SARS-CoV-2 Infection during the Omicron Surge among Patients Receiving Dialysis: The Role of Circulating Receptor-Binding Domain Antibodies and Vaccine Doses

BACKGROUND

It is unclear whether circulating antibody levels conferred protection against SARS-CoV-2 infection among patients receiving dialysis during the Omicron-dominant period.

METHODS

We followed monthly semiquantitative SARS-CoV-2 RBD IgG index values in a randomly selected nationwide cohort of patients receiving dialysis and ascertained SARS-CoV-2 infection during the Omicron-dominant period of December 25, 2021 to January 31, 2022 using electronic health records. We estimated the relative risk for documented SARS-CoV-2 infection by vaccination status and by circulating RBD IgG using a log-binomial model accounting for age, sex, and prior COVID-19.

RESULTS

Among 3576 patients receiving dialysis, 901 (25%) received a third mRNA vaccine dose as of December 24, 2021. Early antibody responses to third doses were robust (median peak index IgG value at assay limit of 150). During the Omicron-dominant period, SARS-CoV-2 infection was documented in 340 (7%) patients. Risk for infection was higher among patients without vaccination and with one to two doses (RR, 2.1; 95% CI, 1.6 to 2.8, and RR, 1.3; 95% CI, 1.0 to 1.8 versus three doses, respectively). Irrespective of the number of vaccine doses, risk for infection was higher among patients with circulating RBD IgG <23 (506 BAU/ml) (RR range, 2.1 to 3.2, 95% CI, 1.3 to 3.4 and 95% CI, 2.2 to 4.5, respectively) compared with RBD IgG ≥23.

CONCLUSIONS

Among patients receiving dialysis, a third mRNA vaccine dose enhanced protection against SARS-CoV-2 infection during the Omicron-dominant period, but a low circulating RBD antibody response was associated with risk for infection independent of the number of vaccine doses. Measuring circulating antibody levels in this high-risk group could inform optimal timing of vaccination and other measures to reduce risk of SARS-CoV-2 infection.

SARS-CoV-2 infection during the Omicron surge among patients receiving dialysis: the role of circulating receptor-binding domain antibodies and vaccine doses

Background

It is unclear whether a third dose of mRNA platform vaccines, or antibody response to prior infection or vaccination confer protection from the Omicron variant among patients receiving dialysis.

Methods

Monthly since February 2021, we tested plasma from 4,697 patients receiving dialysis for antibodies to the receptor-binding domain (RBD) of SARS-CoV-2. We assessed semiquantitative median IgG index values over time among patients vaccinated with at least one dose of the two mRNA vaccines. We ascertained documented COVID-19 diagnoses after December 25, 2021 and up to January 31, 2022. We estimated the relative risk for documented SARS-CoV-2 infection by vaccination status using a log-binomial model accounting for age, sex, and prior clinical COVID-19. Among patients with RBD IgG index value available during December 1-December 24, 2021, we also evaluated the association between the circulating RBD IgG titer and risk for Omicron variant SARS-CoV-2 infection.

Results

Of the 4,697 patients we followed with monthly RBD assays, 3576 are included in the main analysis cohort; among these, 852 (24%) were unvaccinated. Antibody response to third doses was robust (median peak index IgG value at assay limit of 150, equivalent to 3270 binding antibody units/mL). Between December 25-January 31, 2022, SARS-CoV-2 infection was documented 340 patients (7%), 115 (36%) of whom were hospitalized. The final doses of vaccines were given a median of 272 (25 ^th , 75 ^th percentile, 245-303) days and 58 (25 ^th , 75 ^th percentile, 51-95) days prior to infection for the 1-2 dose and 3 dose vaccine groups respectively. Relative risks for infection were higher among patients without vaccination (RR 2.1 [95%CI 1.6, 2.8]), and patients with 1-2 doses (RR 1.3 [95%CI 1.0, 1.8]), compared with patients with three doses of the mRNA vaccines. Relative risks for infection were higher among patients with RBD index values < 23 (506 BAU/mL), compared with RBD index value ≥ 23 (RR 2.4 [95%CI 1.9, 3.0]). The higher risk for infection among patients with RBD index values < 23 was present among patients who received three doses (RR 2.1 [95%CI 1.3, 3.4]).

Conclusions

Among patients receiving hemodialysis, patients unvaccinated, without a third mRNA vaccine dose, or those lacking robust circulating antibody response are at higher risk for Omicron variant infection. Low circulating antibodies could identify the subgroup needing intensified surveillance, prophylaxis or treatment in this patient population.

SARS-CoV-2 Vaccine Antibody Response and Breakthrough Infection in Patients Receiving Dialysis

BACKGROUND

Whether breakthrough SARS-CoV-2 infections after vaccination are related to the level of postvaccine circulating antibody is unclear.

OBJECTIVE

To determine longitudinal antibody-based response and risk for breakthrough infection after SARS-CoV-2 vaccination.

DESIGN

Prospective study.

SETTING

Nationwide sample from dialysis facilities.

PATIENTS

4791 patients receiving dialysis.

MEASUREMENTS

Remainder plasma from a laboratory processing routine monthly tests was used to measure qualitative and semiquantitative antibodies to the receptor-binding domain (RBD) of SARS-CoV-2. To evaluate whether peak or prebreakthrough RBD values were associated with breakthrough infection, a nested case-control analysis matched each breakthrough case patient to 5 control patients by age, sex, and vaccination month and adjusted for diabetes status and region of residence.

RESULTS

Of the 4791 patients followed with monthly RBD assays, 2563 were vaccinated as of 14 September 2021. Among the vaccinated patients, the estimated proportion with an undetectable RBD response increased from 6.6% (95% CI, 5.5% to 7.8%) 14 to 30 days after vaccination to 20.2% (CI, 17.0% to 23.3%) 5 to 6 months after vaccination. Estimated median index values decreased from 91.9 (CI, 78.6 to 105.2) 14 to 30 days after vaccination to 8.4 (CI, 7.6 to 9.3) 5 to 6 months after vaccination. Breakthrough infections occurred in 56 patients, with samples collected a median of 21 days before breakthrough infection. Compared with prebreakthrough index RBD values of 23 or higher (equivalent to ≥506 binding antibody units per milliliter), prebreakthrough RBD values less than 10 and values from 10 to less than 23 were associated with higher odds for breakthrough infection (rate ratios, 11.6 [CI, 3.4 to 39.5] and 6.0 [CI, 1.5 to 23.6], respectively).

LIMITATIONS

Single measure of vaccine response; ascertainment of COVID-19 diagnosis from electronic health records.

CONCLUSION

The antibody response to SARS-CoV-2 vaccination wanes rapidly in persons receiving dialysis. In this population, the circulating antibody response is associated with risk for breakthrough infection.

PRIMARY FUNDING SOURCE

Ascend Clinical Laboratory.

SARS-CoV-2 vaccine antibody response and breakthrough infection in dialysis

BACKGROUND

Patients receiving dialysis are a sentinel population for groups at high risk for death and disability from COVID-19. Understanding correlates of protection post-vaccination can inform immunization and mitigation strategies.

METHODS

Monthly since January 2021, we tested plasma from 4791 patients receiving dialysis for antibodies to the receptor-binding domain (RBD) of SARS-CoV-2 using a high-throughput assay. We qualitatively assessed the proportion without a detectable RBD response and among those with a response, semiquantitative median IgG index values. Using a nested case-control design, we matched each breakthrough case to five controls by age, sex, and vaccination-month to determine whether peak and pre-breakthrough RBD IgG index values were associated with risk for infection post-vaccination.

RESULTS

Among 2563 vaccinated patients, the proportion without a detectable RBD response increased from 6.6% [95% CI 5.5-8.1] in 14-30 days post-vaccination to 20.2% [95% CI 17.1-23.8], and median index values declined from 92.7 (95% CI 77.8-107.5) to 3.7 (95% CI 3.1-4.3) after 5 months. Persons with SARS-CoV-2 infection prior-to-vaccination had higher peak index values than persons without prior infection, but values equalized by 5 months (p=0.230). Breakthrough infections occurred in 56 patients, with samples collected a median of 21 days pre-breakthrough. Peak and pre-breakthrough RBD values <23 (equivalent to <506 WHO BAU/mL) were associated with higher odds for breakthrough infection (OR: 3.7 [95% CI 2.0-6.8] and 9.8 [95% CI 2.9-32.8], respectively).

CONCLUSIONS

The antibody response to SARS-CoV-2 vaccination wanes rapidly, and in persons receiving dialysis, the persisting antibody response is associated with risk for breakthrough infection.

SARS-CoV-2 Vaccine Acceptability in Patients on Hemodialysis: A Nationwide Survey

BACKGROUND

Patients on dialysis are at increased risk for COVID-19-related complications. However, a substantial fraction of patients on dialysis belong to groups more likely to be hesitant about vaccination.

METHODS

With the goal of identifying strategies to increase COVID-19 vaccine uptake among patients on hemodialysis, we conducted a nationwide vaccine acceptability survey, partnering with a dialysis network to distribute an anonymized English and Spanish language online survey in 150 randomly selected facilities in the United States. We used logistic regression to evaluate characteristics of vaccine-hesitant persons.

RESULTS

A total of 1515 (14% of eligible) patients responded; 20% of all responders, 29% of patients aged 18-44 years, and 29% of Black responders reported being hesitant to seek the COVID-19 vaccine, even if the vaccine was considered safe for the general population. Odds of vaccine hesitancy were higher among patients aged 18-44 years versus those 45-64 years (odds ratio [OR], 1.5; 95% confidence interval [95% CI], 1.0 to 2.3), Black patients versus non-Hispanic White patients (OR, 1.9; 95% CI, 1.3 to 2.7), Native Americans or Pacific Islanders versus non-Hispanic White patients (OR, 2.0; 95% CI, 1.1 to 3.7), and women versus men (OR, 1.6; 95% CI, 1.2 to 2.0). About half (53%) of patients who were vaccine hesitant expressed concerns about side effects. Responders' main information sources about COVID-19 vaccines were television news and dialysis staff (68% and 38%, respectively).

CONCLUSIONS

A substantial proportion of patients receiving in-center hemodialysis in the United States are hesitant about seeking COVID-19 vaccination. Facilitating uptake requires outreach to younger patients, women, and Black, Native American, or Pacific Islander patients, and addressing concerns about side effects.

PODCAST

This article contains a podcast at https://www.asn-online.org/media/podcast/JASN/2021_07_07_JASN2021010104.mp3.

Estimated SARS-CoV-2 Seroprevalence in US Patients Receiving Dialysis 1 Year After the Beginning of the COVID-19 Pandemic

IMPORTANCE

Seroprevalence studies complement data on detected cases and attributed deaths in assessing the cumulative spread of the SARS-CoV-2 virus.

OBJECTIVE

To estimate seroprevalence of SARS-CoV-2 antibodies in patients receiving dialysis and adults in the US in January 2021 before the widespread introduction of COVID-19 vaccines.

DESIGN, SETTING, AND PARTICIPANTS

This cross-sectional study used data from the third largest US dialysis organization (US Renal Care), which has facilities located nationwide, to estimate SARS-CoV-2 seroprevalence among US patients receiving dialysis. Remainder plasma (ie, plasma that would have otherwise been discarded) of all patients receiving dialysis at US Renal Care facilities from January 1 to 31, 2021, was tested for SARS-CoV-2 antibodies. Patients were excluded if they had a documented dose of SARS-CoV-2 vaccination or if a residence zip code was missing from electronic medical records. Crude seroprevalence estimates from this sample (January 2021) were standardized to the US adult population using the 2018 American Community Survey 1-year estimates and stratified by age group, sex, self-reported race/ethnicity, neighborhood race/ethnicity composition, neighborhood income level, and urban or rural status. These data and case detection rates were then compared with data from a July 2020 subsample of patients who received dialysis at the same facilities.

EXPOSURES

Age, sex, race/ethnicity, and region of residence as well as neighborhood race/ethnicity composition, poverty, population density, and urban or rural status.

MAIN OUTCOMES AND MEASURES

The spike protein receptor-binding domain total antibody assay (Siemens Healthineers; manufacturer-reported sensitivity of 100% and specificity of 99.8%) was used to estimate crude SARS-CoV-2 seroprevalence in the unweighted sample, and then the estimated seroprevalence rates for the US dialysis and adult populations were calculated, adjusting for age, sex, and region.

RESULTS

A total of 21 464 patients (mean [SD] age, 63.1 [14.2] years; 12 265 men [57%]) were included in the unweighted sample from January 2021. The patients were disproportionately older (aged 65-79 years, 7847 [37%]; aged ≥80 years, 2668 [12%]) and members of racial/ethnic minority groups (Hispanic patients, 2945 [18%]; non-Hispanic Black patients, 4875 [29%]). Seroprevalence of SARS-CoV-2 antibodies was 18.9% (95% CI, 18.3%-19.5%) in the sample, with a seroprevalence of 18.7% (95% CI, 18.1%-19.2%) standardized to the US dialysis population, and 21.3% (95% CI, 20.3%-22.3%) standardized to the US adult population. In the unweighted sample, younger persons (aged 18-44 years, 25.9%; 95% CI, 24.1%-27.8%), those who self-identified as Hispanic or living in Hispanic neighborhoods (25.1%; 95% CI, 23.6%-26.4%), and those living in the lowest-income neighborhoods (24.8%; 95% CI, 23.2%-26.5%) were among the subgroups with the highest seroprevalence. Little variability was observed in seroprevalence by geographic region, population density, and urban or rural status in the January 2021 sample (largest regional difference, 1.2 [95% CI, 1.1-1.3] higher odds of seroprevalence in residents of the Northeast vs West).

CONCLUSIONS AND RELEVANCE

In this cross-sectional study of patients receiving dialysis in the US, fewer than 1 in 4 patients had evidence of SARS-CoV-2 antibodies 1 year after the first case of SARS-CoV-2 infection was detected in the US. Results standardized to the US population indicate similar prevalence of antibodies among US adults. Vaccine introduction to younger individuals, those living in neighborhoods with a large population of racial/ethnic minority residents, and those living in low-income neighborhoods may be critical to disrupting the spread of infection.

Antibody Response to COVID-19 vaccination in Patients Receiving Dialysis

Background

Patients receiving dialysis may mount impaired responses to COVID19 vaccination.

Methods

We report antibody response to vaccination from 1140 patients without, and 493 patients with pre-vaccination SARS-CoV-2 RBD antibody. We used commercially available assays (Siemens) to test remainder plasma monthly in association with vaccination date and type, and assess prevalence of absent total receptor binding antibody, and absent or attenuated (index value < 10) semiquantitative receptor binding domain IgG index values. We used Poisson regression to evaluate risk factors for absent or attenuated response to vaccination.

Results

Among patients who were seronegative versus seropositive before vaccination, 62% and 56% were ≥65 years old, 20% and 24% were Hispanic, and 22% and 23% were Black. Median IgG index values rose steadily over time, and were higher among the seropositive than in the seronegative patients after completing vaccination (150 [25th, 75th percentile 23.2, 150.0] versus 41.6 [11.3, 150.0]). Among 610 patients who completed vaccination (assessed ≥14 days later, median 29 days later), the prevalence of absent total RBD response, and absent and attenuated semiquantitative IgG response was 4.4% (95% CI 3.1, 6.4%), 3.4% (2.4, 5.2%), and 14.3% (11.7, 17.3%) respectively. Risk factors for absent or attenuated response included longer vintage of end-stage kidney disease, and lower pre-vaccination serum albumin.

Conclusions

More than one in five patients receiving dialysis had evidence of an attenuated immune response to COVID19 vaccination.

[The Pathogenesis of Pulmonary Emphysema - Laennec was right!]

Pulmonary emphysema is characterised by irreversible destruction and enlargement of alveolar structure distal to terminal bronchioles. Small conducting airways < 2 mm in diameter are the major site of chronic airway inflammation and obstruction in COPD patients. 80 - 90 % of the last generation of small conducting airways, the terminal bronchioles, are destroyed in patients with very severe COPD. Recent data showing, that small airways disease is also a pathological feature in patients with COPD GOLD stage 1 and 2. Although 40 % of terminal and 60 % of transitional bronchioles were destroyed, there was no sign for emphysema. Only a significant loss of terminal and respiratory bronchioles seems to be able to induce pulmonary emphysema and respiratory symptoms.

Germinal Center B Cell-Like (GCB) and Activated B Cell-Like (ABC) Type of Diffuse Large B Cell Lymphoma (DLBCL): Analysis of Molecular Predictors, Signatures, Cell Cycle State and Patient Survival

Aiming to find key genes and events, we analyze a large data set on diffuse large B-cell lymphoma (DLBCL) gene-expression (248 patients, 12196 spots). Applying the loess normalization method on these raw data yields improved survival predictions, in particular for the clinical important group of patients with medium survival time. Furthermore, we identify a simplified prognosis predictor, which stratifies different risk groups similarly well as complex signatures.

We identify specific, activated B cell-like (ABC) and germinal center B cell-like (GCB) distinguishing genes. These include early (e.g. CDKN3) and late (e.g. CDKN2C) cell cycle genes.

Independently from previous classification by marker genes we confirm a clear binary class distinction between the ABC and GCB subgroups. An earlier suggested third entity is not supported. A key regulatory network, distinguishing marked over-expression in ABC from that in GCB, is built by: ASB13, BCL2, BCL6, BCL7A, CCND2, COL3A1, CTGF, FN1, FOXP1, IGHM, IRF4, LMO2, LRMP, MAPK10, MME, MYBL1, NEIL1 and SH3BP5. It predicts and supports the aggressive behaviour of the ABC subgroup. These results help to understand target interactions, improve subgroup diagnosis, risk prognosis as well as therapy in the ABC and GCB DLBCL subgroups.

Frequency of regulatory T cells determines the outcome of the T-cell-engaging antibody blinatumomab in patients with B-precursor ALL

Blinatumomab can induce a complete haematological remission in patients in 46.6% with relapsed/refractory B-precursor acute lymphoblastic leukemia (r/r ALL) resulting in a survival benefit when compared with chemotherapy. Only bone marrow blast counts before therapy have shown a weak prediction of response. Here we investigated the role of regulatory T cells (Tregs), measured by CD4/CD25/FOXP3 expression, in predicting the outcome of immunotherapy with the CD19-directed bispecific T-cell engager construct blinatumomab. Blinatumomab responders (n=22) had an average of 4.82% Tregs (confidence interval (CI): 1.79-8.34%) in the peripheral blood, whereas non-responders (n=20) demonstrated 10.25% Tregs (CI: 3.36-65.9%). All other tested markers showed either no prediction value or an inferior prediction level including blast BM counts and the classical enzyme marker lactate dehydrogenase. With a cutoff of 8.525%, Treg enumeration can identify 100% of all blinatumomab responders and exclude 70% of the non-responders. The effect is facilitated by blinatumomab-activated Tregs, leading to interleukin-10 production, resulting in suppression of T-cell proliferation and reduced CD8-mediated lysis of ALL cells. Proliferation of patients' T cells can be restored by upfront removal of Tregs. Thus, enumeration of Treg identifies r/r ALL patients with a high response rate to blinatumomab. Therapeutic removal of Tregs may convert blinatumomab non-responders to responders.

Revisiting adult neurogenesis and the role of erythropoietin for neuronal and oligodendroglial differentiation in the hippocampus

Recombinant human erythropoietin (EPO) improves cognitive performance in neuropsychiatric diseases ranging from schizophrenia and multiple sclerosis to major depression and bipolar disease. This consistent EPO effect on cognition is independent of its role in hematopoiesis. The cellular mechanisms of action in brain, however, have remained unclear. Here we studied healthy young mice and observed that 3-week EPO administration was associated with an increased number of pyramidal neurons and oligodendrocytes in the hippocampus of ~20%. Under constant cognitive challenge, neuron numbers remained elevated until >6 months of age. Surprisingly, this increase occurred in absence of altered cell proliferation or apoptosis. After feeding a ¹⁵N-leucine diet, we used nanoscopic secondary ion mass spectrometry, and found that in EPO-treated mice, an equivalent number of neurons was defined by elevated ¹⁵N-leucine incorporation. In EPO-treated NG2-Cre-ERT2 mice, we confirmed enhanced differentiation of preexisting oligodendrocyte precursors in the absence of elevated DNA synthesis. A corresponding analysis of the neuronal lineage awaits the identification of suitable neuronal markers. In cultured neurospheres, EPO reduced Sox9 and stimulated miR124, associated with advanced neuronal differentiation. We are discussing a resulting working model in which EPO drives the differentiation of non-dividing precursors in both (NG2+) oligodendroglial and neuronal lineages. As endogenous EPO expression is induced by brain injury, such a mechanism of adult neurogenesis may be relevant for central nervous system regeneration.

[Treatment Strategies for Septic Arthritis of the Sternoclavicular Joint]

Septic arthritis of the sternoclavicular joint (SCJ) is a relatively rare disease. Due to serious complications including mediastinitis and generalised sepsis early diagnosis and rapid onset of treatment are mandatory. The disease often affects immunocompromised patients, diabetics, or patients with other infectious diseases. The therapeutic options range from administration of antibiotics to extended surgery including reconstructive procedures. Apart from rare situations where conservative treatment with antibiotics is sufficient, joint resection followed by plastic surgical procedures are required. We present a retrospective analysis with data from two hospitals. From January 2008 to December 2012 23 patients with radiographically confirmed septic arthritis of various aetiology were included. Fourteen (60.8 %) male, nine (39.2 %) female patients with an average age of 60.3 ± 14.2 years (range: 23-88 years) with septic arthritis of the SCJ were treated. Seven (30.4 %) patients suffered from Diabetes mellitus, nine (39.1 %) had underlying diseases with a compromised immune system. In 14 (60.8 %) out of 23 patients a bacterial focus was detected. Only six (26 %) patients suffered from confined septic arthritis of the SCG, in 17 (73,9 %) patients osteomyelitis of the adjacent sternum, and the clavicle was present. In addition, 15 (65.2 %) patients already suffered from mediastinitis at the time of diagnosis, eight (35 %) patients even from septicaemia. In conclusion, septic arthritis requires an active surgical treatment. Limited incision of the joint and debridement alone is only successful at early stages of the disease. The treatment concept has to include the local joint and bone resection as well as complications like mediastinitis. After successful treatment of the infection, the defect of the chest wall requires secondary reconstructive surgery using a pedicled pectoralis muscle flap.

Broad DNA methylation changes of spermatogenesis, inflammation and immune response-related genes in a subgroup of sperm samples for assisted reproduction

Aberrant sperm DNA methylation patterns, mainly in imprinted genes, have been associated with male subfertility and oligospermia. Here, we performed a genome-wide methylation analysis in sperm samples representing a wide range of semen parameters. Sperm DNA samples of 38 males attending a fertility centre were analysed with Illumina HumanMethylation27 BeadChips, which quantify methylation of >27 000 CpG sites in cis-regulatory regions of almost 15 000 genes. In an unsupervised analysis of methylation of all analysed sites, the patient samples clustered into a major and a minor group. The major group clustered with samples from normozoospermic healthy volunteers and, thus, may more closely resemble the normal situation. When correlating the clusters with semen and clinical parameters, the sperm counts were significantly different between groups with the minor group exhibiting sperm counts in the low normal range. A linear model identified almost 3000 CpGs with significant methylation differences between groups. Functional analysis revealed a broad gain of methylation in spermatogenesis-related genes and a loss of methylation in inflammation- and immune response-related genes. Quantitative bisulfite pyrosequencing validated differential methylation in three of five significant candidate genes on the array. Collectively, we identified a subgroup of sperm samples for assisted reproduction with sperm counts in the low normal range and broad methylation changes (affecting approximately 10% of analysed CpG sites) in specific pathways, most importantly spermatogenesis-related genes. We propose that epigenetic analysis can supplement traditional semen parameters and has the potential to provide new insights into the aetiology of male subfertility.

Phosphorus retention in a mesotrophic lake under transient loading conditions: insights from a sediment phosphorus binding form study

Phosphorus retention in sediments has been estimated for three basins in Lake Simcoe, a mesotrophic lake in Ontario, Canada. Total phosphorous (TP) fractionation was used to examine the concentration of phosphorus (P) binding forms in the sediments of Cook's Bay, Kempenfelt Bay, and the Main Basin. The extended sequential extractions allowed us to differentiate between organic-, inorganic-, carbonate-bounded and redox-sensitive phosphorus. Our results showed different mechanisms of P release in each of the three investigated basins, which may be linked to their distinct loading histories, present land-uses and morphology of the sampling sites. In the deep Main Basin, where moderate changes in P loading have been induced by deforestation, sediments are not an important long-term source of diagenetically mobile P, as almost 75% of P is released within a short time scale. P release is predominantly generated by a continuous epilimnetic P flux, rather than a large inventory of temporary P stored in the sediments. Diagenesis in the upper sediment layers is fast enough to prevent a large accumulation of temporary P. In the much deeper glacially formed Kempenfelt Bay with a highly urbanized catchment, P release from the sediments is dominated by the redox-sensitive P fraction, representing up to 40% and 57% of long- and short-term sediment P release, respectively. In the shallow and agriculturally-impacted Cook's Bay, the main P binding form that can be mobilized through diagenesis is carbonate-bound P. This fraction contributes 40.1% and 37.6% to the long- and short-term P sediment release, respectively. Although different mechanisms of P release have been revealed for the three basins in Lake Simcoe, the vertical profiles indicate that the sediments throughout the system are still able to bind deposited P.

[Septic arthritis of the sternoclavicular joint: radical resection and treatment with a pectoralis flap]

After infection of a vascular prosthesis with generalised sepsis, a 59-year-old male patient suffered from an increasing swelling of his right sternoclavicular joint. We performed an incision and debridement of the SC joint and harvested material for microbiological diagnosis. However, we were not able to overcome the inflammation until we performed a radical resection including the medial aspect of the clavicle and parts of the manubrium followed by coverage with a pectoralis flap. The further course was uneventful with a good functional result. Reviewing data from the literature there are no unequivocal guidelines available for this rare disease. However, in most cases a radical debridement and a consecutive flap coverage are required.

Calcium carbonate precipitation by cyanobacterial polysaccharides

Cyanobacteria have been recognized as key players in the precipitation of calcium carbonate in marine and freshwater systems. These bacteria increase pH, (as a result of photosynthetic activity) and also produce extracellular polysaccharides, which act as binding sites for Ca2+ and CO32−. Both processes influence the morphology and the mineralogy of the carbonate minerals. In order to clarify the role of polysaccharides of picocyanobacteria upon calcium carbonate precipitation, both their buffering capacity and ability to induce precipitation need to be investigated. In this experimental study, we characterized the polysaccharides of three unicellular autotrophic picocyanobacterial Synechococcus-type strains by potentiometric titration and infrared spectroscopy. Potentiometric titrations were conducted to determine the total buffering capacity. The nature and concentration of active sites of the polysaccharides was clarified with the aid of potentiometric titration and spectral analysis of an aqueous cellular suspension. Precipitation experiments with polysaccharides of different strains allowed an estimation of their potential to precipitate calcium carbonate. The results presented here indicate that polysaccharides from cyanobacteria have a strong potential to exchange protons with their surrounding environment. Precipitation experiments demonstrated that extracellular polysaccharides of all the strains studied able to precipitate calcium carbonate.

(R)-roscovitine prolongs the mean open time of unitary N-type calcium channel currents

(R)-roscovitine (Ros) is a cyclin-dependent kinase inhibitor that also has been shown to have direct agonist and antagonist actions on Ca(v)2.1 (P/Q-type) and Ca(v) 2.2 (N-type) families of voltage-gated calcium channels. These kinase-independent effects represent a novel opportunity to advance our understanding of calcium channel function and calcium-triggered neurotransmitter release. Furthermore, such actions on calcium channels may direct the development of Ros derivatives as new therapeutic agents. We used patch clamp recordings to characterize mechanisms that underlie the agonist effects of Ros on unitary N-type calcium channel gating. We found that N-type channels normally gate with either a short or long mean open time, that Ros significantly prolonged the mean open time of the long gating component and increased the probability of observing channels that gated with a long open time, but had no effect on single channel conductance. Using Monte Carlo simulations of a single channel kinetic model and Ros interactions, we were able to reproduce our experimental results and investigate the model's microscopic dynamics. In particular, our simulations predicted that the longer open times generated by Ros were due to the appearance of a long open state combined with an increased amount of time spent in transitions between open states. Our results suggest a mechanism for agonist effects of Ros at the level of single channels, and provide a mechanistic explanation for previously reported agonist effects on whole cell calcium currents.

CaCO3 nucleation by cyanobacteria: laboratory evidence for a passive, surface-induced mechanism

Calcite nucleation on the surface of cyanobacteria of the Synechococcus leopoliensis strain PCC 7942 was investigated to assess the influence of photosynthetic uptake of inorganic carbon and active ion exchange processes across the cell membrane on the nucleation and precipitation mechanisms. We performed long-term precipitation experiments at a constant CO(2) level in ambient air by adding suspensions of previously washed cyanobacteria to solutions of NaHCO(3)/CaCl(2) which were supersaturated with respect to calcite. Induction times between 4 and 110 h were measured over a range of saturation states, Omega, between 8 and 4. The kinetics of CaCO(3) nucleation was compared between experiments: (i) with ongoing photosynthesis, (ii) with cells metabolizing but not undergoing photosynthetic uptake of inorganic carbon and (iii) in darkness without photosynthesis. No significant differences were observed between the three treatments. The results reveal that under low nutrient concentrations and permanent CO(2) supply, photosynthetic uptake of inorganic carbon predominantly uses CO(2) and consequently does not directly influence the nucleation process of CaCO(3) at the surface of S. leopoliensis. Furthermore, ion exchange processes did not affect the kinetics, indicating a passive nucleation process wherein the cell surface or extracellular polymers provided preferential sites for mineral nucleation. The catalyzing effect of the cyanobacteria on calcite nucleation was equivalent to a approximately 18% reduction in the specific interfacial free energy of the calcite nuclei. This result and the ubiquitous abundance of cyanobacteria suggest that this process may have an impact on local and global carbon cycling.

[Effects of soccer-specific strains on the locomotor system]

PROBLEMS

Soccer as a Stop-and-Go-sport goes along with a high level of physical strain on the locomotor system. Compared to similar kinds of sports, soccer is characterized by a high prevalence of overloads/injuries in the pelvic region. Since soccer frequently involves one-sided shot-training, modifications in the pelvic statics are possible.

METHODS

In a pilot study including 15 football-players-FP (age 26.9 +/- 3.1 yrs; 4.4 +/- 0.4 training units/week+ 1 leaque game) the pelvic statics was measured using the 3-d-recording system CMS70 (Zebris, Germany) directly before and after a defined shot training. The positions of the right and the left posterior superior iliac spines - PSIS were compared. Additionally, the stiffness of selective muscles was analyzed.

RESULTS

Before intervention the right PSIS was heightened in 8 FP. In 4 FP the pelvic statics was balanced and in 3 FP the right PSIS was abased. After the shot training, the pelvic statics was balanced in 4 FP. In contrast, 10 FP showed a higher right PSIS and 1 FP had a lower right PSIS. However, modifications of the pelvic statics were detected in all directions.

DISCUSSION

Our study demonstrates modification of the pelvic statics by asymmetric soccer-specific strains, but the reactions were individually different. It is possible, that changes in the pelvic statics may lead to changed function or overstrain of advertising muscles.

Microorganisms, mineral surfaces, and aquatic environments: learning from the past for future progress

The interactions between the geosphere and the biosphere are central questions in environmental and geological research. The relationship between bacteria and their environment is an important example of these interactions. By studying microbial communities in modern environments, it is possible to understand the underlying mechanisms that shape these environments and apply this knowledge to the rock record. Recently, new experimental and theoretical methods, ranging from nano- and biotechnology to mathematical and conceptual modelling, have come into play. Thus, new opportunities for interdisciplinary research in the field of geobiology have emerged. In this paper, we review aspects of state-of-the-art imaging and modelling techniques and propose a research concept linking the experimental and the theoretical approaches.

Germinal center B cell-like (GCB) and activated B cell-like (ABC) type of diffuse large B cell lymphoma (DLBCL): analysis of molecular predictors, signatures, cell cycle state and patient survival

Aiming to find key genes and events, we analyze a large data set on diffuse large B-cell lymphoma (DLBCL) gene-expression (248 patients, 12196 spots). Applying the loess normalization method on these raw data yields improved survival predictions, in particular for the clinical important group of patients with medium survival time. Furthermore, we identify a simplified prognosis predictor, which stratifies different risk groups similarly well as complex signatures. We identify specific, activated B cell-like (ABC) and germinal center B cell-like (GCB) distinguishing genes. These include early (e.g. CDKN3) and late (e.g. CDKN2C) cell cycle genes. Independently from previous classification by marker genes we confirm a clear binary class distinction between the ABC and GCB subgroups. An earlier suggested third entity is not supported. A key regulatory network, distinguishing marked over-expression in ABC from that in GCB, is built by: ASB13, BCL2, BCL6, BCL7A, CCND2, COL3A1, CTGF, FN1, FOXP1, IGHM, IRF4, LMO2, LRMP, MAPK10, MME, MYBL1, NEIL1 and SH3BP5. It predicts and supports the aggressive behaviour of the ABC subgroup. These results help to understand target interactions, improve subgroup diagnosis, risk prognosis as well as therapy in the ABC and GCB DLBCL subgroups.

Factors influencing the formation of small dense low-density lipoprotein particles in dependence on the presence of the metabolic syndrome and on the degree of glucose intolerance

BACKGROUND

Small dense low-density lipoprotein (LDL) particles are known to be especially atherogenic. Several mechanisms are involved in this atherogenicity.

AIMS

We wanted to look for the presence of small dense LDL particles depending on gender, metabolic syndrome (MS) and different degrees of glucose intolerance. Moreover, we looked for anthropometric factors and factors of lipid and carbohydrate metabolism that are associated with changes in the LDL size.

RESULTS

We studied 752 persons (330 males, 422 females; age 40 +/- 17 years). LDL particle size was estimated with polyacrylamide gel electrophoresis. Males had smaller LDL particles than females. Probands with the MS had smaller LDL particles than those without this syndrome. With rising plasma triglyceride (TG) levels more small dense LDL particles were seen. The highest proportion of these small dense LDL particles was observed in the subgroup of type 2 diabetic patients. In the whole material, the mean LDL diameter was correlated negatively with plasma TG and very low-density lipoprotein components (TG, cholesterol and proteins) and positively with high-density lipoprotein cholesterol. In a linear stepwise regression analysis different significant factors influencing the LDL size were found in the whole population, in normoglycaemic probands, in persons with impaired glucose tolerance, in type 2 diabetic patients and in type 2 diabetic patients injecting insulin.

CONCLUSIONS

Our data point to different mechanisms of the formation of small dense LDL particles in dependence on the degree of glucose intolerance. Moreover, the target values for plasma TG should be set lower.

[Measurement of adhesive properties of polymers in vitro]

Adhesive force of branched oligoesters under the in vitro conditions was studied by measuring the maximal force necessary to separate the tested sample from the base (F(max)) under different testing conditions. Branched oligoesters were synthesized from lactic and glycolic acids in the molar ratio 1:1, and from mannitol or dipentaery thritol as the branching components in concentrations of 3%, 5% or 8%. To decrease viscosity and thus to facilitate the workability and administration, triethyl citrate (TEC) in a concentration of 30% was employed. Polymeric systems for adhesive force measurements were prepared by melting oligoesters in a micro oven and by homogenization with TEC. Adhesive force was measured on a material testing device T1-FR050TH.A1K Zwick/Roell at the set rate of separation 10 mm/min or 100 mm/min, contact force 10 N or 20 N, and a period of contact of the sample with the base of 5 s or 10 s. The adhesive force of branched oligoesters was found to be significantly higher than the adhesive force of gelatine gels, methylcellulose, carmelose sodium salt or sodium carbomer salt. Dipentaerythritol-branched oligoesters exerted higher adhesive force than mannitol-branched oligoesters. The value of adhesive force was increased with growing concentration of the branching component in the oligoester. Of the experimental parameters tested, a statistically significant influence of the separation rate of the sample from the base on the magnitude of F(max) was observed. The influence of different periods of contacts was manifested only in some samples, and the influence of different contact forces on F(max) value was not demonstrated in any sample.

Release of albumin from oligoester plastic matrices: effect of magnesium oxide and bivalent stearates

Biodegradable implantable matrices containing bovine serum albumin were prepared from oligoesters by melting, and subsequently tested on in vitro albumin release. The linear poly (DL-lactic acid) and the branched terpolymer of DL-lactic acid, glycolic acid, and mannitol were synthesized. Products were of similar molecular weight and possessed different thermal and swelling characteristics. Oligoesters were loaded with 4% albumin and plasticized by 30% triacetin. Other additives added into the matrices as albumin stabilizers were divalent stearates and magnesium oxide. The influences of oligomer molecules constitution, divalent ion stearates or magnesium oxide addition, and triacetin concentration on the albumin release were quantified. SDS-PAGE revealed protein hydrolysis during the dissolution tests.

Some basic parameters of microspheres fabricated from a branched oligoester by a rapid procedure

Microspheres were prepared from a branched copolymer of DL-lactic acid with mannitol containing native albumin and albumin labelled with fluorescein isothiocyanate, using a rapid method of distribution of methylformate as the solvent of the copolymer from the intermediate phase of the multiple w/o/w emulsion. The primary w/o emulsion was prepared by the method of homogenization with a turbine or, alternatively, by the method of dispersion with ultrasound in modified vessels. Different additives in the external aqueous phase, such as polyvinyl alcohol or the gelatin hydrolyzate as emulsifiers were tested. Ammonium sulphate, methylformate or ethyl acetate were used as moderators of solidification of microspheres. The effect of these selected formulation parameters on the size, encapsulation efficiency, yield of microspheres and on the course of the BSA and FITC-BSA release in vitro conditions were examined.

[Anthracycline-induced cardiotoxicity: cardiac MRI after treatment for childhood cancer]

PURPOSE

Quantification of left and right ventricular function using MRI in young cancer patients treated with cardiotoxic anthracyclines.

MATERIALS AND METHODS

Twenty-eight patients (mean age 16.4 years) underwent cardiac MRI at 1.5 T. The study protocol consisted of morphologic T2-weighted images with fat suppression and cine steady-state free precession sequences (SSFP) for functional analysis. Seven patients were examined at the end of chemotherapy, two of them also repeatedly during therapy, and 21 patients following an average period of three years after finishing chemotherapy (range one month--20 years)

RESULTS

The end-systolic volume index increased and the ejection fraction of the left and right ventricle decreased during anthracycline therapy. Two of seven patients showed a myocardial edema at the end of the therapy. In 15 of all 28 patients, the left ventricular ejection fraction was reduced to less than 55 % (minimum 44 %). No clinical signs of cardiac insufficiency or cardiomyopathy were observed.

CONCLUSION

MRI is able to detect acute as well as chronic subclinical cardiotoxic effects of anthracyclines. Impairment of the right ventricular function should be considered in the diagnosis of anthracycline-induced cardiomyopathy.

[Liberation of folic acids from composite chitosan films]

Thin films were prepared by the method of evaporation of aqueous solutions of chitosan or its mixtures with poloxamer 407, gelatin, or polyvinyl alcohol. Films of varying thickness were cross-linked with phosphate ions. They contained micronized folic acid in a concentration of 9.1% or 3.2%. Prolonged several hours' liberation of folic acid into isotonic phosphate buffer at pH 5.5, 6.0, and 6.5 was examined. In the initial stage, the mechanism of liberation was governed by diffusion of the dissolved fraction, at higher pH values a higher rate of dissolution of the substance played its role. In some composites, sorption of folic acid to chitosan in an extent dependent on the composition of composites and current acidity of the medium was demonstrated.

[Effect of triester glycerol type of plasticizers on release of albumin from biodegradable polymer matrices]

Bovine serum albumin was heterogeneously dispersed in the terpolymer of DL-lactic acid, glycolic acid, and mannitol. The terpolymeric carrier was plasticized by triacetin, tributyrin, or a mixture of triacetin with tricaprylin. Matrices were prepared by mixing a melt of the carrier with the plasticizer and albumin. Liberation was tested in 1/15 mol.l-1 phosphate buffer pH 7.4 and took place in two stages--the burst and the stage of the continual process. The burst represented 30% to 90% of liberated albumin. The second, continual stage began on day 4 of liberation and within ten days maximally 10% of the total amount of albumin was released. The course of liberation was most markedly influenced by the parameters of the oligoester carrier, its molecular weight, and the degree of branching. The total extent of albumin liberation was influenced partly by its irreversible adsorption on the carrier, partly by its polymerization. The extent of adsorption and polymerization of albumin was increased with the molecular weight of the carrier and decreased with the increasing degree of its branching. Albumin liberation was positively influenced by the presence of plasticizers in matrices, triacetin being demonstrated as the best one.

Cell cycle control in glomerular disease

The sequential activation of the cyclin-dependent kinases by their partner cyclins underlies the progression of the cell cycle from quiescence through growth to cell division. More recently a role for these proteins and their inhibitors has been appreciated in several diverse renal and non-renal cell processes, including proliferation, development, differentiation, hypertrophy and apoptosis. The glomerulus represents a unique micro-environment in which to study the cellular outcome following injury, as each of the three resident cell types undergoes a specific and distinct response to a given stimulus. The mesangial cell is capable of marked proliferation, often accompanied by the deposition of extracellular matrix. In contrast, the podocyte has previously been considered a relatively inert cell, and the reparative proliferation of glomerular endothelial cells following injury has recently been described. There is currently increasing awareness of the need to prevent, control and ameliorate the progression of renal diseases. Knowledge of the cell cycle and an understanding of how this may be beneficially manipulated may be crucial to improving the outlook for patients with both diabetic and non-diabetic glomerular disease.

Hypoxia influences generation and propagation of electrical activity in embryonic cardiomyocyte clusters

The influence of tissue hypoxia on the generation and propagation of excitation was studied in spontaneously beating embryonic cardiomyocyte clusters grown in eight 9-12 days old embryoid bodies. Within the embryoid bodies one to three separately active clusters of cardiomyocytes were found, each having its own pacemaker cell. Lowering of tissue PO(2) caused bradycardia as well as arrhythmia in all embryoid bodies investigated. The mean frequency of the extracellularly recorded action potentials decreased under conditions of pronounced hypoxia from a mean of 1.4-1.8 Hz to below 0.8 Hz. In three embryoid bodies hypoxia-sensitive as well as hypoxia-tolerant cardiomyocyte clusters were found. The hypoxia-insensitive cardiomyocytes showed a low frequency of spontaneous activity. In addition to the observed changes in the generation of excitation, tissue hypoxia caused an approximately 60% reduction in the velocity of conduction within the cardiomyocyte clusters. Moreover, in at least one of the eight experiments propagation failure with an incomplete block in spread of excitation was observed. All hypoxia-induced effects on generation and propagation of embryonic cardiomyocyte excitation were completely reversible after reoxygenation.

Antigenic and adjuvant activities of branched aliphatic oligoester (M-DL-LA) microspheres with incorporated bovine rotavirus

Branched aliphatic oligoester microspheres (msp) with incorporated rotavirus were used to induce the production of systemic and mucosal antibodies in mice. The msp with a mean diameter of 7.4 microm were prepared by the w/o/w technique. The mice were immunized intraperitoneally or orally. High ELISA titres of systemic and local IgG and IgA antibodies were indicative of rotavirus incorporation and of the adjuvant activity of msp. Oral immunization with a split dose administered on three consecutive days, resulted in the production of systemic IgG and IgA antibodies, but failed to induce the production of mucosal antibodies even if the immunization dose was increased threefold. Specific antibodies were detectable in faeces of orally immunized mice only after another triple administration of the same dose in the fourth week of the experiment. Reactions of blood serum IgG with the structural viral proteins VP4, VP6, and VP7 were demonstrated by western blotting. Both systemic, and faecal IgA antibodies were specific for the VP6 protein and the dimeric form of the glycoprotein VP4.