Biomedical subjects

T Rahko

Publications and source records attributed to T Rahko.

At least 19 recordsLinked to original sources

PubMed1995

Diet-induced residual formation in pigs.

Six piglets, aged 4 weeks (weaning) at the beginning of the experiment, were fed a diet lacking antioxidants (vitamin E and selenium) and enriched with oxidated cod liver oil (the peroxide value of which was 112.54 meqv/kg). Four of the experimental pigs were killed for necropsy at the age of 2 months and the remaining two pigs at the age of 3 months. Two piglets from the same litter served as controls. Myodegeneration of the skeletal muscles was induced in the experimental group. The livers were pale and mottled. Light microscopy revealed degenerative alterations in the heart and skeletal muscle and infiltrations by lipidic substances. The ultrastructure of some lipidic droplets was analogous to those of ceroid and lipofuscin. Peroxisomes were frequent in degenerating hepatocytes. In order to elucidate the lysosomal involvement in the residual formation, light and electron microscopical immunocytochemistry using copper-zinc superoxide dismutase (CuZnSOD), was applied. Probably zinc was recruited into the antioxidant protection concluding upon the increased erythrocyte superoxide dismutase (E-SOD) activity.

Aging↗

PubMed1995

Hearing and acute otitis media in 13-year-old children.

Air and bone conduction thresholds of 330 unselected urban 13-year-old children with a known history of otitis were measured under ideal conditions, using standard clinical audiometry. In the subgroups of children with different numbers (0, 1-2, 3-7, > or = 8) of attacks of acute otitis media (AOM) in their history, the mean air conduction thresholds varied from 0.2 to 11.5 dB at different frequencies in different AOM subgroups. Air conduction pure tone averages (PTA, mean threshold at 0.5, 1 and 2 kHz) > 20 dB were not found in any of the ears. The mean bone conduction thresholds varied from -0.0 to 1.8 dB, depending on the subgroup and frequency (0.25 to 4.0 kHz) studied. Bone conduction PTAs > 10 dB were measured in 5 (0.8%) ears. Single bone conduction thresholds > 10 dB were found at different frequencies in 3 to 15 (0.5 to 2.3%) of the ears, and thresholds > 20 dB in only 2 ears (0.3%). The mean thresholds and number of ears with decreased hearing were distributed equally between different AOM subgroups, except that some air conduction high frequency losses were more frequent in children with > or = 8 attacks of AOM. We conclude that childhood AOM, even if it occurs frequently, seems not to have a significant harmful long-term effect on hearing.

Acute Disease↗

PubMed1994

Diet-induced lipofuscin and ceroid formation in growing pigs.

Seven piglets, aged 2 weeks at the beginning of the experiment, were fed a diet lacking antioxidants (vitamin E and selenium) and enriched with thermally oxidated cod liver oil (the peroxide value of which was 310 meqv/kg). From one month before to 4 weeks after farrowing (weaning) the sow also received the experimental diet. One pig died at 9 days of age, due to degeneration of the parenchymal tissues. The oxidative stress produced was aggravated in four of the seven remaining pigs by giving them an injection of iron-dextran (300 mg) one day before the animals were killed for necropsy at the age of 2 months. The three other piglets were given an injection of a control saline solution. The nutritional myodegeneration produced ('white muscle disease') was characterized by a pale, yellowish colour and translucence of skeletal muscle, with degeneration, including swelling of the muscle fibres and slackening of the fibrillar pattern. The arrangement of nuclei in chains indicated repair. Ultrastructurally, skeletal muscle showed vacuolization of the sarcoplasmic reticulum, irregularities in the mitochondria and focal dissolution of myofibrils. The sarcoplasmic reticulum displayed condensation and lamellar formations. Hyaline degeneration of the heart muscle occurred both in iron-treated and control pigs, and in six animals a yellowish pigment resembling lipofuscin and ceroid was observed. Ultrastructurally, the ceroid deposits appeared as myelin-like figures. The livers were pale and brittle, four with centrilobular degeneration. By light microscopy, lipidosis was distinguished in four and ceroid accumulations in three pigs. Thiobarbituric-acid-reactive substances, creatine kinase activity and iron increased significantly in the serum as a result of the injection of iron-dextran.

Animal Feed↗

PubMed1991

TCDD decreases rapidly and persistently serum melatonin concentration without morphologically affecting the pineal gland in TCDD-resistant Han/Wistar rats.

The highly toxic environmental contaminant, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) was recently reported to decrease serum melatonin levels throughout the circadian cycle in the most TCDD-susceptible strain of rat, Long-Evans. To find out whether this effect is related to the mechanism of acute lethality of TCDD, serum melatonin levels were measured at the nocturnal peak phase in the most TCDD-resistant rat strain variant, Han/Wistar rats, 6 hr to 28 days after TCDD exposure. The same dose as used in the previous study, 50 micrograms/kg, decreased serum melatonin levels to approximately half the control values by the first day after the treatment. Melatonin concentrations remained at this reduced level over the whole observation period. In an auxiliary experiment, Han/Wistar rats were dosed with 1000 micrograms/kg TCDD and killed on day 3. Neither light nor electron microscopic examination of their pineal glands revealed any alteration attributable to TCDD treatment. These findings might indicate that the reduction of serum melatonin levels in the rat by TCDD is not related to its lethal effect and is not due to a direct damage of the pineal gland.

Animals↗

PubMed1990

Low- and high-frequency hearing in patients with Menière's disease.

We determined the pure-tone hearing thresholds of 25 patients with unilateral active Menière's disease using standard clinical audiometry, high-frequency audiometry (10-18 kHz), and low-frequency audiometry (20-80 Hz). In addition to hearing loss at the conventional frequencies, all of the affected ears showed deterioration of the thresholds at both low- and high-frequency areas as compared with the reference ears. The degree of hearing loss at these frequencies correlated to the degree of the hearing loss at the conventional frequencies, where it was greatest at 0.5-1 kHz. Our findings suggest that in Menière's disease the whole cochlear sensory area is affected, and that the damage caused by Menière's disease advances simultaneously in all parts of the cochlea.

Audiometry↗

PubMed1989

Pure-tone hearing thresholds in otologically healthy 5-year-old children in Finland.

We measured the pure-tone air and bone conduction hearing of 359 randomly selected otologically normal urban preschool children in Finland at the average age of 5.2 years. Children with otoscopically verified middle ear pathology or abnormal impedance audiometry were not included in this sample. The mean air conduction thresholds varied from 16.6 dB at 0.125 kHz to 6.6 dB at 2 kHz, and the mean bone conduction thresholds from 6.0 dB at 0.25 kHz to 0.7 dB at 4 kHz. The pure-tone average (of air conduction thresholds at 0.5, 1 and 2 kHz) of all the ears was 7.6 dB. The distribution of single air conduction hearing thresholds at the frequencies from 0.25 kHz to 4 kHz showed that 66%-75% were at the 5-10 dB level.

Auditory Threshold↗

PubMed1989

Evaluation of the hearing loss associated with cis-platinum treatment by high-frequency audiometry.

The effect of cis-platinum treatment on the hearing of 23 ovarian cancer patients was evaluated using standard and high-frequency audiometry. Twenty-two percent of the patients developed a hearing loss of at least 15 db, 13% in the range 125-8000 Hz and 9% only in the high-frequency area above 8 kHz. However, due to the high-frequency hearing loss (presbyacusis) in older patients high-frequency audiometry was often unobtainable. Hearing screening using standard pure-tone audiometry is recommended for cis-platinum patients as a routine procedure.

Adult↗

PubMed1989

Hearing and hearing loss in 5-year-old children. Pure-tone thresholds and the effect of acute otitis media.

Air and bone conduction pure-tone thresholds of 420 unselected urban children were measured with standard clinical audiometry. The mean of air conduction pure-tone averages (average threshold at 0.5, 1 and 2 kHz) was 8.6 dB HL in girls and 8.3 dB HL in boys. In only 5 ears (0.6%), was this average greater than or equal to 35 dB HL. The threshold greater than or equal to 35 dB HL at 4 kHz was found in 1.4% of the ears and at 8 kHz in 4.1%. The bone conduction threshold greater than 20 dB HL at any of the frequencies from 0.5 to 4 kHz was very rare, and only once, at 4 kHz, was it greater than 35 dB HL. Earlier attacks of acute otitis media seemed to have only a marginal long-term effect on air conduction hearing, and an almost negligible effect on bone conduction hearing.

Acute Disease↗

PubMed1989

Pancreatic enzyme supplementation in normal and exocrine pancreatic insufficient pigs.

The effect of pancreatic enzyme preparation (Combizyme Forte granulate) on the growth rate of normal, sham-operated and pancreatic duct ligated growing pigs was studied in 2 trials. In the first trial 6 normal Yorkshire pigs were fed a pancreatic enzyme supplement and 6 other pigs from the same litter were fed without supplementation. The growth rate over a period of 4 weeks was not significantly greater in the supplemented group. In a second trial exocrine pancreatic insufficiency, without diabetic symptoms, was produced in 12 pigs (aged 1.5 months and weighing 14 kgs) by ligation of the main pancreatic duct. The growth rates over a period of 20 days after surgery were 240 g, 454 g and 483 g/day in ligated pigs, in ligated pigs supplemented with pancreatic enzyme and in sham-operated control pigs, respectively. The difference between the ligated groups was significant (p less than 0.01) indicating the efficiency of the pancreatic enzyme therapy.

Amylases↗

PubMed1988

The prevalence of handicapping hearing loss in a middle-aged population in Finland.

Screening audiometry was performed during the years 1973-1978 in a total of 11,744 subjects aged 35-50 years. The incidence of those persons having a mean hearing threshold of 30 dB or more at 0.5-2 kHz or of 50 dB or more at 2 kHz varied from 0.3% to 2.7% in males of different age subgroups. The results for females were about two-thirds of those for males. Overall, 1.5% of the Finnish population aged 35-54 years were found to be candidates for hearing rehabilitation.

Adult↗

PubMed1988

High frequency audiometry in facial paralysis.

High frequency (10-21 kHz) hearing thresholds were measured in 54 patients with Bell's palsy. In 25 (46%) of the patients the high frequency hearing was worse in the affected side, and in 16 (30%) better. The differences in the mean threshold between the two ears varied from 17.1 to 3.8 dB, being statistically significant at half of the frequencies measured. The findings support the idea that facial palsy is one manifestation of a lesion which extends beyond the VIIth cranial nerve.

Audiometry↗

PubMed1988