Urinary CD4 + T Cells Predict Renal Relapse in ANCA-Associated Vasculitis

SIGNIFICANCE STATEMENT

Early identification of patients at risk of renal flares in ANCA vasculitis is crucial. However, current clinical parameters have limitations in predicting renal relapse accurately. This study investigated the use of urinary CD4 + T lymphocytes as a predictive biomarker for renal flares in ANCA vasculitis. This study, including urine samples from 102 patients, found that the presence of urinary CD4 + T cells was a robust predictor of renal relapse within a 6-month time frame, with a sensitivity of 60% and a specificity of 97.8%. The diagnostic accuracy of urinary CD4 + T cells exceeded that of ANCA titers, proteinuria, and hematuria. Monitoring urinary CD4 + T lymphocytes could help assess the risk of future renal relapse, enabling early preventive measures and tailored treatment strategies.

BACKGROUND

In ANCA-associated vasculitis, there is a lack of biomarkers for predicting renal relapse. Urinary T cells have been shown to differentiate active GN from remission in ANCA-associated vasculitis, but their predictive value for renal flares remains unknown.

METHODS

The PRE-FLARED study was a prospective multicenter biomarker study including 102 individuals with ANCA-associated vasculitis in remission aimed to predict renal relapse by quantifying urinary CD4 + T-cell subsets using flow cytometry at baseline and monitoring clinical outcomes over a 6-month follow-up.

RESULTS

Among the participants, ten experienced renal relapses, two had non-renal flares, and 90 remained in stable remission. The median baseline urinary CD4 + T-cell count was significantly higher in patients who relapsed compared with those in remission. Receiver operating characteristic curve analysis of urinary CD4 + T-cell counts showed an area under the curve value of 0.88 for predicting renal flares, outperforming ANCA titers, hematuria, and proteinuria. Using a cutoff of 490 CD4 + T cells per 100 ml urine, the sensitivity and specificity in identifying patients with future renal flares were 60% and 97.8%, respectively. In a post hoc analysis, combining urinary CD4 + T-cell counts with proteinase-3 ANCA levels suggested improved predictive performance in the PR3 + subgroup. In addition, the number of urinary CD4 + T cells showed a limited correlation with a decline in GFR and an increase in proteinuria over the follow-up period.

CONCLUSIONS

This study concluded that urinary CD4 + T-cell counts could identify patients with ANCA-associated vasculitis at a substantial risk of renal relapse within 6 months. Combining these counts with ANCA levels further improved the prediction of relapse.

CLINICAL TRIAL REGISTRY NAME AND REGISTRATION NUMBER

Urinary T Lymphocytes Predict Renal Flares in Patients With Inactive ANCA-associated Glomerulonephritis (PRE-FLARED), NCT04428398 .

Bilateral non-arteritic posterior ischaemic optic neuropathy following COVID-19 vaccination

We report a case of bilateral posterior ischaemic optic neuropathy, which followed vaccination with ChAdOx1 nCoV-19 for COVID-19 prophylaxis. A man in his early 60s was initially assessed for bilateral acute vision loss following 3 days of frontal headaches. The patient denied any other preceding visual concerns or symptoms of giant cell arteritis. The patient received his first dose of the ChAdOx1 nCoV-19 vaccination 10 days before the onset of his symptoms.At initial presentation, visual acuity was counting fingers bilaterally. Blood work found normal erythrocyte sedimentation rate (6 mm/hour) and C reactive protein (<5 mg/L) as well as a negative infectious and autoimmune serology. He was negative for COVID-19 with PCR testing. Diffusion-weighted MRI showed restricted diffusion along both optic nerves. After 5 months, the patient's visual acuity remained counting fingers bilaterally with pale optic nerves. Isolated bilateral posterior ischaemic optic neuropathy has not been reported in association with the ChAdOx1 nCoV-19 vaccine.

Addition of formaldehyde releaser imidazolidinyl urea and MOPS buffer to urine samples enables delayed processing for flow cytometric analysis of urinary cells: A simple, two step conservation method of urinary cells for flow cytometry

INTRODUCTION

Kidney diseases are a major health concern worldwide. Currently there is a large unmet need for novel biomarkers to non-invasively diagnose and monitor kidney diseases. Urinary cells are promising biomarkers and their analysis by flow cytometry has demonstrated its utility in diverse clinical settings. However, up to date this methodology depends on fresh samples, as cellular event counts and the signal-to-noise-ratio deter over time. Here we developed an easy-to-use two-step preservation method for conservation of urine samples for subsequent flow cytometry.

METHODS

The protocol utilizes a combination of the formaldehyde releasing agent imidazolidinyl urea (IU) and MOPS buffer, leading to gentle fixation of urinary cells.

RESULTS

The preservation method increases acceptable storing time of urine samples from several hours to up to 6 days. Cellular event counts and staining properties of cells remain comparable to fresh untreated samples.

OUTLOOK

The hereby presented preservation method facilitates future investigations on flow cytometry of urinary cells as potential biomarkers and may enable broad implementation in clinical practice.

Early Ultrastructural Changes in Biopsies From Patients With Symptomatic CKD of Uncertain Etiology

Introduction

Although the investigation of chronic kidney disease of uncertain etiology (CKDu) has identified many possible influencing factors in recent years, the exact pathomechanism of this disease remains unclear.

Methods

In this study, we collected 13 renal biopsies from patients with symptomatic CKDu (Sym-CKDu) from Sri Lanka with well-documented clinical and socioeconomic factors. We performed light microscopy and electron microscopic evaluation for ultrastructural analysis, which was compared with 100 biopsies from German patients with 20 different kidney diseases.

Results

Of the 13 Sri Lankan patients, 12 were men (92.3%), frequently employed in agriculture (50%), and experienced symptoms such as feeling feverish (83.3%), dysuria (83.3%), and arthralgia (66.6%). Light microscopic evaluation using activity and chronicity score revealed that cases represented early stages of CKDu except for 2 biopsies, which showed additional signs of diabetes. Most glomeruli showed only mild changes, such as podocyte foot process effacement on electron microscopy. We found a spectrum of early tubulointerstitial changes including partial loss of brush border in proximal tubules, detachment of tubular cells, enlarged vacuoles, and mitochondrial swelling associated with loss of cristae and dysmorphic lysosomes with electron-dense aggregates. None of these changes occurred exclusively in Sym-CKDu; however, they were significantly more frequent in these cases than in the control cohort.

Conclusion

In conclusion, our findings confirm the predominant and early alterations of tubular structure in CKDu that can occur without significant glomerular changes. The ultrastructural changes do not provide concrete evidence of the cause of CKDu but were significantly more frequent in Sym-CKDu than in the controls.

Urinary single-cell sequencing captures kidney injury and repair processes in human acute kidney injury

Acute kidney injury (AKI) is a major health issue, the outcome of which depends primarily on damage and reparative processes of tubular epithelial cells. Mechanisms underlying AKI remain incompletely understood, specific therapies are lacking and monitoring the course of AKI in clinical routine is confined to measuring urine output and plasma levels of filtration markers. Here we demonstrate feasibility and potential of a novel approach to assess the cellular and molecular dynamics of AKI by establishing a robust urine-to-single cell RNA sequencing (scRNAseq) pipeline for excreted kidney cells via flow cytometry sorting. We analyzed 42,608 single cell transcriptomes of 40 urine samples from 32 patients with AKI and compared our data with reference material from human AKI post-mortem biopsies and published mouse data. We demonstrate that tubular epithelial cells transcriptomes mirror kidney pathology and reflect distinct injury and repair processes, including oxidative stress, inflammation, and tissue rearrangement. We also describe an AKI-specific abundant urinary excretion of adaptive progenitor-like cells. Thus, single cell transcriptomics of kidney cells excreted in urine provides noninvasive, unprecedented insight into cellular processes underlying AKI, thereby opening novel opportunities for target identification, AKI sub-categorization, and monitoring of natural disease course and interventions.

Urinary CD8+HLA-DR+ T Cell Abundance Non-invasively Predicts Kidney Transplant Rejection

Early detection of kidney transplant (KT) rejection remains a challenge in patient care. Non-invasive biomarkers hold high potential to detect rejection, adjust immunosuppression, and monitor KT patients. So far, no approach has fully satisfied requirements to innovate routine monitoring of KT patients. In this two-center study we analyzed a total of 380 urine samples. T cells and tubular epithelial cells were quantified in KT patients with graft deterioration using flow cytometry. Epigenetic urine cell quantification was used to confirm flow cytometric results. Moreover, a cohort of KT patients was followed up during the first year after transplantation, tracking cell subsets over time. Abundance of urinary cell counts differed in patients with and without rejection. Most strikingly, various T cell subsets were enriched in patients with T cell-mediated rejection (TCMR) compared to patients without TCMR. Among T cell subsets, CD8+HLA-DR+ T cells were most distinctive (AUC = 0.91, Spec.: 95.9%, Sens.: 76.5%). Epigenetic analysis confirmed T cell and tubular epithelial cell quantities as determined by flow cytometry. Urinary T cell abundance in new KT patients decreased during their first year after transplantation. In conclusion urinary T cells reflect intrarenal inflammation in TCMR. T cell subsets yield high potential to monitor KT patients and detect rejection. Hereby we present a promising biomarker to non-invasively diagnose TCMR.

Dialysis-Associated Nonarteritic Anterior Ischemic Optic Neuropathy: A Case Series and Review

BACKGROUND

Dialysis-associated nonarteritic ischemic optic neuropathy (DA-NAION) occurs secondary to intradialytic hypotension often with catastrophic consequences and is one of the rare situations where NAION can recur in the same eye. We describe 3 cases of DA-NAION associated with hypotension, review the current literature on DA-NAION, and provide recommendations for decreasing the risk of intradialytic hypotension.

METHODS

In addition to describing 3 cases of DA-NAION, PubMed was searched for all reports of DA-NAION in adults with documented episodes of hypotension preceding the onset of NAION. A total of 50 eyes of 31 patients were included. Age, visual acuity at presentation, rate of bilateral involvement at presentation, sequential involvement of the fellow eye, and recurrence of NAION in the same eye were analyzed.

RESULTS

We found that most cases of DA-NAION occur in relatively young patients (47.7 ± 14.7 years) with a high rate of bilateral involvement at presentation (23%) and bilateral sequential involvement (39%). Vision loss is severe with 64% of patients presenting with 20/200 acuity or worse in the involved eye and 19% of patients with final visual acuity of 20/200 or worse in both eyes. 3 patients (9.7%) had recurrence of NAION in the previously affected eye.

CONCLUSIONS

Neuro-ophthalmologists have an important role in identifying patients who have suffered DA-NAION and communicating their findings to nephrologists to minimize the chance of involvement of the fellow eye and recurrence in the same eye. Intradialytic blood pressure must be closely monitored, and fluid balance, dialysate composition, and dialysis protocol must be optimized to prevent occurrence of intradialytic hypotension, which is the culprit for DA-NAION.

Lipomatosis and optic neuropathy clinches the diagnosis of myoclonic epilepsy with ragged red fibres (MERRF) syndrome

We present a rare case of myoclonic epilepsy with ragged red fibres with high level of heteroplasmy presenting with optic neuropathy and a rare phenotype of lipomatosis. Cutaneous lipomas are typically thought of as a benign/isolated entity and this case emphasises importance of considering mitochondrial disease in all patients with lipomatosis especially in the presence of other systemic abnormalities.

Correction: Addressing Implementation Challenges to Digital Care Delivery for Adults With Multiple Chronic Conditions: Stakeholder Feedback in a Randomized Controlled Trial

[This corrects the article DOI: 10.2196/23498.].

The Restless Spinal Cord in Degenerative Cervical Myelopathy

BACKGROUND AND PURPOSE

The spinal cord is subject to a periodic, cardiac-related movement, which is increased at the level of a cervical stenosis. Increased oscillations may exert mechanical stress on spinal cord tissue causing intramedullary damage. Motion analysis thus holds promise as a biomarker related to disease progression in degenerative cervical myelopathy. Our aim was characterization of the cervical spinal cord motion in patients with degenerative cervical myelopathy.

MATERIALS AND METHODS

Phase-contrast MR imaging data were analyzed in 55 patients (37 men; mean age, 56.2 [SD,12.0] years; 36 multisegmental stenoses) and 18 controls (9 men, P = .368; mean age, 62.2 [SD, 6.5] years; P = .024). Parameters of interest included the displacement and motion pattern. Motion data were pooled on the segmental level for comparison between groups.

RESULTS

In patients, mean craniocaudal oscillations were increased manifold at any level of a cervical stenosis (eg, C5 displacement: controls [n = 18], 0.54 [SD, 0.16] mm; patients [n = 29], monosegmental stenosis [n = 10], 1.86 [SD, 0.92] mm; P < .001) and even in segments remote from the level of the stenosis (eg, C2 displacement: controls [n = 18], 0.36 [SD, 0.09] mm; patients [n = 52]; stenosis: C3, n = 21; C4, n = 11; C5, n = 18; C6, n = 2; 0.85 [SD, 0.46] mm; P < .001). Motion at C2 differed with the distance to the next stenotic segment and the number of stenotic segments. The motion pattern in most patients showed continuous spinal cord motion throughout the cardiac cycle.

CONCLUSIONS

Patients with degenerative cervical myelopathy show altered spinal cord motion with increased and ongoing oscillations at and also beyond the focal level of stenosis. Phase-contrast MR imaging has promise as a biomarker to reveal mechanical stress to the cord and may be applicable to predict disease progression and the impact of surgical interventions.

Addressing Implementation Challenges to Digital Care Delivery for Adults With Multiple Chronic Conditions: Stakeholder Feedback in a Randomized Controlled Trial

Background

Digital tools accessed via smartphones can promote chronic condition management, reduce disparities in health care and hospital readmissions, and improve quality of life. However, whether digital care strategies can be implemented successfully on a large scale with traditionally underserved populations remains uncertain.

Objective

As part of a randomized trial comparing care delivery strategies for Medicaid and Medicare-Medicaid beneficiaries with multiple chronic conditions, our stakeholders identified implementation challenges, and we developed stakeholder-driven adaptions to improve a digitally delivered care management strategy (high-tech care).

Methods

We used 4 mechanisms (study support log, Patient Partners Work Group log, case interview log, and implementation meeting minutes) to capture stakeholder feedback about technology-related challenges and solutions from 9 patient partners, 129 participants, and 32 care managers and used these data to develop and implement solutions. To assess the impact, we analyzed high-tech care exit surveys and intervention engagement outcomes (video visits and condition-specific text message check-ins sent at varying intervals) before and after each solution was implemented.

Results

Challenges centered around 2 themes: difficulty using both smartphones and high-tech care components and difficulty using high-tech care components due to connectivity issues. To respond to the first theme’s challenges, we devised 3 solutions: tech visits (eg, in-person technology support visits), tech packet (eg, participant-facing technology user guide), and tailored condition-specific text message check-ins. During the first 20 months of implementation, 73 participants received at least one tech visit. We observed a 15% increase in video call completion for participants with data before and after the tech visit (n=25) and a 7% increase in check-in completion for participants with data before and after the tech visit (n=59). Of the 379 participants given a tech packet, 179 completed care during this timeframe and were eligible for an exit survey. Of the survey respondents, 76% (73/96) found the tech packet helpful and 64% (62/96) actively used it during care. To support condition-specific text message check-in completion, we allowed for adaption of day and/or time of the text message with 31 participants changing the time they received check-ins and change in standard biometric settings with 13 physicians requesting personalized settings for participants. To respond to the second theme’s challenges, tech visits or phone calls were made to demonstrate how to use a smartphone to connect or disconnect from the internet, to schedule video calls, or for condition-specific text message check-ins in a location with broadband/internet.

Conclusions

Having structured stakeholder feedback mechanisms is key to identify challenges and solutions to digital care engagement. Creating flexible and scalable solutions to technology-related challenges will increase equity in accessing digital care and support more effective engagement of chronically ill populations in the use of these digital care tools.

Trial Registration

ClinicalTrials.gov NCT03451630; https://clinicaltrials.gov/ct2/show/NCT03451630.

Extrapyramidal plasticity predicts recovery after spinal cord injury

Spinal cord injury (SCI) leads to wide-spread neurodegeneration across the neuroaxis. We explored trajectories of surface morphology, demyelination and iron concentration within the basal ganglia-thalamic circuit over 2 years post-SCI. This allowed us to explore the predictive value of neuroimaging biomarkers and determine their suitability as surrogate markers for interventional trials. Changes in markers of surface morphology, myelin and iron concentration of the basal ganglia and thalamus were estimated from 182 MRI datasets acquired in 17 SCI patients and 21 healthy controls at baseline (1-month post injury for patients), after 3, 6, 12, and 24 months. Using regression models, we investigated group difference in linear and non-linear trajectories of these markers. Baseline quantitative MRI parameters were used to predict 24-month clinical outcome. Surface area contracted in the motor (i.e. lower extremity) and pulvinar thalamus, and striatum; and expanded in the motor thalamus and striatum in patients compared to controls over 2-years. In parallel, myelin-sensitive markers decreased in the thalamus, striatum, and globus pallidus, while iron-sensitive markers decreased within the left caudate. Baseline surface area expansions within the striatum (i.e. motor caudate) predicted better lower extremity motor score at 2-years. Extensive extrapyramidal neurodegenerative and reorganizational changes across the basal ganglia-thalamic circuitry occur early after SCI and progress over time; their magnitude being predictive of functional recovery. These results demonstrate a potential role of extrapyramidal plasticity during functional recovery after SCI.

Characterization of an epilepsy-associated variant of the human Cl-/HCO3(-) exchanger AE3

Anion exchanger 3 (AE3), expressed in the brain, heart, and retina, extrudes intracellular HCO(3)(-) in exchange for extracellular Cl(-). The SLC4A3 gene encodes two variants of AE3, brain or full-length AE3 (AE3(fl)) and cardiac AE3 (cAE3). Epilepsy is a heterogeneous group of disorders characterized by recurrent unprovoked seizures that affect about 50 million people worldwide. The AE3-A867D allele in humans has been associated with the development of IGE (IGE), which accounts for approximately 30% of all epilepsies. To examine the molecular basis for the association of the A867D allele with IGE, we characterized wild-type (WT) and AE3(fl)-A867D in transfected human embryonic kidney (HEK)-293 cells. AE3(fl)-A867D had significantly reduced transport activity relative to WT (54 +/- 4%, P < 0.01). Differences in expression levels or the degree of protein trafficking to the plasma membrane did not account for the defect of AE3(fl)-A867D. Treatment with 8-bromo-cAMP (8-Br-cAMP) increased Cl(-)/HCO(3)(-) exchange activity of WT and AE3(fl)-A867D to a similar degree, which was abolished by preincubation with the protein kinase A (PKA)-specific inhibitor H89. This indicates that PKA regulates WT and AE3(fl)-A867D Cl(-)/HCO(3)(-) exchange activity. No difference in Cl(-)/HCO(3)(-) exchange activity was found between cultures of mixed populations of neonatal hippocampal cells from WT and slc4a3(-/-) mice. We conclude that the A867D allele is a functional (catalytic) mutant of AE3 and that the decreased activity of AE3(fl)-A867D may cause changes in cell volume and abnormal intracellular pH. In the brain, these alterations may promote neuron hyperexcitability and the generation of seizures.

Omega- and Omega+ production in central Pb + Pb collisions at 40 and 158A GeV

Results are presented on Omega production in central Pb+Pb collisions at 40 and 158A GeV beam energy. For the first time in heavy ion reactions, rapidity distributions and total yields were measured for the sum Omega(-) + Omega(+) at 40A GeV and for Omega(-) and Omega(+) separately at 158A GeV. The yields are strongly underpredicted by the string-hadronic UrQMD model but agree better with predictions from hadron gas models.

System-size dependence of strangeness production in nucleus-nucleus collisions at squareroot[sNN]=17.3 GeV

Emission of pi+/-, K+/-, phi, and Lambda was measured in near-central C+C and Si+Si collisions at 158 AGeV beam energy. Together with earlier data for p+p, S+S, and Pb+Pb, the system-size dependence of relative strangeness production in nucleus-nucleus collisions is obtained. Its fast rise and the saturation observed at about 60 participating nucleons can be understood as the onset of the formation of coherent systems of increasing size.

Lambda and lambda production in central Pb-Pb collisions at 40, 80, and 158A GeV

Production of Lambda and Antilambda hyperons was measured in central Pb-Pb collisions at 40, 80, and 158A GeV beam energy on a fixed target. Transverse mass spectra and rapidity distributions are given for all three energies. The Lambda/pi ratio at midrapidity and in full phase space shows a pronounced maximum between the highest BNL Alternating Gradient Synchrotron and 40A GeV CERN Super Proton Synchrotron energies, whereas the Lambda/pi ratio exhibits a monotonic increase.

Evidence for an exotic S= -2, Q= -2 baryon resonance in proton-proton collisions at the CERN SPS

Results of resonance searches in the Xi(-)pi(-), Xi(-)pi(+), Xi;(+)pi(-), and Xi;(+)pi(+) invariant mass spectra in proton-proton collisions at sqrt[s]=17.2 GeV are presented. Evidence is shown for the existence of a narrow Xi(-)pi(-) baryon resonance with mass of 1.862+/-0.002 GeV/c(2) and width below the detector resolution of about 0.018 GeV/c(2). The significance is estimated to be above 4.2sigma. This state is a candidate for the hypothetical exotic Xi(--)(3/2) baryon with S=-2, I=3 / 2, and a quark content of (dsdsū). At the same mass, a peak is observed in the Xi(-)pi(+) spectrum which is a candidate for the Xi(0)(3/2) member of this isospin quartet with a quark content of (dsus[-]d). The corresponding antibaryon spectra also show enhancements at the same invariant mass.

Event-by-event fluctuations of the Kaon-to-Pion ratio in central Pb+Pb collisions at 158 GeV per nucleon

We present the first measurement of fluctuations from event to event in the production of strange particles in collisions of heavy nuclei. The ratio of charged kaons to charged pions is determined for individual central Pb+Pb collisions. After accounting for the fluctuations due to detector resolution and finite number statistics we derive an upper limit on genuine nonstatistical fluctuations, which could be related to a first- or second-order QCD phase transition. Such fluctuations are shown to be very small.

[Capillary telangiectasis, angiographically occult vascular malformations. MRI symptomatology apropos of 7 cases]

OBJECTIVE

Describe the MRI findings in capillary telangiectasias.

MATERIALS AND METHODS

Between 1996 and 1999, we observed 9 cases of capillary telangiectasia in 7 patients explored 5 times for posterior fossa symptoms. In two cases capillary telangiectasia was a fortuitous discovery. All patients were explored by MRI with T1 sequences with and without gadolinium injections, turbo spin echo T2 coupled in 5 cases with a double echo gradient echo T2 sequence (TR: 970 ms, TE: 15 and 35 ms). Two patients also underwent vertebral angiography.

RESULTS

The telangiectasia gave a low intensity signal on T1 sequences in 2 of the 9 cases and a discretely high intensity signal on T2 sequences in all cases. After gadolinium injection, 9 telangiectasias showed homogeneous or speckled enhancement. The echo-gradient T2 images showed a very low intensity signal in 7 out of 7 cases on the second echo. At the first echo, 4 capillary telangiectasias were undetectable. The two vertebral angiographies were normal and the follow-up MRI in 5 patients showed lesion stability.

CONCLUSION

Pontile lesions with no mass effect showing enhancement after gadolinium injection and with or without a discrete T2 high intensity signal but with a frank echo-gradient T2 signal strongly suggest capillary telangiectasia.

[Symptomatic venous angioma. Report of a case]

We report a case of venous angioma revealed by seizure after a non hemorrhagic venous infarct. The initial neuroradiological work-up with CT scan, angiography and brain MRI evidenced the venous infarction with abnormal contrast uptake. The control MRI 3 months later showed clear involution of the venous infarct. Non-hemorrhagic venous infarction on venous angiomas are exceptional. Only 2 cases have been reported in the literature. Impaired venous drainage could be implicated.

[Current imaging of an "aberrant course" of the internal carotid artery]

Blood flow via an aberrant internal carotid artery within the tympanic cavity is a rare pathogenic embryonic variation causing pulsatile tintinus and a vascularized tympanum. CT-scan provides the diagnosis. MRI and 3D time-of-flight MRA appear ideal for exploring aberrant flow both for diagnostic purposes and to establish the vascular morphology.

Dose proportionality studies of novel thiazolidinedione derivatives as potent antidiabetic agents in mice

The determination of the plasma concentrations of the new oral antidiabetic agents BM 13.1246 ((+/-)-5-[4-[2-(5-methyl-2-phenyl-4-oxazolyl)-ethoxy] benzyl]-2,4-thiazolidinedione), [sequence: see text] BM 13.1215 ((+/-)-5-[(5-methyl-2-phenyl-4-oxazolyl)-methyl-2- benzofuranyl-5-methyl]-2,4-oxazolidinedione), [sequence: see text] and BM 50.1050 ((+/-)-5[4-[2-(5-methyl-2-phenyl-4-oxazolyl)-ethoxy] naphthalyl]methyl-2,4-thiazolidinedione) [sequence: see text] in ob/ob mice plasma was performed by using liquid-liquid extraction and high-performance liquid chromatography with ultraviolet (270 nm) detection. The analytical procedures have recoveries of more than 80%, and a between-run precision of less than 4% for all analysed compounds. The pharmacokinetic behaviour, especially the dose proportionality, was investigated in ob/ob mice after repeated oral doses of 1 and 10 mg/kg, respectively. All compounds were absorbed quickly and attained maximum plasma concentrations within 2-5 h after administration. In the examined interval of dosing, an approximately proportional increase of the plasma levels for BM 13.1246 and BM 50.1050 was observed. After repeated oral doses the terminal half-lives are about 4 h for BM 13.1246, 8 h for BM 13.1215, and 6 h for BM 50.1050.

Pharmacokinetics of some new oral blood glucose-lowering agents in dogs

The determination of the plasma concentrations of the new oral antidiabetic agents BM 17.0505 (2-(4-cyclopentylphenoxy)-7- (4-chlorphenyl)-heptanic acid), BM 13.1196 (2-(4-chlorphenyl)- heptanic acid), BM 13.1196 (2-(4-cyclopentylphenoxy)-7-(2-methoxy- phenyl)-heptanic acid: BM 13.1188 (2-(4-benzylphenoxy)-7-(2-methoxy- phenyl)-heptanic acid) and BM 13.1180 (2-(4-butylphenoxy)-5- (4-chlorphenyl)-pentanic acid) in dog plasma were performed by using liquid-liquid extraction and high-performance liquid chromatography with ultraviolet (220 nm) detection. The analytical procedures have recoveries of more than 90%, and a between-run precision of less than 5% for all analysed compounds. The pharmacokinetic behaviour, especially the dose proportionality, was investigated in dogs after a single oral dose of 5 and 50 mg/kg and repeated oral doses of 5 and 50 mg/kg, respectively. All compounds were absorbed quickly and attained maximum plasma concentrations within 1-3 h after administration. In the examined interval of dosing, a clear non proportional increase of the plasma levels was observed. After repeated oral doses the terminal half-lives are about 60-70 h (BM 17.0505), 80 h (BM 13.1196), 30 h (BM 13.1180) and 100-140 h (BM 13.1180).

Pharmacokinetics of the new oral blood glucose-lowering agent (-)-2-(4-tert.-butylphenoxy)-7-(4-chlorophenyl)-heptanic acid sodium salt in mice, rats and dogs

The pharmacokinetic behavior of the alpha-activated carbonic acid (-)-2-(4-tert.-butylphenoxy)-7-(4-chlorophenyl)-heptanic acid sodium salt ((-)-BM 13.1074-Na) was examined in ob/ob mice, rats and dogs. By applying an enantioselective HPLC-method, the in vivo stability of the administered (-)-enantiomer could be demonstrated in all tested species. After oral administration the compound was absorbed quickly and maximum plasma levels were reached within 1 h (ob/ob mice and rats) and 3 h (dogs), respectively. In dose proportionally studies in ob/ob mice, with doses of 0.25 and 1 mg/kg, a clear non proportional-increase of the plasma levels was observed. The terminal half-lives of (-)-BM 13.1074 after multiple dosing are approx. 30 h in ob/ob mice, 9 h in rats and approx. 380 h in dogs. The average effective plasma concentration in ob/ob mice is found to be 43.5 mg/l; minimal toxic concentrations are 58.8 mg/l in rats and 105.6 mg/l in dogs, respectively.

(-)-BM 13.0913: a new oral antidiabetic agent that improves insulin sensitivity in animal models of type II (non-insulin-dependent) diabetes mellitus

Insulin resistance is one of the key features of non-insulin-dependent diabetes mellitus (NIDDM). Therefore, a drug that causes an improvement in insulin sensitivity would be of great interest for the treatment of NIDDM. In addition to the insulin-sensitizing thiazolidinediones, we have found another class of insulin-sensitizing agents: the alpha-activated carbonic acids. (-)-BM 13.0913, a member of this class, was effective in improving insulin resistance in hyperinsulinemic and hypoinsulinemic insulin-resistant animal models of NIDDM. The 50% effective dose (ED50) for the glucose-lowering action was 4, 2.4, and 8 mg/kg in ob/ob, yellow KK, and db/db mice, respectively. The ED50 for the insulin-lowering action was 14.5, 5, and 26 mg/kg. This rightward shift of the dose-response curve for insulin indicates that improving glucose homeostasis is the primary effect of the drug, followed by an insulin-decreasing action. This effect on glucose homeostasis may be brought about by sensitizing peripheral target tissues to the effects of insulin. An increase in deoxyglucose uptake and glucose oxidation measured in adipocytes from rats that had been treated for 14 days with (-)-BM 13.0913 supports this conclusion. Glucose uptake and oxidation was increased at all insulin concentrations tested, suggesting an improved responsiveness. Insulin sensitivity in adipocytes was not influenced by the drug. Studies in the moderately hypoinsulinemic, low-dose streptozotocin (STZ) diabetic rat with a residual insulin concentration showed a decrease in blood glucose concentrations, as well as a decrease in urinary glucose.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of the new oral antidiabetic agent (-)-BM 13.0913.Na on insulin resistance in lean and obese Zucker rats

The new antidiabetic agent (-)-BM 13.0913.Na (BM) was administered to 12-week-old lean and obese Zucker rats, an animal model of insulin resistance, at a daily dose of 50 mg/kg for 14 days. Hyperinsulinemic-euglycemic clamps were performed on treated and untreated lean and obese Zucker rats. Basal hepatic glucose production (HGP) rates were similar in lean and obese untreated animals. Insulin-induced suppression of HGP was significantly less effective in obese animals. In addition, these animals exhibited the characteristic impaired glucose utilization. In obese animals, drug treatment improved insulin suppression of HGP and total glucose utilization (GU) during clamp studies. Furthermore, drug treatment decreased insulin levels during clamp studies, suggesting an acceleration of insulin clearance. Drug treatment also decreased basal plasma insulin levels and serum and liver concentrations of cholesterol in both fasted lean and obese rats. Additionally, blood glucose, plasma nonesterified fatty acids (NEFA), and serum triglyceride levels were reduced in fasted obese rats, but only minor changes in liver triglycerides were observed in lean and obese rats. On the basis of these results, we suggest that BM is an effective antidiabetic agent that may reduce abnormalities of glucose and lipid metabolism.

Failure rate of pulse oximetry in the postanesthesia care unit

OBJECTIVE

The objective of this study was to prospectively examine the incidence of patient-related failure of pulse oximetry in the postanesthesia care unit (PACU).

METHODS

We studied 2,937 patients who, after receiving anesthesia, were admitted to the PACU at the University of Washington Medical Center from December 1989 through May 1990. Pulse oximetry readings were recorded using a Nellcor N-200 oximeter without electrocardiographic synchronization. Failure was defined as the inability to obtain a pulse oximetry reading for 2 or more 15-minute periods after eliminating probe position or mechanical malfunctions.

RESULTS

The overall failure rate in our study was 0.64%, with 19 patient-related pulse oximetry failures from 2,937 cases. Patients on whom the device failed were significantly older (62 +/- 18 vs 46 +/- 19 yr [mean +/- SD]; p < 0.01), had higher median American Society of Anesthesiologists status (3 vs 2), and had longer operations than nonfailure patients (328 +/- 182 vs 185 +/- 127 min; p < 0.01). There was no difference in the duration of PACU times for both groups.

CONCLUSIONS

The failure rate and patient characteristics compare favorably with a previously published study of intraoperative pulse oximetry failure. We conclude that while the pulse oximeter is a reliable instrument for the measurement of blood oxygenation, there is a small but consistent incidence of patient-related failure with this monitoring device in the PACU.

Development of glucose intolerance in obese (fa/fa) Zucker rats

Development of glucose intolerance in genetically obese (fa/fa) rats was investigated. Comparisons were made with lean (FA/?) control rats. Oral glucose tolerance tests were performed in 7-8 weeks, 9-10 weeks, 12-13 weeks and 16-17 weeks old rats. Irrespectively of age, the obese rats showed impaired glucose tolerance and insulin sensitivity compared with age-matched lean rats. While in FA/? rats only minor changes of glucose-stimulated insulin secretion and glucose tolerance were observed with progression of age, glucose intolerance in obese animals became more pronounced with aging. Obese rats older than 12-13 weeks showed no further progression of glucose intolerance. Glucose-stimulated insulin secretion increased with aging, but basal insulinemia was unaffected. Hence, we conclude that glucose intolerance and insulin resistance in genetically obese (fa/fa) rats is almost completely developed with approximately 12 weeks.

Normal insulin receptor tyrosine kinase activity and glucose transporter (GLUT 4) levels in the skeletal muscle of hyperinsulinaemic hypertensive rats

The spontaneous hypertensive rat is an animal model characterized by a syndrome of hypertension, insulin resistance and hyperinsulinaemia. To elucidate whether in analogy to other insulin resistant animal models an inactivity of the insulin receptor kinase or an alteration of the glucose transporter (GLUT 4) level in the skeletal muscle might contribute to the pathogenesis of insulin resistance we determined insulin receptor kinase activity and GLUT 4 level in the hindlimbs of spontaneous hypertensive rats and normotensive control rats. Normotensive normoinsulinaemic Lewis and Wistar rats were used as insulin sensitive controls, obese Zucker rats were used as an insulin resistant control with known reduced skeletal muscle insulin receptor kinase activity. Binding of 125I-insulin, crosslinking of 125I-B26-insulin, autophosphorylation in vitro with 32P-ATP and phosphorylation of the synthetic substrate Poly (Glu 4: Tyr 1) were performed after partial purification of solubilized receptors on wheat germ agglutinin columns. GLUT 4 levels were determined by Western blotting of subcellular muscle membranes. Insulin receptors from spontaneous hypertensive rats compared to those from Lewis and Wistar rats showed no difference of the binding characteristics or the in vitro auto- and substrate phosphorylation activity of the receptor, while in the Zucker rats the earlier described insulin receptor kinase defect was clearly evident. Western blots of subcellular muscle membrane fractions with antibodies against GLUT 4 revealed no difference in transporter levels. These data suggest that insulin resistance in spontaneous hypertensive rats is caused neither by an insulin receptor inactivity nor by a decreased number of glucose transporters in the skeletal muscle.

In vitro investigations on a new positive inotropic and vasodilating agent (BM 14.478) that increases myocardial cyclic AMP content and myofibrillar calcium sensitivity

BM 14.478 (7,7-dimethyl-2-(4-pyridyl)-6,7-dihydro-3H,5H pyrrolo[2,3-f]benz-imidazol-6-one) was investigated in several in vitro experiments to elucidate its positive inotropic and vasodilating efficacy and its mode of action. A direct positive inotropic action was achieved in papillary muscles (10(-6) to 5 X 10(-4) M) and electrically driven atria (10(-8) to 5 X 10(-4) M) from guinea pig hearts. The effect was not affected by propranolol, cimetidine, or tetrodotoxin, but diminished by carbachol. The effect of isoprenaline was amplified by threshold concentrations of BM 14.478 (10(-6) M). There was only a slight intrinsic chronotropic activity in spontaneously beating guinea pig atria. Atrial cyclic AMP (cAMP) was increased from 1.46 +/- 0.06 to 1.97 +/- 0.03 pmol/mg wet wt, at 3 X 10(-6) M. This might be due to an inhibition of cardiac phosphodiesterase(s) (PDE). IC50 of bovine PDE was 7.2 X 10(-5) M (5.4 X 10(-5) M to 9.7 X 10(-5) M). BM 14.478 shortened the duration of transmembrane action potential (90% repol.) by 8% and increased the Vmax of slow action potentials by 32% at 3 X 10(-4) M. In skinned porcine heart muscle fibers an increase in calcium-activated force up to 43 +/- 7% was observed (10(-7) to 10(-4) M). Rat aortas were relaxed by about 75% maximally (10(-7) to 10(-4) M). It is concluded that BM 14.478 is a potent inotropic drug which acts via an increase in myocardial cAMP content and in calcium sensitivity of contractile proteins.