HPRT-deficient (Lesch-Nyhan) mouse embryos derived from germline colonization by cultured cells

Embryonal stem (ES) cell lines, established in culture from peri-implantation mouse blastocysts, can colonize both the somatic and germ-cell lineages of chimaeric mice following injection into host blastocysts. Recently, ES cells with multiple integrations of retroviral sequences have been used to introduce these sequences into the germ-line of chimaeric mice, demonstrating an alternative to the microinjection of fertilized eggs for the production of transgenic mice. However, the properties of ES cells raise a unique possibility: that of using the techniques of somatic cell genetics to select cells with genetic modifications such as recessive mutations, and of introducing these mutations into the mouse germ line. Here we report the realization of this possibility by the selection in vitro of variant ES cells deficient in hypoxanthine guanine phosphoribosyl transferase (HPRT; EC 2.4.2.8), their use to produce germline chimaeras resulting in female offspring heterozygous for HPRT-deficiency, and the generation of HPRT-deficient preimplantation embryos from these females. In human males, HPRT deficiency causes Lesch-Nyhan syndrome, which is characterized by mental retardation and self-mutilation.

Pregnancies from biopsied human preimplantation embryos sexed by Y-specific DNA amplification

Over 200 recessive X chromosome-linked diseases, typically affecting only hemizygous males, have been identified. In many of these, prenatal diagnosis is possible by chorion villus sampling (CVS) or amniocentesis, followed by cytogenetic, biochemical or molecular analysis of the cells recovered from the conceptus. In others, the only alternative is to determine the sex of the fetus. If the fetus is affected by the defect or is male, abortion can be offered. Diagnosis of genetic defects in preimplantation embryos would allow those unaffected to be identified and transferred to the uterus. Here we report the first established pregnancies using this procedure, in two couples known to be at risk of transmitting adrenoleukodystrophy and X-linked mental retardation. Two female embryos were transferred after in vitro fertilization (IVF), biopsy of a single cell at the six- to eight-cell stage, and sexing by DNA amplification of a Y chromosome-specific repeat sequence. Both women are confirmed as carrying normal female twins.

The role of the T3/antigen receptor complex in T-cell activation

The role of the T3/antigen receptor complex is summarized by the diagram presented in Figure 4. Signals transmitted through T3/Ti activate a phosphodiesterase. This enzyme acts on its substrate PIP2 to generate two important mediators, IP3 and diacylglycerol. IP3 mobilizes calcium from bound intracellular stones. This increase in [Ca2+]i is one intracellular signal which, in conjunction with others, induces expression of lymphokine genes by influencing pretranslational, presumably transcriptional, events. Several problems remain. Which of the five molecules in the T3/Ti complex serves as the effector molecule in the transmembrane signaling process is not known. Which molecules serve to link T3/Ti to the phosphodiesterase enzyme is under investigation. The role diacylglycerol protein kinase C and other mediators play in signalling activation is not established. Finally, for those events occurring after the early events pictured in Figure 4 that result in gene activation, the sequence is a black box. Approaches to address each of these questions are available, and answers should be forthcoming.

The human blastocyst: cell number, death and allocation during late preimplantation development in vitro

The development of 181 surplus human embryos, including both normally and abnormally fertilized, was observed from day 2 to day 5, 6 or 7 in vitro. 63/149 (42%) normally fertilized embryos reached the blastocyst stage on day 5 or 6. Total, trophectoderm (TE) and inner cell mass (ICM) cell numbers were analyzed by differential labelling of the nuclei with polynucleotide-specific fluorochromes. The TE nuclei were labelled with one fluorochrome during immunosurgical lysis, before fixing the embryo and labelling both sets of nuclei with a second fluorochrome (Handyside and Hunter, 1984, 1986). Newly expanded normally fertilized blastocysts on day 5 had a total of 58.3 +/− 8.1 cells, which increased to 84.4 +/− 5.7 and 125.5 +/− 19 on days 6 and 7, respectively. The numbers of TE cells were similar on days 5 and 6 (37.9 +/− 6.0 and 40.3 +/− 5.0, respectively) and then doubled on day 7 (80.6 +/− 15.2). In contrast, ICM cell numbers doubled between days 5 and 6 (20.4 +/− 4.0 and 41.9 +/− 5.0, respectively) and remained virtually unchanged on day 7 (45.6 +/− 10.2). There was widespread cell death in both the TE and ICM as evidenced by fragmenting nuclei, which increased substantially by day 7. These results are compared with the numbers of cells in morphologically abnormal blastocysts and blastocysts derived from abnormally fertilized embryos. The nuclei of arrested embryos were also examined. The number of TE and ICM cells allocated in normally fertilized blastocysts appears to be similar to the numbers allocated in the mouse. Unlike the mouse, however, the proportion of ICM cells remains higher, despite cell death in both lineages.

Formation and early development of follicles in the polycystic ovary

BACKGROUND

Polycystic ovary syndrome is the most common cause of anovulatory infertility. It has long-term health implications and is an important risk factor for type 2 diabetes. However, little is known about the cause of polycystic ovaries. We have used detailed morphological analysis to assess the hypothesis that there is an intrinsic ovarian abnormality that affects the earliest stages of follicular development.

METHODS

We took small cortical biopsies during routine laparoscopy from 24 women with normal ovaries and regular cycles and from 32 women with polycystic ovaries, 16 of whom had regular, ovulatory cycles and 16 of whom had oligomenorrhoea. We used computerised image analysis to assess the density and developmental stage of small preantral follicles in serial sections of fixed tissue.

FINDINGS

Median density of small preantral follicles, including those at primordial and primary stages, was six-fold greater in biopsies from polycystic ovaries in anovulatory women than in normal ovaries (p=0.009). In both ovulatory and anovulatory women with polycystic ovaries, we noted a significant increase in the percentage of early growing (primary) follicles and a reciprocal decrease in the proportion of primordial follicles compared with normal ovaries.

INTERPRETATION

Our findings indicate that there are fundamental differences between polycystic and normal ovaries in early follicular development, suggesting an intrinsic ovarian abnormality. The increased density of small preantral follicles in polycystic ovaries could result from increased population of the fetal ovary by germ cells, or from decreased rate of loss of oocytes during late gestation, childhood, and puberty.

Insulin glargine or NPH combined with metformin in type 2 diabetes: the LANMET study

AIMS/HYPOTHESIS

In type 2 diabetic patients we compared 9 months of combination therapy with insulin glargine and metformin with 9 months of NPH insulin combined with metformin. The primary focus was changes in HbA(1c); secondary focus was diurnal glucose profiles and symptomatic hypoglycaemia.

METHODS

In this investigator-initiated open, parallel-group clinical trial involving seven centres, 110 insulin-naive type 2 diabetic patients with poor glycaemic control (HbA(1c) >or=8.0%) on oral hypoglycaemic agents (90% using sulfonylurea plus metformin) were randomised to receive bedtime insulin glargine with metformin (G+MET) or bedtime NPH with metformin (NPH+MET) for 36 weeks. The patients were taught how to self-adjust their insulin dose and use a modem to send the results of home glucose monitoring to treatment centres. The goal was to achieve a fasting plasma glucose (FPG) of 4.0 to 5.5 mmol/l in both groups.

RESULTS

During the last 12 weeks, FPGs averaged 5.75+/-0.02 and 5.96+/-0.03 mmol/l (p<0.001) and insulin doses were 68+/-5 and 70+/-6 IU/day (0.69+/-0.05 and 0.66+/-0.04 IU kg(-1) day(-1), NS) in the G+MET and NPH+MET groups, respectively. At 36 weeks, mean HbA(1c) was 7.14+/-0.12 and 7.16+/-0.14%, respectively (NS). Symptomatic, but not confirmed symptomatic, hypoglycaemia was significantly lower during the first 12 weeks in the G+MET group (4.1+/-0.8 episodes/patient-year) than in the NPH+MET group (9.0+/-2.3 episodes/patient-year, p<0.05), but not significantly different thereafter. Glucose levels before dinner were higher in the NPH+MET group (10.1+/-0.3 mmol/l) than in the G+MET group (8.6+/-0.3 mmol/l, p=0.002) throughout the 36-week study. With regard to baseline characteristics such as initial glycaemia or C-peptide, there was no difference between patients who achieved good glycaemic control (HbA(1c) <7.0%) and those who did not. Differences were seen in the following: between study centres, weight gain during the run-in period and insulin therapy, and FPG during the last 12 weeks (5.7+/-0.2 vs 6.7+/-0.3 mmol/l for patients reaching vs those not reaching target, p<0.01).

CONCLUSIONS/INTERPRETATION

Good glycaemic control can be achieved with both G+MET and NPH+MET. Use of G+MET reduces symptomatic hypoglycaemia during the first 12 weeks and dinner time hyperglycaemia compared with NPH+MET.

Cell death in the mammalian blastocyst

Cell death is a widespread feature in the blastocysts of many mammals. Isolated cells in both the inner cell mass and the trophectoderm undergo cell death. These dying cells appear morphologically to be undergoing apoptosis. In mouse blastocysts, a wave of cell death is seen in vivo, suggesting that it plays an important role in normal development. However, cell death is increased under suboptimal culture conditions. There is evidence that levels of cell death are regulated by 'survival' factors produced both by the embryo itself and by the maternal reproductive tract. The role of cell death in development is unknown, but could involve the elimination of abnormal cells, or a sublineage of cells with an inappropriate developmental potential. Work in other systems has demonstrated that cell death is regulated by the activity of apoptosis genes. Whether these genes are implicated in blastocyst cell death, and the reasons for apoptosis in the early embryo, remain to be determined.

Human preimplantation development in vitro is not adversely affected by biopsy at the 8-cell stage

Normally fertilized human embryos biopsied 3 days after in-vitro fertilization (IVF) have been examined for effects on viability and development in vitro after removal of one or two cells at the 8-cell stage (1/8 and 2/8) from each embryo. A high proportion of 7/8 and 6/8 biopsied and unmanipulated embryos developed to the blastocyst stage between days 5 and 6 (79, 71 and 59%, respectively), and many biopsied embryos (56%) hatched from the zona pellucida in vitro. The viability of biopsied embryos which developed to the blastocyst stage was assessed by daily non-invasive measurement of the uptake of two energy substrates, glucose and pyruvate. Uptake of both substrates was generally lower in 7/8 and 6/8 biopsied embryos but only in proportion to the reduced cellular mass. The total cell number and the numbers of both trophectoderm (TE) and inner cell mass (ICM) cells in biopsied embryos at the blastocyst stage, counted by differential labelling of their nuclei, were also reduced in proportion but the ratio of ICM to TE cells was maintained in both 7/8 and 6/8 biopsied embryos. We conclude that removal of one or two cells at the 8-cell stage, while reducing the cellular mass, does not adversely affect the preimplantation/development of biopsied embryos in vitro and suggest that this approach could be used for preimplantation diagnosis of genetic defects.

Growth factor expression and function in the human and mouse preimplantation embryo

There is increasing evidence that even before implantation, human development is regulated by embryonically and maternally derived growth factors. Studies in other mammalian species have shown that growth factors and their receptors are expressed by the preimplantation embryo and the reproductive tract. Furthermore, a number of growth factors have been shown to affect rate of embryo development, the proportion of embryos developing to the blastocyst stage, blastocyst cell number, metabolism and apoptosis. Growth factor ligands and receptors are also expressed in human embryos and the maternal reproductive tract, and supplementation of culture medium with exogenous growth factors affects cell fate, development and metabolism of human embryos in vitro. Autocrine, paracrine and endocrine pathways that may operate within the embryo and between the embryo and the reproductive tract before implantation are proposed.

Apoptosis in the human embryo

Preimplantation human embryos are characterized by various degrees of cytoplasmic fragmentation, and a high incidence of developmental arrest before the blastocyst stage. This review examines the current morphological and biochemical evidence that apoptosis plays a role in early human development and embryonic loss. Embryos examined 24 h or more after arrest often show characteristic features of apoptosis including cytoplasmic, nuclear and DNA fragmentation. In contrast, embryos of good morphology that appear to be developing normally show no evidence of apoptosis before compaction. However, at the morula and blastocyst stages, scattered cells with fragmented nuclei and DNA characteristic of cells undergoing apoptosis are common features. Apoptosis may result from suboptimal culture conditions, or may be involved in the elimination of abnormal cells. However, the causes, role and regulation of apoptosis in the human preimplantation embryo remain to be determined.

Effects of follicle-stimulating hormone and serum substitution on the in-vitro growth of human ovarian follicles

In-vitro maturation (IVM) of human ovarian follicles and oocytes could benefit infertile women, and allow the development of in-vitro systems for the study of human follicular development. Little is known about the initiation of growth of primordial follicles and the regulation of early folliculogenesis. An ovarian tissue-slice culture system was used to examine the effects of media composition, follicle stimulating hormone (FSH) and serum substitution on the development of small human follicles in vitro. Human ovarian cortex biopsies were cut into small pieces and cultured for 5, 10 or 15 days. Control (non-cultured) and cultured tissue was fixed, serially sectioned, and stained. The follicles contained within the tissue pieces were counted, measured, and assessed for stage of development and viability. Comparison of the ability of alpha-minimum essential medium (alpha-MEM), Waymouth's, or Earle's balanced salt solution (EBSS) culture media (all with 10% human serum) to support follicle growth demonstrated significantly increased initiation and growth of follicles in alpha-MEM during the first 10 days of culture. The supplementation of alpha-MEM with 300 mIU/ml FSH significantly reduced levels of atresia and increased the mean diameter of healthy follicles. Follicles in tissue cultured for 10 days with human serum albumin and ITS (insulin/transferrin/selenium mix) were significantly larger, more developed and showed significantly less atresia than those cultured with serum alone. Primordial to small preantral follicles can be grown under serum-substituted conditions in tissue-slice culture, and are responsive to FSH, which is thought to be acting mainly as a survival factor at these early stages.

Human primordial, primary and secondary ovarian follicles in long-term culture: effect of partial isolation

Ovarian cortical tissue, donated by 20 women aged 25-43 years during gynaecological laparoscopies or laparotomies, was first cultured for 7-9 days as tissue slices, 0.1-0.3 mm in thickness, in extracellular matrix, to initiate the growth of the primordial and primary follicles. It was then divided into two parts, one of which was cultured further as slices, and the other one used for enzymatic (collagenase at 1, 0.5 or 0.25 mg/ml; 17 patients) or mechanical (four patients) partial isolation of the follicles. The tissue slices and the partially isolated follicles were cultured for a further 1-3 weeks in the matrix. After approximately 2 weeks in culture, some oocytes began to extrude from the follicles, which were usually at the secondary stage. They were small, 20-80 micrometer in diameter, and had a thin or absent zona. Polar bodies and meiotic chromosomes could be seen in these naked oocytes. This premature extrusion probably resulted from sub-optimal culture conditions. It occurred sooner in follicles that had been partially isolated using collagenase. Histologically, larger numbers of oocytes were observed in non-isolated slice cultures than in the partially isolated cultures. Initiation of growth of the follicles occurred during the first 7-9 days in culture within slices. In non-isolated slices and following mechanical partial isolation there were significantly more secondary follicles after 11-18 days in culture than following isolation with collagenase. The proportion of atretic follicles increased during all cultures, and it was significantly higher after partial isolation. Because partial isolation did not improve the survival or development of the follicles the optimal method for human ovarian follicles could be to culture them non-isolated within small tissue slices.

Presynaptic dopaminergic deficits in Lesch-Nyhan disease

BACKGROUND

Lesch-Nyhan disease is a rare, devastating, X-linked recessive disorder of purine synthesis. Patients present with hyperuricemia, choreoathetosis, dystonia, and aggressive and self-injurious behavior. Although the genetic and biochemical abnormalities have been identified, the causes of the neuropsychiatric syndrome remain unclear.

METHODS

We used positron-emission tomography to measure presynaptic accumulation of fluorodopa F 18 tracer in the dopaminergic regions of the brains of 12 patients with Lesch-Nyhan disease (age, 10 to 20 years) and 15 healthy controls (age, 12 to 23). The results were expressed as ratios of specific to nonspecific radioactive counts. A low ratio indicates decreased dopa decarboxylase activity and dopamine storage.

RESULTS

The fluorodopa F 18 ratio was significantly lower in the putamen (31 percent of control values), caudate nucleus (39 percent), frontal cortex (44 percent), and ventral tegmental complex (substantia nigra and ventral tegmentum; 57 percent) in the patients with Lesch-Nyhan disease than in the controls. Uptake of the tracer was abnormally low even in the youngest patients tested, and there was no overlap in the values between patients and controls.

CONCLUSIONS

Patients with Lesch-Nyhan disease have abnormally few dopaminergic nerve terminals and cell bodies. The abnormality involves all dopaminergic pathways and is not restricted to the basal ganglia. These dopaminergic deficits are pervasive and appear to be developmental in origin, which suggests that they contribute to the characteristic neuropsychiatric manifestations of the disease.

Impaired insulin-dependent glucose metabolism in granulosa-lutein cells from anovulatory women with polycystic ovaries

BACKGROUND

Insulin resistance and hyperinsulinaemia are well-recognized characteristics of anovulatory women with polycystic ovary syndrome (PCOS) but, paradoxically, steroidogenesis by PCOS granulosa cells remains responsive to insulin. The hypothesis to be tested in this study is that insulin resistance in the ovary is confined to the metabolic effects of insulin (i.e. glucose uptake and metabolism), whereas the steroidogenic action of insulin remains intact.

METHODS

Granulosa-lutein cells were obtained during IVF cycles from seven women with normal ovaries, six ovulatory women with PCO (ovPCO) and seven anovulatory women with PCO (anovPCO). Mean body mass index was in the normal range in all three groups. Granulosa-lutein cells were cultured with insulin (1, 10, 100 and 1000 ng/ml) and LH (1, 2.5 and 5 ng/ml). Media were sampled at 24 and 48 h and analysed for glucose uptake, lactate production and (48 h only) progesterone production.

RESULTS

Insulin-stimulated glucose uptake by cells from anovPCO was attenuated at higher doses of insulin (100 and 1000 ng/ml) compared with that by cells from either ovPCO (P=0.02) or controls (P=0.02). Insulin and LH stimulated lactate production in a dose-dependent manner, but insulin-dependent lactate production was markedly impaired in granulosa-lutein cells from anovPCO compared with either normal (P=0.002) or ovPCO (P<0.0001). By contrast, there was no difference in insulin-stimulated progesterone production between granulosa-lutein cells from the three ovarian types.

CONCLUSIONS

Granulosa-lutein cells from women with anovPCOS are relatively resistant to the effects of insulin-stimulated glucose uptake and utilization compared with those from normal and ovPCO, whilst maintaining normal steroidogenic output in response to physiological doses of insulin. These studies support the probability of a post-receptor, signalling pathway-specific impairment of insulin action in PCOS.

Non-invasive measurement of glucose and pyruvate uptake by individual human oocytes and preimplantation embryos

Pyruvate and glucose uptake by 73 individual human oocytes and preimplantation embryos was measured non-invasively, using an ultramicrofluorescence assay to analyse changes in substrate levels in microdroplets of culture medium. The uptake of both substrates was measured over successive daily incubations between days 1 (unfertilized oocytes) or 2 ('spare' embryos which were not transferred) and day 6 (day 0 = day of insemination). Under these conditions, 58% (25/43) of fertilized embryos with two pronuclei on day 1 developed to the blastocyst stage by day 6. The pyruvate uptake of these embryos increased from approximately 28 to a maximum of 40 pmol/embryo/h between days 2.5 and 4.5. Similarly, glucose uptake increased from approximately 8 to 14 pmol/embryo/h between days 2.5 and 4.5, but then increased further to 24 pmol/embryo/h on day 5 at the blastocyst stage. [corrected] The pyruvate uptake of fertilized embryos which arrested at cleavage stages was significantly lower than for those which developed to the blastocyst stage. Polyspermic and parthenogenetic embryos, and unfertilized oocytes also had lower pyruvate uptakes at later stages. The glucose uptake of unfertilized oocytes and abnormal embryos never reached the level of fertilized embryos at the blastocyst stage on day 5.5. Non-invasive measurement of pyruvate uptake before embryo transfer may provide a valuable functional criterion for the selection of viable embryos capable of developing to the blastocyst stage.

Plasmid-determined silver resistance in Pseudomonas stutzeri isolated from a silver mine

A silver-resistant strain of Pseudomonas stutzeri was isolated from a silver mine. It harbored three plasmids, the largest of which (pKK1; molecular weight, 49.4 X 10(6)) specified silver resistance. Plasmid pKK1 was apparently nonconjugative but could be transferred to Pseudomonas putida by mobilization with plasmid R68.45.

From cell death to embryo arrest: mathematical models of human preimplantation embryo development

Human preimplantation embryos exhibit high levels of apoptotic cells and high rates of developmental arrest during the first week in vitro. The relation between the two is unclear and difficult to determine by conventional experimental approaches, partly because of limited numbers of embryos. We apply a mixture of experiment and mathematical modeling to show that observed levels of cell death can be reconciled with the high levels of embryo arrest seen in the human only if the developmental competence of embryos is already established at the zygote stage, and environmental factors merely modulate this. This suggests that research on improving in vitro fertilization success rates should move from its current concentration on optimizing culture media to focus more on the generation of a healthy zygote and on understanding the mechanisms that cause chromosomal and other abnormalities during early cleavage stages.

Modulation of A(beta) peptides by estrogen in mouse models

Clinical studies have shown that estrogen deprivation through menopause is a risk factor in both the initiation and progression of Alzheimer's disease (AD) and that estrogen replacement therapy may be protective. One of the major pathological features in the human AD brain is the senile plaque, a proteinaceous structure composed mainly of heterogeneous peptides collectively known as A-beta (A(beta)). In vitro studies have linked estrogen with A(beta) modulation, suggesting that one-way that estrogen depletion at menopause may exacerbate the features of AD is through A(beta) accumulation. To test this, two studies were performed on transgenic models of amyloidosis. Firstly, transgenic mice without detectable amyloid aggregates were subjected to ovariectomy and estradiol supplementation, and A(beta) levels were assessed. Secondly, the effects of estrogen modulation were assessed in mice at an age when plaques would be forming initially. Overall, A(beta) levels were higher in estrogen-deprived mice than intact mice, and this effect could be reversed through the administration of estradiol. These data suggest that, in vivo, estrogen depletion leads to the accumulation of A(beta) in the CNS, which can be reversed through replacement of estradiol. These results provide evidence that post-menopausal estrogen depletion may be linked to an increased risk of AD through A(beta) modulation.

Anti-apoptotic action of insulin-like growth factor-I during human preimplantation embryo development

Insulin-like growth factor I (IGF-I) has been shown to increase the proportion of embryos forming blastocysts and the number of inner cell mass cells in human and other mammalian preimplantation embryos. Here we examined whether the increased cell number resulted from increased cell division or decreased cell death. Normally fertilized, Day 2 human embryos of good morphology were cultured to Day 6 in glucose-free Earle's balanced salt solution supplemented with 1 mM glutamine, with (n = 42) and without (n = 45) 1.7 nM IGF-I. Apoptotic cells in Day 6 blastocysts were identified using terminal deoxynucleotidyl dUTP terminal transferase (TUNEL) labeling to detect DNA fragmentation and 4'-6-diamidino-2-phenylindole (DAPI) counterstain to evaluate nuclear morphology. The number of nuclei and extent of DNA and nuclear fragmentation was assessed using laser scanning confocal microscopy. IGF-I significantly increased the proportion of embryos developing to the blastocyst stage from 49% (control) to 74% (+IGF-I) (P < 0.05). IGF-I also significantly decreased the mean proportion of apoptotic nuclei from 16.3 +/- 2.9% (-IGF-I) to 8.7 +/- 1.4% (+IGF-I) (P < 0.05). The total number of cells remained similar between both groups (61.7 +/- 4.6 with IGF-I; 54.5 +/- 5.1 without IGF-I). The increased number of blastocysts combined with reduced cell death suggests that IGF-I is rescuing embryos in vitro which would otherwise arrest and acting as a survival factor during preimplantation human development.

Recombinant human growth hormone, insulin-like growth factor 1, and combination therapy in AIDS-associated wasting. A randomized, double-blind, placebo-controlled trial

OBJECTIVE

To increase lean body mass and improve health status in patients with wasting associated with the acquired immunodeficiency syndrome (AIDS) by treatment with recombinant human growth hormone (rhGH), recombinant human insulin-like growth factor 1 (rhIGF-1), or both.

DESIGN

Randomized, double-blind, placebo-controlled clinical trial.

SETTING

University of New Mexico Clinical Research Center and University of Texas Southwestern Medical Center.

PATIENTS

60 patients with AIDS and wasting as defined by the Centers for Disease Control and Prevention. Patients were divided into four groups of 15 patients each.

INTERVENTION

Group 1 received 1.4 mg of rhGH once daily plus placebo twice daily; group 2 received 5 mg of rhIGF-1 twice daily plus placebo once daily; group 3 received 5 mg of rhIGF-1 twice daily plus 1.4 mg of rhGH once daily; and group 4 received placebo three times daily.

MEASUREMENTS

Body weight, body composition, muscle strength, protein catabolism, quality of life, and immune status were assessed at baseline, and changes in these variables were measured at 6 and 12 weeks.

RESULTS

At 6 weeks, lean body mass had increased and total fat mass had decreased in the groups receiving rhGH, rhIGF-1, or both. Group 3 had the greatest changes in lean body mass (mean +/- SE, 3.2 +/- 0.59 kg; P < 0.001); only in this group were changes in body mass maintained at 12 weeks. Only patients in group 1 had improvement in muscular strength of the knees and upper body (P = 0.04) and quality of life (P = 0.01). Immunologic function did not improve in any group.

CONCLUSIONS

Growth factor therapy had significantly increased lean body mass and decreased fat mass by 6 weeks, but these improvements persisted for 12 weeks only in group 3. Growth factor therapy at the dosages used in this study is not recommended because the magnitude of weight gain was modest and improvements in quality-of-life measures varied.

Routine addition of human insulin-like growth factor-I ligand could benefit clinical in-vitro fertilization culture

Animal studies suggest that the insulin-like growth factors play an important role in preimplantation embryo development. Human preimplantation embryos express mRNA for insulin-like growth factor-I receptor (IGF-IR) but the ligand, insulin-like growth factor-I (IGF-I), is not expressed by the embryo until after implantation. We tested the hypothesis that IGF-I produced by the female reproductive tract may bind to these receptors, augmenting embryo survival, growth and development. Transcripts of mRNA for IGF1 were detected using reverse transcription-polymerase chain reaction in midcycle human Fallopian tube. Immunohistochemistry localized immunoreactive IGF-I to the cytoplasm of all the major structures of the Fallopian tube, with the most intense staining seen in the tubal epithelial lining. Maternally produced IGF-I was present in the fluid found in the human tube and uterus at concentrations of 8.0 and 10.9 nM respectively. Supplementation of culture medium with IGF-I increased the proportion of embryos developing to the blastocyst stage from 35% in controls to 60% in the presence of IGF-I. In addition the total number of cells in day 6 blastocysts was increased by 19% (64.44 versus 54.08% in control, not significant), due entirely to a statistically significant 59% increase (25 versus 15.75%, P = 0.020) in the number of cells in the inner cell mass. The effect of IGF-I was mediated through the IGF-I receptor. Immunocytochemistry using an alphaIR3 antibody confirmed the presence of IGF-I receptor in human blastocysts and the same antibody completely inhibited the stimulation of blastocyst formation by IGF-I. These data suggest that human preimplantation development is enhanced by maternal IGF-I. Mimicking this in-vivo paracrine relationship may improve clinical in-vitro embryo culture and IVF pregnancy rates.

Selection criteria for human embryo transfer: a comparison of pyruvate uptake and morphology

PURPOSE

Pyruvate uptake is higher in human embryos developing to the blastocyst stage than those arresting at cleavage stages. To investigate whether pyruvate uptake provides an improved criterion for selecting embryos for transfer, we have measured uptakes by individual embryos noninvasively over 24-hr periods between the first day (day 1) postinsemination and embryo transfer on day 2 to 3 and correlated the levels with implantation and pregnancy outcome.

RESULTS

The mean uptake was significantly lower for embryos that implanted than for those which failed to implant: 22.9 +/- 1.0 and 27.1 +/- 0.6 pmol/embryo/hr, respectively on day 2, and 22.4 +/- 1.5 and 26.9 +/- 0.8 pmol/embryo/hr, respectively, on day 3, but the wide range of uptakes by individual embryos was overlapping.

CONCLUSION

We conclude that pyruvate uptake as the sole criterion for embryo selection cannot predict which embryos will implant after transfer. Assessment of embryos using morphological and developmental criteria, therefore, remains the most consistent, though inefficient, indicator of pregnancy potential.

Inhibition of human neutrophil beta2-integrin-dependent adherence by hyperbaric O2

Animal and clinical investigations have reported that exposure to hyperbaric O(2) improved the outcome of some reperfusion injuries. Animal studies have suggested that this may be due to an inhibition of leukocyte adherence to injured endothelium. This investigation tested the hypothesis that exposure to hyperbaric O(2) would inhibit beta2-integrin-dependent adherence of human neutrophils. Subjects were exposed to O(2) at partial pressures of up to 3 atmospheres absolute (ATA; 1 ATA = 0.1 MPa) for 45 min, and neutrophil binding to nylon columns and to fibrinogen-coated surfaces was measured. Exposure to O(2) at 2.8 or 3.0 ATA inhibited beta2-integrin-dependent neutrophil adherence but had no effect on the cell-surface expression of beta2-integrins, respiratory burst in response to phorbol ester, or non-beta2-integrin-dependent adherence to plastic plates coated with a fibronectin-like protein. beta2-Integrin adherence was restored by incubating blood with 8-bromoguanosine 3',5'-cyclic monophosphate (cGMP) and hyperbaric O(2) inhibited synthesis of cGMP by neutrophils stimulated with N-formyl-Met-Leu-Phe (FMLP). In studies of cell fractions, the activity of membrane guanylate cyclase was found to be increased by incubation with FMLP as well as by atrial natriuretic peptide (ANP) plus ATP. Hyperbaric O(2) had no effect on the basal activity of soluble or membrane-bound guanylate cyclase. However, hyperbaric O(2) inhibited the function of both the extracellular binding domain of membrane guanylate cyclase as well as intracellular catalytic activity. There are approximately 7,300 membrane guanylate cyclase molecules per cell, based on binding studies with ANP, with a dissociation constant of approximately 450 pM. Hyperbaric O(2) inhibits the function of human neutrophil beta2-integrins by a process linked to impaired synthesis of cGMP.

Non-invasive measurement of pyruvate and glucose uptake and lactate production by single human preimplantation embryos

The consumption of pyruvate and glucose and the production of lactate by 40 single human preimplantation embryos has been measured using a non-invasive technique. Twelve of the embryos showed abnormal fertilization. Of the 28 normally fertilized embryos, nine (32%) developed to the blastocyst stage in culture while the remainder degenerated or arrested during cleavage. In the normal embryos, pyruvate uptake exceeded that of glucose in the early developmental stages (days 2-5 post-insemination) before glucose became the predominant substrate in the blastocyst (day 6). Considerable quantities of lactate were formed throughout development, rising from a value of 43.6 pmol/embryo/h on day 2.5 to 95.4 pmol/embryo/h on day 5.5. The values of pyruvate and glucose uptake and lactate production of those embryos which arrested were below those which developed normally. On the basis that one mole of glucose can give rise to two moles of lactate, only 50% of the lactate produced could be accounted for in terms of glucose uptake from the medium. This figure rose to 90% in the blastocyst. The remaining lactate must be derived from endogenous sources, most probably glycogen. It is proposed that the high production of lactate by human preimplantation embryos in vitro is an adaptation to the conditions of culture.

Binucleate blastomeres in preimplantation human embryos in vitro: failure of cytokinesis during early cleavage

The nuclei of disaggregated blastomeres from two hundred preimplantation human embryos were examined between days 2 and 4 after insemination in vitro by vital labelling with a polynucleotide-specific fluorochrome. Although the majority of blastomeres had a single nucleus, binucleate blastomeres containing two nuclei of equal size were common and other blastomeres had fragmented nuclei or were anucleate. Seventeen per cent of normally fertilized embryos at two- to four-cell stage had at least one binucleate blastomere, and this increased to 65% at the nine- to 16-cell stage when individual embryos had between one and six binucleate blastomeres. The proportion of binucleate blastomeres in normally fertilized embryos increased from 5 to 10% over this period, whereas in abnormally fertilized, polyspermic or parthenogenetic, embryos the proportion was significantly higher during early cleavage stages but decreased at the nine- to 16-cell stage when the majority of these embryos arrest (25 and 6%, respectively). The incidence of anucleate blastomeres in normally fertilized embryos was also high, especially in those of poor morphology. In contrast, blastomeres with fragmented nuclei were relatively uncommon and the incidence was variable among classes and stages of development. Estimates of the volume of binucleate blastomeres based on measurement of their diameters and comparison with mononucleate blastomeres at various cleavage stages indicated that these blastomeres arise from a failure of cytokinesis between the second and fourth cleavage divisions. On this basis, assignment of binucleate blastomeres to particular cleavage stages in normally fertilized day 4 embryos suggests that at least some of these blastomeres arising during early cleavage persist without further cell division for up to 48 h. At the cellular level, therefore, blastomeres with either binucleate or abnormal nuclei contribute to cleavage stage arrest in vitro.