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Biomedical subjects

E Koskela

Publications and source records attributed to E Koskela.

At least 19 recordsLinked to original sources
PubMed2001

Optimal allocation of reproductive effort: manipulation of offspring number and size in the bank vole.

The number of offspring attaining reproductive age is an important measure of an individual's fitness. However, reproductive success is generally constrained by a trade-off between offspring number and quality. We conducted a factorial experiment in order to study the effects of an artificial enlargement of offspring number and size on the reproductive success of female bank voles (Clethrionomys glareolus). We also studied the effects of the manipulations on growth, survival and reproductive success of the offspring. Potentially confounding effects of varying maternal quality were avoided by cross-fostering. Our results showed that the number of offspring alive in the next breeding season was higher in offspring number manipulation groups, despite their smaller body size at weaning. Offspring size manipulation had no effect on offspring growth or survival. Further, the first litter size of female offspring did not differ between treatments. In conclusion, females may be able to increase the number of offspring reaching reproductive age by producing larger litters, whereas increasing offspring size benefits neither the mother nor the offspring.

Animals↗
PubMed1999

Maternal effort and male quality in the bank vole, Clethrionomys glareolus.

Parental investment in reproduction is adjusted according to potential benefits in terms of offspring survival and/or mating success. If male quality affects the reproductive success of a female, then females mating with high-quality males should invest more in reproduction. Although the subject has been of general interest, further experimental verification of the hypothesis is needed. We studied whether female bank voles (Clethrionomys glareolus) adjusted their maternal effort according to male quality, measured as mating success. To enable the measurement of maternal effort during nursing separately from male genetic effects the litters were cross-fostered. Further, the genetic background of male quality was examined. Male quality did not correlate with litter size or offspring size at birth. Offspring growth was positively related to food consumption and milk production of mothers. However, these direct measurements of maternal effort were independent of male quality. Male mating success appeared to be significantly heritable indicating that there are genetic benefits. Still, females did not adjust maternal effort according to the genetic quality of their offspring. We suggest that female bank voles gain significant genetic benefits from mating with high-quality males whereas they cannot improve their reproductive success by increasing maternal effort.

Animals↗
PubMed1999

Sex and age-specific differences in ultraviolet reflectance of scent marks of bank voles (Clethrionomys glareolus).

Scent markings of voles are visible via their ultraviolet reflection. Kestrels, and possibly other diurnal raptors, may use this property when hunting. We performed a laboratory study on bank voles to determine whether UV-reflectance of scent marks differs in relation to sex, age and social status. When reflectance spectra of scent marks were measured with a spectro-radiometer, we found UV reflectance to be strongest in mature males. There were no differences between mature females and immature juveniles, nor between sexes in juveniles or mature and immature individuals in females. Moreover, we did not find any difference in UV reflectance between dominant and subordinate mature males. The results of this study support earlier findings that UV sensitive predators may use UV reflectance of scent marks as a prey cue. Consequently, studies on differing vulnerability of voles to avian predators should take into account not only their space use and behaviour but also the UV reflectance of their scent marks.

Aging↗
PubMed1995

Reproductive costs and litter size in the bank vole.

The potential reproductive costs for free-ranging bank vole (Clethrionomys glareolus) offspring and mothers were assessed by manipulating litter size and by determining the effects of nursing varied numbers of offspring. Litter enlargement did not increase the number of weanlings per mother. The mass of juveniles was significantly lower in the enlarged litters and higher in the reduced litters, compared to the control group. However, the survival of juveniles from weaning aged three months did not depend on their mass at weaning. Data from a previous study (Mappes et al. 1995) indicated that a higher mass at weaning may increase juveniles' abilities to maturate and breed during their summer of birth. Manipulation of litter size did not significantly affect the mass or survival of mothers or the success of subsequent breeding. The size of home ranges did correlate positively with the initial litter size. However, space use by females did not change with the degree of manipulation. Our results indicate that females nursing enlarged litters produce smaller offspring at weaning with no residual effects on future maternal survival or reproduction. Mothers did not seem to compensate the nursing costs with increased parental effort (which should be reflected in the condition of mothers or in the use of resources), for example, in an enlarged size of home range. Probably the possibility of obtaining a larger home range is constrained by the other breeding females, in a saturated breeding population. These results may support the optimal investment hypothesis that a female will produce a particular litter size which gives the best reproductive success in the particular environment where offspring are nursed.

Analysis of Variance↗
PubMed1992

Exclusion of coronary artery disease by exercise thallium-201 tomography in patients with aortic valve stenosis.

In many patients with valvular aortic stenosis (AS), management decisions may be possible without invasive studies if coexistent coronary artery disease (CAD) can be ruled out noninvasively. The use of thallium-201 single-photon emission computed tomography to the exclusion of CAD was studied in 44 patients aged 41 to 78 years with AS. In addition to cardiac catheterization and selective coronary angiography, patients underwent a cardiac ultrasound study and thallium-201 myocardial perfusion imaging at rest and after bicycle ergometer exercise. Two thirds of the patients had critical AS (valve area index less than or equal to 0.5 cm2/m2) but none had left ventricular systolic dysfunction. Twenty-one patients had angiographically significant CAD (greater than or equal to 50% diameter stenosis in greater than or equal to 1 coronary artery), whereas 23 had either a fully normal angiogram (n = 17) or mild (less than 50%) stenoses (n = 6). Each patient with significant CAD had an abnormal thallium-201 tomogram, either a strictly segmental perfusion defect (n = 19), or a patchy nonsegmental abnormality (n = 2); however, 10 of 23 patients free of significant CAD had similar results. Thus, the sensitivity and specificity of an abnormal scintigram were 100 and 57%, respectively. If only segmental perfusion defects typical of CAD had been considered abnormal, then the sensitivity of the test would have been 90% and the specificity 70%. Patients with false abnormal scintigrams had more severe AS and more angiographically nonsignificant CAD than those with true normal findings.(ABSTRACT TRUNCATED AT 250 WORDS)

Aortic Valve Stenosis↗
PubMed1989

Melanosis coli. Prevalence, distribution, and histologic features in 200 consecutive autopsies at Kuopio University Central Hospital.

The occurrence of large-bowel melanosis was evaluated by microscopy in 200 large bowels at autopsy. Melanin was seen as yellow-brown pigment in the macrophages of the lamina propria. The pigment stained with diastase-alcian blue PAS, Fontana, and iron stains. One hundred nineteen of 200 (59.5 percent) bowels showed melanosis, which was equally common in both sexes. Usually more than one segment was involved (most commonly, four segments). Melanosis was common in the proximal part of the colon, but much rarer in distal parts (sigmoid and rectum). Affected segments were successive; negative segments between positive ones were exceptional. If the rectum was affected, all five proximal segments were affected in 11 of 12 cases. The intensity of melanosis was directly related to the number of segments involved. In the oral part of the colon, affected males had a higher intensity of melanosis than affected women, but about the same intensity in the sigmoid and rectum. The fraction of patients with melanosis increased with age. Of men and women in the age group of 20 to 54 years, 32 and 44 percent were affected, and above the age of 75 years, 76 and 67 percent, respectively.

Adult↗
PubMed1985

Prevalence of polyps in an autopsy series from areas with varying incidence of large-bowel cancer.

The results of this multicentre autopsy study emphasize the relationship between the prevalence of adenomas and the incidence of large-bowel cancer. The highest proportion of autopsies with adenomas was observed in the area with the highest incidence of large-bowel cancer. The segmental distribution of adenomas within the colon was found to be similar to the site distribution of cancer. However, the lowest proportion of adenomas was found in the rectum, the segment in which cancer is most frequent. The latter finding suggests that either the adenoma-carcinoma sequence is a less important pathway in the pathogenesis of rectal cancer, or that more rectal than colonic adenomas become malignant. The high proportion of hyperplastic polyps in the rectum, and statistically significant regional differences following the same patterns as the incidence of rectal cancer suggest that there could be at least an indirect relationship between hyperplastic polyps and cancer of the rectum. Adenomas of both colon and rectum were more frequent in men than in women, contrary to findings with colon cancer. However, as for colon cancer, the sex ratio of adenomas changed with age, from slightly below unity in persons under 65, to above unity for those aged 65 and over. A major difficulty that emerged was the histological identification of "polyps" because of the degree of autolysis of epithelial cells in the mucous membrane, and this difficulty largely contributed to the poor consistency of histological reporting. Regular consistency surveys of histological preparations should be recommended in any type of multicentre study in which histological examination is included.

Adult↗
PubMed1982

Function of the intestinal substituted bladder.

Bladder function of 15 patients treated with total cystectomy, subtotal cystectomy or bladder resection, combined with sigmoidal, caecal or ileal cystoplasty, was evaluated with synchronous bladder pressure-flow-electromyography studies. Micturition was good or satisfactory in 14 patients. Eight patients had nocturnal incontinence. Bladder-sphincter dyssynergia of varying degree impaired the function of the intestinal substituted bladder in 9 patients. However, in selected cases intestinal cystoplasty is the best solution for retaining the normal way of voiding. After total cystoprostatectomy it is possible to replace the motor function of the bladder with sigmoidal cystoplastic substitution of the bladder. Patients with sigmoidal bladders also gradually developed sensations of fullness closely simulating those of their earlier bladders.

Adult↗
PubMed1982

External sphincterotomy in functional urinary bladder outlet obstruction.

Transurethral external sphincterotomy was performed in 36 male and 2 female patients with obstructive symptoms. The patients were studied with synchronous pressure-flow-electromyography investigations. They all had hypoactive bladders without organic obstruction, as determined by urethroscopy, micturition urethrocystography, urethral pressure profile and sphincterometry. 11 patients had urinary retention. Sphincterotomy was done at the 12 o'clock position. Voiding improved in 33 (91%) of the 36 male patients. During the follow-up time, 7 patients were reoperated with altogether 15 sphincterotomies, most often within 3 months after the first sphincterotomy. Transurethral resection of the prostate was done in 4 patients, with resultant incontinence in one case. In one female patient several sphincterotomies as well as bladder neck resections provided only temporary improvement necessitating clean intermittent self-catheterization. External sphincterotomy is a suitable and effective method for male patients with functional urinary disorders without organic obstruction.

Adolescent↗
PubMed1981

Verrucous squamous cell carcinoma of the female genital tract. Report of three cases and survey of the literature.

Three new cases of gynecological verrucous squamous cell carcinomas are reported; one in the uterine cervix, and two in the vulva. The English literature covering the 49 cases reported previously is surveyed with special reference to the diagnostic and therapeutic aspects of these tumors, as well as with their clinical behavior and possible relationship to viral (HPV) lesions (Condylomas) of the genital tract. It was concluded that so far the exact relationship between the different verrucous squamous cell lesions in the genital tract remains obscure, all such lesions should be regarded as potentially malignant, and treated accordingly by radical surgery.

Aged↗
PubMed1977

The simultaneous radioimmunoassay of seven steroids in human spermatic and peripheral venous blood.

Seven unconjugated neutral steroids, including testosterone and some of its precursors and metabolites, were measured in the peripheral and spermatic venous blood males, employing specific radioimmunoassays after the fractionation of steroids on Lipidex-5000 (hydroxyalkoxypropyl Sephadex) microcolumns. Respective mean concentrations (ng/ml) and ranges of steroids estimated in peripheral and spermatic venous blood in all groups of patients were as follows: pregnenolone, 0.71 (0.29-2.39) and 10.97 (0.83-30.1); progesterone, 0.31 (0.02-0.57) and 10.17 (1.51-33.24); 17 alpha-hydroxyprogesterone, 1.04 (0.48-2.20) and 37.33 (1.68-141.00); androstenedione, 1.01 (0.26-2.65) and 11.87 (0.97-30.18); testosterone, 3.84 (0.63-10.64) and 255.1 (2.85-619.1); 5alpha-dihydrotestosterone, 0.19 (0.07-0.28) and 3.74 (0.04-9.71); androsterone, 0.27 (0.12-0.47) and 0.97 (0.20-2.15). Concentrations are similar to those estimated by mass spectrometry and protein binding assays, except for androsterone which has not previously been measured in this context. The low, but significant testicular secretion of both 5alpha-hydrotestosterone and androsterone suggests that these two steroids are testicular androgen metabolites, and that androgen metabolism in this tissue may be monitored by way of their measurement in spermatic vein blood.

Adult↗