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Introduction: Postoperative imaging after neurosurgical interventions is usually performed in the first 72 hours after surgery to provide an accurate assessment of postoperative resection status. Patient frequently report that early postoperative examination after craniotomy for tumour and vascular procedures is associated with distress, exertion, nausea and pain. Delayed postoperative imaging (between 36 and 72 hours postoperatively) may have an advantage regarding psychological and physical stress compared with early imaging. The goal of this study is to evaluate and determine the optimal time frame for postoperative imaging with MRI and CT in terms of medical and neuroradiological implications and patient's subjective stress level., Methods and Analysis: Data will be prospectively collected from all patients aged 18-80 years who receive postoperative MRI or CT imaging following a craniotomy for resection of a cerebral tumour (benign and malignant) or vascular surgery. Participants have to complete questionnaires containing visual analogue scores (VAS) for headache and nausea, Body Part Discomfort score and a single question addressing subjective preference of timing of postoperative imaging after craniotomy. The primary endpoint of the study is the difference in subjective stress due to imaging studies after craniotomy, measured just before and after postoperative MRI or CT with the above-mentioned instruments. Subjective stress is defined as a combination of the scores VAS pain, VAS nausea and 0.5* Body Part Discomfort core.This study determines whether proper timing of postoperative imaging can improve patient satisfaction and reduce pain, stress and discomfort caused by postoperative imaging. Factors causing additional postoperative stress are likely responsible for delayed recovery of neurosurgical patients., Ethics and Dissemination: The institutional review board (Kantonale Ethikkommission Zürich) approved this study on 4 August 2020 under case number BASEC 2020-01590. The authors are planning to publish the data of this study in a peer-reviewed paper. After database closure, the data will be exported to the local data repository (Zurich Open Repository and Archive) of the University of Zurich. The sponsor (LR) and the project leader (MR.G) will make the final decision on the publication of the results. The data that support the findings of this study are available on request from the corresponding author LT. The data are not publicly available due to privacy/ethical restrictions., Trial Registration Number: NCT05112575; ClinicalTrials.gov., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2022. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Introduction: The integration of sex-related differences in neurosurgery is crucial for new, possible sex-specific, therapeutic approaches. In neurosurgical emergencies, such as traumatic brain injury and aneurysmal subarachnoid hemorrhage, these differences have been investigated. So far, little is known concerning the impact of sex on frequency of postoperative complications after elective craniotomy. This study investigates whether sex-related differences exist in frequency of postoperative complications in patients who underwent elective craniotomy for intracranial lesion., Material and Methods: All consecutive patients who underwent an elective intracranial procedure over a 2-year period at our center were eligible for inclusion in this retrospective study. Demographic data, comorbidities, frequency of postoperative complications at 24 hours following surgery and at discharge, and hospital length of stay were compared among females and males., Results: Overall, 664 patients were considered for the analysis. Of those, 339 (50.2%) were females. Demographic data were comparable among females and males. More females than males suffered from allergic, muscular, and rheumatic disorders. No differences in frequency of postoperative complications at 24 hours after surgery and at discharge were observed among females and males. Similarly, the hospital length of stay was comparable., Conclusions: In the present study, no sex-related differences in frequency of early postoperative complications and at discharge following elective craniotomy for intracranial lesions were observed., Competing Interests: The authors have no conflicts of interest to disclose., (Copyright © 2022 the Author(s). Published by Wolters Kluwer Health, Inc.)

Objective: Several microsurgical techniques are available for the decompression of lumbar spinal stenosis (LSS). More recently, a spinous process-splitting laminectomy (SPSL) technique was introduced, with the premise of diminishing paraspinal muscle damage. This study aims to compare the neurologic and functional outcomes, as well as the differences in early postoperative pain and analgesic use during hospitalization after conventional decompression (CD) versus SPSL surgery for LSS., Methods: Single-center retrospective analysis of all spinal decompression procedures (CD or SPSL) that were performed or supervised by one consulting spine surgeon, performed for LSS between 2015 and 2020. Preoperative neurologic symptoms, functional outcomes, as well as perioperative analgesic use and reported pain scales during hospitalization were analyzed., Results: From a total of 106 patients, 58 were treated using CD and 48 using SPSL. In both groups, around one-third of the patients were taking opiates preoperatively (38% for CD, 31% for SPSL). Patients submitted to SPSL reported more pain on first postoperative day but significantly less pain in the further postoperative course (day 3 numeric rating scale [NRS] 2.4 vs. 3.4, P = 0.03 and on day 5 NRS 2.5 vs. 3.7, P = 0.009). Equal or less cumulative doses of analgesics were administered postoperatively (significantly less paracetamol on day 5 compared with CD; P = 0.013). Both groups showed a similarly favorable outcome in terms of improved mobility and there were no significant differences between complications and re-stenosis rates between both techniques., Conclusions: Patients treated with SPSL technique for LSS showed an equivalent favorable functional outcome compared to CD. However, SPSL patients showed significantly less subacute postoperative pain while using equal amounts or fewer analgesics postoperatively., (Copyright © 2021 The Author(s). Published by Elsevier Inc. All rights reserved.)

A nuclear protein of testis (NUT) carcinoma, also known as NUT midline carcinoma, is a rare subtype of squamous carcinoma known for its aggressive growth behaviour. It can form anywhere in the body. Although, it usually occurs along midline structures (head, neck, lungs). The authors present the first report of intrasellar NUT carcinoma with cavernous sinus infiltration in a 47-year-old patient. MRI showed an inhomogeneous, gadolinium-enhancing lesion with intra- and suprasellar growth, invasion of the cavernous sinus without clear differentiation from normal pituitary tissue. Given the lymphoma diagnosis in the frozen section and invasion of the cavernous sinus, the patient underwent endoscopic, transnasal, and transsphenoidal subtotal resection only. Local tumour and spinal metastases showed a good response to radio-chemotherapy. Despite combined radio-chemotherapy, the patient died of pulmonary insufficiency due to rapid progression of pulmonary metastasis 6 months after the initial diagnosis., (© 2021. The Author(s), under exclusive licence to Springer-Verlag GmbH Austria, part of Springer Nature.)

Introduction: Ever since the beginning of cerebral bypass surgery, the role of the bypass has been debated and indications have changed over the last 5 decades. This systematic literature research analysed all clinical studies on cerebral bypass that have been published from January 1959 to January 2020 for their year of publication, country of origin, citation index, role of and indication for bypass, bypass technique, revascularized territory, flow capacity, and title (for word cloud analysis per decade)., Methods: A systematic literature research was conducted using PubMed, Web of Science, EMBASE, and SCOPUS databases. All studies that have been published until January 1, 2020, were included., Results: Of 6,013 identified studies, 2,585 were included in the analysis. Of these, n = 1,734 (67%) studies addressed flow-augmentation bypass and n = 701 (27%) addressed flow-preservation bypass. The most common indication reported for flow augmentation is moyamoya (n = 877, 51%), followed by atherosclerotic steno-occlusive disease (n = 753, 43%). For flow preservation, the most common indication is studies reporting on cerebral aneurysm surgery (n = 659, 94%). The increasing popularity of reporting on these bypass operations almost came to an end with the FDA approval of flow diverters for aneurysm treatment in 2011. Japan is the country with the most bypass studies (cumulatively published 933 articles), followed by the USA (630 articles) and China (232 articles)., Discussion/conclusion: Clinical studies on cerebral bypass surgery have become increasingly popular in the past decades. Since the introduction of moyamoya as a distinct pathologic entity, Asian countries in particular have a very active community regarding this disease, with an increasing number of articles published every year. Studies on bypass for chronic steno-occlusive disease peaked in the 1980s but have remained the main focus of bypass research, particularly in many European departments. The number of reports published on these bypass operations significantly decreased after the FDA approval of flow diverters for aneurysm treatment in 2011., (© 2021 The Author(s) Published by S. Karger AG, Basel.)

Background: The literature on white matter anatomy underlying the human orbitofrontal cortex (OFC) is scarce in spite of its relevance for glioma surgery., Objective: To describe the anatomy of the OFC and of the underlying white matter fiber anatomy, with a particular focus on the surgical structures relevant for a safe and efficient orbitofrontal glioma resection. Based on anatomical and radiological data, the secondary objective was to describe the growth pattern of OFC gliomas., Methods: The study was performed on 10 brain specimens prepared according to Klingler's protocol and dissected using the fiber microdissection technique modified according to U.T., under the microscope at high magnification., Results: A detailed stratigraphy of the OFC was performed, from the cortex up to the frontal horn of the lateral ventricle. The interposed neural structures are described together with relevant neighboring topographic areas and nuclei. Combining anatomical and radiological data, it appears that the anatomical boundaries delimiting and guiding the macroscopical growth of OFC gliomas are as follows: the corpus callosum superiorly, the external capsule laterally, the basal forebrain and lentiform nucleus posteriorly, and the gyrus rectus medially. Thus, OFC gliomas seem to grow ventriculopetally, avoiding the laterally located neocortex., Conclusion: The findings in our study supplement available anatomical knowledge of the OFC, providing reliable landmarks for a precise topographical diagnosis of OFC lesions and for perioperative orientation. The relationships between deep anatomic structures and glioma formations described in this study are relevant for surgery in this highly interconnected area., (© Congress of Neurological Surgeons 2021.)

Intraoperatively acquired diffusion-weighted imaging (DWI) sequences in cranial tumor surgery are used for early detection of ischemic brain injuries, which could result in impaired neurological outcome and their presence might thus influence the neurosurgeon's decision on further resection. The phenomenon of false-negative DWI findings in intraoperative magnetic resonance imaging (ioMRI) has only been reported in single cases and therefore yet needs to be further analyzed. This retrospective single-center study's objective was the identification and characterization of false-negative DWI findings in ioMRI with new or enlarged ischemic areas on postoperative MRI (poMRI). Out of 225 cranial tumor surgeries with intraoperative DWI sequences, 16 cases with no additional resection after ioMRI and available in-time poMRI (< 14 days) were identified. Of these, a total of 12 cases showed false-negative DWI in ioMRI (75%). The most frequent tumor types were oligodendrogliomas and glioblastomas (4 each). In 5/12 cases (41.7%), an ischemic area was already present in ioMRI, however, volumetrically increased in poMRI (mean infarct growth + 2.1 cm 3 ; 0.48-3.6), whereas 7 cases (58.3%) harbored totally new infarcts on poMRI (mean infarct volume 0.77 cm 3 ; 0.05-1.93). With this study we provide the most comprehensive series of false-negative DWI findings in ioMRI that were not followed by additional resection. Our study underlines the limitations of intraoperative DWI sequences for the detection and size-estimation of hyperacute infarction. The awareness of this phenomenon is crucial for any neurosurgeon utilizing ioMRI., (© 2021. The Author(s).)

Intraoperative MRI (ioMRI) has become a frequently used tool to improve maximum safe resection in brain tumor surgery. The usability of intraoperatively acquired diffusion-weighted imaging sequences to predict the extent and clinical relevance of new infarcts has not yet been studied. Furthermore, the question of whether more aggressive surgery after ioMRI leads to more or larger infarcts is of crucial interest for the surgeons' operative strategy. Retrospective single-center analysis of a prospective registry of procedures from 2013 to 2019 with ioMRI was used. Infarct volumes in ioMRI/poMRI, lesion localization, mRS, and NIHSS were analyzed for each case. A total of 177 individual operations (60% male, mean age 45.5 years old) met the inclusion criteria. In 61% of the procedures, additional resection was performed after ioMRI, which resulted in a significantly higher number of new ischemic lesions postoperatively (p < .001). The development of new or enlarged ischemic areas upon additional resection could also be shown volumetrically (mean volume in ioMRI 0.39 cm 3 vs. poMRI 2.97 cm 3 ; p < .001). Despite the surgically induced new infarcts, mRS and NIHSS did not worsen significantly in cases with additional resection. Additionally, new perilesional ischemia in eloquently located tumors was not associated with an impaired neurological outcome. Additional resection after ioMRI leads to new or enlarged ischemic areas. However, these new infarcts do not necessarily result in an impaired neurological outcome, even when in eloquent brain areas., (© 2020. The Author(s).)

Objective: For currently available augmented reality workflows, 3D models need to be created with manual or semiautomatic segmentation, which is a time-consuming process. The authors created an automatic segmentation algorithm that generates 3D models of skin, brain, ventricles, and contrast-enhancing tumor from a single T1-weighted MR sequence and embedded this model into an automatic workflow for 3D evaluation of anatomical structures with augmented reality in a cloud environment. In this study, the authors validate the accuracy and efficiency of this automatic segmentation algorithm for brain tumors and compared it with a manually segmented ground truth set., Methods: Fifty contrast-enhanced T1-weighted sequences of patients with contrast-enhancing lesions measuring at least 5 cm3 were included. All slices of the ground truth set were manually segmented. The same scans were subsequently run in the cloud environment for automatic segmentation. Segmentation times were recorded. The accuracy of the algorithm was compared with that of manual segmentation and evaluated in terms of Sørensen-Dice similarity coefficient (DSC), average symmetric surface distance (ASSD), and 95th percentile of Hausdorff distance (HD95)., Results: The mean ± SD computation time of the automatic segmentation algorithm was 753 ± 128 seconds. The mean ± SD DSC was 0.868 ± 0.07, ASSD was 1.31 ± 0.63 mm, and HD95 was 4.80 ± 3.18 mm. Meningioma (mean 0.89 and median 0.92) showed greater DSC than metastasis (mean 0.84 and median 0.85). Automatic segmentation had greater accuracy for measuring DSC (mean 0.86 and median 0.87) and HD95 (mean 3.62 mm and median 3.11 mm) of supratentorial metastasis than those of infratentorial metastasis (mean 0.82 and median 0.81 for DSC; mean 5.26 mm and median 4.72 mm for HD95)., Conclusions: The automatic cloud-based segmentation algorithm is reliable, accurate, and fast enough to aid neurosurgeons in everyday clinical practice by providing 3D augmented reality visualization of contrast-enhancing intracranial lesions measuring at least 5 cm3. The next steps involve incorporation of other sequences and improving accuracy with 3D fine-tuning in order to expand the scope of augmented reality workflow.

Electrolyte disorders are relatively frequent and potentially serious complications after pituitary surgery. Both DI (diabetes insipidus) and SIADH (syndrome of inappropriate antidiuresis) can complicate and prolong hospital and intensive care unit stay, and the latter may even be preventable. We aim to assess the incidence of both electrolyte disorders and their risk factors. From a prospective registry of patients who underwent endoscopic transnasal transsphenoidal surgery (TSS) for pituitary adenoma, patients with postoperative DI and SIADH were identified. Univariable and multivariable statistics were carried out to identify factors independently associated with the occurrence of either DI or SIADH. A total of 174 patients were included, of which 73 (42%) were female. Mean age was 54 years (range 20-88). During postoperative hospital stay, 13 (7.5%) patients presenting with DI and 11 (6.3%) with SIADH were identified. Patients who developed DI after surgery had significantly longer hospital stays (p = 0.022), as did those who developed SIADH (p = 0.002). Four (2.3%) patients were discharged with a diagnosis of persistent DI, and 2 (1.1%) with the diagnosis of SIADH. At the last follow-up, 5 (2.9%) patients presented with persistent DI, while none of the patients suffered from SIADH. Younger age (odds ratio (OR) 0.97, 95% confidence interval (CI) 0.94-1.01, p = 0.166) and pituitary apoplexy (OR 2.69, 95% CI 0.53-10.65, p = 0.184) were weakly associated with the occurrence of DI. We identified younger age (OR 0.96, 95% CI 0.92-0.99, p = 0.045) and lower preoperative serum sodium (OR 0.83, 95% CI 0.71-0.95, p = 0.008) as independent risk factors for SIADH. Although we found a weak association among age, pituitary apoplexy, and the occurrence of DI, no independent predictor was identified for DI. For postoperative SIADH however, lower age and preoperative serum sodium were identified as significant predictors. None of these findings were sufficiently supported by preexisting literature. Both electrolyte disorders are exquisitely hard to predict preoperatively, and further research into their early detection and prevention is warranted.

Acute Traumatic Central Cord Syndrome: Etiology, Pathophysiology, Clinical Manifestation, and Treatment Abstract. The acute traumatic central cord syndrome (ATCCS) represents an injury to the spinal cord with disproportionately greater motor impairment of the upper than the lower extremities, with bladder dysfunction and with varying degrees of sensory loss below the level of the respective lesion. The mechanism of ATCCS is most commonly a traumatic hyperextension injury of the cervical spine at the base of an underlying spondylosis and spinal stenosis. The mean age is 53 years, and segments C4 to Th1 are most frequently affected. In addition to medical history and clinical examination, the definitive diagnosis is made by magnetic resonance imaging, where T2-hyperintense lesions are typically observed in the affected spinal cord segment. Surgical decompression (and fusion) of the respective segment is recommended to prevent repetitive trauma to the spinal cord and to stop progression of clinical symptoms. Patients with diagnosed ATCCS and who are treated adequately usually have a good prognosis.

Objective: The 6-minute walking test (6WT) is used to determine restrictions in a subject's 6-minute walking distance (6WD) due to lumbar degenerative disc disease. To facilitate simple and convenient patient self-measurement, a free and reliable smartphone app using Global Positioning System coordinates was previously designed. The authors aimed to determine normative values for app-based 6WD measurements., Methods: The maximum 6WD was determined three times using app-based measurement in a sample of 330 volunteers without previous spine surgery or current spine-related disability, recruited at 8 centers in 5 countries (mean subject age 44.2 years, range 16-91 years; 48.5% male; mean BMI 24.6 kg/m2, range 16.3-40.2 kg/m2; 67.9% working; 14.2% smokers). Subjects provided basic demographic information, including comorbidities and patient-reported outcome measures (PROMs): visual analog scale (VAS) for both low-back and lower-extremity pain, Core Outcome Measures Index (COMI), Zurich Claudication Questionnaire (ZCQ), and subjective walking distance and duration. The authors determined the test-retest reliability across three measurements (intraclass correlation coefficient [ICC], standard error of measurement [SEM], and mean 6WD [95% CI]) stratified for age and sex, and content validity (linear regression coefficients) between 6WD and PROMs., Results: The ICC for repeated app-based 6WD measurements was 0.89 (95% CI 0.87-0.91, p < 0.001) and the SEM was 34 meters. The overall mean 6WD was 585.9 meters (95% CI 574.7-597.0 meters), with significant differences across age categories (p < 0.001). The 6WD was on average about 32 meters less in females (570.5 vs 602.2 meters, p = 0.005). There were linear correlations between average 6WD and VAS back pain, VAS leg pain, COMI Back and COMI subscores of pain intensity and disability, ZCQ symptom severity, ZCQ physical function, and ZCQ pain and neuroischemic symptoms subscores, as well as with subjective walking distance and duration, indicating that subjects with higher pain, higher disability, and lower subjective walking capacity had significantly lower 6WD (all p < 0.001)., Conclusions: This study provides normative data for app-based 6WD measurements in a multicenter sample from 8 institutions and 5 countries. These values can now be used as reference to compare 6WT results and quantify objective functional impairment in patients with degenerative diseases of the spine using z-scores. The authors found a good to excellent test-retest reliability of the 6WT app, a low area of uncertainty, and high content validity of the average 6WD with commonly used PROMs.

Aims:  To evaluate the clinical and radiologic results of patients treated with dorsal cervical C1-C2 fusion using C1 lateral mass screws, C2 lamina screws, and interarcual bone graft., Methods:  We retrospectively analyzed the clinical and radiologic results of eight patients treated from 2011 to 2016. Neck pain, neurologic deficits, use of analgesics, vertebral artery injury, C2 root injury, radiologic fusion rate, malposition of screws, and implant failure were examined on day 3 and at 3 and 12 months postoperatively., Results:  One patient required revision surgery for a right-sided medial cutout of a lamina screw. None of the patients had vascular or neurologic complications. All patients were pain free and had ceased all analgesic therapy at the first follow-up examination. At the 1-year follow-up there were no complaints of neck pain, no radiologic signs of implant failure were found, and a bony union between C1 and C2 was present in all patients., Conclusion:  Dorsal cervical C1-C2 fusion using C1 lateral mass screws, C2 lamina screws, and interarcual bone graft are less common techniques, although they can be used safely and demonstrated excellent clinical results with regard to pain relief and a high fusion rate. The technique is an ideal alternative when other techniques are not safe for anatomical reasons., Competing Interests: None., (Georg Thieme Verlag KG Stuttgart · New York.)

Background:  Spinal stenosis is frequently caused by spondylolisthesis, and surgical treatment may be indicated. However, whether decompression alone or decompression with dynamic stabilization offers better surgical outcomes remains unclear. We compared the clinical and radiologic results of patients with single-level lumbar spinal stenosis and grade 1 spondylolisthesis undergoing microsurgical decompression alone or decompression with transpedicular dorsal dynamic stabilization., Methods:  We retrospectively analyzed 20 patients undergoing microsurgical decompression and dorsal dynamic transpedicular stabilization using polyetheretherketone (PEEK) rods in one center from 2011 to 2017. Twenty patients with the same diagnosis undergoing microsurgical decompression alone were used as controls. Reoperation of the index and neighboring segments, back/leg pain, neurologic deficits, and the use of pain medication were assessed. For stabilization patients, radiographic progression of degeneration in the neighboring segments, listhesis degree in the index segment, and implant failure were assessed., Results:  All patients had good clinical outcomes at 3 and 12 months postoperatively. In stabilization patients, the visual analog scale (VAS) score for leg pain decreased from 5 points (median) to 1.6 at 3 months and 0.6 at 1 year postoperatively. In controls, the VAS score improved from 4.8 points to 1.1 at 3 months and 0.3 at 1 year postoperatively. The VAS score for back pain in stabilization patients decreased from 7.6 points (median) to 1.7 at 3 months and 0.1 at 1 year postoperatively. In controls, it decreased from 7.7 points to 1.1 at 3 months and 0.2 at 1 year postoperatively. In patients with additional dynamic stabilization, a longer hospital stay (stabilization group: 8.7 ± 4.1; control: 6.2 ± 1.6 days), longer operative time (stabilization group: 132.7 ± 41.3; control: 83.2 ± 31.7 minutes), and higher complication rates (revision surgery performed in two stabilization patients) were found., Conclusion:  No indications in our study showed that additional dynamic stabilization with PEEK rods offers any advantage over decompression alone., Competing Interests: None declared., (Georg Thieme Verlag KG Stuttgart · New York.)

Solitary fibrous tumors (SFTs) are rare mesenchymal neoplasms commonly involving visceral or parietal pleura. We present the first report of tumor-to-tumor metastasis involving a pulmonary adenocarcinoma donor and an intradural SFT recipient. The patient presented with a 1 year history of diffuse back pain. A spinal intradural contrast-enhancing mass at the T9/10 level and a tumor of the lung were diagnosed radiologically. Bronchoscopic biopsy confirmed pulmonary adenocarcinoma in the right upper lung lobe. Due to deteriorating neurological status with conus medullaris syndrome, we performed a neurosurgical excision of the lesion. Histological analysis of the tumor revealed tumor-to-tumor metastasis of the adenocarcinoma to the SFT.

Background: Although an abundance of literature about the treatment of chronic subdural hematoma is available, it provides little evidence to clarify which treatment is most successful., Objective: The aim of this study was to examine and compare current clinical standards between several hospitals., Methods: Chairmen of all neurosurgical units in Austria, Germany, and Switzerland, as listed on the national neurosurgical societies' websites, were invited to participate with a personal token to access a web-based survey. A total of 159 invitations were sent and up to 5 reminder e-mails., Results: Eighty-four invitees (53%) completed the survey. The most common surgical intervention was a single burr hole in 52 (65%) of the responding neurosurgical units, double burr holes were performed as primary procedure in 16 centers (20%), a small osteoplastic craniotomy in 4 (5%), and a twist drill craniostomy in 8 (10%). Seventy-two (90%) would place a drain in estimated 75%-100% of cases or whenever possible/safe. Sixty-five used subdural-external drains, and 7 used subgaleal-external drains. Seventeen applied suction to the drains. Thirty-six (49%) agreed with the statement that watchful waiting was an option for the treatment of chronic subdural hematomas and 19 (23.4%) disagreed. Eighteen (23%) would consider corticosteroids and 34 (45%) tranexamic acid as part of their armamentarium for the treatment of subdural hematomas., Conclusions: The results of this survey reflect the current evidence available in literature. Although the benefits of using of a drain are widely recognized, no consensus regarding the type of drain and surgical approach to the hematoma was reached., (Copyright © 2018 Elsevier Inc. All rights reserved.)

An unusual triclonal IgG combination in the serum of a 56-year old male with clinical stage IIIB multiple myeloma is reported. The patient initially had an IgG4(lambda) monoclonal protein in his serum and later developed an IgG2(kappa) and an IgG (kappa) which possessed the characteristics of both IgG1 and IgG3 subclasses with an unusual combination of allotypic markers. Three M-proteins did not share idiotypic determinants. A rare class-switch recombination followed by mutation has been considered as a possible mechanism leading to this combination.

In this paper, the relation between anti-albumin antibodies and HBeAg/anti-HBe in patients with viral hepatitis B was studied. It was shown that anti-albumin antibodies occur more frequently in HBeAg-positive patients (48.1%) than in anti-HBe-positive patients (20.0%). In sera that contained anti-albumin antibodies it was found that HBeAg was positive in 60.5%, but only in 25.7% of sera which did not contain anti-albumin antibodies. The results were discussed from the point of view of a possible protective role of anti-albumin antibodies.

We have prepared and characterized four monoclonal antibodies (MAbs) to human C3b of high specificity and affinity. Our procedure did not require a purified source of C3b for immunization. Instead, C3b and C3bi were deposited on Sepharose 4B via the alternative pathway of complement activation in normal human serum, and this C3b(i)-Sepharose served as the immunogen. C3b(i)-Sepharose was also prepared from a number of primate and non-primate sources, and this allowed us to demonstrate that the anti-human C3b MAbs cross-reacted with primate-derived C3b, but not with C3b from non-primates. The procedures we have developed may be useful in the further investigation of species-specific C3 fragment-binding proteins from both primate and non-primate sources.

We have examined in mice the immune adherence (IA) reactivity and the fate (clearance kinetics and organ distribution) of a variety of preformed and nascent soluble antibody/125I-DNA immune complexes prepared at antibody excess. Parallel studies of the clearance kinetics and organ deposition of free DNA were also conducted. Preformed immune complexes prepared with large dsDNA bound to mouse platelets in vivo and exhibited clearance kinetics in general agreement with our previous observations in rabbits. Very little kidney deposition was evident for these immune complexes, but three to four times as many counts were found in the kidneys when free DNA was injected. Nascent immune complexes did form in the circulation, but in contradistinction to our previous studies of nascent immune complexes in rabbits and rhesus monkeys, these immune complexes did not demonstrate IA and had clearance kinetics and organ distributions intermediate between the preformed immune complexes and free DNA. Thus, complement-fixing antibody/DNA immune complexes that could form in the circulation might be cleared both via immune complex recognition mechanisms and via DNA recognition mechanisms. The role of IA in modulating the organ deposition of complement-fixing immune complexes is also discussed.