A European regulatory pathway for Tidepool loop following clearance in the United States?

The recent clearance by the United States Food and Drug Administration of Tidepool Loop sets an important precedent within the medical device landscape. For the first time, an automated insulin delivery mobile application-based on an algorithm initially designed and developed by users -has been recognised as safe and effective by a regulatory body. The aim of this paper is twofold: firstly, we map out the regulatory pathways and processes that were navigated by Tidepool, the non-profit behind Tidepool Loop, in order to make this landmark moment possible. Secondly, we set out potential approvals processes in the European Union and United Kingdom with a view to examining the challenges to obtaining regulatory clearance for Tidepool Loop in these jurisdictions. In so doing, we highlight the significant differences, not only between the United States and European systems but also between the European Union and Great Britain systems. We conclude by arguing that the complexity encountered when seeking to introduce an innovative solution in different regulatory systems has the potential to act as a disincentive to open source developers from seeking regulatory approvals for such technologies in the future.

Evidence from clinical trials on high-risk medical devices in children: a scoping review

BACKGROUND

Meeting increased regulatory requirements for clinical evaluation of medical devices marketed in Europe in accordance with the Medical Device Regulation (EU 2017/745) is challenging, particularly for high-risk devices used in children.

METHODS

Within the CORE-MD project, we performed a scoping review on evidence from clinical trials investigating high-risk paediatric medical devices used in paediatric cardiology, diabetology, orthopaedics and surgery, in patients aged 0-21 years. We searched Medline and Embase from 1st January 2017 to 9th November 2022.

RESULTS

From 1692 records screened, 99 trials were included. Most were multicentre studies performed in North America and Europe that mainly had evaluated medical devices from the specialty of diabetology. Most had enrolled adolescents and 39% of trials included both children and adults. Randomized controlled trials accounted for 38% of the sample. Other frequently used designs were before-after studies (21%) and crossover trials (20%). Included trials were mainly small, with a sample size <100 participants in 64% of the studies. Most frequently assessed outcomes were efficacy and effectiveness as well as safety.

CONCLUSION

Within the assessed sample, clinical trials on high-risk medical devices in children were of various designs, often lacked a concurrent control group, and recruited few infants and young children.

IMPACT

In the assessed sample, clinical trials on high-risk medical devices in children were mainly small, with variable study designs (often without concurrent control), and they mostly enrolled adolescents. We provide a systematic summary of methodologies applied in clinical trials of medical devices in the paediatric population, reflecting obstacles in this research area that make it challenging to conduct adequately powered randomized controlled trials. In view of changing European regulations and related concerns about shortages of high-risk medical devices for children, our findings may assist competent authorities in setting realistic requirements for the evidence level to support device conformity certification.

Quality and transparency of evidence for implantable cardiovascular medical devices assessed by the CORE-MD consortium

BACKGROUND AND AIMS

The European Union Medical Device Regulation 2017/745 challenges key stakeholders to follow transparent and rigorous approaches to the clinical evaluation of medical devices. The purpose of this study is a systematic evaluation of published clinical evidence underlying selected high-risk cardiovascular medical devices before and after market access in the European Union (CE-marking) between 2000 and 2021.

METHODS

Pre-specified strategies were applied to identify published studies of prospective design evaluating 71 high-risk cardiovascular devices in seven different classes (bioresorbable coronary scaffolds, left atrial appendage occlusion devices, transcatheter aortic valve implantation systems, transcatheter mitral valve repair/replacement systems, surgical aortic and mitral heart valves, leadless pacemakers, subcutaneous implantable cardioverter-defibrillator). The search time span covered 20 years (2000-21). Details of study design, patient population, intervention(s), and primary outcome(s) were summarized and assessed with respect to timing of the corresponding CE-mark approval.

RESULTS

At least one prospective clinical trial was identified for 70% (50/71) of the pre-specified devices. Overall, 473 reports of 308 prospectively designed studies (enrolling 97 886 individuals) were deemed eligible, including 81% (251/308) prospective non-randomized clinical trials (66 186 individuals) and 19% (57/308) randomized clinical trials (31 700 individuals). Pre-registration of the study protocol was available in 49% (150/308) studies, and 16% (48/308) had a peer-reviewed publicly available protocol. Device-related adverse events were evaluated in 82% (253/308) of studies. An outcome adjudication process was reported in 39% (120/308) of the studies. Sample size was larger for randomized in comparison to non-randomized trials (median of 304 vs. 100 individuals, P < .001). No randomized clinical trial published before CE-mark approval for any of the devices was identified. Non-randomized clinical trials were predominantly published after the corresponding CE-mark approval of the device under evaluation (89%, 224/251). Sample sizes were smaller for studies published before (median of 31 individuals) than after (median of 135 individuals) CE-mark approval (P < .001). Clinical trials with larger sample sizes (>50 individuals) and those with longer recruitment periods were more likely to be published after CE-mark approval, and were more frequent during the period 2016-21.

CONCLUSIONS

The quantity and quality of publicly available data from prospective clinical investigations across selected categories of cardiovascular devices, before and after CE approval during the period 2000-21, were deemed insufficient. The majority of studies was non-randomized, with increased risk of bias, and performed in small populations without provision of power calculations, and none of the reviewed devices had randomized trial results published prior to CE-mark certification.

The IDEAL framework for surgical robotics: development, comparative evaluation and long-term monitoring

The next generation of surgical robotics is poised to disrupt healthcare systems worldwide, requiring new frameworks for evaluation. However, evaluation during a surgical robot's development is challenging due to their complex evolving nature, potential for wider system disruption and integration with complementary technologies like artificial intelligence. Comparative clinical studies require attention to intervention context, learning curves and standardized outcomes. Long-term monitoring needs to transition toward collaborative, transparent and inclusive consortiums for real-world data collection. Here, the Idea, Development, Exploration, Assessment and Long-term monitoring (IDEAL) Robotics Colloquium proposes recommendations for evaluation during development, comparative study and clinical monitoring of surgical robots-providing practical recommendations for developers, clinicians, patients and healthcare systems. Multiple perspectives are considered, including economics, surgical training, human factors, ethics, patient perspectives and sustainability. Further work is needed on standardized metrics, health economic assessment models and global applicability of recommendations.

Clinical investigations to evaluate high-risk orthopaedic devices: a systematic review of the peer-reviewed medical literature

Purpose

The objective of this systematic review was to give an overview of clinical investigations regarding hip and knee arthroplasty implants published in peer-reviewed scientific medical journals before entry into force of the EU Medical Device Regulation in May 2021.

Methods

We systematically reviewed the medical literature for a random selection of hip and knee implants to identify all peer-reviewed clinical investigations published within 10 years before and up to 20 years after regulatory approval. We report study characteristics, methodologies, outcomes, measures to prevent bias, and timing of clinical investigations of 30 current implants. The review process was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines.

Results

We identified 2912 publications and finally included 151 papers published between 1995 and 2021 (63 on hip stems, 34 on hip cups, and 54 on knee systems). We identified no clinical studies published before Conformité Européene (CE)-marking for any selected device, and no studies even up to 20 years after CE-marking in one-quarter of devices. There were very few randomized controlled trials, and registry-based studies generally had larger sample sizes and better methodology.

Conclusion

The peer-reviewed literature alone is insufficient as a source of clinical investigations of these high-risk devices intended for life-long use. A more systematic, efficient, and faster way to evaluate safety and performance is necessary. Using a phased introduction approach, nesting comparative studies of observational and experimental design in existing registries, increasing the use of benefit measures, and accelerating surrogate outcomes research will help to minimize risks and maximize benefits.

European expert recommendations on clinical investigation and evaluation of high-risk medical devices for children

Several high-risk medical devices for children have become unavailable in the European Union (EU), since requirements and costs for device certification increased markedly due to the EU Medical Device Regulation. The EU-funded CORE-MD project held a workshop in January 2023 with experts from various child health specialties, representatives of European paediatric associations, a regulatory authority and the European Commission Directorate General Health and Food Safety. A virtual follow-up meeting took place in March 2023. We developed recommendations for investigation of high-risk medical devices for children building on participants' expertise and results of a scoping review of clinical trials on high-risk medical devices in children. Approaches for evaluating and certifying high-risk medical devices for market introduction are proposed.

Learning From Experience and Finding the Right Balance in the Governance of Artificial Intelligence and Digital Health Technologies

Artificial intelligence (AI) and machine learning medical tools have the potential to be transformative in care delivery; however, this change will only be realized if accompanied by effective governance that ensures patient safety and public trust. Recent digital health initiatives have called for tighter governance of digital health. A correct balance must be found between ensuring product safety and performance while also enabling the innovation needed to deliver better approaches for patients and affordable efficient health care for society. This requires innovative, fit-for-purpose approaches to regulation. Digital health technologies, particularly AI-based tools, pose specific challenges to the development and implementation of functional regulation. The approaches of regulatory science and "better regulation" have a critical role in developing and evaluating solutions to these problems and ensuring effective implementation. We describe the divergent approaches of the European Union and the United States in the implementation of new regulatory approaches in digital health, and we consider the United Kingdom as a third example, which is in a unique position of developing a new post-Brexit regulatory framework.

The European Medical Device Regulation-What Biomedical Engineers Need to Know

The Medical Device Regulation (EU) 745/2017 (MDR) has replaced the medical device directives which were in place since the early 1990s. MDR introduces a number of changes of relevance to biomedical engineers who work in healthcare institutions or with medical devices. This includes changes relating to devices produced in healthcare institutions, custom-made devices, single use devices, devices without an intended medical purpose, clinical investigations and device traceability. There are also challenges in implementation of the MDR, with a shortage of available notified bodies needed to conduct conformity assessment, with a consequent risk of product unavailability. Understanding these changes is important as implementing new requirements in practice may require additional resources or the introduction of new processes or systems.

Improved clinical investigation and evaluation of high-risk medical devices: the rationale and objectives of CORE-MD (Coordinating Research and Evidence for Medical Devices)

In the European Union (EU), the delivery of health services is a national responsibility but there are concerted actions between member states to protect public health. Approval of pharmaceutical products is the responsibility of the European Medicines Agency, while authorising the placing on the market of medical devices is decentralised to independent ‘conformity assessment’ organisations called notified bodies. The first legal basis for an EU system of evaluating medical devices and approving their market access was the Medical Device Directive, from the 1990s. Uncertainties about clinical evidence requirements, among other reasons, led to the EU Medical Device Regulation (2017/745) that has applied since May 2021. It provides general principles for clinical investigations but few methodological details – which challenges responsible authorities to set appropriate balances between regulation and innovation, pre- and post-market studies, and clinical trials and real-world evidence. Scientific experts should advise on methods and standards for assessing and approving new high-risk devices, and safety, efficacy, and transparency of evidence should be paramount. The European Commission recently awarded a Horizon 2020 grant to a consortium led by the European Society of Cardiology and the European Federation of National Associations of Orthopaedics and Traumatology, that will review methodologies of clinical investigations, advise on study designs, and develop recommendations for aggregating clinical data from registries and other real-world sources. The CORE–MD project (Coordinating Research and Evidence for Medical Devices) will run until March 2024. Here, we describe how it may contribute to the development of regulatory science in Europe.

Cite this article: EFORT Open Rev 2021;6:839-849. DOI: 10.1302/2058-5241.6.210081

Improved clinical investigation and evaluation of high-risk medical devices: the rationale and objectives of CORE-MD (Coordinating Research and Evidence for Medical Devices)

In the European Union (EU) the delivery of health services is a national responsibility but there are concerted actions between member states to protect public health. Approval of pharmaceutical products is the responsibility of the European Medicines Agency, while authorising the placing on the market of medical devices is decentralised to independent 'conformity asssessment' organisations called notified bodies. The first legal basis for an EU system of evaluating medical devices and approving their market access was the medical device directives, from the 1990s. Uncertainties about clinical evidence requirements, among other reasons, led to the EU Medical Device Regulation (2017/745) that has applied since May 2021. It provides general principles for clinical investigations but few methodological details ‒ which challenges responsible authorities to set appropriate balances between regulation and innovation, pre- and post-market studies, and clinical trials and real-world evidence. Scientific experts should advise on methods and standards for assessing and approving new high-risk devices, and safety, efficacy, and transparency of evidence should be paramount. The European Commission recently awarded a Horizon 2020 grant to a consortium led by the European Society of Cardiology and the European Federation of National Associations of Orthopaedics and Traumatology, that will review methodologies of clinical investigations, advise on study designs, and develop recommendations for aggregating clinical data from registries and other real-world sources. The CORE‒MD project (Coordination of Research and Evidence for Medical Devices) will run until March 2024; here we describe how it may contribute to the development of regulatory science in Europe.

New medical device regulations: the regulator's view

Advances in medical device technology have been dramatic in recent years resulting in both an increased number of medical devices and an increase in the invasiveness and critical function which devices perform. Two new regulations entered into force in Europe in May 2017, the Medical Device Regulation (MDR) and the In Vitro Diagnostic Device Regulation (IVDR). These regulations will replace the current directives over the coming years. These regulations, for the first time introduce requirements relating to registries.

Medical device manufacturers are required to have systematic methods for examining their devices once available on the market, by systematically gathering, recording and analysing data on safety and performance.

Registries can assist public health protection in very practical ways, for example, to help urgently identify patients or devices. Registries can also be powerful tools for collecting and appraising real-world clinical evidence concerning medical devices. Clinical investigations are limited in terms of the sample size and the duration of follow-up which can reasonably be expected. Registries may also be the only available tool to examine rare adverse effects, sub-populations or for time durations which it is not possible or feasible to study in a clinical investigation. By ensuring that a core dataset is collected which can be compared to other registries or trial data, it is possible to pool data to better examine outcomes. There are a range of excellent initiatives which have aimed at ensuring the appropriate regulatory application of registry data.

Cite this article: EFORT Open Rev 2019;4 DOI: 10.1302/2058-5241.4.180061

Modelling the effect of hydration on skin conductivity

BACKGROUND

Electrical signals are recorded from and sent into the body via the skin in a number of applications. In practice, skin is often hydrated with liquids having different conductivities so a model was produced in order to determine the relationship between skin impedance and conductivity.

METHODS

A model representing the skin was subjected to a variety of electrical signals. The parts of the model representing the stratum corneum were given different conductivities to represent different levels of hydration.

RESULTS

The overall impedance and conductivity of the cells did not vary at frequencies below 40 kHz. Above 40 kHz, levels of increased conductivity caused the overall impedance to decrease.

CONCLUSION

The variation in impedance with conductivity between 5 and 50 mSm^-1 can be modelled quadratically while variation in impedance with conductivity between 5 and 5000 mSm^-1 can be modelled with a double exponential decay.

Multi-modal particle manipulator to enhance bead-based bioassays

By sequentially pushing micro-beads towards and away from a sensing surface, we show that ultrasonic radiation forces can be used to enhance the interaction between a functionalised glass surface and polystyrene micro-beads, and identify those that bind to the surface by illuminating bound beads using an evanescent field generated by guided light. The movement towards and immobilisation of streptavidin coated beads onto a biotin functionalised waveguide surface is achieved by using a quarter-wavelength mode pushing beads onto the surface, while the removal of non-specifically bound beads uses a second quarter-wavelength mode which exhibits a kinetic energy maximum at the boundary between the carrier layer and fluid, drawing beads towards this surface. This has been achieved using a multi-modal acoustic device which exhibits both of these quarter-wavelength resonances. Both 1-D acoustic modelling and finite element analysis has been used to design this device and to investigate the spatial uniformity of the field. We demonstrate experimentally that 90% of specifically bound beads remain attached after applying ultrasound, with 80% of non-specifically bound control beads being successfully removed acoustically. This approach overcomes problems associated with lengthy sedimentation processes used for bead-based bioassays and surface (electrostatic) forces, which delay or prevent immobilisation. We explain the potential of this technique in the development of DNA and protein assays in terms of detection speed and multiplexing.

Quenching of CdSe quantum dot emission, a new approach for biosensing

The emission of CdSe quantum dots linked to the 5'-end of a DNA sequence is efficiently quenched by hybridisation with a complementary DNA strand with a gold nanoparticle attached at the 3'-end; contact of the quantum dot and gold nanoparticle occurs.

Submicron patterning of DNA oligonucleotides on silicon

The covalent attachment of DNA oligonucleotides onto crystalline silicon (100) surfaces, in patterns with submicron features, in a straightforward, two-step process is presented. UV light exposure of a hydrogen-terminated silicon (100) surface coated with alkenes functionalized with N-hydroxysuccinimide ester groups resulted in the covalent attachment of the alkene as a monolayer on the surface. Submicron-scale patterning of surfaces was achieved by illumination with an interference pattern obtained by the transmission of 248 nm excimer laser light through a phase mask. The N-hydroxysuccinimide ester surface acted as a template for the subsequent covalent attachment of aminohexyl-modified DNA oligonucleotides. Oligonucleotide patterns, with feature sizes of 500 nm, were reliably produced over large areas. The patterned surfaces were characterized with atomic force microscopy, scanning electron microscopy, epifluorescence microscopy and ellipsometry. Complementary oligonucleotides were hybridized to the surface-attached oligonucleotides with a density of 7 x 10(12) DNA oligonucleotides per square centimetre. The method will offer much potential for the creation of nano- and micro-scale DNA biosensor devices in silicon.

Oligonucleotide-conjugated thiazole orange probes as "light-up" probes for messenger ribonucleic acid molecules in living cells

"Light-up" probes, icosa-alpha-thymidylate-thiazole orange conjugates, for the in situ time-resolved detection of messenger ribonucleic acid (mRNA) in living cells are evaluated. Upon annealing with polyA in aqueous solutions, the icosa-alpha-thymidylate-thiazole orange conjugates were shown to be up to 15 times more fluorescent. Microinjection of these probes into adherent fibroblasts resulted in high yields of hybridization and fluorescent signals. Incubation of cells in the presence of these probes resulted in facile internalization of the probe and similar painting of the messenger RNA in the nuclear and cytosolic regions.

Guanine is the target for direct ionisation damage in DNA, as detected using excision enzymes

Exposure of an aqueous, aerated solution (pH 7) of a double-stranded DNA to 193 nm light, of sufficient energy to ionise DNA, leads to selective, non-random modification at guanine in the form of frank single-strand break (ssb) and base modifications, revealed by treatment with either Escherichia coli formamidopyrimidine-DNA glycosylase (Fpg), Escherichia coli endonuclease III (Nth) or hot piperidine treatment. There is a similar neighbouring base sequence dependence for Fpg- and Nth-sensitive damage as that previously reported for both hot alkali-labile damage and prompt ssb. Low yields of photoproducts, namely pyrimidine dimers, are also revealed using the enzyme T4 endonuclease V (T4 endo V). Although irradiation of DNA with 193 nm light causes photoionisation of all the nucleic acid bases, these results indicate that guanine is the predominant site for localisation of the oxidative damage. These findings are consistent with migration of the radical cation to 'target' damage at guanine sites.

Irradiation of DNA with 193 nm light yields formamidopyrimidine-DNA glycosylase(Fpg) protein-sensitive lesions

Irradiation of aqueous solutions of plasmid DNA (pUC18) at pH 7.6 with 193 nm laser light results in low yields of prompt single strand breakage (air-saturated sample phi ssh = [1.5 +/- 0.1] x 10(4), argon-saturated sample phi ssh = [0.9 +/- 0.1] x 10(4). Treatment of the irradiated DNA samples with Escherichia coli formamidopyrimidine-DNA glycosylase (Fpg) protein results in an approximate 20-fold increase in the yield of single strand break-age (air-saturated sample phi fpg = [33.1 +/- 3.1] x 10(-4), argon-saturated sample phi fpg = [23.8 +/- 2.6] x 10(-4). This result indicates that 193 nm light induces other modification(s) (most likely of the purine moieties) that are 20 times more abundant than prompt strand breakage within the DNA matrix.

The reaction of triplet 2-methyl-1,4-naphthoquinone (menadione) with DNA and polynucleotides

The photoreaction of 2-methyl-1,4-naphthoquinone (MQ, menadione) with DNA and polynucleotides in argon-saturated aqueous solution (pH 7) was studied. Results from laser flash photolysis experiments indicate that triplet quinone reacts with DNA and polyA but not detectably with polyU by one-electron oxidation of the bases of the nucleic acid with formation of the radical anion of the quinone. Irradiation of argon-saturated solutions containing MQ and DNA or polynucleotides (polyU, polyA, polyG or polyC) with 334 nm light leads to an increase in molecular weight for single-stranded DNA, polyA and to a much less extent for polyU. This finding indicates crosslink formation with quantum yields in the range of 10(-5)-10(-3).

193 nm light induces single strand breakage of DNA predominantly at guanine

Irradiation of DNA with 193 nm light results in monophotonic photoionization, with the formation of a base radical cation and a hydrated electron (phi PI = 0.048-0.065). Although > 50% of the photoionization events initially occur at guanine in DNA, migration of the "hole" from the other bases to guanine occurs to yield predominantly its radical cation or its deprotonated form. From sequence analysis, the data reveal that 193 nm light induces single strand breaks (ssb) in double-stranded DNA preferential 3' to a guanine residue. However, it has previously been reported that 193 nm light yields very low yields of ssb (< 2% of the yield of e-aq). The distribution of these ssb at guanine is nonrandom, showing a dependence on the neighboring base moiety. The efficiency of ssb formation at nonguanine sites is estimated to be at least one order of magnitude lower. The preferred cleavage at guanine is consistent with migration and localization of the electron loss center at guanine. It is argued that singlet oxygen and the photoionized phosphate group of the sugar moiety are not major precursors to ssb. At present, the mechanisms of strand breakage are not known although a guanine radical or one of its products remain potential precursors.

Influence of nucleic acid base composition on radiation-induced strand breakage in single stranded DNA: a time resolved study

The following study investigates the pathways involved in the induction of single strand breaks (ssb) in various samples of single stranded (ss) DNA (calf thymus, Micrococcus lysodeikticus, Clostridium perfringens) with differing nucleic acid base composition. The time scale for the induction of ssb was determined from changes in the light scattering intensity following pulse irradiation of aqueous solutions containing these ssDNA samples at pH7.8 under either aerated or deaerated conditions. The induction of ssb under these conditions is predominantly by the hydroxyl radical and shows various kinetically distinct components. The immediate ssb (t < 0.02 s) account for approximately 40-60% of the total yield of ssb. The majority of these ssb are suggested to arise from the 'common' initial attack of the hydroxyl radicals at the sugar phosphate backbone for each of the three DNA samples. Furthermore, slower components for ssb formation (t > 0.02 s) were observed and are suggested to occur through base radical mediated H-atom abstraction from the sugar moiety. The half lives for formation of the majority of ssb, formed through this base radical-mediated H-atom abstraction(s), are in the range of 20-43 ms. The yields of these 'base-mediated' ssb vary markedly (under both aerobic and anaerobic conditions) and reflect the base composition of the DNA sample. It is suggested from these studies that the OH-induced base radicals of guanine/cytosine are more effective precursors for strand breakage than those from adenine/thymine in ssDNA.

Management of nephrotic syndrome in childhood

Nephrotic syndrome is defined as proteinuria sufficiently severe to result in hypoalbuminaemia, oedema and hyperlipidaemia. The early modern history of this illness was characterised by the serendipitous development of renal biopsy technique at approximately the same time as the use of corticosteroids for nephrotic syndrome. The coincidence of these events set the stage for evaluating therapeutic response to corticosteroids and cytotoxic agents in relation to renal histology and ultimate clinical outcome. The International Study of Kidney Disease in Children (ISKDC) was initiated in the 1960s as a multicentre study examining these relationships in children. Over the next decade this study, as well as contributions from other investigators, helped define optimum therapy for these children. It was determined that a child with nephrotic syndrome under the age of 6 years, who did not present with hypertension, azotaemia, hypocomplementaemia or signs of systemic illness, had an approximately 85% chance of responding to corticosteroid therapy. If only those children who had minimal change histology on biopsy were considered, 94% responded. The original regimen which is still used today, was 60 mg/m2 bsa/day prednisone administered on a 3 times per day dosage schedule for 4 weeks, followed by an additional 4 weeks of therapy at a dose of 40 mg/m2 bsa given as a single oral dose every other day. Of those who respond roughly one-third will have no relapses, while almost half will have frequent relapses (greater than or equal to 2 in 6 months) and the rest will have infrequent relapses. Patients in relapse are treated as at presentation but are usually converted to the 40 mg/m2 bsa dose when the urine has been free of protein for 3 days, and are then tapered off or maintained on this dose for several weeks, depending on the individual's history of relapses and incidence of side effects from corticosteroids. For those children who are suffering frequent relapses and severe corticosteroid side effects (e.g. growth failure, morbid obesity, aseptic necrosis of bone), cytotoxic agents were identified as providing long term remission. After inducing remission with conventional corticosteroid dosages, cyclophosphamide is administered at a dose of 2 mg/kg/day given as a single dose for 8 weeks. This regimen was shown to lead to approximately 70% of patients being in remission 2 years after completion of this course of therapy. Chlorambucil given at a dose of 0.2 mg/kg/day as a single oral dose has been equally efficacious.(ABSTRACT TRUNCATED AT 400 WORDS)

A comparison of 2 protocols for living-related renal transplantation in children: donor-specific transfusions versus cyclosporine

We analyzed the results obtained with protocols for immunosuppression of pediatric recipients of haploidentical living-related renal transplants. In the donor-specific transfusion group transfusion of blood products obtained from the prospective organ donor was performed before transplantation, and at transplantation maintenance immunosuppression of azathioprine and prednisone was begun. In the cyclosporine group donor-specific transfusion was not used, and maintenance immuno-suppression of cyclosporine and azathioprine was begun 1 week before transplantation, with the addition of prednisone at transplantation. Of 24 donor-specific transfusion recipients 3 had circulating cytotoxic antibodies to the prospective donor for an incidence of 12%. There was no significant difference between groups with respect to 1-year actual patient and graft survival (100 and 89 versus 100 and 86%, respectively), 1-year mean serum creatinine level (1.1 versus 1.2 mg./dl.), rejection treatments per patient (2.5 versus 2.6) and total days hospitalized during year 1 after transplantation (27 versus 18), with donor-specific transfusion data presented first. Initial hospitalization was significantly shorter (10 versus 16 days, p less than 0.05) and the incidence of rejection crises within 3 months was significantly less (68 versus 94%, p less than 0.05) in the cyclosporine group. We believe that cyclosporine and azathioprine pre-treatment of pediatric recipients of haploidentical living-related renal transplants with the addition of prednisone at transplantation is preferable to a donor-specific transfusion protocol because there is no risk of recipient sensitization to the prospective donor, and patient and graft survival is not adversely affected.

The association of Wilms' tumor with nephrologic disease

Three cases of nephrologic disease characterized clinically by nephrotic syndrome and histologically with mesangial sclerosis associated with Wilms' tumor are documented. Two children were born with ambiguous genitalia and an XY chromosome constitution. A third patient had a 46,XY karyotype and developed a Wilms' tumor but had a normal female phonotype. The evaluation and current management of this syndrome are discussed.

Monoclonal antibody OKT3 therapy in pediatric kidney transplant recipients

Thirty-one pediatric patients with acute renal allograft rejection were treated with the monoclonal antibody OKT3. In 24 cases, increased doses of steroids followed by a polyclonal antithymocyte globulin were ineffective in reversing the rejection episode. Twenty-eight patients completed the prescribed minimum 10-day treatment course, with effective rejection reversal in 22. Three patients failed to complete the course of therapy: one because of leukopenia that developed after the first dose, one because of a clotted graft, and another because of symptomatic cytomegalovirus infection. The overall success rate of OKT3 for rejection reversal was 74%; however, 55% of recipients had rebound rejection, and 85% of patients had detectable anti-OKT3 antibodies after completion of the course of therapy. Ten patients were treated with a second course of OKT3, and in eight of these patients, rejection was at least temporarily reversed. The starting dose of OKT3 for second-course therapy was the same as that used during first-course therapy, but in five cases the dose was increased during the course because of inadequate therapeutic response. Seven of these patients lost their grafts a mean of 6.5 months after completion of second-course therapy. We looked for anti-OKT3 antibody in nine recipients after completion of a second treatment course and found it in all nine. Our observations regarding a second treatment course with this monoclonal antibody preparation suggest that although rejection reversal may be observed, ultimate graft survival is poor and anti-OKT3 antibody formation is enhanced.

The photochemistry of acetyl-substituted aroyl azides: the design of photolabeling agents for inert sites in hydrophobic regions

The photochemistry, photophysics and hydrolytic stability of three substituted aroyl azides were investigated. The azides were selected as model compounds for potential photolabeling agents based on the extreme electrophilic reactivity of aroylnitrenes. Each of the azides studied is a derivative of benzoyl azide containing an acyl group to act as an internal triplet sensitizer and an additional functional group useful for linking the azide to a site-selecting probe molecule. The findings show that benzoyl azides containing the three substituents in a 1,3,5-pattern might be useful for labeling of lipophilic molecules.

Long-term follow-up of patients with steroid-dependent, minimal change nephrotic syndrome

A subgroup of patients with steroid-responsive minimal change nephrotic syndrome (MCNS) is classified as steroid-dependent because of repeated relapses of proteinuria during prednisone taper, or within four weeks of withdrawal of prednisone. The long-term outcome of this subgroup of patients has not been documented. Thirteen patients with onset of steroid-dependent MCNS (biopsy-proven) in childhood have been followed for 10-22 years (mean 15.6 years); 8 patients have been in stable remission for 2-13 years (mean 5.5 years); 3 remain steroid-dependent 12, 18 and 22 years after onset; and 2 had steroid-responsive relapses after 5 and 8 years of remission. In 3 patients steroid-dependent MCNS remitted without cytotoxic therapy 7-11 years after onset. Cyclophosphamide was administered to the remaining 10 patients: 8 had prolonged remissions (1.1-13 years, mean 4.3 years) and 2 relapsed shortly after cyclophosphamide therapy. Of the 8 patients who had prolonged remissions after cyclophosphamide, 3 have had no relapses 5-13 years after therapy. In 5 of these 8 patients steroid-dependency recurred 1.1-3 years after cyclophosphamide and a second course was given, resulting in remissions of 1.4-8 years in 3 patients, change to a frequently relapsing pattern in 1 patient and remission of 3 months in one patient who then became steroid-dependent again. We conclude that the long-term outcome of steroid-dependent MCNS is favorable. Cyclophosphamide is useful in the management of these patients and a prolonged course of alternate-day prednisone therapy after cyclophosphamide may be helpful in maintaining remission.

Idiopathic linear glomerular IgA deposition

Linear deposition of IgA immunoglobulin was found along the glomerular basement membrane in two patients with normal renal function and no pulmonary abnormalities. One patient had recurrent gross hematuria and a mild focal proliferative glomerulonephritis without deposits on electron microscopy; the second patient had a renal cell carcinoma. This observation of linear IgA antibody deposition in the absence of Goodpasture's syndrome or diabetes mellitus extends the spectrum of diseases associated with glomerular basement membrane-IgA deposition.

Amyloid P component is not present in the glomerular basement membrane in Alport-type hereditary nephritis

Serum amyloid P component (SAP) is a normal plasma glycoprotein immunochemically indistinguishable from amyloid P, a glycoprotein found in all tissue amyloid deposits. SAP has also been shown to be a constituent of normal glomerular basement membrane (GBM). In this study the authors discovered a unique association between SAP and Goodpasture (GP) antigen. In those patients whose GBM lack GP antigen (those with Alport-type hereditary nephritis) SAP is also uniformly absent. Although the relationship between these two components is unknown, this association may provide clues to the abnormality of GBM in Alport-type hereditary nephritis.

Selective binding of IgG4 and other negatively charged plasma proteins in normal and diabetic human kidneys

Renal tissue from 9 patients with diabetes mellitus (4 with mild and 5 with end-stage disease) and 3 with antiglomerular basement membrane (GBM) nephritis, as well as 5 normal human kidneys, were examined by immunofluorescence microscopy for the presence of plasma proteins of varying isoelectric point (pI). In normal and diabetic kidneys, IgG deposition in basement membranes was restricted to IgG4 (pI 5.5-6.0), the subclass present in lowest concentration in human plasma. IgG1, IgG2, and IgG3 (pI 7.0-9.5) were not detected. In contrast, in anti-GBM nephritis, all four subclasses were present in a linear pattern in GBM. Other plasma proteins of low isoelectric point were detected in basement membranes: albumin (pI 4.9), alpha-1-acid glycoprotein (pI 2.7), amyloid P (pI 3.9-4.8), and alpha-1-antitrypsin (pI 4.5). These studies are consistent with the hypothesis that circulating anionic plasma proteins are electrostatically bound in vivo to positively charged moieties in normal and especially diabetic basement membranes.

No evidence for a specific role of IgM in mesangial proliferation of idiopathic nephrotic syndrome

To define the relationship of mesangial IgM to various morphologic categories of idiopathic nephrotic syndrome (INS), an analysis of 100 patients was carried out in which five morphologic subgroups were evaluated: group 1, minimal glomerular change (38 patients); group 2, minimal change with focal global sclerosis (18 patients); group 3, focal segmental glomerulosclerosis ( FSG ) (23 patients); group 4, mesangial proliferation (12 patients); group 5, focal segmental glomerulosclerosis with mesangial proliferation (9 patients). Immunohistochemical studies failed to demonstrate any differences between these five groups. The intensities of immunofluorescence and the percentage of tissue samples demonstrating IgM and/or C3 in the glomerular mesangium and subendothelial regions were similar. In addition, the presence or intensity of mesangial IgM did not predict the patients' current status or responsiveness to steroid therapy. Morphologic transitions were observed in patients who had more than one biopsy: one of five in group 2 and two of eight in group 3 developed mesangial proliferation; and nine of ten patients with mesangial proliferation in the first biopsy continued to show this finding in the second. In general, a complete response to steroid therapy and a favorable outcome is less likely in patients with this morphologic abnormality. In nine of the 27 repeat biopsies, there was lack of agreement between the first and second tissue samples with respect to the presence or absence of mesangial IgM. Although mesangial proliferation is a consistent feature of the morphology of certain patients with INS, these studies do not support a unique association with mesangial IgM.

Experimental IgA nephropathy in bile duct ligated rats

Polymeric IgA and polymeric IgA-containing immune complexes are transported from blood to bile through hepatocyte-bound secretory component. In order to investigate interruption of this transport and its effect on the glomerulus, Sprague-Dawley rats underwent bile duct ligation. Renal tissue obtained at the time of sacrifice was stained by immunofluorescent techniques with antibodies to IgG, IgM, and IgA, and secretory component (SC) and C3. A progressive selective increase in the staining intensity of the glomerular mesangium was observed for IgA, C3, and SC in bile duct ligated rats. These changes were paralleled by a rise in serum IgA and C3. These findings are consistent with the view that glomerular deposition of IgA, C3, and SC in bile duct ligated rats may result from impairment of normal handling of polymeric IgA and polymeric IgA-containing immune complexes.