The history of Belgian assisted reproduction technology cycle registration and control: a case study in reducing the incidence of multiple pregnancy.

STUDY QUESTION: What is the effect of a legal limitation of the number of embryos that can be transferred in an assisted reproductive technology (ART) cycle on the multiple delivery rate? SUMMARY ANSWER: The Belgian national register shows that the introduction of reimbursement of ART laboratory costs in July 2003, and the imposition of a legal limitation of the number of embryos transferred in the same year, were associated with a >50% reduction of the multiple pregnancy rate from 27 to 11% between 2003 and the last assessment in 2010, without any reduction of the pregnancy rate per cycle. WHAT IS KNOWN ALREADY: Individual Belgian IVF centres have published their results since the implementation of the law, and these show a decrease in the multiple pregnancy rate on a centre by centre basis. However, the overall national picture remains unpublished. STUDY DESIGN, SIZE, DURATION: Cohort study from 1990 to 2010 of all ART cycles in Belgium (2685 cycles in 1990 evolving to 19 110 cycles in 2010), with a retrospective analysis from 1990 to 2000 and prospective online data collection since 2001. PARTICIPANTS/MATERIALS, SETTING, METHODS: Registration evolved from paper written reports per centre to a compulsory online registration of all ART cycles. From 2001 up to mid-2009, data were collected from Excel spread sheets or MS Access files into an MS Access database. Since mid-2009, data collection is done via a remote and secured web-based system (www.belrap.be) where centres can upload their data and get immediate feedback about missing data, errors and inconsistencies. MAIN RESULTS AND THE ROLE OF CHANCE: National Belgian registration data show that reimbursement of IVF laboratory costs in July 2003, coupled to a legal limitation in the number of embryos transferred in utero, were associated with a 50% reduction of the multiple pregnancy rate from 27 to 11% without reduction of the pregnancy rate per cycle, and with an increase in the number of fresh and frozen ART cycles due to improved access to treatment. LIMITATIONS, REASONS FOR CAUTION: There is potential underreporting of complications of ART treatment, pregnancy outcome and neonatal health. WIDER IMPLICATIONS OF THE FINDINGS: Over the 20 years of registration, the pregnancy rate has remained constant, despite the reduction in the number of embryos transferred, optimization of laboratory procedures and stimulation protocols, introduction of quality systems and implementation of the EU Tissue Directive over the period 2004-2010. STUDY FUNDING/COMPETING INTEREST(S): No external funding was sought for this study. None of the authors has any conflict of interest to declare.

Characterization of a novel trans-sialidase of Trypanosoma brucei procyclic trypomastigotes and identification of procyclin as the main sialic acid acceptor.

Here we report the presence of a trans-sialidase on the surface of Trypanosoma brucei culture-derived procyclic trypomastigotes. The enzyme is not detected in lysates of bloodstream trypomastigotes enriched for either stumpy or slender forms. The trans-sialidase catalyzes the transfer of alpha(2-3)-linked sialic acid residues to lactose. beta-galactopyranosyl residues are at least 100 times better acceptors for sialic acid than alpha-galactopyranosyl residues. In the absence of efficient acceptors, the purified enzyme transfers sialic acid to water, i.e., it acts as a sialidase. Although the T. cruzi and T. brucei trans-sialidases have very similar donor and acceptor specificities, they are antigenically distinct. Sodium dodecyl sulfate-polyacramide gel electrophoresis under nonreducing conditions and silver staining of the purified trans-sialidase reveals a single band of 63 kD. When the surface membrane of live procyclic trypomastigotes is trans-sialylated, using radioactive sialyllactose as the donor substrate, it appears that the only sialylated surface molecule is procyclin. Pronase treatment of live parasites removes only part of the surface sialic acid, in agreement with recent data showing that the glycosylphosphatidylinositol anchor of procyclin is sialylated (Ferguson, M. A. J., M. Murray, H. Rutherford, and M. J. McConville. 1993. Biochem. J. In press).

Uterine bathing with sonography gel prior to IVF/ICSI-treatment in patients with endometriosis, a multicentre randomised controlled trial.

STUDY QUESTION: What is the effect of uterine bathing with sonography gel prior to IVF/ICSI-treatment on live birth rates after fresh embryo transfer in patients with endometriosis? SUMMARY ANSWER: After formal interim analysis and premature ending of the trial, no significant difference between uterine bathing using a pharmacologically neutral sonography gel compared to a sham procedure on live birth rate after fresh embryo transfer in endometriosis patients (26.7% vs. 15.4%, relative risk (RR) 1.73, 95% confidence interval (CI) 0.81-3.72; P-value 0.147) could be found, although the trial was underpowered to draw definite conclusions. WHAT IS KNOWN ALREADY: Impaired implantation receptivity contributes to reduced clinical pregnancy rates after IVF/ICSI-treatment in endometriosis patients. Previous studies have suggested a favourable effect of tubal flushing with Lipiodol® on natural conceptions. This benefit might also be explained by enhancing implantation through endometrial immunomodulation. Although recent studies showed no beneficial effect of endometrial scratching, the effect of mechanical stress by intrauterine infusion on the endometrium in endometriosis patients undergoing IVF/ICSI-treatment has not been investigated yet. STUDY DESIGN SIZE DURATION: We performed a multicentre, patient-blinded, randomised controlled trial in which women were randomly allocated to either a Gel Infusion Sonography (GIS, intervention group) or a sham procedure (control group) prior to IVF/ICSI-treatment. Since recruitment was slow and completion of the study was considered unfeasible, the study was halted after inclusion of 112 of the planned 184 women. PARTICIPANTS/MATERIALS SETTING METHODS: We included infertile women with surgically confirmed endometriosis ASRM stage I-IV undergoing IVF/ICSI-treatment. After informed consent, women were randomised to GIS with intrauterine instillation of ExEm-gel® or sonography with gel into the vagina (sham). This was performed in the cycle preceding the embryo transfer, on the day GnRH analogue treatment was started. The primary endpoint was live birth rate after fresh embryo transfer. Analysis was performed by both intention-to-treat and per-protocol. MAIN RESULTS AND THE ROLE OF CHANCE: Between July 2014 to September 2018, we randomly allocated 112 women to GIS (n = 60) or sham procedure (n = 52). The live birth rate after fresh embryo transfer was 16/60 (26.7%) after GIS versus 8/52 (15.4%) after the sham (RR 1.73, 95% CI 0.81-3.72; P-value 0.147). Ongoing pregnancy rate was 16/60 (26.7%) after GIS versus 9/52 (17.3%) in the controls (RR 1.54, 95% CI 0.74-3.18). Miscarriage occurred in 1/60 (1.7%) after GIS versus 5/52 (9.6%) in the controls (RR 0.17, 95% CI 0.02-1.44) women. Uterine bathing resulted in a higher pain score compared with a sham procedure (visual analogue scale score 2.7 [1.3-3.5] vs. 1.0 [0.0-2.0], P < 0.001). There were two adverse events after GIS compared with none after sham procedures. LIMITATIONS REASONS FOR CAUTION: The study was terminated prematurely due to slow recruitment and trial fatigue. Therefore, the trial is underpowered to draw definite conclusions regarding the effect of uterine bathing with sonography gel on live birth rate after fresh embryo transfer in endometriosis patients undergoing IVF/ICSI-treatment. WIDER IMPLICATIONS OF THE FINDINGS: We could not demonstrate a favourable effect of uterine bathing procedures with sonography gel prior to IVF/ICSI-treatment in patients with endometriosis. STUDY FUNDING/COMPETING INTERESTS: Investigator initiated study. IQ Medical Ventures provided the ExEm FOAM® kits free of charge, they were not involved in the study design, data management, statistical analyses and/or manuscript preparation, etc. C.B.L. reports receiving grants from Ferring, Merck and Guerbet, outside the submitted work. C.B.L. is Editor-in-Chief of Human Reproduction. V.M. reports grants and other from Guerbet, outside the submitted work. B.W.M. reports grants from NHMRC (GNT1176437), personal fees from ObsEva, Merck and Merck KGaA, Guerbet and iGenomix, outside the submitted work. N.P.J. reports research funding from Abb-Vie and Myovant Sciences and consultancy for Vifor Pharma, Guerbet, Myovant Sciences and Roche Diagnostics, outside the submitted work. K.D. reports personal fees from Guerbet, outside the submitted work. The other authors do not report any conflicts of interest. No financial support was provided. TRIAL REGISTRATION NUMBER: NL4025 (NTR4198). TRIAL REGISTRATION DATE: 7 October 2013. DATE OF FIRST PATIENT'S ENROLMENT: 22 July 2014.

Cross-border reproductive care in Belgium.

BACKGROUND: Cross-border reproductive care indicates the cross-border movements made by patients to obtain infertility treatment they cannot obtain at home. The problem at present is that empirical data on the extent of the phenomenon are lacking. This article presents the data on infertility patients going to Belgium for treatment. METHODS: A survey was conducted among the centres for reproductive medicine that are allowed to handle oocytes and create embryos (B-centres). Data were collected on the nationality of patients and the type of treatment for which they attended during the period 2000-2007. RESULTS: Sixteen of 18 centres responded to the questionnaire. The flow of foreign patients has stabilized since 2006 at approximately 2100 patients per year. The majority of foreign nationals seeking treatment in Belgium were French women for sperm donation. The next highest group was patients entering the country to obtain ICSI with ejaculated sperm. CONCLUSIONS: There are clear indications that numerous movements are motivated by the wish to evade legal restrictions in one's home country, either because the technology is prohibited or because the patients have characteristics, which exclude them from treatment in their own countries.

No influence of the indication of freeze-all strategy on subsequent outcome to frozen-thawed embryo transfer cycle.

BACKGROUND: Freezing all embryos generated during an IVF/ICSI attempt is used increasingly as a strategy to optimize results. We investigated whether we could find differences in outcome between subpopulations of patients undergoing the so-called "freeze all" procedure. METHODS: Non-interventional, observational, retrospective study of 131 freeze-all cycles performed between July 2015 and December 2016 at the University Hospital of Ghent (Belgium). Freeze-all indications were categorized in 4 groups: group 1, high progesterone level (PE) on the day of hCG administration defined as >1.5 ng/ml (n= 50); group 2, risk of Ovarian Hyperstimulation Syndrome (OHSS) (n=38); group 3, partner donation in lesbian couples (n=23) and group 4, a miscellany of other reasons (n=20). Clinical pregnancy with fetal heart beat after the first thawed embryo transfer (ET) after ovum pick-up and cumulative clinical pregnancy rate per attempt were used as primary outcome variables. RESULTS: Clinical pregnancy rate (CPR) with fetal heart beat in the first thawed ET and cumulative clinical pregnancy rate per cycle (CCPR) were not statistically different between the four groups. In the group of PE a cumulative clinical pregnancy rate was observed of 40,5%, this in comparison to the 3 other groups involving risk of OHSS (66,7%), partner donation (61,1%) and other reasons (57,1%). More rFSH was used in the group with Progesterone elevation (PE) (P=0.04), as described earlier in the literature. CONCLUSION: Our findings indicate comparable (cumulative) clinical pregnancy rates per attempt between the four groups of freeze-all indications.

Outcome of one hundred consecutive ICSI attempts using patient operated home sonography for monitoring follicular growth.

OBJECTIVE: cohort study describing clinical and laboratory outcomes in ICSI patients using self-operated endovaginal tele-monitoring (SOET). SETTING: University department of reproductive medicine. PATIENTS: 78 patients undergoing 100 consecutive ICSI attempts. INTERVENTIONS: patients' recorded vaginal sonograms and sent recordings using the cloud based Sonaura device to the care provider who procured responses, avoiding hospital visits. MAIN OUTCOME MEASURES: Number of cycles without hospital visit, laboratory and clinical variables, transportation avoided. RESULTS: In 100 attempts, only one patient missed her follicles, 9 hospital visits occurred for circumstantial reasons and 90 attempts were completed without any hospital visit between initiation and puncture. Mean number ± 2SD was for oocytes 11.7±6.6, metaphase-II oocytes 8.5±5.4, 2PN zygotes 5.5±3.7, good day-5 blastocysts 2.4±2.4, embryos transferred 1.0±0.7 and embryos frozen 1.3±2.2. Percentages of total (+HCG), clinical (cardiac activity) and on-going pregnancies (>20 weeks) were 40%, 35% and 29% per started cycle and 48.8%, 42.7% and 35.4% per embryo transfer. CONCLUSIONS: Using SOET, 90% of ICSI (and IVF) patients can avoid visits to care providers for making sonograms. Results were similar as in patients with a similar profile using traditional monitoring. In appropriate patients, SOET is an efficient, safe and patient-friendly alternative for ovarian stimulation monitoring in IVF/ICSI programmes.

Seasons in the sun: the impact on IVF results one month later.

BACKGROUND: Several retrospective studies have evaluated seasonal variations in the outcome of IVF treatment. Some also included weather conditions, mostly temperature and hours of daylight. The results were conflicting. METHODS: In a retrospective study we analysed all fresh cycles (N = 9865) that were started between January 1, 2007 and December 31, 2012. Because some patients were included more than once, correction for duplicate patients was performed. We focused on individual variables provided as monthly results by our national meteorological institute. We evaluated if weather conditions determined by temperature, rain and sunshine at the start of ovarian stimulation had an effect on the outcome of IVF in terms of number of mature and fertilized oocytes, pregnancy and live birth rates. We shifted the results in IVF outcome to the weather results of one month earlier, as we supposed that the selection of good quality oocytes might start in the weeks before ovarian stimulation is initiated. RESULTS: There was a clear trend towards better results when the "early" weather conditions (one month before the treatment cycle) were good. There was a statistically significant correlation between the number of rainy days (Pearson Correlation -0.326; p < 0.01) and the rain flow (Pearson Correlation -0.262; p < 0.05) on the one hand and the live birth rate per cycle on the other. The live birth rate per cycle was statistically different between cohorts of patients that were stratified into quartiles of sunshine hours (p < 0.01) and of number of rainy days (p < 0.05) during the month before the start of ovarian stimulation. CONCLUSIONS: Weather conditions during the month before IVF treatment have an impact on live birth rate.

Three matrix metalloproteinases form a non-covalent association with the rhoptry-associated protein-1 of Plasmodium falciparum.

During the characterization of malaria vaccine candidate proteins, three metalloproteinases having a molecular mass of 220, 95 and 70 kDa were found to be co-isolated with the rhoptry-associated protein-1 (RAP-1) complex, but not with RAP-3 or gp195. These enzymes were also found in detergent extracts of saponin-lysed Plasmodium falciparum. Of nine proteinase inhibitors tested, only EDTA was found to abrogate activity. Dose-dependent curves were determined for several metal ions and cobalt was found to synergistically enhance enzyme activity. The gelatinases were immunoprecipitated with monospecific polyclonal antisera to macrophage and fibroblast gelatinase; however, these sera did not react with intracellular parasites by indirect immunofluorescence. These results indicate that the matrix metalloproteinases co-isolated with RAP-1 originate from human serum used to cultivate P. falciparum in vitro.

Clonality analysis of hematopoietic cell lineages in acute myeloid leukemia and translocation (8;21): only myeloid cells are part of the malignant clone.

Bone marrow from six patients with acute myeloid leukemia (AML) and t(8;21) (q22;q22) or a variant t(8;13;21) was studied by simultaneous analysis of cell morphology and karyotype. Combination of May-Grünwald-Giemsa (MGG) and fluorescence in situ hybridization (FISH) using probes specific for the breakpoint regions of chromosome 8 and 21 allowed us to establish the extent of cell-lineage involvement of the translocation. The translocation was found in all myeloid blasts and in high percentages of the more mature neutrophilic cells. In one patient we could demonstrate the translocation in the eosinophils as well. Erythroblasts and lymphocytes did not show the t(8;21) abnormality. These results indicate that the t(8;21) in AML is restricted to the myeloid (granulocytic) lineage.

Does transferring three or more embryos make sense for a well-defined population of infertility patients undergoing IVF/ICSI?

Recently, there has been a marked increase in the use of Single Embryo Transfer (SET) subsequent to In Vitro Fertili-zation (IVF) and Intracytoplasmic Sperm Injection (ICSI), with the aim of reducing the risk of multiple gestations. However, critics have stated that by reducing the number of embryos transferred, a group of women with an a priori reduced chance of pregnancy are at particular greater risk of undertreatment. This group includes women who are of a certain age (≥ 40 years) or have already received a number of - failed - IVF attempts. We wanted to study whether the practice of three or more embryos being transferred would be of added value to these patients and whether the strategy of Heavy Load Transfer (HLT) is likely to boost the pregnancy rates to an acceptable level. We performed both a literature study and a retrospective cohort analysis of 7,850 IVF/ICSI cycles of early cleavage stage embryo transfer. Notwithstanding the limitations associated with this approach, we contend that HLT in the group of patients with poor prognosis should be recommended. This article outlines a suggested protocol within the legal framework relevant to Belgium.

Anti-interferon-gamma antibody protects mice against the generalized Shwartzman reaction.

A generalized Shwartzman reaction was found to occur in non-SPF-NMRI mice given a local injection of S. marcescens lipopolysaccharide (LPS) in the footpad, followed, with an interval of 24 h, by an i.v. injection. The reaction occurred several hours after the second injection. It was characterized by disseminated subcutaneous bleedings at the mouth, anus, conjuctiva, nose tip and tail end. Most mice died within 24-48 h. The size of the LPS dose given in the footpad (5 micrograms) was found to be critical in that the reaction failed to occur with higher as well as lower doses. The reaction was found to be completely absent in mice that had received one or more systemic injections of monoclonal antibodies with neutralizing potential for murine interferon-gamma (IFN-gamma). Mice treated with control preparations, including a monoclonal antibody with binding but no neutralizing activity for murine IFN-gamma, remained sensitive to induction of the reaction. These observations assign a crucial role to endogenous IFN-gamma in the elicitation of the generalized Shwartzman reaction and open perspectives for the prevention or therapy of clinical conditions related to the Shwartzman reaction by the use of antibodies to IFN-gamma.

Screening for multiple pregnancy. Determination of human chorionic gonadotropin (hCG), alpha-fetoprotein (alpha-FP) and human placental lactogen (hPL) in blood during the second trimester of pregnancy.

The value of single determinations of serum hCG, hPL, and alpha FP for the detection of multiple pregnancy was investigated in a consecutive series of 992 women between the 14th and 24th week of pregnancy. With the 90th percentile as referent value, all twin pregnancies (n = 10) were detected by the combined results of the three determinations. Considered separately, hPL proved to be the most useful indicator of multiple gestation; the sensitivity of hPL alone was 70% and the predictive value of hPL concentrations above the 90th percentile was 8.1.

The induction of Trypanosoma cruzi trypomastigote to amastigote transformation by low pH.

Following cell invasion, Trypanosoma cruzi trypomastigotes transform into amastigotes, which are the mammalian replicative forms of the parasite. Although amastigotes represent a critical stage in the life-cycle of T. cruzi, little is known of the factors controlling trypomastigote to amastigote transformation. Kanbera et al. (1990) observed that exposure of trypomastigotes to acidic pH induced their transformation into rounded forms resembling amastigotes. We confirm their observation and, using two strains of T. cruzi, establish that these transformants are ultrastructurally and biochemically indistinguishable from natural amastigotes. Incubation of trypomastigotes in medium at pH 5.0 for 2 h was sufficient to trigger their transformation into forms resembling amastigotes. Electron microscopical analysis confirmed that the kinetoplast structure, and general morphological features of the acid-induced, extracellular amastigotes were indistinguishable from those of intracellular-derived amastigotes. The extracellular transformation was accompanied by the acquisition of the stage-specific surface antigen of the naturally transformed amastigotes (Ssp-4), and loss of a stage-specific trypomastigote antigen (Ssp-3). Trypomastigotes incubated at neutral pH did not transform into amastigotes, and did not acquire the Ssp-4 epitope or lose the Ssp-3 epitope. Finally, acid-induced amastigotes subsequently incorporated [3H]thymidine into their DNA, indicating that the important replicative property of intracellular amastigotes is also exhibited by these in vitro transformants. This effect of low pH appears to be of physiological relevance, and acid-induced extracellular transformation appears to represent a valid experimental technique for studies of the molecular mechanisms involved in the differentiation process.

Mammalian cell sialic acid enhances invasion by Trypanosoma cruzi.

We have used a Chinese hamster ovary cell mutant (Lec2) that express much less sialic acid on the surface than the parental cell line (Pro5) to investigate whether sialic acid plays a role during cell invasion by Trypanosoma cruzi. Trypomastigotes derived from a tissue culture (corresponding to bloodstream trypomastigotes) and metacyclic trypomastigotes (corresponding to infective stages of the insect vector) invaded the Lec2 mutant less efficiently than the parental cell line. Invasion of the Lec2 mutant cells could be restored to the Pro5 level by resialylation of the mutant cells with T. cruzi trans-sialidase and sialyllactose. Conversely, pretreatment of the Pro5 parental cells with bacterial neuraminidase decreased invasion. These results indicate that sialic acid associated with the host cell contributes to invasion by T. cruzi.

Enhancement of experimental allergic encephalomyelitis in mice by antibodies against IFN-gamma.

Acute experimental allergic encephalomyelitis (EAE) was induced in C57BL/6J and SJL/J mice by injection of isologous spinal cord homogenate given in conjunction with Bordetella pertussis and Freund's adjuvant. SJL/J mice showed a highly aggressive and 100% lethal form of the disease; C57BL/6J mice were much less susceptible as they had low morbidity rates (20 to 40%), low disease scores, and mostly no mortality. Treatment of these low susceptibility mice with neutralizing mAb against IFN-gamma caused an increase in morbidity rates as well as significant mortality (up to 80%). Similar antibody treatment did not affect the course of the disease in the high susceptibility SJL/J mice. However, treatment of these mice with IFN-gamma resulted in reduced morbidity and mortality. A similar but less pronounced inhibition of the disease in SJL/J mice could be obtained by administration of IFN-alpha/beta or by acute infection with lactate dehydrogenase virus. The results indicate that endogenous as well as exogenous IFN can exert a down-regulating effect on the development of EAE. They also indicate that endogenous IFN-gamma is produced during the development of EAE and plays a disease-limiting role.

Regulation by interferons of the local inflammatory response to bacterial lipopolysaccharide.

Footpad swelling developing in mice after local injection of LPS (S. marcescens) was found to consist of two phases with peaks occurring on days 2 to 3 and 6 to 8, respectively. Histopathologically, the reaction was characterized by edema and mononuclear cell infiltration; the second peak was associated with intravascular thrombosis as is typically described for the Shwartzman reaction to LPS. Recombinant DNA-derived IFN-gamma, administered by i.p. injection, had a suppressive effect on the development of the reaction. The same effect was seen with recombinant DNA-derived IFN-alpha 1 and with the natural mixture of IFN-alpha and -beta. In mice pretreated with neutralizing monoclonal antibodies to IFN-gamma, the footpad response to LPS was modified in that a delayed monophasic rather than a biphasic response occurred. These data indicate that LPS induces local production of IFN-gamma, which acts as a trigger or positive regulator of the reaction. The effect of a single pretreatment with neutralizing anti-IFN-gamma antibody was found to last for as long as 6 wk. Experiments in which antibody administration was delayed till after LPS challenge indicated that endogenous IFN-gamma was also involved in the late phases of the inflammation. The results show that regulation of inflammation by interferons is complex in that local IFN-gamma acts as a positive factor, whereas systemic IFN-alpha 1 and -gamma, probably through indirect mechanisms, downregulate inflammation.

Cranial ultrasound after forceful midpelvis vacuum extraction at term.

The heads of 28 non-hypoxic, full-term infants of normal gravidas delivered by forceful vacuum extraction were examined with ultrasound during the early neonatal period. All echographic findings were normal and all neonates had an uneventful evolution during the first week of life. Addendum: Since this article was completed, a massive intracranial haemorrhage occurred in a non-hypoxic full-term newborn after elective midpelvic vacuum extraction. The intervention was performed by a resident who, despite the guidelines did not call the senior obstetrician after three unsuccessful attempts to extract the fetus. The head was stationed, 2 cm above the level of the ischial spines, not completely flexed with the occiput in the right-anterior position. The newborn died at the age of 3 hours. Autopsy showed a tear of the tentorium cerebelli and the vena cerebri magna.

Cytogenetic clonality analysis: typical patterns in myelodysplastic syndrome and acute myeloid leukaemia.

The cell morphology and karyotype of bone marrow samples from 24 patients with myelodysplastic syndrome (MDS) and acute myeloid leukaemia (AML) were studied simultaneously with a combined technique of May-Grünwald-Giemsa (MGG) staining and fluorescence in situ hybridization (FISH) with chromosome-specific DNA probes. This enabled us to investigate cell lineage involvement in three malignant conditions: MDS (n = 12), leukaemia-transformed MDS (LT-MDS) (n = 5) and de novo AML (n = 7). In MDS we found blasts and often significant proportions of mature granulocytic and erythroid cells to be cytogenetically abnormal. Percentages of granulocytic and erythroid cells with cytogenetic aberrations were generally less than those of blasts. These data support the involvement of a transformed pluripotent stem cell that has retained maturation abilities. In two patients with chronic myelomonocytic leukaemia (CMMoL) the clonal involvement of monocytes was predominant. Results in the five patients with LT-MDS were similar to those in MDS. In the bone marrow of five of the seven de novo AML patients the cytogenetic abnormalities were restricted to the blasts and did not include the more mature granulocytic or erythroid populations. In the other two patients with AML, both with a t(8;21) and a loss of the Y chromosome, high percentages of mature neutrophils were cytogenetically abnormal. These patterns of clonal lineage involvement in MDS, LT-MDS, t(8;21) AML and AML appear typical and may be of clinical use, for example, for distinguishing LT-MDS from de novo AML in newly presenting patients.

Resialylation of sialidase-treated sheep and human erythrocytes by Trypanosoma cruzi trans-sialidase: restoration of complement resistance of desialylated sheep erythrocytes.

Trypanosoma cruzi trans-sialidase (TS) is a recently described enzyme which transfers alpha(2-3)-linked sialic acid from host-derived sialylated glycoconjugates to parasite surface molecules [Schenkman et al. (1991) Cell, 65, 1117]. We report here on the ability of TS to transfer sialic acid from donor sialyl-alpha(2-3)lactose to sialidase-treated sheep and human erythrocytes. Up to approximately 50% resialylation of both desialylated red cells could be attained. Resialylation of desialylated sheep erythrocytes restores their resistance to lysis by human complement. This ascribes a possible biological role for T. cruzi TS and demonstrates directly that sialic acid is solely responsible for preventing alternative pathway activation of human complement by sheep erythrocytes.