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P Sundström

Publications and source records attributed to P Sundström.

At least 37 records · Page 2Linked to original sources
PubMed1994

Characterization of mouse-hamster-human cross-reacting antioocyte monoclonal antibodies produced by intrasplenic immunization of mice with 12 zona-free mouse oocytes.

Several intrasplenic immunizations with batches of approximately 15 or approximately 30 zona-free, unfertilized mouse oocytes resulted in 200-300 hybrids, respectively, among which about 20 positive clones were selected from each fusion between splenic plasma cells and SP2/0 myeloma cells. When nonimmunized splenic plasma cells were used, only one antibody, showing weak immunoreaction, was obtained from approximately 370 hybrids collected from 2 fusions. From one immunization with a total of 12 zona-free, unfertilized mouse oocytes, 15 positive clones were selected for further study. Eleven of these 15 antibodies reacted with antigens only in unfertilized oocytes but not in fertilized, pronuclear stage oocytes. Three antibodies, which recognized antigens in paraffin-embedded oocyte sections, did not label growing ovarian oocytes, indicating that the antibodies were specific to ovulated, unfertilized oocytes. These antibodies did not detect any antigen epitopes in the panel of tissues examined. The molecular weight of one antigen, corresponding to a IgM antibody that is present both in ooplasma and zona pellucida, was approximately 116 kDa. Cross-reactivity to blots of unfertilized zona-free hamster oocytes was demonstrated by 6 antibodies and to unfertilized human oocytes by 7 antibodies. Three antibodies cross-reacted with both hamster and human oocytes. The study indicates that the intrasplenic immunization is an appropriate means of raising antibodies against unfertilized, zona-free mouse oocytes and that the method applied offers an easy way to select antibodies against human oocytes for functional studies.

Animals↗
PubMed1993

[Past and present--the roots of our modern concept of disease in 19th century clinical practice and science].

Historically speaking, our current clinical conceptions of disease are derived from 19th century science and clinical practice. In the early 19th century, large hospitals with hundreds of patients were erected for the first time. This provided "material" to which the physicians could apply their new diagnostic techniques and tools: percussion and auscultation, aided by the newly invented stethoscope. Eventually, what was found at the bedside was systematically compared with what was discovered on the autopsy table. This clinical research programme was challenged by, though later combined with, the experimental physiology and "laboratory medicine" of men like François Magendie and Claude Bernard. Their strong programme to introduce pure science, i.e. physics and chemistry, into medicine was paralleled by further developments in the old solidistic pathological tradition; an improved microscope and new techniques for preparing tissues for the microscope, led to the development of truly microscopic anatomy and cellular pathology. The idea that disease may be caused by microscopic living organisms was tested by means of strict experimental, scientific methods by men such as Louis Pasteur and Robert Koch; and our current conception of infectious disease is still very similar to that of the first microbiologists of the 1870s and 80s. The last 19th century root of our modern conceptions of disease discussed in the present essay is the visualization of the interior of the body--indeed, the visualization of disease--by X-rays.

Anatomy↗
PubMed1992

Human oocytes express murine retroviral equivalents.

Unfertilized human oocytes expressed a gp70-related epitope as observed when staining section immunocytochemically with a panel of monoclonal antibodies against gp70 of murine leukemia virus. Some oocytes also expressed virus-like particles at the cell membrane. Follicular fluids, corresponding to these oocytes, contained p30- and gp70-related antigens, reverse transcriptase, and an increased titer of interferon. The three- to four-cell human cleavage stages did not contain the gp70-related epitope. It is concluded that human oocytes, but not early cleavage stages, express products that suggest the presence of an active endogenous retrovirus genome.

Antigens, Viral↗
PubMed1991

AIDS, myth, and ethics.

The present paper is a commentary on an article by Larry Churchill. Churchill has argued that the negative attitudes and adverse behavior we commonly encounter in connection with (suspected) AIDS patients may be understood in terms of a dualistic 'myth' inspiring a 'ritual' avoidance of 'dirt', of 'dirt' as something that does not belong to a 'clean' world order. The deep-seated mythical character of attitudes and behavior here makes them less accessible to the kind of rational argument commonly employed in ethics. Churchill also proposes a remedy for the (morally outrageous) dualistic mythical-ritual behavior he has focused - a remedy that may be overly intellectualistic. Three further comments are made: on the metaphorical meaning of 'myth', on a reductionist tendency in Churchill's 'deep'-looking project, and on an ethically crucial ambiguity in the meaning of the other person's 'otherness'. These (mildly critical) comments do not, however, detract from a positive overall evaluation of Churchill's basic idea that we will understand more about adverse attitudes and behavior in connection with AIDS if we think in terms of 'myth', 'ritual', 'dirt', and 'cleanliness'.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Evaluation of variations in pregnancy rates, implantation rates and early abortion rates within an in-vitro fertilization programme.

Despite the application at this clinic of a standardized programme for in-vitro fertilization of human oocytes over the last 27 months, great variations in the rates of implantation, clinical pregnancy and early abortion have been observed during certain periods. A retrospective evaluation of these results showed that these variations occurred in periods when various commercially available batches of Earle's medium (the medium was the only variable changed during the 27 months) were used and that two sub-optimal batches of Earle's medium from one of the sources used during one of three periods (period 2) was most likely to be responsible for sub-optimal embryo quality and, consequently, for a halving of the pregnancy rate (30 versus 15%) and of the implantation rate (11 versus 5%) and an increase in the early abortion rate (23 versus 50%). It is concluded that the quality of the culture medium is of major importance for the success of an IVF programme. The factor(s) in the medium responsible for the decrease in embryo quality has not been identified.

Abortion, Spontaneous↗
PubMed1989

Blastocyst implantation precedes induction of insulin-like growth factor II gene expression in human trophoblasts.

The cytotrophoblast cell population of the human embryonic conceptus proliferates rapidly during the first month following blastocyst implantation. Since the trophectoderm lineage is established in preimplantation morula/blastocysts, the scenario underlying initiation and maintenance of the rapid proliferative phenotype of cytotrophoblasts is a central issue. The insulin-like growth factor II (IGF-II) gene is highly expressed in proliferative cytotrophoblasts of first trimester placenta and performs as a placenta growth factor. To establish a temporal correlation between IGF-II expression and initiation of highly proliferative trophoblasts in human development, we employed in situ hybridization analysis of the expression of the IGF-II and human chorionic gonadotropin beta-subunit (beta-HCG) genes in human pre- and postimplantation development. The data show that the appearance of high steady-state levels of IGF-II transcripts in trophoblasts is a postimplantation event, whereas beta-HCG transcripts can already be detected in preimplantation development. This observation makes a role for endogenously produced IGF-II in the normal development of preimplantation embryos unlikely, but suggests that endogenously produced IGF-II participates in the formation and subsequent expansion of the rapid proliferative phenotype of the trophoblastic shell, following implantation.

Blastocyst↗
PubMed1988

Meiotic and cytoplasmic maturation of oocytes collected in stimulated cycles is asynchronous.

Oocytes collected in stimulated cycles are more readily fertilized after preincubation than are oocytes inseminated immediately after collection. It has not been ascertained, however, whether this increase in the fertilization rate is due to extrusion of the first polar body (meiotic maturation) during this period, or to some conclusive cytoplasmic maturation subsequent to the polar body extrusion. When analysing oocytes with a polar body (n = 14) by transmission electron microscopy, differences were observed in the appearance of cytoplasmic features which were correlated to the total durations both of systemic human chorionic gonadotrophin influence before collection and of oocyte culture. These differences were manifested as a delayed formation in aggregates of the smooth endoplasmic reticulum in the ooplasm of oocytes having a polar body and might have signified a cytoplasmic maturation. The degree of asynchrony in the oocytes varied and this could explain why some oocytes can be fertilized when inseminated shortly after collection and others not until 8 h or even more after collection. Thus, although meiotic and cytoplasmic maturation is likely to be synchronized at ovulation of an oocyte in a natural cycle, they appear to be mainly asynchronous in oocytes collected in stimulated cycles.

Adult↗
PubMed1987

Pregnancy rate in relation to number of cleaved eggs replaced after in-vitro fertilization in stimulated cycles monitored by serum levels of oestradiol and progesterone as sole index.

A simple model for monitoring ovarian stimulation in in-vitro fertilization cycles was designed using daily serum levels of 17 beta-oestradiol and progesterone as the only index to determine the day of ovum retrieval. Human chorionic gonadotropin was administered in the evening 2 days after a level of 2500 pmol/l oestradiol in serum was exceeded provided the serum progesterone level was less than 5 nmol/l. Ovarian stimulation was initiated in 128 women scheduled for laparoscopic oocyte retrieval. Twelve cycles (9%) were cancelled before ovum pick up due to sub-optimal hormone levels in serum and five for other reasons. In 107 successful laparoscopies, 616 oocytes (mean 5.8 per laparoscopy) were recovered. The cleavage rate after IVF was 65% in the egg replacement group. In 87 women, a total of 271 cleaved eggs (range 1-6, mean 3.1) were replaced. The most important factor for establishing a pregnancy was the number of eggs replaced at the same time. Clinical pregnancies were achieved after 30% of replacements, increasing to 50% after replacement of 5-6 eggs. The ongoing/delivered pregnancy rate after the 18th week of gestation was 69%. It was concluded that the simple monitoring model used was consistent with a high pregnancy rate and a low rate of cancelled cycles.

Chorionic Gonadotropin↗
PubMed1986

Virus p30-related protein in follicular fluids and C virus-like particles on the cell membrane of the human oocyte.

Fluids from 208 follicles were analyzed with respect to the concentration of estradiol and progesterone and to the presence of RD 114 retrovirus p30-related protein (rp), assuming that such a protein indicates the presence of C-virus particles in the follicular fluids. The results obtained showed that 60-80% of the follicular fluids within the same range of steroid hormone levels contained virus p30 rp. Electron microscopy showed 80-nm virus-like particles, more or less well preserved, in about half of the number of oocytes examined. Negative staining of purified follicular fluid particles showed ring-like structures with a size of 100-200 mm. It is concluded that the presence of virus p30 rp in follicular fluids is correlated neither to a certain steroid hormone concentration nor to the oocyte capability to become fertilized and cleave. The observed expression of an endogenous virus genome during oocyte maturation strengthens the hypothesis that this type of genome is active at early developmental stages.

Cell Membrane↗
PubMed1985

Ultrastructural characteristics of human oocytes fixed at follicular puncture or after culture.

The material consisted of 73 oocytes obtained at follicle aspiration in ovarian-stimulated women. Oocytes in various stages of maturation were either immediately fixed or cultured before fixation. Observations by transmission electron microscopy disclosed that 20% of the immature oocytes, which appeared normal in the light microscope, had commenced atresia, and one immediately fixed oocyte surrounded by a normal-appearing preovulatory cumulus mass was found to be degenerated. Further, a cumulus mass judged as preovulatory contained an oocyte possessing a germinal vesicle. Light microscopy is thus not always adequate for judging the condition of ova surrounded by cumulus cells. Cytoplasmic changes which were regarded as being related to oocyte maturation were a decrease in the number of vacuoles and multivesicular bodies, an increase in the volume of the endoplasmic reticulum, a clustering of mitochondria, and the appearance of aggregates of tubuli of the smooth endoplasmic reticulum surrounded by mitochondria and mitochondria-vesicle complexes. Certain features were found to cause misinterpretations at examination of oocytes in a light microscope. For instance, polar bodies can be mimicked by corona cells in the perivitelline space and pronuclei in oocytes by large mitochondria-vesicle complexes in the ooplasm. Consequently, not all oocytes in which polar body-like or pronuclei-like structures are observed are necessarily fertilized oocytes.

Cell Differentiation↗