18.5%, respectively. No changes in the plasma concentration of triglycerides or high-density lipoprotein (HDL) cholesterol were observed. RS-86505-007 tended to reduce total and LDL cholesterol concentrations less in patients with the epsilon 4 allele of the apolipoprotein E than in those with epsilon 3 allele. In contrast, the XbaI or EcoRI polymorphisms of the apolipoprotein B gene seemed to have no effect on the hypocholesterolaemic efficacy of the drug. The drug had no effect on the lipoprotein (a) concentration. Sixty-three percent of patients receiving 3 micrograms t.i.d. and 81% receiving 6 micrograms t.i.d. had adverse events, two-thirds of which related to the gastrointestinal tract. One patient in the 3-micrograms group and three patients in the 6-micrograms group terminated the study prematurely due to adverse effects.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗
PubMed1995

Hippocampal event-related potentials to pitch deviances in an auditory oddball situation in the cat: experiment I.

Hippocampal event-related potentials (ERP) in the areas CA1, CA3, and dentate fascia (Df) were recorded in cats during an oddball situation when pitch deviant tones occurred in a series of standard tones. When difference waves were calculated by subtracting ERPs to the standard tones from those to the deviant tones, no clear N40d, corresponding to a cat analogue of the human mismatch negativity (MMN) observed in earlier studies, could be detected. Instead, a prominent later negativity (N130d) was observed. A possible extra-hippocampal source of the process reflected by the MMN-like negativity, and a relation between an orienting response (OR) and the N130d are discussed.

Acoustic Stimulation↗
PubMed1995

Behavioral and hippocampal evoked responses in an auditory oddball situation when an unconditioned stimulus is paired with deviant tones in the cat: experiment II.

Event-related potentials (ERP) in the areas CA1, CA3 and dentate fascia (Df) of the hippocampal formation were recorded during an oddball situation in the cat. A rewarding electrical stimulation of the lateral hypothalamus (US) was paired with deviant tones (2500 Hz) that occurred randomly in a series of the standard tones (2000 Hz) given to the left ear. In addition to developing orienting head movements to the side of the deviant tones, an increase in the amplitude of parallel hippocampal ERPs was observed. Both the behavioral and neural responses appeared not until a 50 ms latency range. Furthermore, time-amplitude characteristics of the ERPs corresponded to time-acceleration characteristics of the conditioned orienting head movements. The results are discussed in the context of a cat analogue of the human mismatch negativity (MMN) and a role of the hippocampal formation to model and predict the conditioned behavioral orienting responses.

Acoustic Stimulation↗
PubMed1994

Decreased clearance of low-density lipoprotein in patients with chronic renal failure.

The clearance of low-density lipoprotein (LDL) isolated from uremic patients (autologous-LDL) and from a control subject (control-LDL) was studied in 12 uremic patients on conservative management and compared to the LDL clearance in control subjects. The clearances of autologous-LDL and control-LDL were almost the same in the patients. However, the fractional catabolic rate (FCR) of the autologous-LDL (0.307 +/- 0.094 pools/day, mean +/- SD) and the control-LDL (0.289 +/- 0.081 pools/day) were significantly lower (P < 0.05 and P < 0.01, respectively) than the FCR for LDL in the control subjects (0.376 +/- 0.045 pools/day). Moreover, one-half of the patients had an abnormally low LDL clearance rate ranging from 0.146 to 0.282 pools/day. The FCR for the autologous-LDL varied from 0.146 to 0.416 pools/day between the patients and was negatively related (r = -0.68, P = 0.02) to the serum urea concentration (from 11.8 to 39.2 mmol/liter) and tended to correlate positively with the glomerular filtration values (from 9.2 to 48.3 ml/min/1.73 m2; r = 0.57, P = 0.096, non-linear relationship). In conclusion, the clearance of LDL in patients with advanced uremia on conservative management is frequently decreased. This alteration in the metabolism of the most atherogenic particle in plasma may contribute to the accelerated atherosclerosis in uremic patients.

Apolipoproteins B↗
PubMed1994

Temperament and sleeping patterns in colicky infants during the first year of life.

A prospective study of 59 colicky infants and 58 age-matched controls assessed infants' temperament at the ages of 3 and 12 months and their sleeping patterns at the ages of 8 and 12 months. At age 3 months, the mothers regarded the colicky infants as more intense in their reactions, less persistent, more distractible, and more negative in their mood. At age 12 months, mothers regarded 23% of the colicky infants to be more difficult than average compared to 5% of controls. The mothers regarded their colicky infants as more active and less persistent. However, the Toddler Temperament Scale showed no difference between the groups in any area of temperament. No significant difference was found between the two groups in sleeping patterns. The discrepancy between infants' actual temperament and mothers' general perception of temperament may reflect the influence of infantile colic on the mother-infant relationship.

Arousal↗
PubMed1993

Effects of lateralized US and CS presentations on conditioned head turning and bilateral cingulate cortex responses in cats.

A lateralized tone conditioned stimulus (CS+) paired with a rewarding medial forebrain bundle (MFB) stimulation unconditioned stimulus (US) was presented to one ear of the cat, while the same tone was presented to the other ear alone (CS-). Specifically, the electrical stimulation of the MFB elicited a contralateral head turn as the unconditioned response (UR). Correspondingly, the CS+ was given to an ear contralateral to the direction of the UR. During the CS test session the cats oriented toward the tones, but these head movements habituated rapidly. During conditioning the cats developed stereotypical extended vigorous head turns to the CS+, with significantly greater acceleration and shorter onset latencies to the CS+ than to the CS-. Head turns in response to the CS+ were always ipsilateral to the tone, but responses to the CS- were in some cats ipsilateral and in most cats contralateral to the tone. Recordings of the slow potential responses showed a broad negative deflection in the cingulate cortex, with peaks at 140 and 250 ms. The amplitude of this negative potential to the CS+ was larger than that to the CS-, but no asymmetries were found between the hemispheres. The present behavioral paradigm is potentially useful for studying the neural basis of conditioned approach responses.

Acoustic Stimulation↗
PubMed1993

Regulation and binding properties of S fimbriae cloned from E. coli strains causing urinary tract infection and meningitis.

S fimbriae are able to recognize receptor molecules containing sialic acid and are produced by pathogenic E. coli strains causing urinary tract infection and menigitis. In order to characterize the corresponding genetic determinant, termed S fimbrial adhesin (sfa) gene cluster, we have cloned the S-specific genes from a urinary pathogen and from a meningitis isolate. Nine genes are involved in the production of S fimbriae, two of these, sfaB and sfaC code for regulatory proteins being necessary for the expression of S fimbriae. Two promoters, PB and PC, are located in front of these genes. Transcription of the sfa determinant is influenced by activation of the promoters via SfaB and SfaC, the action of the H-NS protein and an RNaseE-specific mRNA processing. In addition, a third promoter, PA, located in front of the major subunit gene sfaA, can be activated under special circumstances. Four genes of the sfa determinant code for the subunit-specific proteins, SfaA (16 kda), SfaG (17 kda), SfaS (14 kda) and SfaH (29 kda). It was demonstrated that the protein SfaA is the major subunit protein while SfaS is identical to the sialic-acid-specific adhesin of S fimbriae. The introduction of specific mutations into sfaS revealed that a region of six amino acids of the adhesin which includes two lysine and one arginine residues is involved in the receptor specific interaction of S fimbriae. Additionally, it has been shown that SfaS is necessary for the induction of fimbriation while SfaH plays a role in the stringency of binding of S fimbriae to erythrocytes.

Adhesins, Escherichia coli↗
PubMed1993

Bilaterally recorded multiple-unit activity of the cingulate cortex during head turning conditioning with unilateral medial forebrain bundle stimulation.

Cats were conditioned to turn their heads using a tone conditioned stimulus (CS) and medial forebrain bundle stimulation (MFB) unconditioned stimulus (US). The CS+ was delivered to one ear at a time, in random order, followed by the US. A tone of a different frequency was used as a CS-. The cats learned to respond differentially to the CSs showing head movements of greater acceleration to the CS+ than CS- over sessions. Bilateral recordings of cingulate cortex multiple-unit activity showed increased response amplitudes over sessions and larger responses in the hemisphere ipsilateral to the US. Since ipsilateral multiple-unit responses did not differ for the CSs, the asymmetry was probably due to the sensitizing effect of the unilateral US. Although increases in cingulate cortex neural activity coincided with increases in conditioned head movements, larger activation of the cingulate cortex ipsilateral to the US suggests that the neural changes were independent of these movements.

Animals↗
PubMed1993

The patient-doctor relationship and metabolic control in patients with type 1 (insulin-dependent) diabetes mellitus.

OBJECTIVE: Our hypothesis was that patient-doctor relationship experienced positively by the patient is associated with adequate compliance behavior and thus to the long-term metabolic control of diabetes. METHOD: Cross-sectional study of 100 consecutive adult patients with Type 1 diabetes treated in a diabetes out-patient department. From a questionnaire, four scores (direct estimate of physician, satisfaction with the place of treatment, self-esteem score, security with the patient-doctor relationship) determining the patient-doctor relationship were formed. In score 3 (self-esteem score) the impact of the patient-doctor relationship to the patients' self-esteem was indirectly estimated. The anonymous data taken from diabetes register including information about treatment of diabetes, metabolic control and end-organ complications were returned together with the questionnaire. On the basis of GHbA1c diabetic patients were divided into two groups: with adequate metabolic control (GHbA1c < or = 8.0%) or with poor/moderate control (GHbA1c > 8.0%). RESULTS: In univariate analyses the score 3 associated with metabolic control (p < 0.001). In logistic regression analyses the nephropathy (t = 2.80, p < 0.05) and score 3 (t = 3.98, p < 0.001) were associated with metabolic control. CONCLUSION: Patient's positively-experienced patient-doctor relationship was associated with good metabolic control of diabetes.

Adult↗