Biomedical subjects

T Riise

Publications and source records attributed to T Riise.

87 records · Page 5Linked to original sources

PubMed1990

Analysis of neurologic symptoms in deep diving: implications for selection of divers.

Eighteen professional divers (age range 24-33 yr, mean 28.3) participated in one simulated dive to 360 meters of seawater (msw) in a helium-oxygen (heliox) atmosphere with equal compression and decompression profiles. All divers were given an extensive neurologic examination before diving. Clinical neurologic symptoms observed during the dives were equilibrium disorder, sleep disturbances, fatigue, nausea, loose stools, stomach pain, tremor, mental disturbances, reduced appetite, and headache. Symptoms were scored individually by each diver. The symptoms were analyzed statistically by factor analysis, which grouped them into four factors. These symptoms are presumably related to functional disturbances in the brain stem and the cerebellum. Factor 3 symptoms (tremor, mental disturbances, reduced appetite) correlated significantly to a history of predive decompression sickness (P = 0.006) and to cerebral concussion (P = 0.023). Three divers were periodically unable to work at bottom due to equilibrium disorder, diarrhea, or nausea. One diver with mild polyneuropathy and slight cerebral atrophy as seen by computerized tomography and another diver with abnormal electroencephalography were periodically unable to work due to equilibrium disorder and nausea, respectively. We advocate that divers with signs of central or peripheral nervous system dysfunction should not be selected for deep diving.

Adult↗

PubMed1989

Associated disorders in myasthenia gravis: autoimmune diseases and their relation to thymectomy.

The prevalence of myasthenia gravis (MG) in the counties of Hordaland and Sogn & Fjordane on January 1, 1984 was 9.6 per 100,000 inhabitants. Other autoimmune diseases were found in 11 out of 48 MG patients. The occurrence of autoimmune thyroiditis (5 patients, 10.4%) and systemic lupus erythematosus (4 patients, 8.3%) in the MG patients was clearly higher than that reported in the general population. Rheumatoid arthritis was found in 2 patients (4.2%). The autoimmune diseases were mainly recorded among the nonthymectomized MG patients. In addition to those with definite diseases of autoimmune nature, 3 other MG patients had thyroid antibodies and 1 had antinuclear factor without clinical evidence of autoimmune disease. Seven MG patients (14.6%) had unspecific arthralgia during active periods of MG. Two MG patients had ankylosing spondylitis.

Arthritis, Rheumatoid↗

PubMed1989

The non-linear relationship between nerve conduction velocity and skin temperature.

Median motor and sensory nerves were examined in 20 healthy subjects. Superficial stimulating and recording electrodes were used, and the nerves were examined at natural skin temperature, after cooling and after heating of the arm. The conduction velocity for the fastest and slow conducting sensory fibres (temperature range 17-37 degrees C), and for the fastest conducting motor fibres (temperature range 19-38 degrees C) increased non-linearly with increase in skin temperature. Similarly, distal motor latencies increased non-linearly with decrease in skin temperature. The effect of temperature was most pronounced in the low temperature range, and change in conduction velocity per degree centigrade was reduced toward higher skin temperature. Sensory nerve response duration increased linearly with decline in skin temperature. Sensory and motor amplitude did not show any significant relation to skin temperature.

Adult↗

PubMed1989

Nerve conduction velocity in man during deep diving to 360 msw.

The function of the sensory and motor median nerves was examined in 6 divers during a simulated dive to 360 meters of seawater (msw), with a mixture of helium and oxygen (heliox) as breathing gas. Divers were examined in the compression chamber before the dive, at 360, 300, 240, 130, 50, and 5 msw, and with skin temperatures ranging from 29.2 degrees to 35.2 degrees C. Examinations were performed with superficial stimulating and recording electrodes. Fast sensory nerve conduction decreased with increase in hyperbaric pressure and with decrease in skin temperature. There was no significant correlation between slow sensory conduction and hyperbaric pressure. Distal motor latency increased with increase in hyperbaric pressure and with decrease in skin temperature. The effect of pressure was independent of temperature. No significant functional changes were detected in the main nerve trunk proximal to the wrist or in the F-wave responses.

Adult↗

PubMed1988

Rhythmic variations of different hemopoietic cell lines and maturation stages in aging mice.

Non-proliferative and proliferative myeloid, and lymphoid and erythroid bone marrow cells were studied in aging female C3H mice. A chronobiological approach was used and mice aged 16, 21 and 26 months were examined vs. 3 month-old mice every 3 h during the 24-h period in three different experiments. Significant circadian fluctuations were observed in most of the cell populations, even in the oldest mice. The rhythmicity patterns might be different at different times of the year, and in young mice seasonal fluctuations in the 24-h mean values were observed. The absolute numbers of the 24-h means seemed to be highest at 21 months of age in all cell lines and maturation stages. Sinus function fitting indicated a decline of the amplitudes in aging mice. Minor age-related phase-differences were indicated in some populations. However, the fitting of original data to single sinus functions was variable and often obscured important features in the cell number variations. The present investigation illustrates the importance of performing time-sequence studies in hematology.

Aging↗

PubMed1988

Prognostic factors for life expectancy in multiple sclerosis analysed by Cox-models.

To determine if such factors as first symptom, sex, age at onset and initial clinical course have any influence on life expectancy of multiple sclerosis patients, a survival analysis from date of diagnosis for 598 MS-patients in Norway was performed. To study the effect of all the variables simultaneously we used the Cox proportional hazards regression model with incomplete data. Median survival time was 27 years after diagnosis. The variable which most strongly predicted the duration of the disease was age at onset. High age at onset and a progressive course of the disease were correlated with a more unfavourable prognosis. The onset symptom, vertigo, was also correlated with a shorter life expectancy. No significant effect of sex was found. We found in this material an indication of improved survival over the study period.

Actuarial Analysis↗

PubMed1988

Seamen exposed to organic solvents. A cross-sectional study with special reference to the nervous system.

A cross-sectional study of 85 long-term solvent exposed seamen working on chemical tankers compared to 59 unexposed seamen. Symptoms from the nervous system, clinical neurological findings and neurographic measurements were studied. The examinations were performed at least 2 weeks after the last solvent exposure. A stepwise multiple regression analysis was used to evaluate the dose-response relationship between the registered data on one hand and solvent exposure, employment on chemical tankers, age, alcohol and chloroquine phosphate consumption on the other. A significant correlation was found between increasing solvent exposure and reduced sensory nerve conduction velocities, as well as between increasing solvent exposure and prolonged distal latencies of motor nerves, and between increasing exposure and reduction of action potential amplitudes of sensory nerves. No correlation was found between solvent exposure and symptoms from the nervous system or clinical neurological findings.

Chloroquine↗

PubMed1988

Age-related differences and circadian and seasonal variations of myelopoietic progenitor cell (CFU-GM) numbers in mice.

The effect of aging on the myelopoietic progenitor cell (CFU-GM) numbers in mice was studied with special emphasis on biological rhythms in hemopoiesis. Female C3H mice, 16-, 21- and 26-month-old, were investigated versus 3-month-old controls every 3 hours during the 24-h period at three different times of the year. Strong circadian rhythms were observed in both CFU-GM concentration and content in the femur of all age-groups. The amplitudes and the 24-h mean values were declining in mice aged 21 and 26 months. From 16 months of age, a significant advance of circadian peak phases was observed. The overlapping was variable during the 24-h period. The present results may explain previous inconsistencies regarding myelopoietic progenitor cell numbers in aging mice. Some seasonal differences in rhythmicity patterns were also observed. Fitting of original data to single sinus functions was highly significant, although important details sometimes were obscured.

Aging↗

PubMed1988

Circadian and circannual variations of cell cycle distribution in the mouse bone marrow.

The cell cycle distribution of bone marrow cells from the femurs of female C3H mice has been investigated by flow cytometry according to the time of the day and month of the year. Both circadian and seasonal variations were found for the different cell cycle phases as well as the total cell numbers per femur. Both the mesor, the acrophase and the amplitude of the S, G2 and (G1 + G0) phases varied significantly in some months, while in other months only insignificant rhythms were found. The relative cell cycle distribution only partly reflected variations in the total numbers of proliferating cells, since the total cell number per femur was also variable. The total numbers of cells in DNA synthesis seem to be higher in the first part of the year, indicating increased cell proliferation during winter and spring. In this period the acrophases of DNA synthesis and G2 were in the morning, while the second half of the year showed the peak later in the day. In general, hemopoietic cell proliferation seems to constitute a labile equilibrium with rapidly changing activities.

Animals↗

PubMed1985

Multiple sclerosis--more than one disease?

We have previously found an increase in prevalence and incidence of multiple sclerosis (MS) in the county of Hordaland, Western Norway. This study shows that the increase in incidence over a 30-year period is due to an increase of remittent and remittent/progressive MS. The incidence of the chronic progressive form of MS has remained stable during the same period. The two subgroups of MS also vary in symptomatology and age at onset. This suggests that MS has two different forms which behave differently when considered epidemiologically and clinically. The remitting and progressive forms may therefore each have a different etiology.

Adult↗

PubMed1985

Clustering of multiple sclerosis in the county of Hordaland, Western Norway.

We studied the distribution of MS cases in the county of Hordaland, Western Norway. The total MS population comprised 426 patients. The prevalence on January 1st, 1963, and on January 1st, 1983, and the average annual incidence in the period 1963-1982 were all lower in the coastal area compared to the inland area. An increase in incidence started in the urban area and was followed some 10 years later in the rural area. The Knox method revealed no statistically significant evidence of clustering either for time/place of onset or for time/place of birth. Indications of clustering according to year of onset were, however, observed in the rural area.

Humans↗

PubMed1984

An increase in the incidence of multiple sclerosis in western Norway.

In the county of Hordaland, Western Norway, the prevalence of MS has been shown to have increased from 20/100,000 in 1963 to 60/100,000 in 1983. This study shows that the increase in prevalence was caused by a highly significant and marked increase in incidence over a 30-year period. The average annual incidence of about 2 per 100,000 population in 1953-1962 increased to 4 per 100,000 in the period 1968-1977. The rise in incidence was parallel for both sexes until 1970. In the last 10 years, the incidence has continued to increase among females, whereas a decrease has been observed among males.

Adult↗

PubMed1984

Western Norway, a high-risk area for multiple sclerosis: a prevalence/incidence study in the county of Hordaland.

Prevalence studies and investigations based on death certificates and disability assistance have shown that western Norway has been a medium-frequency area for MS. The prevalence of definite/probable MS on January 1, 1963 was 20.1/100,000. Based on the same diagnostic criteria, the prevalence of definite/probable MS had increased to 59.8/100,000 on January 1, 1983 in the county of Hordaland. We consider this increase of MS cases in the population to be due to real biologic changes, although factors affecting the figures were found. Most important was a reduction in the interval from onset to diagnosis. The rise in prevalence was also supported by an increase in the annual incidence of the disease. The incidence rate averaging 2 per 100,000 in the period 1953 to 1962 rose to 3.5 for 1968 to 1977. This marked rise in prevalence/incidence supports the concept that an exogenous factor is important in the pathogenesis of MS.

Adult↗

PubMedDate not supplied

Epidemiology of multiple sclerosis in the county of Vestfold, eastern Norway: incidence and prevalence calculations.

The county of Vestfold in the South-eastern part of Norway has undergone two incidence and prevalence surveys on multiple sclerosis. The prevalence of definite/probable MS on January 1, 1963 was 61.6/100,000. Based on the same diagnostic criteria, the present study reports a slight increase in prevalence to 86.4/100,000 on January 1st 1983. The average annual incidence was calculated for 5 years periods from 1953 to 1983. The time periods 1953-1962 and 1973-1977 showed age-adjusted incidence rates between 4.50 and 5.49/100,000 while the 10-year period 1963-1972 showed significantly lower rates. The fluctuating pattern of MS incidence and prevalence over time supports the view that MS is not a stable disease, and that exogenous factors are influencing the disease pattern.

Adolescent↗

PubMedDate not supplied

Chemical exposure of deck crew on product tankers loading the cargo with the hatches open.

Exposure of the deck crew to volatile hydrocarbon compounds and polycyclic aromatic hydrocarbon PAH compounds was observed and monitored on two Norwegian product tankers. The tankers were loading their cargo with the hatches open during the monitoring period. One of the tankers loaded gas oil. This type of cargo is not volatile, and very low concentrations of the monitored chemical PAH compounds were found on this tanker. The second tanker loaded gasoline. On this tanker high concentrations of hydrocarbon compounds were found; benzene was as high as 55 ppm, toluene was as high as 34 ppm, hydrocarbon compounds in the C5-C7 range were as high as 570 ppm, n-hexane was as high as 25 ppm. The levels of PAH-compounds were low. None of the seamen working on the deck did use respiratory protective equipment during the work. The exposure of the deck crew to volatile hydrocarbon compounds ought to be reduced on product tankers. Better routines concerning the use of respiratory protective equipment is an immediate action which ought to take place. Loading volatile cargo like gasoline with the hatches open should be avoided.

Environmental Monitoring↗