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Biomedical subjects

B Fischer

Publications and source records attributed to B Fischer.

At least 289 records · Page 16Linked to original sources
PubMed1989

[Testing with the computer--the Diamed System].

The Diamed System has been developed to reduce the time-consuming testing routines involved in psychopathometric studies of disease course in the field of medicine. Test administration was to be relieved of those activities, in particular in repeat testing, examiners experienced as weary, unpleasant, repetitive, and uncreative. An important aim had been to permit data collection by as independent a dialogue as possible between the patient and the micro-computer, and extremely simple operations and instructions were considered of great importance. The opportunity has, however, also been utilized to implement promising performance testing procedures for measuring basic parameters of mental capability. Beside mental-amnestic capacity, the procedures cover subjective complaints because these, too, frequently are relevant in measuring the course of psychic disorders. The procedures incorporated in the Diamed System permit reliability verifications as to whether self-assessment and independent computerized testing might not be asking too much of the patients intellectually. Most of the procedures will be used for studying disease course in acute Organic Psychosyndromes and in all disorders that are associated with changes in mood and/or with subjective complaints. Diagnostic assistance moreover is offered for determining the presence of acute Organic Psychosyndromes. Under the name of "brain jogging", an economical programme is introduced for mental training, aimed at maintaining and improving basic central information processing capacities. Its effect on intelligence and memory has been demonstrated on in-patient populations, both with and without brain-organic disorders. Notably in the case of acute Organic Psychosyndromes, it has turned out to be an effective supplement to drug treatment.

Arousal↗
PubMed1988

Development of preimplantation rabbit embryos after in-vitro culture and embryo transfer: an electron microscopic study.

Compared to in vivo development, in vitro culture of mammalian embryos results in developmental retardation. To study the potential of reversibility of growth retardation we investigated ultrastructurally day 3 rabbit embryos after 1 day in vitro, and cultured embryos that were transferred after culture into recipient rabbits for 1 day. Morphology was compared with ultrastructure of noncultured controls. The noncultured embryos were compacted morulae; the characteristic ultrastructure is described in detail. After 1 day in culture, morulae had developed into early blastocysts. However, unlike the results in vivo, expansion of the blastocysts did not occur and some of the cultured embryos developed trophoblast herniations. In all cultured embryos morphological signs of degeneration were seen with swollen mitochondria, with a dense, granular appearance of the cytoplasm, and with an increase in number of lysosomes. Transfer of cultured blastocysts into uteri of day 3 pseudopregnant recipients resulted in ultrastructurally intact and expanded blastocysts. Transfer into uteri of day 4 pseudopregnant recipients and into uteri of nonpregnant recipients, however, did not yield reversibility of the unphysiological features suffered during the previous time in culture. Although blastocysts were well expanded, distinct signs of injury to the blastomeres were present, proceeding from loss of complete blastomeres to structural changes such as large lamellar structures, dilation of smooth endoplasmic reticulum and Golgi complexes, and clumping of mitochondria. We conclude that developmental retardation during in vitro culture is accompanied by distinct morphological changes. As soon as 24 hr after transfer, these changes can be reversed. This compensation, however, is achieved only if embryos are transferred into recipients that are adapted to the embryo's developmental stage, which is not identical to the embryo's chronological age. Our findings demonstrate that the period of 24 hr of in vitro development matches only a few hours of in vivo development.

Animals↗
PubMed1988

Ultrastructure of preimplantation rabbit embryos exposed to visible light and room temperature.

Early cleavage stage embryos (day 1 p.c.) and morulae (day 3 p.c.) of rabbits were exposed to visible (standard) lighting (1600 lx) and room (standard) temperature (23 degrees C) during a 24 h in-vitro culture. Control embryos were cultured in darkness at 37 degrees C. Development was assessed by light and electron microscopy as well as by the cytochemical demonstration of glycogen. In day 1 and day 3 embryos standard temperature induced swelling of the SER and Golgi complex vesicles. Major changes in day 1 embryos consisted of smallish microtubules - like crystalloids, and in day 3 embryos of unusually large SER vesicles. In both embryonic ages cleavage rate and development was more retarded by standard temperature than by standard lighting. Standard lighting, however, led to distinct signs of degeneration and cell death. The mode of cell damage seemed to be different in light exposed early cleavage stages and morulae: In day 1 embryos cytoplasmic degeneration was predominant while the majority of cells in day 3 embryos died by apoptosis. Despite clear indications of cell damage, cleavage rate was not notably impaired compared with non-exposed controls. Glycogen increased during development from cleavage stages to early blastocysts. The distribution was not changed either by exposure to standard temperature nor by standard lighting. The results demonstrate that day 1 embryos were clearly more susceptible to lighting whereas day 3 embryos were more affected by temperature. The mode of damage exerted by both the physical environmental factors was different. Reduction to standard temperature interfered mainly with the organization of the cytoskeleton and intracellular transport of organelles, while exposure to standard lighting led to cell degeneration and death.

Animals↗
PubMed1988

Significance of attentive fixation for the selection of saccade targets in different parts of the visual field of the rhesus monkey.

Two monkeys were presented with a task in which they were free to make a saccade to one of two simultaneously presented targets. The data from both animals show that the preference for one of the targets depends on at least two factors: (i) active and attentive fixation of the central fixation point at the time when the two targets occur; (ii) relative position of the two targets in the visual field. The results were different for the two monkeys with respect to the role of stimulus position in the visual field. However, both animals changed their preference systematically when the fixation point was turned off before the two targets occurred as compared to the case in which the fixation point remained visible. With respect to the paradigm (fixation point off versus fixation point on) the stimulus selection of either animal was constant throughout the several weeks of testing.

Animals↗
PubMed1988

Potential risk of light and room temperature exposure to preimplantation embryos.

Adverse effects of simultaneous exposure to visible light and room temperature were investigated in rabbit early cleavage stages and morulae. Routine laboratory conditions were mimicked as close as possible. Embryonic development was assessed by cell proliferation via incorporation of tritiated thymidine, by gross morphology, and by electron microscopy. Damage was detectable in both stages at 1-hour exposure by statistically significant impaired cell proliferation. Compared with single exposure to each individual stressor, combined exposure to light and room temperature amplified detrimental effects. Ultrastructural analysis of light-exposed cleavage stages revealed no indication of cell injury at 4-hour exposure. Gross morphology proved to be too inaccurate to evaluate damage imposed by exposure toward both physical factors investigated.

Blastocyst↗
PubMed1988

[Cerebral convulsion following peridural anesthesia with bupivacaine in cesarean section].

Maternal convulsions and severe fetal bradycardia resulted from the accidental intravascular injection of 0.5% bupivacaine for epidural anesthesia in preparation for caesarean section. Ventilation with oxygen, application of anticonvulsive drugs, relaxation and intubation was promptly performed followed by immediate caesarean section. The newborn was depressed at birth, recovered quickly and showed no neurologic deficits neither in the immediate postnatal period nor in neurobehaviour tests at the age of three months.

Adult↗
PubMed1988

Correlation between diameter and DNA or protein synthetic activity in rabbit blastocysts.

Noninvasive parameters are desirable to assess viability of preimplantation embryos. The objective of the present study was to investigate how noninvasive morphometric criteria are related to invasive metabolic parameters. In Day 4 and 5 noncultured and Day 4 in vitro-cultured rabbit blastocysts, diameters as well as DNA or protein synthesis (by incorporation of tritiated precursors) were measured. From the diameter of the blastocyst, total volume of embryonic cells was calculated and used for statistical analysis. In noncultured controls, cellular volume and thymidine, leucine, or methionine incorporation were highly correlated, with coefficients of correlation ranging between 0.7 and 0.9. The calculated equations of regression were linear. Blastocysts cultured for 24 or 48 h in medium supplemented with uterine flushings showed comparable coefficients of correlation and regression. After culture in serum-supplemented medium, however, a less close relationship was found, with statistically significant lower coefficients of correlation and regression. Our results demonstrate the following: (1) There is a close relationship between blastocyst diameter and metabolic criteria in noncultured rabbit blastocysts, indicating that simple measurement of the diameter of a useful tool for assessment of blastocyst metabolic activity. (2) In cultured blastocysts, however, measurement of diameter is of doubtful validity due to a substantially altered embryonic metabolism in vitro. (3) Blastocysts cultured in medium that contained uterine flushings maintained normal expansion and metabolic activity for some time.

Animals↗
PubMed1988

Trichinella pseudospiralis larvae express natural killer (NK) cell-associated asialo-GM1 antigen and stimulate pulmonary NK activity.

Natural killer (NK) cell function was evaluated in mice infected with either Trichinella pseudospiralis or T. spiralis larvae. T. pseudospiralis-infected mice consistently demonstrated augmented pulmonary NK cell-mediated clearance of YAC-1 tumor cells in vivo but failed to display enhanced splenic NK cell-mediated lysis of the same tumor cells in vitro. Attempts to alter NK cell function in vivo by the injection of anti-asialo-GM1 antibody resulted in anaphylaxis and death of the hosts infected with T. pseudospiralis but not of mice infected with T. spiralis. Immunofluorescence studies demonstrated that larvae of both species bound large quantities of anti-asialo-GM1 antibody but did not react with another NK-associated antibody, anti-NK-1.1. Even though anti-asialo-GM1 antibody reacted with larvae of both species, intravenous injection of antibody elicited anaphylaxis only in hosts that were infected with T. pseudospiralis.

Adrenal Cortex Hormones↗
PubMed1988

A 2 year follow-up of effects of biotechniques on reproduction in the domestic rabbit, Oryctolagus cuniculus.

Routinely employed reproductive techniques such as gonadotropin treatment (0.3 mg follicle-stimulating hormone (FSH) subcutaneously twice daily for three consecutive days) followed by natural mating or artificial insemination as well as induction of ovulation by human chorionic gonadotropin (hCG) (75 i.u. hCG intravenously) were analysed in the rabbit after 2 years of consecutive experiments. 85% of gonadotropin-treated animals mated spontaneously. All 222 FSH-primed donor rabbits and 59 hCG-injected non-primed controls ovulated. The average number of ovulations per female was 30 (FSH and hCG) and 7.4 (hCG only). The fertilization rate was 88%, and 22.7 embryos were recovered per FSH-treated donor rabbit. With increasing time after mating the embryo recovery rate decreased (day 1 post coitum (p.c.), 36 embryos per rabbit; day 3 p.c., 26 embryos per rabbit; day 5 p.c., 16 embryos per rabbit) and a higher percentage of females had no embryos recovered. Embryo recovery was poor in donors with ovulation numbers greater than 40. Artificial insemination of nonreceptive females yielded smaller numbers of embryos compared with natural mating. Differences in fertility between the seasons of the year was revealed to be small. We conclude that gonadotropin treatment is efficient in increasing the number of embryos. Management of laboratory rabbits (dating, mating and expected number of embryos) is more predictable, and experiments can be performed successfully in all seasons of the year. However, the incidence of embryonic mortality seems to be increased when gonadotropin treatment is applied.

Animals↗
PubMed1988

Studies on prostaglandin metabolism in corpora lutea of rabbits during pregnancy and pseudopregnancy.

Corpora lutea and ovarian stromal tissue were analysed for prostaglandin (PG) concentrations and activities of enzymes involved in PG metabolism at 8, 10, 12, 13 and 15 days after induction of ovulation. In CL of pseudopregnant rabbits, the PGE-2-9-ketoreductase (PGE-2-9-KR) was highly active on Days 10, 12 and 15 when compared with Day 8 (P less than 0.01; P less than 0.001; P less than 0.05). In pregnant animals PGE-2-9-KR activity was only increased on Day 12 (P less than 0.05) but declined to basal levels on Days 13 and 15. Comparing PGE-2-9-KR activity of pseudopregnant and pregnant animals, a significant elevation was found on Day 15 of pseudopregnancy (P less than 0.025). Activities of PG-15-hydroxydehydrogenase did not exhibit any significant changes with time in pseudopregnant or pregnant rabbits. PGE-2 concentrations were increased on Days 12, 13 and 15 (P less than 0.025) when compared with Day 8. Changes in PGF-2 alpha concentrations paralleled those of PGE-2-9-KR. The concentrations of PG metabolites 13,14-dihydro-15-keto-PGE-2 and -PGF-2 alpha were lower than those of the primary PGs and did not show stage-specific changes in pseudopregnant and pregnant animals. These results demonstrate that the rabbit CL possesses enzymes to convert PGE-2 to PGF-2 alpha and to metabolize both PGs. PGE-2-9-KR may be involved in regulating the PGF-2 alpha/PGE-2 ratio and possibly in controlling the life-span of the corpus luteum.

Animals↗
PubMed1988

Influence of visible light and room temperature on cell proliferation in preimplantation rabbit embryos.

During in-vitro culture rabbit early cleavage stages (Day 1 p.c.) and compacted morulae (Day 3 p.c.) were exposed to visible light or to room temperature (23 degrees C) for various lengths of time (0.5-24 h). The light source used resembled closely routine laboratory lighting. Controls were cultured simultaneously for 24 h under standard conditions (37 degrees C, darkness). Development was assessed by incorporation of tritiated thymidine as an indicator of cell proliferation. In comparison to non-exposed controls cell proliferation of Day-1 embryos was more impaired by light than by room temperature whereas in Day-3 embryos thymidine incorporation was more reduced following exposure to room temperature than to light. No statistically significant decrease in thymidine incorporation was detectable up to 1 h (light) and 8 h (room temperature) in Day-1 embryos. Morulae tolerated room temperature and visible light for up to 3 h and 8 h, respectively. Split-dose exposure (e.g. 4 x 1 h) to visible light or room temperature revealed no statistically significant differences compared with one long en-bloc exposure (e.g. 1 x 4 h). These results demonstrate a stage-dependent susceptibility of preimplantation embryos to physical environmental factors. The major risk, indicated by the shortest tolerance times, was provoked by visible light to early cleavage stages.

Animals↗
PubMed1987

RADPLANET--a functional radiology digital image network.

RADPLANET is a functioning LAN (Local Area Network) designed to integrate the many and varied facilities of a university medical center radiology department (Department of Radiation Sciences) into an efficient unified resource providing state-of-the-art diagnostic capabilities and delivering precision radiotherapy. RADPLANET links diagnostic work stations, radiation-therapy planning work stations, and therapy machine stations into an integrated whole. The RADPLANET project exploits technology currently evolving in the PACS (Picture Archiving and Communicating Systems) community but also addresses digital image networking requirements peculiar to radiation therapy. RADPLANET is designed as a modular, expandable, piecemeal updatable system in order to incorporate new, more cost-effective technology as it becomes available and to provide new resources to meet the needs of a growing department and an increasingly sophisticated medical profession. The paper discusses design criteria and rationale, current status of the network, and plans for continuing expansion and enhancement.

Hospital Departments↗
PubMed1987

Mechanisms of visual attention revealed by saccadic eye movements.

This paper summarizes recent data on the initiation of saccadic eye movement in relation to the mechanisms of visual attention. In particular, the occurrence of express saccades, defined by their extremely short reaction times, is discussed on the basis of the observation that these saccades do not occur when the subjects (man or monkey) are attending to either a fixation point or to any other visual stimulus in the periphery of their field of view including the "future" saccade target location. It is concluded that the system of visual attention can be in two states: engaged or disengaged. In order to generate a saccade or to move attention from one point to another visual attention must be in the disengaged state. The disengagement takes some time which is or is not included in the saccadic reaction time depending on whether or not visual attention is engaged at the time of the onset of the saccade target. During engaged visual attention saccades are inhibited thereby providing steady central fixation or the absence of saccades during directed peripheral attention.

Attention↗
PubMed1987

Quantitative aspects of protein synthesis in non-cultured and cultured rabbit blastocysts.

Day 4 rabbit blastocysts were cultured in Ham's F-10 medium supplemented either with homologous serum or uterine flushings. Development was assessed by leucine and methionine incorporation at 24 h and 48 h, respectively, after initiation of culture and compared with day 4 and day 5 non-cultured controls. After 24 h in culture, incorporation data were similar for both media groups. After 48 h, a significantly higher protein synthesis activity was found in blastocysts which had access to uterine secretions in vitro. However, incorporation levels of day 5 controls were not reached. Modes of incorporation of leucine and methionine revealed to be very similar in all experimental groups but ranged on a different level. Leucine was incorporated on a 5.5-fold higher level than methionine. We conclude that (i) supplementation of culture media with uterine secretions is beneficial for blastocyst development, and (ii) further studies should focus on non-serum components within the uterine fluid and their significance for embryonic development.

Animals↗