9-Month observational Dia-Vacc study of vaccine type influence on SARS-CoV-2 immunity in dialysis and kidney transplant patients

BACKGROUND

SARS-CoV-2mRNA vaccination related seroconversion rates are reduced in dialysis and kidney transplant patients.

METHODS

We evaluated nine months follow up data in our observational Dia-Vacc study exploring specific cellular (interferon-γ release assay) or/and humoral immune responses after 2x SARS-CoV-2mRNA vaccination in 880 participants including healthy medical personnel (125-MP), dialysis patients (595-DP), kidney transplant recipients (111-KTR), and apheresis patients (49-AP) with positive seroconversion (de novo IgA or IgG antibody positivity by ELISA) after eight weeks.

FINDINGS

Nine months after first vaccination, receptor binding domain (RBD) antibodies were still positive in 90 % of MP, 86 % of AP, but only 55 %/48 % of DP/KTR, respectively. Seroconversion remained positive in 100 % of AP and 99·2 % of MP, but 86 %/81 % of DP/KTR, respectively. Compared to MP, DP but not KTR or AP were at risk for a strong RBD decline, while KTR kept lowest RBD values over time. By multivariate analysis, BNT162b2mRNA versus 1273-mRNA vaccine type was an independent risk factor for a strong decline of RBD antibodies. Within the DP group, only time on dialysis was another (inverse) risk factor for the DP group. Compared to humoral immunity, T-cell immunity decline was less prominent.

INTERPRETATION

While seroconverted KTR reach lowest RBD values over time, DP are at specific risk for a strong decline of RBD antibodies after successful SARS-CoV-2mRNA vaccination, which also depends on the vaccine type being used. Therefore, booster vaccinations for DP should be considered earlier compared to normal population.

A quantitative 3D intravital look at the juxtaglomerular renin-cell-niche reveals an individual intra/extraglomerular feedback system

The juxtaglomerular niche occupied by renin cells (RCN) plays an important role in glomerular repair but the precise temporal and spatial interrelations remain unclear. This study proposes the hypothesis of a local intra-extraglomerular regenerative feedback system and establishes a new quantifiable system for RCN responses in individual glomeruli in vivo. A strictly intraglomerular two-photon laser-induced injury model was established. Labeled renin cells (RC) in transgenic renin reporter mice were fate-traced in healthy and injured glomeruli over several days by intravital microscopy and quantified via new three-dimensional image processing algorithms based on ray tracing. RC in healthy glomeruli demonstrated dynamic extraglomerular protrusions. Upon intraglomerular injury the corresponding RCN first increased in volume and then increased in area of dynamic migration up to threefold compared to their RCN. RC started migration reaching the site of injury within 3 hours and acquired a mesangial cell phenotype without losing physical RCN-contact. During intraglomerular repair only the corresponding RCN responded via stimulated neogenesis, a process of de novo differentiation of RC to replenish the RCN. Repeated continuous intravital microscopy provides a state-of-the-art tool to prove and further study the local intraglomerular RCN repair feedback system in individual glomeruli in vivo in a quantifiable manner.

MMF/MPA Is the Main Mediator of a Delayed Humoral Response With Reduced Antibody Decline in Kidney Transplant Recipients After SARS-CoV-2 mRNA Vaccination

Kidney transplant recipients (KTR) show significantly lower seroconversion rates after SARS-CoV-2 mRNA vaccination compared to dialysis patients (DP). Mycophenolate mofetil or mycophenolic acid (MMF/MPA) in particular has been identified as a risk factor for seroconversion failure. While the majority of all KTR worldwide receive MMF/MPA for immunosuppressive therapy, its impact on antibody decline in seroconverted KTR still remains unclear. In an observational study (NCT04799808), we investigated whether 132 seroconverted KTR (anti-spike S1 IgG or IgA positive after 2 vaccinations) show a more rapid antibody decline with MMF/MPA than those without this medication. A total of 2 months after mRNA vaccination, average anti-spike S1 IgG levels of KTR with MMF/MPA were lower than without (p = 0.001), while no differences between these two groups were observed after 6 months (p = 0.366). Similar results were obtained for anti-RBD IgG antibodies (T2 p = 0.003 and T3 p = 0.135). The probability of severe IgG decline with MMF/MPA was three times lower than without (p = 0.003, OR 0.236, 95% CI 0.091-0.609). In the multivariate analysis, neither immunosuppressants, such as calcineurin inhibitors, mTOR inhibitors (mTOR-I; mechanistic target of rapamycin), glucocorticoids, nor vaccine type, sex, or age showed a significant influence on IgG titer decline between 2 and 6 months. For the decision on additional booster vaccinations, we consider immunosurveillance to be needed as an integral part of renal transplant follow-up after SARS-CoV-2 mRNA vaccination. Not only the lack of seroconversion but also the peak and titer decline of the specific IgG and RBD IgG antibody formation after two mRNA vaccinations is significantly influenced by MMF/MPA.

Risk of strong antibody decline in dialysis and transplant patients after SARS-CoV-2mRNA vaccination: Six months data from the observational Dia-Vacc study

Background

Vulnerable dialysis and kidney transplant patients show impaired seroconversion rates compared to medical personnel eight weeks after SARS-CoV-2mRNA vaccination.

Methods

We evaluated six months follow up data in our observational Dia-Vacc study exploring specific cellular (interferon-γ release assay) or/and humoral immune responses after 2x SARS-CoV-2mRNA vaccination in 1205 participants including medical personnel (125 MP), dialysis patients (970 DP) and kidney transplant recipients (110 KTR) with seroconversion (de novo IgA or IgG antibody positivity by ELISA) after eight weeks.

Findings

Six months after vaccination, seroconversion remained positive in 98% of MP, but 91%/87% of DP/KTR (p = 0·005), respectively. Receptor binding domain-IgG (RBD-IgG) antibodies were positive in 98% of MP, but only 68%/57% of DP/KTR (p < 0·001), respectively. Compared to MP, DP and KTR were at risk for a strong IgG or RBD-IgG decline (p < 0·001). Within the DP but not KTR group male gender, peritoneal dialysis, short time on dialysis, BNT162b2mRNA vaccine, immunosuppressive drug use and diabetes mellitus were independent risk factors for a strong decline of IgG or RBD antibodies. The percentage of cellular immunity decline was similar in all groups.

Interpretation

Both vulnerable DP and KTR groups are at risk for a strong decline for IgG and RBD antibodies. In KTR, antibody titres peak at a markedly lower level and accelerated antibody decline is mixed with a delayed/increasing IgG, RBD-IgG, or cellular immune response in a 16% fraction of patients. In both populations, immune monitoring should be used for early timing of additional booster vaccinations.

Funding

This study was funded by the Else Kröner Fresenius Stiftung, Bad Homburg v. d. H., grant number Fördervertrag EKFS 2021_EKSE.27.

Cellular and Humoral Immune Responses After 3 Doses of BNT162b2 mRNA SARS-CoV-2 Vaccine in Kidney Transplant

Supplemental Digital Content is available in the text.

Humoral and cellular immunity to SARS-CoV-2 vaccination in renal transplant versus dialysis patients: A prospective, multicenter observational study using mRNA-1273 or BNT162b2 mRNA vaccine

Background

Dialysis and kidney transplant patients are vulnerable populations for COVID-19 related disease and mortality.

Methods

We conducted a prospective study exploring the eight week time course of specific cellular (interferon-γ release assay and flow cytometry) or/and humoral immune responses (ELISA) to SARS-CoV-2 boost vaccination in more than 3100 participants including medical personnel, dialysis patients and kidney transplant recipients using mRNA vaccines BNT162b2 or mRNA-1273.

Results

SARS-CoV-2-vaccination induced seroconversion efficacy in dialysis patients was similar to medical personnel (> 95%), but markedly impaired in kidney transplant recipients (42%). T-cellular immunity largely mimicked humoral results. Major risk factors of seroconversion failure were immunosuppressive drug number and type (belatacept, MMF-MPA, calcineurin-inhibitors) as well as vaccine type (BNT162b2 mRNA). Seroconversion rates induced by mRNA-1273 compared to BNT162b2 vaccine were 97% to 88% (p < 0.001) in dialysis and 49% to 26% in transplant patients, respectively. Specific IgG directed against the new binding domain of the spike protein (RDB) were significantly higher in dialysis patients vaccinated by mRNA-1273 (95%) compared to BNT162b2 (85%, p < 0.001). Vaccination appeared safe and highly effective demonstrating an almost complete lack of symptomatic COVID-19 disease after boost vaccination as well as ceased disease incidences during third pandemic wave in dialysis patients.

Conclusion

Dialysis patients exhibit a remarkably high seroconversion rate of 95% after boost vaccination, while humoral response is impaired in the majority of transplant recipients. Immunosuppressive drug number and type as well as vaccine type (BNT162b2) are major determinants of seroconversion failure in both dialysis and transplant patients suggesting immune monitoring and adaption of vaccination protocols.

Lethal hyperammonemia in a CAR-T cell recipient due to Ureaplasma pneumonia: a case report of a unique severe complication

We report the first incidence of Ureaplasma infection causing lethal hyperammonemia in a chimeric receptor antigen T cell (CAR-T) recipient. A 53-year-old woman, after receiving CAR-T therapy, suffered sepsis and encephalopathy. She was found to have hyperammonemia up to 643 µmol/L. Imaging revealed lung consolidations and bronchoalveolar lavage PCR was positive for U. parvum. Workup excluded liver failure and metabolic abnormalities. Antibiotics, lactulose, dextrose, arginine, levocarnitine, sodium phenylbutyrate and dialysis were used. Despite these, the patient suffered persistent elevations in ammonia, status epilepticus and cerebral oedema. Early recognition of this rare infection in susceptible populations is needed. CAR-T patients are at risk due to their immunocompromised state and may have amplified harm due to the impact of CAR-T therapy on astrocytes. An early aggressive multimodality approach is needed given the high mortality rates. These include antimicrobials, possibly with double coverage for Ureaplasma. Additionally, concurrent ammonia-suppressing and ammonia-eliminating treatments are necessary.

Expression of components of the urothelial cholinergic system in bladder and cultivated primary urothelial cells of the pig

BACKGROUND

Porcine urinary bladders are widely used for uro-pharmacological examinations due to their resemblance to the human organ. However, characterisations of the porcine urothelium at the molecular level are scarce up to now. As it has become clear over the last years that this tissue plays an important role in the signaling-pathways of the bladder, we examined whether the transporter and receptor pattern (with focus on the transmitter acetylcholine) is comparable to the human urothelium. With regard to in vitro studies, we also investigated if there is a difference between the native tissue and cultivated primary urothelial cells in culture.

METHODS

Urothelium from German Landrace and Göttingen Minipig bladders was collected. One part of the German Landrace tissue was used for cultivation, and different passages of the urothelial cells were collected. The actual mRNA expression of different transporters and receptors was examined via quantitative real-time PCR. These included the vesicular acetylcholine transporter (VAChT), the choline acetyl transferase (ChAT), organic cation transporters 1-3 (OCT1-3), organic anion transporting polypeptide 1A2 (OATP1A2), P-glycoprotein (ABCB1), the carnitine acetyl-transferase (CarAT), as well as the muscarinic receptors 1-5 (M1-5).

RESULTS

There is a strong qualitative resemblance between the human and the porcine urothelium with regard to the investigated cholinergic receptors, enzymes and transporters. CarAT, OCT1-3, OATP1A2 and ABCB1 could be detected in the urothelium of both pig races. Moreover, all 5 M-receptors were prominent with an emphasis on M2 and M3. VAChT and ChAT could not be detected at all. Cultures of the derived urothelial cells showed decreased expression of all targets apart from ABCB1 and CarAT.

CONCLUSIONS

Based on the expression pattern of receptors, transporters and enzymes of the cholinergic system, the porcine urinary bladder can be regarded as a good model for pharmacological studies. However, cultivation of primary urothelial cells resulted in a significant drop in mRNA expression of the targets. Therefore, it can be concluded that the intact porcine urothelium, or the whole pig bladder, may be appropriate models for studies with anticholinergic drugs, whereas cultivated urothelial cells have some limitation due to significant changes in the expression levels of relevant targets.

Dehydropolymerisation of methylamine borane using a dinuclear 1,3-allenediyl bridged zirconocene complex

The dinuclear zirconocene chloride complex 1 is a highly active precatalyst for the dehydropolymerisation of methylamine borane. Comparison with mononuclear Zr chlorides and related dinuclear complexes suggests that the nature of the bridging motif is essential for the unique reactivity of 1.

Diffuse alveolar hemorrhage is most often fatal and is affected by graft source, conditioning regimen toxicity, and engraftment kinetics

Diffuse alveolar hemorrhage after hematopoietic stem cell transplantation is a frequently fatal complication with no standard therapy. Although significant changes in supportive and intensive care measures for patients undergoing hematopoietic stem cell transplantation have been made over the past decades, the impact of these changes on the incidence and outcome of patients with diffuse alveolar hemorrhage has not been examined. We analyzed 1228 patients who underwent allogeneic hematopoietic stem cell transplantation between 2008-2015 at the University of Minnesota to study the incidence, risk factors, and outcomes of diffuse alveolar hemorrhage. Diffuse alveolar hemorrhage developed in 5% of allogeneic hematopoietic stem cell transplant recipients, at a median of 30 days (range +3 to +168 days) after transplantation. The incidence of diffuse alveolar hemorrhage was significantly greater in recipients of umbilical cord blood than peripheral blood or bone marrow grafts (HR: 2.08, 95% CI: 1.16-3.74; P=0.01). In multivariate analysis, delayed neutrophil engraftment or primary graft failure was a risk factor for diffuse alveolar hemorrhage following peripheral blood or bone marrow hematopoietic stem cell transplants (HR: 5.51, 95% CI: 1.26-24; P=0.02) and delayed platelet engraftment was associated with significantly increased diffuse alveolar hemorrhage in umbilical cord blood transplant recipients (HR: 6.96, 95% CI: 2.39-20.29; P<0.05). Myeloablative regimens including total body irradiation were also risk factors for diffuse alveolar hemorrhage (HR: 1.8, 95% CI: 1.03-3.13, P=0.05) in both peripheral blood or bone marrow and umbilical cord blood hematopoietic stem cell transplants (HR: 1.87, 95% CI: 0.95-3.71). Patients with diffuse alveolar hemorrhage had an inferior 6-month treatment-related mortality (HR: 6.09, 95% CI: 4.33-8.56, P<0.01) and 2-year overall survival (HR: 4.16, 95% CI: 3.06-5.64; P<0.01) using either graft source. The etiology of diffuse alveolar hemorrhage is multifactorial, involving lung injury influenced by high-dose total body irradiation, graft source, and delayed engraftment or graft failure. The survival of patients with diffuse alveolar hemorrhage after hematopoietic stem cell transplantation remains poor. Clinical interventions or experimental studies (e.g., cell expansion for umbilical cord blood transplants or thrombopoietin use) that modulate these risk factors may limit the incidence and improve the outcomes of diffuse alveolar hemorrhage.

The Rare Complication and Diagnostic Challenges of Pulmonary Eosinophilia in Graft versus Host Disease Patients after Hematopoietic Stem Cell Transplantation

PURPOSE

Chronic graft versus host disease (cGvHD) is a common complication of hematopoietic stem cell transplantation (HSCT). Eosinophilic lung disease is a rare poorly understood complication in HSCT patients with cGvHD. These patients present similarly to those with Acute Eosinophilic Pneumonia (AEP). The purpose of this study is to better elucidate the presentation and potential treatment of this phenomenon.

METHODS

We reviewed over 170 bronchoscopies in post-HSCT patients with respiratory symptoms. Of these, four patients, whose course was complicated by cGvHD, presented with respiratory symptoms, diffuse ground-glass opacities (GGO) on chest computerized tomography (CT), bronchoalveolar lavage (BAL) eosinophilia, and no evidence of infection. The clinical course of these patients was reviewed.

RESULTS

Despite clinical presentation similar to AEP, not all patients had > 25% eosinophils on BAL, one criterion for AEP, however all improved with steroids. Steroid initiation was often delayed in favor of empiric antibiotics despite negative infectious workup. Several patients had recurrent episodes. Regarding possible associations, we examined but found no link between particular demographics, reason for HSCT, chemotherapy, immunosuppressants, or peripheral eosinophil count and pulmonary eosinophilia in these patients. GGO present on initial CT imaging became chronic in several of these patients.

CONCLUSION

We propose that in post-HSCT patients with GvHD presenting with respiratory symptoms, GGO on CT, BAL eosinophilia of > 10%, and negative respiratory cultures, an autoimmune eosinophilic process may be occurring. Earlier recognition and initiation of corticosteroids in these patients may improve their outcomes as an autoimmune diagnosis was often delayed in favor of antibiotics.

Mechanical induction of bi-directional orientation of primary porcine bladder smooth muscle cells in tubular fibrin-poly(vinylidene fluoride) scaffolds for ureteral and urethral repair using cyclic and focal balloon catheter stimulation

To restore damaged organ function or to investigate organ mechanisms, it is necessary to prepare replicates that follow the biological role model as faithfully as possible. The interdisciplinary field of tissue engineering has great potential in regenerative medicine and might overcome negative side effects in the replacement of damaged organs. In particular, tubular organ structures of the genitourinary tract, such as the ureter and urethra, are challenging because of their complexity and special milieu that gives rise to incrustation, inflammation and stricture formation. Tubular biohybrids were prepared from primary porcine smooth muscle cells embedded in a fibrin gel with a stabilising poly(vinylidene fluoride) mesh. A mechanotransduction was performed automatically with a balloon kyphoplasty catheter. Diffusion of urea and creatinine, as well as the bursting pressure, were measured. Light and electron microscopy were used to visualise cellular distribution and orientation. Histological evaluation revealed a uniform cellular distribution in the fibrin gel. Mechanical stimulation with a stretch of 20% leads to a circumferential orientation of smooth muscle cells inside the matrix and a longitudinal alignment on the outer surface of the tubular structure. Urea and creatinine permeability and bursting pressure showed a non-statistically significant trend towards stimulated tissue constructs. In this proof of concept study, an innovative technique of intraluminal pressure for mechanical stimulation of tubular biohybrids prepared from autologous cells and a composite material induce bi-directional orientation of smooth muscle cells by locally and cyclically applied mechanical tension. Such geometrically driven patterns of cell growth within a scaffold may represent a key stage in the future tissue engineering of implantable ureter replacements that will allow the active transportation of urine from the renal pelvis into the bladder.

A 66-Year-Old Woman With Sudden Onset of Disseminated Intravascular Coagulation, Lactic Acidosis, and Hypoglycemia

A 66-year-old woman presented to an urgent care clinic for 2 to 3 weeks of general malaise, nausea/vomiting, night sweats, and dyspnea. On examination, she was tachycardic, and her laboratory evaluation was normal except for a lactate level of 4.4 mmol/L and platelet count of 118 × 10⁹/L. CT imaging was performed. Two days later in the follow-up clinic, the patient's international normalized ratio (INR) was elevated, and she was hospitalized with initial findings of disseminated intravascular coagulation (DIC) (ie, INR > 10, platelets 97 × 10⁹/L, fibrinogen < 60 mg/dL, positive D-dimer result). Bone marrow aspirate and peripheral blood smears were unrevealing. On day 4 of her hospitalization, the patient developed severe lactic acidosis (24 mmol/L) and hypoglycemia (11 mg/dL), and she was transferred to our institution. The patient had a history of a benign ovarian tumor, was a nonsmoker, did not drink alcohol, and was not taking any medications prior to admission. No ingestions or environmental exposures were noted.

Interaction of cations, anions, and weak base quinine with rat renal cation transporter rOCT2 compared with rOCT1

The rat organic cation transporter (rOCT)-2 was characterized by electrical and tracer flux measurements compared with rOCT1. By applying choline gradients to voltage-clamped Xenopus oocytes expressing rOCT2, potential-dependent currents could be induced in both directions. Tracer flux measurements with seven organic cations revealed similar Michaelis-Menten constant values for both transporters, with the exception of guanidine. In parallel experiments with rOCT2 and rOCT1, inhibition of tetraethylammonium transport by 12 cations, 2 weak bases, corticosterone, and the anions para-amminohippurate, alpha-ketoglutarate, and probenecid was characterized. The IC(50) values of many inhibitors were similar for both transporters, whereas others were significantly different. Mepiperphenidol and O-methylisoprenaline showed an approximately 70-fold lower and corticosterone a 38-fold higher affinity for rOCT2. With the use of these inhibitors together with previous information on cation transporters, experimental protocols are proposed to dissect out the individual contributions of rOCT2 and rOCT1 in intact proximal tubule preparations. Inhibition experiments at different pH levels strongly suggest that the weak base quinine passively permeates the plasma membrane at physiological pH and inhibits rOCT2 from the intracellular side.

Multichannel auditory brainstem implant: US clinical trial results

Since 1994, a US Food and Drug Administration clinical trial evaluated the multichannel auditory brainstem implant (ABI) on 92 subjects with neurofibromatosis type 2 (NF2). The trial has shown that 85 per cent of patients receive auditory sensations. A small number of patients demonstrate a clinically significant degree of open-set sentence recognition in the sound-alone condition; however, when the ABI is combined with lip-reading cues, 93 per cent of patients demonstrate improved sentence understanding at three to six months. In addition, the majority of recipients report daily use of their devices, and satisfaction with the decision to receive the ABI.

A two-stage model for visual-auditory interaction in saccadic latencies

In two experiments, saccadic response time (SRT) for eye movements toward visual target stimuli at different horizontal positions was measured under simultaneous or near-simultaneous presentation of an auditory nontarget (distractor). The horizontal position of the auditory signal was varied, using a virtual auditory environment setup. Mean SRT to a visual target increased with distance to the auditory nontarget and with delay of the onset of the auditory signal relative to the onset of the visual stimulus. A stochastic model is presented that distinguishes a peripheral processing stage with separate parallel activation by visual and auditory information from a central processing stage at which intersensory integration takes place. Two model versions differing with respect to the role of the auditory distractors are tested against the SRT data.

The transport modifier RS1 is localized at the inner side of the plasma membrane and changes membrane capacitance

Previously we cloned membrane associated (M(r) 62000-67000) polypeptides from pig (pRS1), rabbit (rbRS1) and man (hRS1) which modified transport activities that were expressed in Xenopus laevis oocytes by the Na(+)-D-glucose cotransporter SGLT1 and/or the organic cation transporter OCT2. These effects were dependent on the species of RS1 and on the target transporters. hRS1 and rbRS1 were shown to be intronless single copy genes which are expressed in various tissues and cell types. Earlier immunohistochemical data with a monoclonal IgM antibody suggested an extracellular membrane association of RS1. In the present paper antibodies against recombinant pRS1 were raised and the distribution and membrane localization of RS1 reevaluated. After subcellular fractionation of renal cortex RS1 was found associated with brush border membranes and an about 1:200 relation between RS1 and SGLT1 protein was estimated. Also after overexpression in X. laevis oocytes RS1 was associated with the plasma membrane, however, at variance to the kidney it was also observed in the cytosol. Labeling experiments with covalently binding lipid-permeable and lipid-impermeable biotin analogues showed that RS1 is localized at the inner side of the plasma membrane. Western blots with plasma membranes from Xenopus oocytes revealed that SGLT1 protein in the plasma membrane was reduced when hRS1 was coexpressed with human SGLT1 which leads to a reduction in V(max) of expressed glucose transport. Measurements of membrane capacitance and electron microscopic inspection showed that the expression of hRS1 leads to a reduction of the oocyte plasma membrane surface. The data suggest that RS1 is an intracellular regulatory protein that associates with the plasma membrane. Overexpression of RS1 may effect the incorporation and/or retrieval of transporters into the plasma membrane.

A chemiluminescence test for predicting the outcome of transfusing incompatible blood

A chemiluminescent test (CLT) which measures the metabolic response of human monocytes to sensitized red cells was developed to distinguish antibodies capable of causing the increased destruction of transfused incompatible red cells from antibodies which are clinically benign. Thirty sera containing IgG antibodies to high-frequency antigens were tested; 27 of these sera were also tested using the monocyte monolayer assay (MMA). The clinical significance of antibodies in 14 of the sera was known: three (anti-Ata (two), -JMH) caused accelerated clearance of 51Cr-labelled cells, five (anti-'MiIII', -Yta, three unidentified) caused haemolytic transfusion reactions and six (anti-Yta, -Ge, -JMH, -Xga, -Kna (two)) did not appear to affect red cell survival. Overall, results from the MMA and CLT showed good agreement; seven sera were negative in both assays, 18 sera were positive in both assays and two sera were positive in the MMA but negative in the CLT. There was no clear relationship between the activity of different antibodies and the level of sensitization as determined by flow cytometry. Antibody activity could be either increased or decreased by incubation of sensitized red cells with fresh serum. MMA results were in concordance with the clinical significance of antibodies where known in eight of 10 cases. CLT results were in concordance with clinical significance in 12 of 14 cases. Both assays gave false-positive results with serum from a patient with anti-Kna who had received red cell transfusions without adverse effect. This appeared to be due to the ability of anti-Kna to cross-link complement receptor 1 (CR1) on red cells to CR1 on monocytes; negative results were obtained using autologous monocytes.

Selectivity of the polyspecific cation transporter rOCT1 is changed by mutation of aspartate 475 to glutamate

After site-directed mutagenesis, the organic cation transporter rOCT1 was expressed in Xenopus laevis oocytes or human embryonic kidney cells and functionally characterized. rOCT1 belongs to a new family of polyspecific transporters that includes transporters for organic cations and anions and the Na(+)-carnitine cotransporter. When glutamate was substituted for Asp475 (middle of the proposed 11th transmembrane alpha-helix), the V(max) values for choline, tetraethylammonium (TEA), N(1)-methylnicotinamide, and 1-methyl-4-phenylpyridinium were reduced by 89 to 98%. The apparent K(m) values were also decreased (choline by 15-fold, TEA by 8-fold, N(1)-methylnicotinamide by 4-fold) or remained constant (1-methyl-4-phenylpyridinium). After the mutation, the membrane potential dependence of the K(m) value for [(3)H]choline uptake was abolished. The affinity of n-tetraalkyl ammonium compounds to inhibit TEA uptake was increased. This affinity and its increase by the D475E mutation were increased with the length of the n-alkyl chains. After expression in X. laevis oocytes, the IC(50) ratios of wild-type and D475E mutant were 1.7 (tetramethylammonium), 4.3 (TEA), 5.0 (tetrapropylammonium), 5.0 (tetrabutylammonium), and 65 (tetrapentylammonium). Cationic inhibitors with ring structures were differentially affected: the IC(50) value for TEA inhibition by cyanine 863 remained unchanged, whereas it was increased for quinine. The data suggest that rOCT1 contains a large cation-binding pocket with several interaction domains that may be responsible for high-affinity binding of structurally different cations and that Asp475 is located close to one of these interaction domains.

Testicular abnormalities in male rats after lactational exposure to nonylphenols

Lactational exposure of male rat pups to nonylphenols (NPs) decreased the size of their testes and male accessory glands. At 31 d of age, NP-treatment of male rats resulted in less cellular differentiation of the seminiferous tubules (STs) and increased intertubular space compared to controls. At maturity, NP-treated males showed varying degrees of abnormalities in the affected testes. In the moderately affected ones, about 20-30% of their STs had poorly differentiated germinal elements. Cell lineage was less organized. In extreme cases, all STs of the affected testis failed to differentiate into germinal elements. These abnormalities in germinal element differentiation might be the primary cause for a number of the NP-treated males having a lower epididymal sperm count and a lower percentage of motile sperm compared to age-matched control males. Zymogram analysis of testis homogenates by sodium dodecyl sulfate gelatin gels revealed two major forms (64-66 kDa and 50-52 kDa) of gelatinases. Only the 50-52-kDa form was greatly reduced or absent in the affected testis. Lactational exposure of male pups to NPs thus leads to various testicular abnormalities including lack of differentiation of STs, lowering of sperm count, and reduction in the percentage of motile sperm and modulation of a specific form of testicular proteinases.

Mycoplasma pneumoniae-associated bronchiolitis causing severe restrictive lung disease in adults: report of three cases and literature review

STUDY OBJECTIVES

To characterize adult Mycoplasma pneumoniae-induced bronchiolitis requiring hospitalization.

DESIGN

We encountered an adult patient with severe bronchiolitis in the absence of pneumonia due to M. pneumoniae. To determine the relative frequency of such a condition, we retrospectively reviewed the medical records of adults over a 4-year period with a hospital discharge diagnosis of "bronchiolitis" from a university hospital.

SETTING

University Hospital of the University of Colorado Health Sciences Center, Denver, CO.

STUDY SUBJECTS

From 1994 to 1998, 10 adult inpatients were identified with a diagnosis of bronchiolitis. There were two with respiratory bronchiolitis, one with panbronchiolitis, one patient with bronchiolitis obliterans organizing pneumonia (BOOP), and six with acute inflammatory bronchiolitis. Including the initial patient, three had a definitive clinical diagnosis of Mycoplasma-associated bronchiolitis.

RESULTS

The three adult patients with bronchiolitis due to M. pneumoniae are unusual because they occurred in the absence of radiographic features of a lobar or patchy alveolar pneumonia. Hospital admission was occasioned by the severity of symptoms and gas exchange abnormalities. One patient had bronchiolitis as well as organizing pneumonia (BOOP) that responded favorably to corticosteroid treatment. The other two had high-resolution CT findings diagnostic of an acute inflammatory bronchiolitis. One of the patients with inflammatory bronchiolitis had an unusual pattern of marked ventilation and perfusion defects localized predominantly to the left lung. All three had restrictive ventilatory impairment on physiologic testing.

CONCLUSIONS

In adults, Mycoplasma-associated bronchiolitis without pneumonia is rarely reported, but in hospitalized patients, it may be more common than expected and may be associated with severe physiologic disturbances.

Human neurons express the polyspecific cation transporter hOCT2, which translocates monoamine neurotransmitters, amantadine, and memantine

Recently, we cloned the human cation transporter hOCT2, a member of a new family of polyspecific transporters from kidney, and demonstrated electrogenic uptake of tetraethylammonium, choline, N1-methylnicotinamide, and 1-methyl-4-phenylpyridinium. Using polymerase chain reaction amplification, cDNA sequencing, in situ hybridization, and immunohistochemistry, we now show that hOCT2 message and protein are expressed in neurons of the cerebral cortex and in various subcortical nuclei. In Xenopus laevis oocytes expressing hOCT2, electrogenic transport of norepinephrine, histamine, dopamine, serotonin, and the antiparkinsonian drugs memantine and amantadine was demonstrated by tracer influx, tracer efflux, electrical measurements, or a combination. Apparent Km values of 1.9 +/- 0.6 mM (norepinephrine), 1.3 +/- 0.3 mM (histamine), 0.39 +/- 0.16 mM (dopamine), 80 +/- 20 microM (serotonin), 34 +/- 5 microM (memantine), and 27 +/- 3 microM (amantadine) were estimated. Measurement of trans-effects in depolarized oocytes and human embryonic kidney cells expressing hOCT2 suggests that there were different rates and specificities for cation influx and efflux. The hypothesis is raised that hOCT2 plays a physiological role in the central nervous system by regulating interstitial concentrations of monoamine neurotransmitters that have evaded high affinity uptake mechanisms. We show that amantadine does not interact with the expressed human Na+/Cl- dopamine cotransporter. However, concentrations of amantadine that are effective for the treatment of Parkinson's disease may increase the interstitial concentrations of dopamine and other aminergic neurotransmitters by competitive inhibition of hOCT2.

Membrane localization of the electrogenic cation transporter rOCT1 in rat liver

The polyspecific cation transporter rOCT1 in the rat was the first identified member of a new protein family with 12 presumed membrane-spanning alpha-helices and two large hydrophilic loops. Previous studies showed that rOCT1 is mainly expressed in liver and mediates electrogenic uptake of small organic cations into cells. Antibodies against partial sequences of rOCT1 were raised and their specificity was verified. Immunohistochemistry with rat liver and Western blots with isolated membranes showed that rOCT1 is localized within sinusoidal membranes of hepatocytes. Antibody reactions were also performed with intact and permeabilized human embryonic kidney cells that were stably transfected with rOCT1. They showed that the large hydrophilic loop after the first alpha-helix of rOCT1 is located extracellularly, while the C-terminus is located intracellularly. Translational regulation is suggested since the message of rOCT1 was distributed throughout the liver lobuli, whereas rOCT1 protein was observed only in hepatocytes surrounding the central veins.

Clinical significance of an anti-Dib assessed by flow cytometry

Although antibodies to the Dib antigen are generally considered to be of potential clinical significance, we know of no reports assessing the clinical significance of anti-Dib (in vivo or in vitro). We report on an 88-year-old Japanese male gastrectomy patient who had alloanti-Dib. After transfusion of two Di(b-) units, three Di(b+) units had to be transfused, and there were no clinical signs of acute hemolysis. Di(b+) RBC survival was followed retrospectively by flow cytometry. On days 1, 7, and 10, the percent of circulating Di(b+) RBCs was determined to be 39, 30, and 11 percent, respectively, compared to an expected 49, 43, and 41 percent based on calculations. The Di(b+) RBCs appear to have been tolerated for about 6 days, then were removed from the circulation. Direct anti-IgG tests were 1-2+ mixed field with all posttransfusion samples. Monocyte monolayer assays (MMAs), which have been reported to predict the clinical significance of alloantibodies, gave borderline positive results. MMA results using sera from days 0, 3, and 9 were 2.7 and 5.5, 0.8 and 4.8, and 3.0 and 3.7 percent, respectively, without and with added fresh normal serum as a source of complement (clinical significance = > 3% reactivity). The subclass of the anti-Dib was IgG1. This is the first documentation of the clinical significance of an anti-Dib.

Severe autoimmune hemolytic anemia associated with IgM warm autoantibodies directed against determinants on or associated with glycophorin A

BACKGROUND AND OBJECTIVES

Autoimmune hemolytic anemiA (AIHA) is rarely caused by IgM warm autoantibodies, and is sometimes difficult to diagnose. We describe three patients with severe AIHA caused by IgM warm autoantibodies; in two of the three, the hemolysis was fatal.

MATERIALS AND METHODS

Conventional hematologic and serologic procedures were used.

RESULTS

The IgM autoantibodies in all three cases were directed against determinants on or associated with glycophorin A (Ena, Wrb, and Pr). The IgM autoantibodies and unusual serological characteristics, in that the agglutinins were detected or greatly enhanced only by the presence of albumin or a low pH, and/or the agglutinins reacted optimally at 20-30 degrees C.

CONCLUSIONS

IgM warm autoantibodies directed at determinants on or associated with glycophorin A appear to cause severe (often fatal) hemolytic anemia.

Electrogenic properties and substrate specificity of the polyspecific rat cation transporter rOCT1

The previously cloned rat cation transporter rOCT1 detected in renal proximal tubules and hepatocytes (Gründemann, D., Gorboulev, V., Gambaryan, S., Veyhl, M., and Koepsell, H. (1994) Nature 372, 549-552) was expressed in Xenopus oocytes, and transport properties were analyzed using tracer uptake studies and electrophysiological measurements. rOCT1 induced highly active transport of a variety of cations, including the classical substrates for cation transport, such as N-1-methylnicotinamide, 1-methyl-4-phenylpyridinium (MPP), and tetraethylammonium (TEA), but also the physiologically important choline. In oocytes rOCT1 also mediated efflux of MPP, which could be trans-stimulated by MPP and TEA. Cation transport via rOCT1 was electrogenic. In voltage-clamped oocytes, transport of TEA and choline via rOCT1 produced inwardly directed currents, which were independent of extracellular ion composition or pH. The choline- and TEA-induced currents were voltage-dependent at nonsaturating concentrations, and the apparent affinity of these cations was decreased at depolarized voltages. Other substrates transported by rOCT1 were the polyamines spermine and spermidine. Interestingly, the previously described potent inhibitors of rOCT1, cyanine 863, quinine, and D-tubocurarine were substrates themselves. The data indicate that rOCT1 is an effective transport system that is responsible for electrogenic uptake of a wide variety of organic cations into epithelial cells of renal proximal tubules and hepatocytes.