Search PubMed⌕ Search

Biomedical subjects

R Lappalainen

Publications and source records attributed to R Lappalainen.

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

Low levels of nerve growth factor in cerebrospinal fluid of children with Rett syndrome.

A role of neurotrophic factors has been postulated in some human neurodegenerative disorders such as Alzheimer's and Parkinson's disease. The known developmental effects of these substances suggested that, in some neurologic diseases affecting children, neurotrophic factors might be inadequate. Using a sensitive, two-site enzyme-linked immunoassay, we examined the content of nerve growth factor in the cerebrospinal fluid of 11 children with Rett syndrome and of 24 control patients with various neurologic diagnoses or suffering from other diseases. Nerve growth factor levels were significantly lower in the cerebrospinal fluid of the patients with Rett syndrome than in control patients. The lower level of cerebrospinal fluid nerve growth factor in Rett syndrome suggests that lack of nerve growth may be involved in the pathogenesis of this disease or reflect the underlying brain damage present.

Adolescent↗
PubMed1996

Why cardiac patients do not follow the nutritionist's advice: barriers in nutritional advice perceived in rehabilitation.

The aim of the present study was to identify reasons why cardiac patients do not follow nutritional advice which is given during rehabilitation. Barriers or expected problems in nutritional advice perceived during rehabilitation were obtained via a structured interview. Forty-eight cardiac patients (41-82 years; 15 females, 33 males) were interviewed during rehabilitation. The majority of patients (54%) reported one or more barriers. The most frequently reported barriers were associated with situations in which the patients were eating in company (52%), or in which there was too much food available (44%). Another common reason for non-compliance was that healthy foods did not taste good (42%). On the other hand, barriers were seldom associated with disinterest (4%) or lack of knowledge (4%). These results indicate that non-compliance in nutritional counselling may be associated with emotional responses related to eating and with lack of social skills to manage eating in social situations.

Adult↗
PubMed1995

Long-distance running alters bone anthropometry, elemental composition and mineral density of young dogs.

Ten young beagle dogs were run on a treadmill for 1 year, the last 15 weeks 40 km/day. Thereafter bone anthropometric variables, elemental composition, mineral density (BMD) and serum markers of bone metabolism were analyzed and compared with matched-paired control dogs. More osteophytes developed, weight-bearing bones grew larger and BMD of axial skeleton was reduced in the trained group. Zinc and sodium accumulated in bones of the runners. Zinc correlated negatively with BMD. Serum osteocalcin and C-terminal propeptide of type I procollagen did not correlate with the observed differences in BMD. This experiment implies that intensive endurance training in adolescence may reduce the peak bone mass and alter the structural properties of bone.

Animals↗
PubMed1994

Wetting the repair surface with methyl methacrylate affects the transverse strength of repaired heat-polymerized resin.

This study investigated the transverse strength of repaired test specimens of heat-cured acrylic resin. The repair surfaces of the specimens were wetted with methyl methacrylate for various amounts of time before the autopolymerizing acrylic resin was applied to the joint space. A three-point loading test was used to determine the transverse strength of the test specimens, and the morphologic changes in the methyl methacrylate-wetted repair surface was analyzed by scanning electron microscopy. Visual inspection was used to determine whether the failures were adhesive or cohesive. The results revealed that repaired test specimens were weaker than those unrepaired (p < 0.001). The strength of the test specimens increased as the duration of methyl methacrylate wetting of the repair surfaces increased (p < 0.001). Furthermore, the number of adhesive failures was small if the repair surfaces were adequately wetted with methyl methacrylate. Scanning electron micrographs revealed that after 60- and 180-second wetting periods, the poly(methyl methacrylate) was noted to be dissolved with a smooth surface texture. This study suggests that proper wetting of the repair surface makes an important contribution to the strength of repaired acrylic resin.

Acrylic Resins↗
PubMed1994

In vitro fatigue fracture of an acrylic resin-based partial denture: an exploratory study.

In this study the fatigue life of heat-cured acrylic resin test specimens shaped as maxillary partial dentures was examined. Ten test specimens were prepared from polymethyl methacrylate and were tested by a constant force fatigue test at 150 N immersed in +37 degrees C water. The fatigue-fracture surfaces of the test specimens were compared with a one-bend fracture surface of the control specimen by scanning electron microscopy. The correlation coefficient between the number of loading cycles required to cause fatigue failure in the midline section was calculated as was the concentration of residual methyl methacrylate. Results revealed that the fatigue life of the test specimens varied greatly (483 x 10(3) +/- 371 x 10(3) cycles) and that the correlation between the number of loading cycles and the midline section was poor (r -0.455). The correlation coefficient between the number of loading cycles and the concentration of residual methyl methacrylate was r 0.476 and p > 0.5. The fatigue-fracture surface of the test specimens was smoother in texture on the tension side than on the one-bend fracture surface.

Denture Design↗
PubMed1994

Acrylic resin-fiber composite--Part I: The effect of fiber concentration on fracture resistance.

This study tested the effect on the fracture resistance of acrylic resin test specimens when different amounts of fibers were incorporated in the resin matrix. The fibers used included glass, carbon, and aramid fibers, with 30 test specimens of each concentration of fibers. Transverse sections of the specimens were studied by scanning electron microscope to establish how the fibers behave in the polymerization process. The results indicated that an increase in the amount of fibers enhanced the fracture resistance of the test specimens (p < 0.001). The SEM micrographs of transverse sections of test polymerized specimens revealed void spaces of different sizes inside the fiber roving.

Analysis of Variance↗
PubMed1994

Inhibition of anticipatory salivation and craving in response to food stimuli.

Two experiments were done to study inhibition of cue-dependent salivation and craving responses. Experiment 1 suggests that total prevention of tasting during cue exposure inhibits salivation responses to chocolate cues. On the other hand, salivation was triggered by chocolate cues after tasting a very small amount of chocolate, indicating a very robust and rapid learning of conditioned salivation responses. However, prevention of tasting during cue exposure did not affect craving, suggesting that this method cannot decrease craving or that craving is affected at different rate than salivation. Experiment 2 tested the hypothesis that tasting irrelevant food during repeated exposure to chocolate cues would inhibit anticipatory salivation and craving responses to these cues. No support for this hypothesis was observed.

Adolescent↗
PubMed1994

Transverse strength and fatigue of denture acrylic-glass fiber composite.

OBJECTIVES: The aims of this experiment were: 1) to test the effect of a high concentration of continuous glass fibers on the transverse strength of test specimens made of heat-cured acrylic resin; and 2) to determine the fatigue weakening of both unreinforced and continuous glass fiber-reinforced specimens of heat-cured acrylic resin shaped into upper complete dentures. METHODS: A three-point loading test was used to determine the transverse strength of test specimens (n = 30 per group). The fatigue test was the constant deflection test (n = 10 per group). RESULTS: The results revealed that, compared to unreinforced specimens, continuous glass fibers at a concentration of 58 wt% enhanced the transverse strength of the test specimens up to 146% (p < 0.001) and increased the fatigue resistance (p < 0.001) during 5 x 10(5) loading cycles. SIGNIFICANCE: This study suggests that by incorporating glass fibers into PMMA denture bases, the strength of the denture can be increased.

Composite Resins↗
PubMed1994

Clodronate prevents immobilization osteopenia in rats.

We investigated the effect of clodronate on immobilization osteopenia (IO) induced by sciatic neurectomy in rats. 100 Wistar female rats were divided into 5 groups of 20 animals each: 1) sham-operated, control group, 2) IO+saline control group, 3) IO+clodronate 3 mg/kg/day, 4) IO+clodronate 10 mg/kg/day, and 5) IO+clodronate 30 mg/kg/day. Clodronate was administered subcutaneously beginning on the day after nerve sectioning. After 7 weeks, the animals were killed and both tibiae were removed. Bone mineral density, ash weight and calcium, phosphorus and magnesium contents of the ash of the tibiae were analyzed. The weight of the rats did not differ between the groups during the experiment. The ash weight of the tibiae decreased by 6.6 percent and the mineral density decreased by 5.1 percent after neurectomy. Clodronate reduced IO in a dose-dependent manner and the highest dose neutralized the effect of neurectomy. The calcium content of the ash decreased after neurectomy as compared to the sham-operated group, and clodronate increased it to the sham-operated level. The bone Ca/P ratio remained normal.

Animals↗
PubMed1993

Reliability and interobserver variability of ultrasonographic measurement of gastric emptying rate.

Scintigraphy and real-time ultrasound are valid techniques to measure parameters of gastric emptying. However, scintigraphy involves exposure to ionizing radiation, while the precision of real-time ultrasound has not been previously evaluated. The objectives of the present study were to determine the inter observer and day-to-day variability of liquid gastric emptying rate measured by real-time ultrasonography in healthy volunteers and to compare the gastric emptying rate of males and females. Twenty healthy volunteers had ultrasonographic measurement of gastric emptying rate after ingestion of 300 ml beef broth. Nine subjects had a concurrent assessment by a second observer. Nine subjects had two studies performed on different days by the same sonographer. The T1/2 for 20 subjects was 24.77 +/- 6.84 min with no difference between the half-emptying time for males (25.89 +/- 6.99 min) and females (24.02 +/- 6.94 min). The Pearson and intraclass correlation coefficients for observations made by two observers were 0.83 and 0.625, with a difference due to observer of 2.37 min +/- 5.26 (NS). The test-retest reliability across successive days was 0.136, representing considerable day-to-day variability within subjects. The variability between subjects was also large, explaining up to 79% of the total variance. We conclude that ultrasound is a useful method to evaluate gastric emptying with good interobserver agreement. Due to substantial day-to-day variability, sample sizes larger than previously suggested are required to demonstrate clinically important changes in gastric emptying rate in clinical trials.

Adult↗
PubMed1993

Evaluation of damage to removable dentures in two cities in Finland.

The number of damaged dentures and type of damage to removable dentures repaired in dental laboratories was investigated using a questionnaire sent to 24 dental laboratories in Finland. Eight variables were examined for each damaged denture. The results showed that the type of dentures most commonly needing repair was the complete upper denture (49%). The most frequent type of damage was breakdown of the acrylic base and loosening of an artificial tooth. The chi-square test established a statistical dependence (p < 0.005) between damaged dentures and their age. Damaged upper partial dentures most frequently had natural teeth or fixed prostheses as antagonist teeth. Damaged lower skeletal dentures and acrylic partial dentures had a complete denture as the antagonist (p < 0.05). Removable dentures made of acrylic resin material seemed to break despite strengtheners, such as clasp wire.

Chi-Square Distribution↗
PubMed1993

Drinking water with a meal: a simple method of coping with feelings of hunger, satiety and desire to eat.

This study examined whether drinking of water with breakfast affects the feelings of satiety and hunger, and how long after the meal this effect is maintained. Eight healthy, normal-weight women had three breakfasts with two extra glasses (4 dl) of water and three similar breakfasts without water. The breakfasts were served on three successive mornings during a 2 week period. The subjects filled in forms with visual analogue scales on feelings of hunger, satiety and desire to eat. The forms were filled just before the breakfast, in the middle of the breakfast before and after drinking of water, after finishing the meal, and thereafter every 30 min until 11.15 a.m. The results show that drinking two glasses of water affects subjective feelings of hunger and satiety during the meal, but this effect is not maintained after the meal. It is suggested that during a meal subjective feelings of hunger and satiety change independently of the food energy consumed. This study allows, however, no conclusions on the possible influence of drinking water on actual food intake during and after a meal.

Adult↗
PubMed1991

Early pregnancy assessment with transvaginal ultrasound scanning.

OBJECTIVE: To establish normal parameters in early pregnancy through transvaginal ultrasonography so that gestational age can be determined and to correlate the sonographic findings with serum human chorionic gonadotropin (hCG) levels calibrated against the first international reference preparation standard. SETTING: Infertility clinic. PATIENTS: Thirty-five women with normal intrauterine pregnancy. INTERVENTIONS: Serial measurement of the serum hCG level and the diameter of the gestational sac through transvaginal ultrasonography. MAIN RESULTS: The gestational sac could not be visualized when the hCG level was less than 1100 IU/L. The average growth rate of the sac was 0.9 mm/d. The threshold values for sac diameter, serum hCG level and gestational age below which the yolk sac was not visible were 3.7 mm, 1900 IU/L and 36 days respectively; the corresponding values above which the yolk sac was always visible were 6.7 mm, 5800 IU/L and 40 days. The threshold values below which cardiac activity was not visible were 8.3 mm, 9200 IU/L and 41 days respectively, and the corresponding values above which cardiac activity was always visible were 14.0 mm, 24,000 IU/L and 46 days. The mean gestational ages and the 95% confidence and prediction intervals were tabulated so that measurement of the gestational sac diameter could be used to estimate gestational age early in normal pregnancy. CONCLUSIONS: Transvaginal ultrasonography enables detection of an intrauterine sac and reliable estimation of gestational age on the basis of sac dimensions before an embryo can be seen.

Chorionic Gonadotropin↗
PubMed1991

In vitro abrasion resistance and hardness of glass-ionomer cements.

The aim of this study was to compare the abrasion resistance and surface hardness of four glass-ionomer cements. The effects of hydration and dehydration on wear resistance were also studied. A composite material, enamel, and dentin were used as controls. For wear testing, the specimens were abraded on abrasion discs under water. All glass ionomers showed greater wear than composite and enamel, but less wear than dentin. Ketac-Fil showed the highest and Ketac-Silver the lowest wear resistance. Hydration or dehydration of the specimens did not significantly influence the wear rate of conventional glass ionomers, but the wear resistance of Ketac-Silver was increased due to dehydration. Ketac-Fil had the highest and Ketac-Silver the lowest hardness rating of the glass ionomers. The cement material did not show abrasion resistance better than that of the conventional glass ionomers, as has previously been suggested.

Cermet Cements↗
PubMed1990

A behavioral economics analysis of food choice in humans.

Three studies on the behavioral economics of food choice were presented. In Experiment 1 subjects were provided a choice of working for food on concurrent VR4 VR20 schedules, and subjects allocated the majority of their responding to the VR4 schedule. Subjects in Experiment 2 were provided a choice between two foods differing in ratings of subjective liking. The lower rated food was available on an FR1 component of a concurrent schedule, while the higher rated food was available on the other component across six comparisons ranging from FR1 through VR32. Subjects initially chose to work for the higher rated food, but as the constraints for this food increased, subjects chose to work for the lower rated food. In Experiment 3, subjects were provided the choice of a breakfast they liked or the monetary equivalent during deprivation and non-deprivation conditions. The food and money were first compared on equal FR1 schedules. Schedule requirements for money were subsequently maintained on a VR2 schedule, while access to food was presented in four phases from VR4 through VR32. Under deprivation, subjects allocated their time to get the preferred food instead of money only at the FR1 FR1 comparison. Under non-deprivation subjects allocated almost all their responding to work for money. These results suggest that the laboratory choice task is sensitive to schedule differences when food is used as a reinforcer, that subjective liking and schedule constraints for food are both important in determining food choice, and that alternative reinforces can complete with food, but the effect is dependent on both the level of deprivation and constraints on access to food.

Adolescent↗
PubMed1990

Hunger/craving responses and reactivity to food stimuli during fasting and dieting.

One group of fasting obese patients and one group of dieting obese patients were instructed to report their feelings of hunger and craving on a continuous basis before and during a three-week treatment period. Once a week they were also exposed to food slides to measure their reactivity to food stimuli. The frequency of hunger/craving responses and reactivity to food stimuli showed radically different changes over time in the fasting and dieting groups. During the last week of fasting, reactivity to food slides was completely abolished, and the frequency of hunger/craving responses was close to zero. Only slight changes of frequency of hunger/craving responses and reactivity to food stimuli were observed in the dieting group. The results suggest that the frequency of hunger/craving responses and reactivity to food stimuli show parallel decreases during fasting, but no changes during dieting.

Appetite↗
PubMed1989

Wear of dental restorative and prosthetic materials in vitro.

The aim of this study was to evaluate the wear of some modern materials for fixed crown and bridge restorations and fillings in vitro. Eighteen commercial materials (8 composites, 4 alloys, 4 façade materials, and 2 denture-base resins) were tested. Enamel was used as the control. Test specimens were abraded on abrasion discs under water or in artificial saliva. There was a great variation in the wear rates of the tested materials. The greatest wear was shown by resins used for base material and the smallest by gold and Cr-Co alloys and porcelain. Most of the composites had a wear rate near that of enamel. The wear for amalgam was slightly greater than for most of the composites. When one is using several different materials for reconstructing occlusion, differences in wear resistance should be taken into account.

Dental Materials↗