PubMed Health⌕ Search

Biomedical subjects

H Alm

Publications and source records attributed to H Alm.

31 records · Page 2Linked to original sources
PubMed1996

Effect of cycloheximide on nuclear maturation of horse oocytes and its relation to initial cumulus morphology.

The period of protein synthesis necessary for meiotic maturation in horse oocytes initially having compact or expanded cumulus cells was studied. Oocytes incubated in the presence of cycloheximide after 0, 4, 8, 12 or 16 h maturation in vitro (total incubation time 24 h) were matured for 24 h, or were incubated with cycloheximide for 24 h and then matured for 24 h. Incubation with cycloheximide from 0 h was effective in suppressing maturation (no significant increase in maturing oocytes compared with controls fixed directly after removal from the follicle) in both expanded and compact groups and was completely reversible, as there was no difference in the proportion of oocytes reaching metaphase II between controls and treatment groups of either cumulus type. Addition of cycloheximide after 4 h maturation resulted in no significant difference in distribution of oocytes compared with addition at 0 h in either cumulus group. A significant decrease in the proportion of germinal vesicle stage oocytes, and an increase in oocytes in metaphase I occurred in oocytes with expanded cumulus cells in the 8 h treatment and in oocytes with compact cumulus cells in the 12 h treatment, compared with oocytes treated after 0 h. A significant increase in the proportion of oocytes at metaphase II occurred in the 12 h treatment for expanded cumulus-oocyte complexes and in the 16 h treatment for compact cumulus-oocyte complexes. These data show that nuclear maturation of horse oocytes can be reversibly suppressed by incubation with cycloheximide from the onset of culture. Oocytes with different initial cumulus type differed in the time required for protein synthesis essential for maturation: expanded cumulus-oocyte complexes required less time to prepare for germinal vesicle breakdown, maturation to metaphase I, and maturation to metaphase II, than did compact cumulus-oocyte complexes.

Animals↗
PubMed1995

The effects of a mobile telephone task on driver behaviour in a car following situation.

The effects of a mobile telephone task on young and elderly drivers' choice reaction time, headway, lateral position, and workload were studied when the subjects were driving in a car-following situation, in the VTI driving simulator. It was found that a mobile telephone task had a negative effect upon the drivers' choice reaction time, and that the effect was more pronounced for the elderly drivers. Furthermore, the subjects did not compensate for their increased reaction time by increasing their headway during the phone task. The subjects' mental workload, as measured by the NASA-TLX, increased as a function of the mobile telephone task. No effect on the subjects' lateral position could be detected. Taken together, these results indicate that the accident risk can increase when a driver is using the mobile telephone in a car following situation. The reasons for the increased risk, and possible ways to eliminate it, are also discussed.

Accidents, Traffic↗
PubMed1994

In vitro maturation of horse oocytes.

Ovaries collected from slaughtered mares of unknown reproductive history were transported to the laboratory, and their oocytes were recovered and cultured in modified TCM 199 supplemented with 20% horse serum and additional granulosa cells. To characterize the ovaries, the size and number of follicles were counted. To determine the time required for nuclear maturation, oocytes were fixed either after 18 h (n=23), 24 h (n=50), or 30 h (n=33) of culture. After co-culture with granulosa cells most oocytes reached metaphase II (M II) by 30 h (72.7%). After 24 h of maturation only 56.0% of the cultured oocytes had reached metaphase II (M II).

Journal Article↗
PubMed1994

Changes in driver behaviour as a function of handsfree mobile phones--a simulator study.

The effects of a mobile telephone task on drivers' reaction time, lane position, speed level, and workload were studied in two driving conditions (an easy or rather straight versus a hard or very curvy route). It was predicted that the mobile telephone task would have a negative effect on drivers' reaction time, lane position, and workload and lead to a reduction of speed. It was also predicted that the effects would be stronger for the hard driving task. The study was conducted in the VTI driving simulator. A total of 40 subjects, experienced drivers aged 23 to 61, were randomly assigned to four experimental conditions (telephone and easy or hard driving task versus control and easy or hard driving task). Contrary to the predictions, the strongest effects were found when the subjects were exposed to the easy driving task. In the condition where drivers had to perform the easy driving task, findings showed that a mobile telephone task had a negative effect on reaction time and led to a reduction of the speed level. In the condition where drivers had to perform the hard driving task, findings showed that a mobile telephone task had an effect only on the drivers' lateral position. Finally, the mobile telephone task led to an increased workload for both the easy and the hard driving task. The results are discussed in terms of which subtask, car driving or telephone task, the subjects gave the highest priority. Some implications for information systems in future cars are discussed.

Adult↗
PubMed1993

Prolactin heterogeneity: a limitation on the evaluation of results from prolactin assays due to differences in immunoassays and the different bioactivities of prolactin forms.

Prolactin exists in biological fluids in several molecular forms. This raises two questions: (1) whether the assay of prolactin by immunotechniques is valid and reliable and (2) whether the different forms have different physiological roles, which might be exploited to improve diagnostic accuracy and data interpretation by the use of appropriate methods. To investigate these questions, prolactin from human amniotic fluid was separated, by concanavalin A-Sepharose affinity chromatography, into bound, retarded and unbound fractions (bound prolactin fraction, retarded prolactin fraction, unbound prolactin fraction), which were characterized by electrophoresis, immunoblotting and glycan detection blot. Virtually no contamination was found in the bound prolactin fraction, and the unbound prolactin fraction and retarded prolactin fraction were 74-83% pure according to densitometry of the electrophoretic and immunoblot patterns. High variability was found among the individual patterns. Glycan detection in the blotted fractions revealed that the bound prolactin fraction bands corresponding to M(r)25,000-29,000 were weakly glycolysated, whereas the bands of M(r)60,000-64,000 were significantly glycan-positive. Immunoreactive bands of unbound prolactin fraction and retarded prolactin fraction also stained positively for glycans. Using two commercial prolactin kits, the bound prolactin fraction forms were virtually undetectable. To demonstrate that the prolactin forms may depend on the hypothalamic state, two behaviourly different breeds of cattle were used as an animal model for studying hypothalamic activities. The number of immunoreactive bands, representing the prolactin forms, and the change of the forms in response to thyroliberin differed strikingly among the groups. The bioactivity of the forms was examined in bovine granulosa, oviductal, endometrial and spleen cells, and in murine splenocytes, the latter being activated by concanavalin A or allogeneically to create in vitro conditions that may have relevance for situations in vivo. The rate of incorporation of [3H]thymidine in murine splenocytes was dose-dependently enhanced only by bound prolactin fraction. The increase was abolished by purified anti-prolactin antiserum. However, the standard prolactin from the kits inhibited the proliferation even in low dose (1.25 microgram/l) and the inhibition was abolished in part by bound prolactin fraction. Thymidine incorporation into the bovine cells was significantly increased by low concentrations (2 micrograms/l) of unbound prolactin fraction and retarded prolactin fraction. Oviduct epithelial cells and splenocytes were stimulated by unbound prolactin fraction but not by retarded prolactin fraction in a dose of 16 micrograms/l. Thymidine incorporation into granulosa cells was inhibited by retarded prolactin fraction (16 micrograms/l) but not by unbound prolactin fraction.(ABSTRACT TRUNCATED AT 400 WORDS)

Amniotic Fluid↗
PubMed1990

[Results of endocrinologic studies in culture media after coculture of bovine oocytes with granulosa cells].

The steroid hormones progesterone (P.), and testosterone (T.) were radio-immunologically determined in 108 medium samples, following co-culturing of bovine oocytes with granulosa cells. P. and T. values recorded from a control group were lower with significance than those recorded from co-culturing groups, that is 72 +/- 21 ng/ml and 264 +/- 84 pg/ml as compared to 208 +/- 138 ng/ml and 2,168 +/- 1,595 pg/ml in the oocyte plus fresh granulosa cell co-culturing group as well as 364 +/- 215 ng/ml and 825 +/- 233 pg/ml in the oocyte plus pre-incubated granulosa cell co-culturing group. These rises were accompanied by decline in maturation rate, increase in oocyte degeneration, and rises in the rates of fertilisation and segmentation.

Animals↗
PubMed1990

[The effect of granulosa cells on maturation, fertilization and cleavage in vitro].

Addition of granulosa cells (GC) (1.10(6)/ml) affected maturation of non-ovulatory oocytes of cattle and caused delay in nuclear maturation (60.8 versus 35.3 or 37.1 percent). In vitro use of pre-incubated GC in the process of maturation led to higher rates of fertilisation (49.4 versus 25.2 or 21.0 percent) and of cleavage (29.6 versus 13.3 or 9.1 percent). No explanation has yet been found for different oocyte behaviours in response to use of fresh or pre-incubated GC. Transfer of seven embryos from maturation with GC as well as in vitro fertilisation and development to four recipients resulted in the birth of one female calf.

Animals↗
PubMed1989

[The effect of postpartum blood collection on the health and liveweight development of calves and the use of neonatal calf serum (NCS) for the in vitro cultivation of mouse embryos].

The influence of postpartal blood taking on health and growing of calves and the use of neonatal calf serum (NCS) for cultivation of mice embryos was investigated in 3 experiments with 134 calves. The results indicate, that the neonatal blood taking (max. 2 h p.p.) is without negative effects on health and growing of calves. It is possible to use the NCS like fetal calf serum (FCS) as additive in cultivation mediums for mice embryos. The utilization of NCS for cultivation of bovine embryos and for other laboratory purposes should be tested.

Animals↗
PubMedDate not supplied

Influence of organochlorine pesticides on development of mouse embryos in vitro.

The effect of DDT, methoxychlor (MXC), and gamma-hexachlorocyclohexane (gamma HCH) on preimplantation mouse embryos in culture was evaluated by the proportion of eight-cell stage embryos developing to expanded and hatched blastocysts. A concentration of 29 micrograms/mL DDT or gamma HCH led to a complete degeneration of exposed embryos. The addition of 29 micrograms/mL MXC showed blastocyst formation (72.3%), but fewer than half of the blastocysts were intact and only 4.3% hatched from the zona pellucida. A concentration of 14.5 micrograms/mL DDT led to 57.5% blastocyst formation and to 6.8% hatched blastocysts; the same concentration of gamma HCH and MXC showed 66.7 and 95.9% blastocyst formation and 22.9 and 49% hatched blastocysts, respectively. The addition of 7.25 micrograms/mL led to 85.9% (DDT), 77.6% (gamma HCH), and 81% (MXC) blastocysts in total, and to 28.2, 35.5, and 49.4% hatched blastocysts, respectively. Compared with untreated controls, only the 3.625 micrograms/mL concentration for all pesticides showed no significant differences in blastocyst formation and hatching. These results show different toxicity of these three pesticides for the preimplantation mouse embryo in the order MXC < gamma HCH < or = DDT).

Animals↗
PubMedDate not supplied

Influence of organochlorine pesticides on maturation and postfertilization development of bovine oocytes in vitro.

The aim of this study was to perform a dose-response test to determine whether bovine oocytes exposed to dichlorodiphenyltrichloroethane (DDT), hexachlorocyclohexane (gammaHCH), or methoxychlor (MXC) in vitro would exhibit changes in maturation rates, cleavage rates at Day 2, or blastocyst rates at Day 7 to 8 after fertilization in vitro (IVF). All three pesticides affected maturation and degeneration rates in a dose-dependent manner, but to different extents. Higher concentrations of pesticides were associated with higher rates of chromatin degeneration. Because the maturation of bovine oocytes was depressed in a dose-dependent manner, the fertilizability and further embryonic development of in vitro matured oocytes was studied at the lowest previously tested concentration (7.25 microg/mL) only. No significant difference in fertilization rates was seen between unexposed control and treated groups. The cleavage rates did not differ among groups 48 h after IVF. The number of morulae and blastocysts on Day 7 to 8 after IVF, which is commonly used as a parameter for normal development, was significantly different between control and DDT- and gammaHCH-treated groups, but not between the control and MXC groups. The pesticides did not differ significantly among themselves. These results show that the tested pesticides decrease the rate of normal oocyte maturation in vitro in a dose-dependent manner. The effect of the lowest concentration of pesticides is seen only after Day 7 of embryo development.

Animals↗
PubMedDate not supplied

Influence of chlorocholinechloride-treated wheat on selected in vitro fertility parameters in male mice.

The aim of this study was to evaluate the influence of feeding with food and water containing chlorocholinechloride (CCC) on the fertility of male mice in a two-generation study. For this purpose the number of testicular spermatozoa and the relative proportion of primary and secondary spermatocytes involved in spermatogenesis were measured. Furthermore, the fertility of epididymal spermatozoa from tested male mice was investigated in a special in-vitro fertilization system. The experimental food was composed of CCC-treated wheat in the first experiment and CCC-free wheat and water mixed with pure CCC in the second experiment. The CCC residue content in the treated food and water was 0.21 mg/kg and 0.2 mg/L, respectively. Under the influence of feeding with CCC-treated wheat (Experiment 1) the fertilization and cleavage rates of oocytes incubated with spermatozoa from CCC-fed mice were reduced: the fertilization rate 65.1% vs. 21.1% and the cleavage rate 51.9% vs. 20.3%, p < 0.01 (control feeding vs. CCC feeding, respectively). Feeding of sperm donors with pure CCC mixed with untreated wheat pellets or water (Experiment 2) led to a reduction in the fertilization and cleavage rate (control: 60.8%, 32.4%; CCC-food: 29.8%, 12.1%; CCC-water: 30.1%, 10.2%; CCC-food/water: 36.6%, 12.5%; p < 0.01, respectively). The normal course of spermatogenesis was unchanged after the exposure to CCC. Testicular weight, the number of spermatozoa, and the proportion of haploid, diploid, and tetraploid testicular cells were not influenced. However, the functional competence of epididymal spermatozoa from CCC-fed donors was reduced, resulting in a significantly diminished fertilization and cleavage rate in vitro. The results suggest that CCC could interfere with epididymal protein secretion and the process of sperm maturation during passage through the epididymis.

Administration, Oral↗
PubMedDate not supplied

[Effect of prolactin in different culture systems on maturation of bovine oocytes and their ability for further development].

We studied the influence of bovine prolactin on the maturation of cumulus-enclosed bovine oocytes in different culture systems as well as on their capacity for subsequent development after in vitro fertilization. The prolactin effect on chromosome transformations in oocytes depended on the hormone concentration in the medium with fetal calf serum. Prolactin at 50 ng/ml proved to stimulate nuclear maturation of the oocytes. This concentration was used to compare various systems of oocytes cultivation. The prolactin effect on bovine oocytes maturation and their capacity for subsequent development depended on the composition of the cultivation medium. The introduction of prolactin into the medium with fetal calf serum, estradiol, and follicle-stimulating hormone had no effect on the reinitiation of meiosis in the oocytes but stimulated its completion, which increased the proportion of the oocytes at the telophase I and metaphase II stages as well as the proportion of the eggs cleft after fertilization. Prolactin affected neither the nuclear maturation nor the capacity for further development of the oocytes cultivated in the medium with serum of estrous cows. The addition of prolactin to the medium with calf serum where the oocytes and granulosa cells were cocultured increased the subsequent yield of the embryos developed to the morula and blastocyst stages. In this culture system, the hormone did not affect the rate of oocytes that reached the final stages of meiosis but inhibited their transition from telophase I to metaphase II. We propose that prolactin may favor the completion of cytoplasmic modifications going into the maturing oocyte.

Animals↗