A Novel Approach to Predicting Early Pregnancy Outcomes Dynamically in a Prospective Cohort Using Repeated Ultrasound and Serum Biomarkers

This study aimed to develop a dynamic model for predicting outcome during the first trimester of pregnancy using baseline demographic data and serially collected blood samples and transvaginal sonographies. A prospective cohort of 203 unselected women with an assumed healthy pregnancy of < 8 weeks' gestation was followed fortnightly from 4-14 weeks' gestation until either miscarriage or confirmed first trimester viability. The main outcome was development of a model to predict outcome from gestational age-dependent hazard ratios using both baseline and updated serial data from each visit. Secondary outcomes were descriptions of risk factors for miscarriage. The results showed that 18% of the women experienced miscarriages. A fetal heart rate detected before 8 weeks' gestation indicated a 90% (95% CI 85-95%) chance of subsequent delivery. Maternal age (≥ 35 years), insufficient crown-rump-length (CRL) and mean gestational sac diameter (MSD) development, and presence of bleeding increased the risk of miscarriage. Serum biomarkers, including hCG, progesterone, and estradiol, were found to impact the risk of miscarriage with estradiol as the most important. The best model to predict miscarriage was a combination of maternal age, vaginal bleeding, CRL, and hCG. The second-best model was the sonography-absent model of maternal age, bleeding, hCG, and estradiol. This study suggests that combining maternal age, and evolving data from hCG, estradiol, CRL, and bleeding could be used to predict fetal outcome during the first trimester of pregnancy.Trial registration ClinicalTrials.gov identifier: NCT02761772.

Cell-free fetal DNA for genetic evaluation in Copenhagen Pregnancy Loss Study (COPL): a prospective cohort study

BACKGROUND

One in four pregnancies end in a pregnancy loss. Although the effect on couples is well documented, evidence-based treatments and prediction models are absent. Fetal aneuploidy is associated with a higher chance of a next successful pregnancy compared with euploid pregnancy loss in which underlying maternal conditions might be causal. Ploidy diagnostics are therefore advantageous but challenging as they require collection of the pregnancy tissue. Cell-free fetal DNA (cffDNA) from maternal blood has the potential for evaluation of fetal ploidy status, but no large-scale validation of the method has been done.

METHODS

In this prospective cohort study, women with a pregnancy loss were recruited as a part of the Copenhagen Pregnancy Loss (COPL) study from three gynaecological clinics at public hospitals in Denmark. Women were eligible for inclusion if older than 18 years with a pregnancy loss before gestational age 22 weeks (ie, 154 days) and with an intrauterine pregnancy confirmed by ultrasound (including anembryonic sac), and women with pregnancies of unknown location or molar pregnancies were excluded. Maternal blood was collected while pregnancy tissue was still in situ or within 24 h after pregnancy tissue had passed and was analysed by genome-wide sequencing of cffDNA. Direct sequencing of the pregnancy tissue was done as reference.

FINDINGS

We included 1000 consecutive women, at the time of a pregnancy loss diagnosis, between Nov 12, 2020, and May 1, 2022. Results from the first 333 women with a pregnancy loss (recruited between Nov 12, 2020, and Aug 14, 2021) were used to evaluate the validity of cffDNA-based testing. Results from the other 667 women were included to evaluate cffDNA performance and result distribution in a larger cohort of 1000 women in total. Gestational age of fetus ranged from 35-149 days (mean of 70·5 days [SD 16·5], or 10 weeks plus 1 day). The cffDNA-based test had a sensitivity for aneuploidy detection of 85% (95% CI 79-90) and a specificity of 93% (95% CI 88-96) compared with direct sequencing of the pregnancy tissue. Among 1000 cffDNA-based test results, 446 (45%) were euploid, 405 (41%) aneuploid, 37 (4%) had multiple aneuploidies, and 112 (11%) were inconclusive. 105 (32%) of 333 women either did not manage to collect the pregnancy tissue or collected a sample classified as unknown tissue giving a high risk of being maternal.

INTERPRETATION

This validation of cffDNA-based testing in pregnancy loss shows the potential and feasibility of the method to distinguish euploid and aneuploid pregnancy loss for improved clinical management and benefit of future reproductive medicine and women's health research.

FUNDING

Ole Kirks Foundation, BioInnovation Institute Foundation, and the Novo Nordisk Foundation.

Early pregnancy reference intervals; 29 serum analytes from 4 to 12 weeks' gestation in naturally conceived and uncomplicated pregnancies resulting in live births

Background Pregnancy introduces major physiological changes that also alter biochemical analytes. Maternal and perinatal health can be optimized by early intervention and therefore, pregnancy-specific reference intervals (RIs) for the local population are warranted. While the second and third trimester-specific changes are well described, the first trimester is less well characterized. We therefore wanted to facilitate early detection of abnormalities by generating first trimester reference values for 29 common analytes. Methods In a prospective early pregnancy (PEP) cohort (2016-2017), 203 pregnant women were recruited from 4 to 8 weeks' gestation. Consecutive blood samples were drawn every 2 weeks until an ongoing second trimester pregnancy (n = 164) or a miscarriage (n = 39) occurred. After exclusion of women with complicated pregnancies or deliveries (n = 42), 122 women were included. The serum samples collected at <6, 6-8, 8-10, 10-12 and >12 weeks' gestation were analyzed for 29 common analytes. Subsequently the RIs were calculated according to the International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) recommendations (2.5-97.5th percentiles) and compared with the conventional RIs for non-pregnant women. Results Human chorionic gonadotropin (hCG), progesterone (P4), estradiol (E2), pregnancy-associated plasma protein A (PAPP-A), cancer antigen 125 (CA125), thyroid stimulating hormone (TSH), creatinine (CREA) and albumin (ALB) showed an early pregnancy-dependent change compared with conventional limits. For ALB the change was seen at 5.5 weeks' gestation. Conclusions We report gestational age-specific RIs available from the early part of the first trimester applicable to everyday clinical care of pregnant women. Well-known alterations of RIs seen in later trimesters are also observed in the first.

Cost-utility of an eHealth application 'Oncokompas' that supports cancer survivors in self-management: results of a randomised controlled trial

Purpose

The eHealth self-management application ‘Oncokompas’ was developed to support cancer survivors in monitoring health-related quality of life (HRQOL) and symptoms, and obtaining personalized feedback and options for supportive care. The aim of this study was to assess the cost-utility of Oncokompas compared with care as usual (CAU) among cancer survivors.

Methods

Survivors were randomly allocated to the intervention or control group. Direct (non-)medical, indirect non-medical costs, and HRQOL were measured at 3- and 6-month follow-up, using iMTA Medical Consumption and Productivity Costs and the EuroQol-5D questionnaires. Mean cumulative costs and quality-adjusted life-years (QALYs) were compared between both groups.

Results

In total, 625 survivors were randomized into intervention (n = 320) or control group (n = 305). Base case analysis showed that incremental costs from a societal perspective were − €163 (95% CI, − 665 to 326), and incremental QALYs were 0.0017 (95% CI, − 0.0121 to 0.0155) in the intervention group compared with those in the control group. The probability that, compared with CAU, Oncokompas is more effective was 60%, less costly 73%, and both more effective and less costly 47%. Sensitivity analyses showed that incremental costs vary between − €40 and €69, and incremental QALYs vary between − 0.0023 and − 0.0057.

Conclusion

Oncokompas is likely to be equally effective on utilities, and not more expensive than CAU, and will therefore contribute to sustainable cancer survivorship care in a (cost-)effective manner.

Implications for Cancer Survivors

Oncokompas seems to improve HRQOL and reduces the burden of several tumour-specific symptoms, while costs from a societal perspective are similar to CAU.

Electronic supplementary material

The online version of this article (10.1007/s11764-020-00912-9) contains supplementary material, which is available to authorized users.

Soluble urokinase plasminogen activator receptor (suPAR) as a biomarker of early pregnancy location and viability compared with hCG, progesterone and estradiol

A circulating biomarker of early pregnancy outcome independent of ultrasonography and gestational age is a coveted goal. This study evaluated soluble urokinase plasminogen activator receptor (suPAR), a well-described marker of inflammation and immunological activation, for this purpose, and compared it with established early pregnancy biomarkers of the luteoplacental phase: progesterone, estradiol and hCG. We merged data from two prospective first trimester cohorts to conduct a case-control study comparing these analytes in women who had either a live birth, a miscarriage or an ectopic pregnancy. The ability to predict pregnancy location and viability was assessed by areas under the receiver operating characteristic curves (AUC). Comparing women irrespective of gestational age with a live birth, miscarriage or ectopic pregnancy showed significantly lower suPAR values in the latter group (2.4 vs. 2.4 vs. 2.0 μg/L, p = 0.032, respectively), as were all other analytes. Before 6 weeks' gestation, suPAR was significantly inferior to progesterone, estradiol and hCG in pregnancy location and viability prediction (in 124 pregnancies, suPAR AUC_location = 0.69 [CI: 0.54-0.83] and AUC_viability = 0.58 [CI: 0.48-0.69], while progesterone AUC_location = 0.95 [CI: 0.87-1.00] and AUC_viability = 0.84 [CI: 0.75-0.92]). After 6 weeks' gestation, suPAR prediction improved but was inferior to hCG, progesterone and estradiol (in 188 pregnanices, suPAR AUC_location = 0.71 [CI: 0.63-0.78] and AUC_viability = 0.70 [CI: 0.63-0.78] compared with hCG AUC_location = 0.96 [CI: 0.93-0.99] and AUC_viability = 0.96 [CI: 0.93-0.98]). Collectively, suPAR is less useful as a predictor of early pregnancy outcome than hCG, progesterone and estradol.

Induction of labor with high- or low-dosage oral misoprostol-A Danish descriptive retrospective cohort study 2015-16

INTRODUCTION

In Denmark, the rate of induced labor from 37 gestational weeks has increased by 108% from 12.4% in 2000 to 25.1% in 2012, and today more than 1 in 4 deliveries are induced. Standard procedure at North Zealand Hospital changed in 2016 from a dosage of 50 µg oral misoprostol 2-3 times daily, to 25 µg up to 8 times daily. Also, since 2016 healthy women with uncomplicated pregnancies (primiparous and multiparous) have been offered induction as an outpatient procedure. This study aimed to compare the current low-dosage procedure (25 µg) with the former high-dosage procedure (50 µg) in terms of induction to delivery time, maternal and fetal outcomes, and risk of uterine hyperstimulation.

MATERIAL AND METHODS

Data from June 2015 to October 2016 were included. Comparable baseline, demographic, and obstetric data for women induced according to high-dosage or low-dosage protocols were retrieved from local medical files. Descriptive statistics, Pearson's chi-squared tests, Kaplan-Meier survival estimates, and logistic regression analyses were performed.

RESULTS

The study included 816 induced deliveries. The high- and low-dosage groups differed in rates of plurality and place of induction. Induction to delivery times lasting longer than 72 hours were significantly decreased in the low-dosage group (adjusted odds ratio [aOR] 0.48, 95% confidence interval [95% CI] 0.27 to 0.86). Women in the low-dosage group also less often needed additional induction (P = 0.02), and the rate of uterine hyperstimulation was low irrespective of protocol (1% vs 3%, P = 0.16). There were no cases of uterine rupture in either group. The probability of vaginal delivery in the low-dosage group increased (adjusted hazard ratio 1.27, 95% CI 1.08 to 1.49), as did the risk of delivery with vacuum extraction (aOR 2.27, 95% CI 1.24 to 4.15), whereas delivery by cesarean section slightly decreased (aOR 0.89, 95% CI 0.59 to 1.33). The risk of meconium-stained liquor was nonsignificantly decreased (aOR 0.82, 95% CI 0.55 to 1.23).

CONCLUSIONS

The low-dosage induction protocol was associated with favorable obstetric outcomes in terms of increased probability of vaginal delivery, but with higher risk of vacuum extraction. Protracted inductions and additional nonmedical interventions were reduced. There were no cases of uterine rupture. Statistically nonsignificant, the risk of uterine hyperstimulation was increased whereas the risk of meconium-stained liquor and of cesarean section was slightly decreased.

The aesthetic nature of the birthing room environment may alter the need for obstetrical interventions - an observational retrospective cohort study

The concept of sensory delivery rooms was introduced in 2013. These rooms offer programmable calming lights, restful blurred pictures displayed on a wall-sized big screen, and sound effects. The primary aim of this observational study was to analyse the risk of obstetrical interventions among women giving birth for the first-time in a sensory delivery room vs. a standard delivery room. We included nulliparous, term pregnant women having a single baby with a cephalic presentation who were in spontaneous labour and gave birth between March 1st 2014 and July 1st 2015 in North Zealand Hospital, Hillerød. A total of 789 women were included in the study, 313 gave birth in a sensory room and 476 in a standard delivery room. The risk of a caesarean delivery was significantly decreased when giving birth in a sensory room compared with a standard delivery room (OR, multiple adjusted: 0.44; 95% CI 0.22-0.87); furthermore, the use of oxytocin infusion was also reduced (OR, multiple adjusted: 0.71; 95% CI 0.50-1.03). This observational cohort study suggests that giving birth in a sensory delivery room could lower the risk of caesarean delivery, potentially reducing the number of such deliveries by one for every 23 patients.

Luteal phase progesterone and oestradiol after ovarian stimulation: relation to response and prediction of pregnancy

Research has focused on optimizing luteal phase support and endometrial receptivity in ovarian stimulation cycles. In this study, serial endocrine measurements were taken in 600 patients after a gonadotrophin-releasing hormone antagonist stimulation protocol. On the day of blastocyst transfer, serum progesterone and oestradiol were similar irrespective of a subsequent positive or negative pregnancy test (median 99 ng/ml versus 103 ng/ml for progesterone, respectively) or a subsequent live birth or pregnancy loss. Serum progesterone was significantly correlated to each ovarian response parameter (total number of follicles, number of oocytes retrieved and oestradiol concentration; r = 0.45, 0.57 and 0.54 respectively, all P < 0.0001). These correlations were consistent irrespective of clinical outcome. On the day of the pregnancy test, these correlations had vanished except in the live birth subgroup showing a weaker correlation (r = 0.22, 0.27 and 0.32 respectively, all P < 0.005). The lowest HCG and progesterone levels associated with live birth were 59.3 IU/l and 12.3 ng/ml, respectively. Fourteen out of 92 patients (15.2%) with pregnancy loss had normal HCG but low progesterone levels (above and below their respective 5th percentile), and miscarried before the end of the 7th week, when the luteal-placental shift occurs.

[Spontaneous bilateral tubal pregnancy following caesarean section]

We describe a rare case of bilateral tubal pregnancy following natural conception in a woman with no other known risk factor than two former caesarean sections. Intraabdominal adhesions following the caesarean sections complicated the salpingectomy thus diminishing certainty of a healthy contralateral tube. The woman was readmitted three weeks later and had an additional salpingectomy on behalf of an unrecognized tubal pregnancy. Considering the rising caesarean section rates clinicians need to be certain of no additional ectopic pregnancy while performing the primary operation.

Combined hormonal contraception and risk of venous thromboembolism within the first year following pregnancy. Danish nationwide historical cohort 1995-2009

Estimating the risk of venous thromboembolism (VTE) associated with combined hormonal contraceptives following early terminated pregnancies or birth, a Danish nationwide retrospective cohort observing a one-year follow-up was defined using three unique registries. All Danish women with confirmed pregnancies aged 15-49 during the period of 1995-2009 were included. The main outcomes were relative and absolute risks of first time venous thromboembolism in users as well as non-users of combined hormonal contraceptives. In 985,569 person-years, 598 venous thromboembolisms were recorded. After early terminated pregnancies and births, respectively, 113 and 485 events occurred in 212,552 and 773,017 person-years. After early terminated pregnancies, the crude VTE incidence ratios were similar, and the numbers needed to harm were equal between groups that did or did not use combined hormonal contraceptives throughout the follow-up year. After childbirth, individuals that used combined hormonal contraceptives were more likely than non-users to experience VTE depicted by crude incidence ratios; however, the difference was only significant after 14 weeks. This implied that the numbers needed to harm were lower for those that used compared to those that did not use combined oral contraceptives in the initial 14 weeks postpartum. In conclusion, the use of combined hormonal contraceptives after early terminated pregnancies was not detrimental, but during the puerperal period, they should be used with caution.

Safe induction of labour with low-dose misoprostol, but less effective than the conventional dinoprostone regimen

INTRODUCTION

Off-label use of the prostaglandin-E1 analogue misoprostol has become standard practice when inducing labour. In Denmark, a low-dosage misoprostol regimen is common. The regimen consists of one 25 µg application on the first day of induction. The registered prostaglandin-E2 analogue dinoprostone is used in 3 and 6 mg doses. This study compared induction procedures with dinoprostone and misoprostol in terms of induction time, foetal outcome and maternal outcome.

MATERIAL AND METHODS

This retrospective study included 1,645 induced deliveries from two periods: 2003-2005, when dinoprostone was standard treatment (n = 635), and 2008-2010, when misoprostol was standard treatment (n = 633). We evaluated the induction method, outcomes and confounders using Kaplan-Meier, Cox and logistic regression analyses.

RESULTS

In the first 24 h, 38% and 59% of women delivered in the misoprostol and dinoprostone groups, respectively. Compared with dinoprostone, misoprostol was associated with a longer induction time (hazard ratio = 0.79, 95% confidence interval (CI): 0.69-0.90). Both regimens showed similar risks of caesarean section (odds ratio (OR) = 0.88, 95% CI: 0.64-1.12), rates of meconium-stained amniotic fluid (OR = 0.85, 95% CI: 0.63-1.15), 5-min Apgar scores < 7 (OR = 1.73, 95% CI: 0.34-8.75), and transfers to neonatal intensive care units (OR = 0.64, 95% CI: 0.38-1.08).

CONCLUSION

Low-dosage misoprostol required more time than dinoprostone to induce labour, but the two drugs were equally safe in terms of the risk of caesarean section and foetal outcomes.

FUNDING

The Danish Ministry of Research and Innovation (#10-093833).

TRIAL REGISTRATION

The Danish Data Protection Agency (#2011-41-5794).

Structure of the PPARalpha and -gamma ligand binding domain in complex with AZ 242; ligand selectivity and agonist activation in the PPAR family

BACKGROUND

The peroxisome proliferator-activated receptors (PPAR) are ligand-activated transcription factors belonging to the nuclear receptor family. The roles of PPARalpha in fatty acid oxidation and PPARgamma in adipocyte differentiation and lipid storage have been characterized extensively. PPARs are activated by fatty acids and eicosanoids and are also targets for antidyslipidemic drugs, but the molecular interactions governing ligand selectivity for specific subtypes are unclear due to the lack of a PPARalpha ligand binding domain structure.

RESULTS

We have solved the crystal structure of the PPARalpha ligand binding domain (LBD) in complex with the combined PPARalpha and -gamma agonist AZ 242, a novel dihydro cinnamate derivative that is structurally different from thiazolidinediones. In addition, we present the crystal structure of the PPARgamma_LBD/AZ 242 complex and provide a rationale for ligand selectivity toward the PPARalpha and -gamma subtypes. Heteronuclear NMR data on PPARalpha in both the apo form and in complex with AZ 242 shows an overall stabilization of the LBD upon agonist binding. A comparison of the novel PPARalpha/AZ 242 complex with the PPARgamma/AZ 242 complex and previously solved PPARgamma structures reveals a conserved hydrogen bonding network between agonists and the AF2 helix.

CONCLUSIONS

The complex of PPARalpha and PPARgamma with the dual specificity agonist AZ 242 highlights the conserved interactions required for receptor activation. Together with the NMR data, this suggests a general model for ligand activation in the PPAR family. A comparison of the ligand binding sites reveals a molecular explanation for subtype selectivity and provides a basis for rational drug design.

Structural basis for the inhibition of porcine pepsin by Ascaris pepsin inhibitor-3

The three-dimensional structures of pepsin inhibitor-3 (PI-3) from Ascaris suum and of the complex between PI-3 and porcine pepsin at 1. 75 A and 2.45 A resolution, respectively, have revealed the mechanism of aspartic protease inhibition by this unique inhibitor. PI-3 has a new fold consisting of two domains, each comprising an antiparallel beta-sheet flanked by an alpha-helix. In the enzyme-inhibitor complex, the N-terminal beta-strand of PI-3 pairs with one strand of the 'active site flap' (residues 70-82) of pepsin, thus forming an eight-stranded beta-sheet that spans the two proteins. PI-3 has a novel mode of inhibition, using its N-terminal residues to occupy and therefore block the first three binding pockets in pepsin for substrate residues C-terminal to the scissile bond (S1'-S3'). The molecular structure of the pepsin-PI-3 complex suggests new avenues for the rational design of proteinaceous aspartic proteinase inhibitors.

The structure of the 2A proteinase from a common cold virus: a proteinase responsible for the shut-off of host-cell protein synthesis

The crystal structure of the 2A proteinase from human rhinovirus serotype 2 (HRV2-2A(pro)) has been solved to 1.95 A resolution. The structure has an unusual, although chymotrypsin-related, fold comprising a unique four-stranded beta sheet as the N-terminal domain and a six-stranded beta barrel as the C-terminal domain. A tightly bound zinc ion, essential for the stability of HRV2-2A(pro), is tetrahedrally coordinated by three cysteine sulfurs and one histidine nitrogen. The active site consists of a catalytic triad formed by His18, Asp35 and Cys106. Asp35 is additionally involved in an extensive hydrogen-bonding network. Modelling studies reveal a substrate-induced fit that explains the specificity of the subsites S4, S2, S1 and S1'. The structure of HRV2-2A(pro) suggests the mechanism of the cis cleavage and its release from the polyprotein.

Crystallization and preliminary X-ray diffraction studies of the heterogeneously glycosylated enzyme rhamnogalacturonan acetylesterase from Aspergillus aculeatus

Well diffracting crystals of rhamnogalacturonan acetylesterase from Aspergillus aculeatus have been obtained in two polymorphic modifications despite its heterogeneous glycosylation. The best-diffracting crystals (resolution 1.55 A) are orthorhombic. The limit of the diffraction pattern of the other (trigonal) form is 2.5 A. The ability of the enzyme to crystallize appears to depend on the glycosylation of the protein sample. This aspect has been investigated by mass spectrometry, which also showed that the orthorhombic crystals have the same glycosylation as the protein sample used in the crystallization.

Three-dimensional structure of a recombinant peroxidase from Coprinus cinereus at 2.6 A resolution

The structure of a recombinant peroxidase from the ink cap, Coprinus cinereus, CiP, is reported to 2.6 A resolution and refined to a R-value of 18.1%. The structure was solved by molecular replacement using the coordinates from a newly published ligninase structure. LiP. CiP crystallizes in space group P2(1)2(1)2(1) with two independent molecules in the asymmetric unit related by the vector 0.29b + 0.5c. The two CiP molecules are structurally identical; each contains two Ca2+ ions in positions equivalent to those found in the LiP structure. Two N-acetylglucosamines and one mannose residue were fitted into the density adjacent to two of the three predicted glycosylation sites. The refinement also included 40 and 41 water molecules, respectively, in the two CiP molecules. The structure of CiP displays a folding very similar to that of LiP. The active sites are almost identical in the LiP and CiP structures. CiP has a much larger opening to the active site than LiP.

Pancreatic spasmolytic polypeptide: first three-dimensional structure of a member of the mammalian trefoil family of peptides

BACKGROUND

The trefoil peptides are a rapidly growing family of peptides, mainly found in the gastrointestinal tract. There is circumstantial evidence that they stabilize the mucus layer, and may affect the rate of healing of the mucosal epithelium.

RESULTS

We have determined the structure of porcine pancreatic spasmolytic polypeptide (PSP) to 2.5 A resolution. The polypeptide contains two trefoil domains. The domain structure is compact, and is composed of a central short antiparallel beta-sheet with one short helix above and one below it. This is a novel motif. The two domains are related by two-fold symmetry, and each domain contains a cleft.

CONCLUSIONS

The cleft within each domain could accommodate a polysaccharide chain, and may therefore be responsible for binding mucin glycoproteins. We suggest that PSP may cross-link glycoproteins, explaining its ability to stabilize the mucus layer.

Crystallization and X-ray diffraction analysis of recombinant Coprinus cinereus peroxidase

Crystals suitable for an X-ray diffraction investigation have been obtained of recombinant Coprinus cinereus peroxidase expressed in Aspergillus oryzae. The crystals were grown by the hanging drop method with polyethylene glycol 6000 as the precipitant. A pH range from 6.2 to 8.0 and CaCl2 or MgCl2 present at a concentration of 0.35 M were essential for the crystal growth. A metastable monoclinic modification can be obtained under certain conditions, and with variations in temperature they are transformed into a stable orthorhombic modification. With CaCl2 as the additive, the unit cell dimensions were a = 74.9 A, b = 76.8 A and c = 128.2 A. With two peroxidase molecules per asymmetric unit, the solvent content is 49% (v/v). In the diffraction pattern, the reflections Okl are systematically very weak for k = 2n + 1. Combined with an analysis of the Patterson function, this showed that the two independent molecules are related by the pseudotranslational symmetry 0.29a + 0.5b. The possible space groups are P2(1)2(1)2(1) or P2(1)22(1) because of this pseudosymmetry. The crystals diffract to a resolution of 2.9 A.

Crystallization and preliminary X-ray diffraction studies of a peroxidase from barley grain

Crystals suitable for X-ray diffraction analysis of both glycosylated and non-glycosylated forms of a barley peroxidase have been grown. The crystals of the glycosylated peroxidase have been grown by the hanging drop vapour diffusion method using polyethylene glycol 4000 as the precipitant in the presence of n-propanol and potassium iodide at pH 8.5. The crystals are needles belonging to the orthorhombic spacegroup P2(1)2(1)2(1) with unit cell dimensions a = 62.95 A, b = 66.24 A and c = 70.78 A. There is one barley peroxidase molecule in the asymmetric unit. The crystals contain approximately 38% solvent and appear to be stable to lengthy X-ray exposure. They diffract to beyond 1.9 A.

Shear sensitivity of hybridoma cells in batch, fed-batch, and continuous cultures

Previously, we observed that CRL-8018 hybridoma cells were more sensitive to well-defined viscometric shear during the lag and stationary phases than during the exponential phase of batch cultures. Some potential hypotheses for explaining the increase in shear sensitivity are (1) nutrient limitations that result in a decrease in production of specific cellular components responsible for the mechanical strength of the cell, (2) nutrient limitations that lead to synchronization of the culture in a cell cycle phase that is more sensitive to shear, or (3) a link between cell growth and shear sensitivity, such that slowly growing cells are more sensitive to shear. Here, the duration of the exponential phase was increased with use of fed-batch, and the effect on shear sensitivity of the cultures was measured with a viscometric technique. Extension of exponential growth resulted in an increased period during which the cells were insensitive to shear. Additionally, the shear sensitivity of the cells was constant over a wide range of growth rates and metabolic yields in chemostat cultures. These observations suggest that as long as the cells are actively (exponentially) growing, their shear sensitivity does not depend on the growth rate or metabolic state of the cell as expressed by metabolic yields. Thus, hypothesis 3 above can be dismissed.