Uterine fibroids and non-informative cell-free DNA screening results

OBJECTIVE

Uterine fibroids are monoclonal tumors, which are often genetically abnormal and associated with false-positive genome-wide cell-free DNA (cfDNA) screening results, particularly when large. It is plausible that fibroids may also increase the risk of cfDNA failure by affecting fetal fraction or due to their genetic anomalies confounding cfDNA algorithms. We aimed to investigate a possible association between fibroids and cfDNA non-informative results.

METHODS

This was a retrospective cohort study of women undergoing cfDNA screening for fetal chromosomal abnormalities between 2013 and 2020, comparing pregnancies with vs without uterine fibroids recorded on any obstetric ultrasound before 24 weeks' gestation. Univariable and multivariable logistic regression models were used to investigate the association between fibroids and cfDNA failure, adjusting for gestational age, maternal age, weight and height at blood sampling, mode of conception, multiple gestation and test platform (chromosome-selective or genome-wide). Analyses were stratified according to the number of fibroids and total fibroid volume. The impact of fibroids on fetal fraction was assessed using linear regression, adjusting for the same covariates.

RESULTS

Among 19 818 pregnancies undergoing cfDNA screening, fibroids were reported in 2038 (10.28%) and cfDNA failure at the first screening attempt occurred in 228 (1.15%) pregnancies. Non-informative results occurred in 1.96% of pregnancies with fibroids and 1.06% of pregnancies without fibroids (adjusted odds ratio (aOR), 2.40 (95% CI, 1.65-3.48)). The risk of failure in the first screening attempt increased progressively with the number of fibroids (aOR, 5.05 (95% CI, 2.29-11.13) in women with four or more fibroids) and total fibroid volume, with greater than a 5-fold and 14-fold increase in risk among women with fibroid volumes of 100.1-400 mL (aOR, 5.52 (95% CI, 2.30-13.25)) and > 400 mL (aOR, 14.80 (95% CI, 4.50-48.69)), respectively. Although test failure was more common with chromosome-selective than genome-wide screening, fibroids similarly increased the risk of failure of both screening platforms. Compared to pregnancies without fibroids, those with fibroids had a fetal fraction on average 0.61% lower (adjusted mean difference, -0.61% (95% CI, -0.77% to -0.45%)).

CONCLUSION

Uterine fibroids are associated with lower fetal fraction and an increased risk of cfDNA screening failure. The strength of this association increases with increasing fibroid number and volume. © 2024 The Author(s). Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Impact of a yogurt matrix and cell microencapsulation on the survival of Lactobacillus reuteri in three in vitro gastric digestion procedures

The goal of this study was to assess the interaction between microencapsulation and a yogurt food matrix on the survival of Lactobacillus reuteri NCIMB 30242 in four different in vitro systems that simulate a gastric environment. The four systems were: United States Pharmacopeia (USP) solutions, a static two-step (STS) procedure which included simulated food ingredients, a constantly dynamic digestion procedure (IViDiS), as well a multi-step dynamic digestion scheme (S’IViDiS). The pH profiles of the various procedures varied between systems with acidity levels being: USP > STS > IViDiS = S’IVIDiS. Addition of a food matrix increased the pH in all systems except for the USP methodology. Microencapsulation in alginate-based gels was effective in protecting the cells in model solutions when no food ingredients were present. The stability of the probiotic culture in the in vitro gastric environments was enhanced when (1) yoghurt or simulated food ingredient were present in the medium in sufficient quantity, (2) pH was higher. The procedure-comparison data of this study will be helpful in interpreting the literature with respect to viable counts of probiotics obtained from different static or dynamic in vitro gastric systems.

Virological failure after 1 year of first-line ART is not associated with HIV minority drug resistance in rural Cameroon

OBJECTIVES

The aim of this study was to describe clinical and virological outcomes in therapy-naive HIV-1-positive patients treated in a routine ART programme in rural Cameroon.

METHODS

In a prospective cohort, 300 consecutive patients starting first-line ART were enrolled and followed for 12 months. Among 238 patients with available viral load data at Month 12, logistic regression was used to analyse risk factors for virological failure (≥1000 HIV RNA copies/mL) including clinical, immunological and virological parameters, as well as data on drug adherence. Population sequencing was performed to detect the presence of drug-resistance mutations in patients with virological failure at Month 12; minority drug-resistance mutations at baseline were analysed using next-generation sequencing in these patients and matched controls.

RESULTS

At Month 12, 38/238 (16%) patients experienced virological failure (≥1000 HIV RNA copies/mL). Patients with virological failure were younger, had lower CD4 cell counts and were more often WHO stage 3 or 4 at baseline. Sixty-three percent of patients with virological failure developed at least one drug-resistance mutation. The M184V (n = 18) and K103N (n = 10) mutations were most common. At baseline, 6/30 patients (20%) experiencing virological failure and 6/35 (17%) matched controls had evidence of minority drug-resistance mutations using next-generation sequencing (P = 0.77). Lower CD4 count at baseline (OR per 100 cells/mm(3) lower 1.41, 95% CI 1.02-1.96, P = 0.04) and poorer adherence (OR per 1% lower 1.05, 95% CI 1.02-1.08, P < 0.001) were associated with a higher risk of virological failure. Unavailability of ART at the treatment centre was the single most common cause for incomplete adherence.

CONCLUSIONS

Virological failure after 1 year of ART was not associated with minority drug resistance at baseline but with incomplete adherence. Strategies to assure adherence and uninterrupted drug supplies are pivotal factors for therapy success.

Enumeration of the contaminating bacterial microbiota in unfermented pasteurized milks enriched with probiotic bacteria

Pasteurized and unfermented milks supplemented with probiotic bacteria are appearing on the market. It then becomes a challenge to ascertain the undesirable contamination microbiota in the presence of a largely superior population of probiotic bacteria. A method to enumerate the contaminating microbial microbiota in such probiotic-enriched milks was developed. The probiotic cultures, Lactobacillus rhamnosus Lb-Immuni-T™ and Bifidobacterium animalis subsp. lactis BB-12®, were added to a pasteurized unfermented milk to reach a minimum of 1 billion CFU per 250 mL portion, as ascertained by plating on de Man – Rogosa – Sharpe (MRS) agar in anaerobic conditions. No growth of B. animalis subsp. lactis BB-12 was noted on plate count agar (PCA) or Petrifilm™ plates, and the presence of this culture did not affect standard plate counts (SPC) of contaminating bacteria. However, L. rhamnosus formed colonies on PCA and Petrifilm™ plates. Attempts were thus made to inhibit the growth of the probiotic lactobacilli in PCA. The addition of 2% sodium phosphate (SP) or 5% glycerophosphate (GP) inhibited the growth of the lactobacilli in broths, but pin-point colonies of L. rhamnosus Lb-Immuni-T nevertheless appeared on PCA supplemented with phosphates. SPC could be obtained on PCA + 2% SP by only counting the large colonies, but this resulted in a significant (4.4 fold) underestimation of SPC values. On Petrifilm™ AC, at dilutions 0 to 2, all colonies were considered as being contaminants, while at dilutions 3 and 4, only large colonies were counted for SPC determinations. There was a direct correlation (R2 = 0.99) between SPC values with Petrifilm™ in uninoculated milks and those obtained on probiotic-enriched milks. The high correlation obtained over the 102 to 106 CFU/mL range of SPC values show that this Petrifilm™ method is appropriate to evaluate the microbiological quality of pasteurized milks enriched with L. rhamnosus Lb-Immuni-T and B. animalis subsp. lactis BB-12.

Spatial distribution of lamin A and B1 in the K562 cell nuclear matrix stabilized with metal ions

When the nucleus is stripped of most DNA, RNA, and soluble proteins, a structure remains that has been referred to as the nuclear matrix, which acts as a framework to determine the higher order of chromatin organization. However, there is always uncertainty as to whether or not the nuclear matrix, isolated in vitro, could really represent a skeleton of the nucleus in vivo. In fact, the only nuclear framework of which the existence is universally accepted is the nuclear lamina, a continuous thin layer that underlies the inner nuclear membrane and is mainly composed of three related proteins: lamins A, B, and C. Nevertheless, a number of recent investigations performed on different cell types have suggested that nuclear lamins are also present within the nucleoplasm and could be important constituents of the nuclear matrix. In most cell types investigated, the nuclear matrix does not spontaneously resist the extraction steps, but must rather be stabilized before the application of extracting agents. In this investigation, by immunochemical and morphological analysis, we studied the effect of stabilization with different divalent cations (Zn(2+), Cu(2+), Cd(2+)) on the distribution of lamin A and B1 in the nuclear matrix obtained from K562 human erythroleukemia cells. In intact cells, antibodies to both lamin A and B1 mainly stained the nuclear periphery, although some immunoreactivity was detected in the nuclear interior. The fluorescent lamin A pattern detected in Cu(2+)- and Cd(2+)-stabilized nuclei was markedly modified, whereas Zn(2+)-incubated nuclei showed an unaltered pattern of lamin A distribution. By contrast, the distribution of lamin B1 in isolated nuclei was not modified by the stabilizing cations. When chromatin was removed by nuclease digestion and extraction with solutions of high ionic strength, a previously masked immunoreactivity for lamin A, but not for lamin B1, became evident in the internal part of the residual structures representing the nuclear matrix. Our results indicate that when metal ions are used as stabilizing agents for the recovery of the nuclear matrix, the distribution of both lamin A and lamin B1 in the final structures, corresponds to the pattern we have very recently reported using different extraction procedures. This observation strengthen the concept that intranuclear lamins may act as structural components of the nuclear matrix.

Evaluation of adenosine deaminase activity in the Mycobacterium tuberculosis culture supernatants

BACKGROUND

Adenosine deaminase (ADA) catalyzes hydrolytic and irreversible deamination of deoxyadenosine into deoxyinosine and of adenosine into inosine, and is related to lymphocytic proliferation and differentiation. The measurement of ADA activity in body fluids is a useful tool in the evaluation of mycobacterial infections. Elevated ADA activity has been found in pleural effusions of patients with pleural tuberculosis relative to those from patients with nontuberculous pleural diseases, and is mainly associated with cellular host factors such as monocyte-macrophages or lymphocytes. In contrast, there is little information about ADA activity measurement in mycobacteria culture supernatants.

METHODS

We evaluated ADA activity as described by Giusti in the culture supernatants of eight Mycobacterium tuberculosis isolates.

RESULTS

Mycobacteria culture supernatants did not display any ADA activity.

CONCLUSIONS

This result supports the notion that Mycobacterium tuberculosis is not the source of ADA activity. However, increased ADA activity in biological fluids from tuberculosis patients might be due to the interaction of the mycobacterium with host factors.

Strong association of autoantibodies to human nuclear lamin B1 with lupus anticoagulant antibodies in systemic lupus erythematosus

OBJECTIVE

To determine the frequency and clinical significance of high titers of IgG autoantibodies to nuclear lamin B1 in a large number of unselected and well-characterized systemic lupus erythematosus (SLE) patients, disease controls, and normal healthy controls.

METHODS

A cross-sectional study of anti-lamin B1 autoantibodies, as measured by enzyme-linked immunosorbent assay using human recombinant lamin B1 autoantigen, was performed on serum samples obtained at first evaluation of 238 consecutive French Canadian adults: 61 healthy control subjects, 20 patients with osteoarthritis, 22 with ankylosing spondylitis, 11 with autoimmune hepatitis, 30 with rheumatoid arthritis, and 94 with SLE. SLE patients were studied for 57 disease manifestations. A case-control study was performed to analyze the relationship between anti-lamin B1 status and thrombotic manifestations between SLE onset and last followup.

RESULTS

High titers of anti-lamin B1 were strikingly restricted to a subset of 8 SLE patients (8.5%). The mean anti-lamin B1 titer was higher in this subset than in the other SLE patients or any control group (P<0.001). By univariate analysis and stepwise multiple logistic regression, the most striking association of anti-lamin B1 was with lupus anticoagulant (LAC) antibodies (P = 0.00001). Although LAC were significantly associated with thrombosis in our SLE patients, anti-lamin B1 was not. The frequency of thrombosis in SLE patients expressing both LAC and anti-lamin B1 was similar to that in patients without LAC (P = 1.0). However, patients expressing LAC without anti-lamin B1 had a greater frequency of thrombosis (P = 0.018).

CONCLUSION

High titers of IgG anti-lamin B1 autoantibodies are highly specific for a subset of SLE patients whose clinical characteristics include the presence of LAC and other laboratory manifestations of the antiphospholipid syndrome. The presence of LAC without anti-lamin B1 may define a subset of SLE patients at greater risk for thrombosis.

Lamin A is part of the internal nucleoskeleton of human erythroleukemia cells

Nuclear lamins are the most abundant components of the nuclear lamina, a 10-50-nm-thick fibrous layer underlying the inner nuclear envelope membrane. Nevertheless, a number of recent investigations performed on epithelial and fibroblast cells have suggested that nuclear lamins are also present within the nucleoplasm and could be important constituents of the nucleoskeleton. We have studied the subnuclear distribution of lamins A and B1 in human erythroleukemia cells by using immunoblotting analysis and immunofluorescent staining of fractionated nuclei. In intact cells and isolated nuclei, antibodies to lamins A and B1 mainly stained the nuclear periphery, although some immunoreactivity was detected in the nuclear interior. However, when chromatin was removed by nuclease digestion and extraction with nonionic detergent or solutions of high ionic strength, a previously masked immunoreactivity for lamin A, but not for lamin B1, became evident in the internal part of the residual structures representing the nuclear matrix or scaffold. Preferential localization of lamin A to the inner part of the nucleus was also demonstrated by the presence of the majority of lamin A in the solubilized inner nuclear network subfraction. In contrast, lamin B1 was mainly recovered in the fraction corresponding to the nuclear periphery. Double labeling experiments showed that lamin A, but not lamin B1, colocalized with coiled and GATA-1 bodies. Thus, our results support the hypothesis that lamin A, but not lamin B1, may be a component of an internal nucleoskeleton in human erythroleukemia cells.

Chromatin condensation is not associated with apoptosis

Apoptosis plays an important role in the survival of an organism, and substantial work has been done to understand the signaling pathways that regulate this process. Characteristic changes in chromatin organization accompany apoptosis and are routinely used as markers for cell death. We have examined the organization of chromatin in apoptotic PC12 and HeLa cells by indirect immunofluorescence and electron spectroscopic imaging. Our results indicate that de novo chromatin condensation normally seen during mitosis does not occur when cells undergo apoptosis. Instead, the condensed chromatin typically observed results from aggregation of the heterochromatin. We present evidence that, early in apoptosis, there is a rapid degradation of the nuclease-hypersensitive euchromatin that contains hyperacetylated histones. This occurs coincident with the loss of nuclear integrity due to degradation of lamins and reorganization of intranuclear protein matrix. These events lead to collapse of the nucleus and aggregation of heterochromatin to produce the appearance of condensed apoptotic chromatin. This heterochromatin aggregate is then digested by nucleases to produce the oligonucleosomal DNA ladder that is a hallmark of late apoptosis. Unlike mitosis, we have not seen any evidence for the requirement of phosphorylated histones H1 and H3 to maintain the chromatin in the condensed state.

Distinct nuclear assembly pathways for lamins A and C lead to their increase during quiescence in Swiss 3T3 cells

The expression of A-type lamins coincides with cell differentiation and as A-type lamins specifically interact with chromatin, a role in the regulation of differential gene expression has been suggested for A-type lamins. Using the mouse Swiss 3T3 cell line as a model, the change in two A-type lamins, lamins A and C, during cellular quiescence has been investigated. This well established model system mimics the first stages of differentiation when cells exit the cell cycle. In fact, quiescence in Swiss 3T3 cells was accompanied by a significant increase (2.6-fold) in lamin A protein levels and a smaller but reproducible increase (1.4-fold) in lamin C. These effects were fully reversible upon restimulation of the cells with serum. No effect upon lamin B levels was observed. Conversely, levels of A-type lamin mRNA decreased markedly as a result of quiescence suggesting transcriptional mechanisms are involved in the change in levels of lamins A and C. No difference in the incorporation of microinjected human lamin A into nuclei of quiescent or proliferating cells was observed. These data suggest A-type lamin binding sites were not limiting and indicated little difference between A-type lamin assembly mechanisms in quiescent and proliferating cells. The data did demonstrate lamin A and lamin C incorporation into the nuclear lamina proceeded by different pathways when microinjected in Swiss 3T3 cells. The incorporation of recombinant lamin C into the nuclear lamina was delayed compared to lamin A and proceeded via intranuclear foci. Such foci were not seen with microinjected lamin A. Instead, recombinant lamin A was rapidly (&lt;20 minutes) incorporated into the nuclear lamina. Comicroinjection of lamin A with lamin C did not prevent foci formation but assisted in the rapid clearing (t1/2=30 minutes) of these structures and the incorporation of both lamins A and C into the lamina. These data suggest that the incorporation of lamin C into the lamina is facilitated by lamin A. They demonstrate a distinct difference in the nuclear assembly pathways of lamins A and C and show for the first time a functional distinction for these two splice variants of the A-type lamin gene. From the differences in assembly pathways and changes in protein levels accompanying quiescence in 3T3 cells, we suggest distinct roles for lamin A and lamin C in proliferating and quiescent states of the cell cycle.

On the correct determination of reference values for serum antibodies against pigeon serum antigen using a group of healthy blood donors

An enzymatic immunoassay was developed in order to evaluate the statistical distribution of IgG serum antibodies against pooled pigeon sera antigen in 102 healthy blood donors (HBD). A non-normal distribution was obtained as demonstrated by abnormal values of skewness (2.02) and kurtosis (6.50). A cut-off point (0.120) was determined from the mean plus 2 standard deviations of the optical density values obtained in the HBD group. This value was able to segregate 94% of subjects. However, when calculation of the mean less 2 SD was performed to delimit 95% of the samples, an aberrant negative value was obtained. In contrast, when the nonparametric method of percentile calculation was applied, an optical density value of 0.130 discriminated 97.5% of samples. In addition, the interval between p97.5 and p2.5 delimited 95% of samples. We conclude that when reference values and cut-off point are determined from an enzymatic immunoassay, careful analysis of the statistical distribution of reference values is necessary in order to avoid the inappropriate application of parametric procedures as demonstrated in this study for antibodies against pigeon serum antigens.

A- and B-type lamins are differentially expressed in normal human tissues

A selection of normal human tissues was investigated for the presence of lamins B1, B2, and A-type lamins, using a panel of antibodies specific for the individual lamin subtypes. By use of immunoprecipitation and two-dimensional immunoblotting techniques we demonstrated that these antibodies do not cross-react with other lamin subtypes and that a range of different phosphorylation isoforms is recognized by each antibody. The lamin B2 antibodies appeared to decorate the nuclear lamina in all tissues examined, except hepatocytes, in which very little lamin B2 expression was observed. In contrast to previous studies, which suggested the ubiquitous expression of lamin B1 in mammalian tissues, we show that lamin B1 is not as universally distributed throughout normal human tissues as was to be expected from previous studies. Muscle and connective tissues are negative, while in epithelial cells lamin B1 seemed to be preferentially detected in proliferating cells. These results correspond well with those obtained for lamin B1 in chicken tissues. The expression of A-type lamins is most prominent in well-differentiated epithelial cells. Relatively undifferentiated and proliferating cells in epithelia showed a clearly reduced expression of A-type lamins. Furthermore, most cells of neuroendocrine origin as well as most hematopoietic cells were negative for A-type lamin antibodies.

Degradation of nuclear matrix and DNA cleavage in apoptotic thymocytes

In dexamethasone-treated thymocyte cultures an increase in nuclear proteolytic activity paralleled chromatin fragmentation and the appearance of small apoptotic cells. The elevation of nuclear proteolytic activity was accompanied by site-specific degradation of nuclear mitotic apparatus protein and lamin B, two essential components of the nuclear matrix. Nuclear mitotic apparatus protein phosphorylation and cleavage into 200 and 48 kDa fragments occurred within 30 minutes of dexamethasone treatment. Cleavage of lamin B, which generated a fragment of 46 kDa consistent with the central rod domain of the protein, was also detected after 30 minutes of exposure to the steroid hormone. The level of lamin B phosphorylation did not change as a result of the dexamethasone treatment and the lamina did not solubilize until the later stages of apoptosis. Initial DNA breaks, detected by the terminal transferase-mediated dUTP-biotin nick end labeling assay, occurred throughout the nuclei and solubilization of lamina was not required for this process to commence. The data presented in this paper support a model of apoptotic nuclear destruction brought about by the site-specific proteolysis of key structural proteins. Both the nuclear mitotic apparatus protein and lamin B were specifically targeted by protease(s) at early stages of the cell death pathway, which possibly initiate the cascade of degradative events in apoptosis.

Characterization of a novel human antibody xenoreactive with fibronectin

Recent reports have used bovine fibronectin (Fn) as source of antigen to study human anti-Fn autoantibodies. We have characterized a novel human antibody (Ab) reactive with bovine and marsupial Fn, but not with human Fn. Indirect immunofluorescence, wet cleaving and protein adherence assays, immunoblotting, blot-affinity purification, a cell adhesion inhibition assay, and competitive experiments with synthetic peptides were used to characterize the anti-Fn Ab in serum from a patient with an undifferentiated connective tissue disease. A characteristic Fn-like network was observed by indirect immunofluorescence on bovine MDBK and marsupial PtK2 cells, but not on various human cell lines. Double immunofluorescence revealed colocalization of the Ab with a mouse monoclonal anti-Fn Ab. A reactive polypeptide of 240 kDa corresponding to the M(r) of Fn was identified by immunoblotting using MDBK and PtK2 total cell lysates. The Ab reacted with the 240-kDa band of purified bovine Fn with an endpoint titer of 1:64,000, while no reactivity was observed with human cellular or plasma Fn. Blot-affinity purification of the Ab from the 240-kDa PtK2 region confirmed that the Fn-like fluorescent pattern observed was due to reactivity with the 240-kDa band and not with other regions of the blot. The Ab affinity-purified from the 240-kDa region also reacted with purified bovine Fn by immunoblotting. Functional analysis disclosed specific inhibition of PtK2 and MDBK cell adhesion by the affinity-purified anti-Fn Ab. Competitive experiments with synthetic peptides demonstrated that the epitope is located in the decapeptide RGDSPASSKP containing the cell-binding domain of Fn. Longitudinal analysis of the Ab revealed its persistence over 6 years. Bovine and marsupial Fn can be the focus of a highly specific and persistent human immune response. Reactivity of a human Ab with bovine Fn does not imply cross-reactivity with human Fn. In light of recent reports using bovine Fn to characterize human anti-Fn "autoantibodies," future studies on human anti-Fn should specifically employ purified human Fn as antigen.

Prostate motion during standard radiotherapy as assessed by fiducial markers

From November 1993 to August 1994, 55 patients with localized prostate carcinoma had three gold seeds placed in the prostate under transrectal ultrasound guidance prior to the start of radiotherapy in order to track prostate motion. Patients had a planning CT scan before initial simulation and again at about 40 Gy, just prior to simulation of a field reduction. Seed position relative to fixed bony landmarks (pubic symphysis and both ischial tuberosities) was digitized from each pair of orthogonal films from the initial and boost simulation using the Nucletron brachytherapy planning system. Vector analysis was performed to rule out the possibility of independent seed migration within the prostate between the time of initial and boost simulation. Prostate motion was seen in the posterior (mean: 0.56 cm; SD: 0.41 cm) and inferior directions (mean: 0.59 cm; SD: 0.45 cm). The base of the prostate was displaced more than 1 cm posteriorly in 30% of patients and in 11% in the inferior direction. Prostate position is related to rectal and bladder filling. Distension of these organs displaces the prostate in an anterosuperior direction, with lesser degrees of filling allowing the prostate to move posteriorly and inferiorly. Conformal therapy planning must take this motion into consideration. Changes in prostate position of this magnitude preclude the use of standard margins.