A New Approach to Study the Physical Stability of Monoclonal Antibody Formulations—Dilution From a Denaturant

The early-stage assessment of the physical stability of new monoclonal antibodies in different formulations is often based on high-throughput techniques that suffer from various drawbacks. Accordingly, new approaches that facilitate the protein formulation development can be of high value to the industry. In this study, a dynamic light scattering plate reader is used to measure the aggregation (by means of the increase in the hydrodynamic radius [R_h]) of monoclonal antibody samples that were subject to incubation and subsequent dilution from different concentrations of a denaturing agent, that is, guanidine hydrochloride. The increase in the R_h of the protein samples is dependent not only on the denaturant concentration used but also on the buffer in which the incubation/dilution was performed. We also compare the aggregation after dilution from a denaturant with other high-throughput stability-indicating methods and find good agreement between the techniques. The proposed approach to probe the physical stability of monoclonal antibodies in different formulation conditions offers a unique combination of features—it is isothermal, probes both the resistance to denaturant-induced unfolding and the colloidal protein stability, it is entirely label-free, does not rely on complex data evaluation, and requires very short instrument measurement time on standard equipment.     

Germ-free housing conditions do not affect aortic root and aortic arch lesion size of late atherosclerotic low-density lipoprotein receptor-deficient mice

ABSTRACT

The microbiota has been linked to the development of atherosclerosis, but the functional impact of these resident bacteria on the lesion size and cellular composition of atherosclerotic plaques in the aorta has never been experimentally addressed with the germ-free low-density lipoprotein receptor-deficient (Ldlr^?/- ) mouse atherosclerosis model. Here, we report that 16 weeks of high-fat diet (HFD) feeding of hypercholesterolemic Ldlr^?/- mice at germ-free (GF) housing conditions did not impact relative aortic root plaque size, macrophage content, and necrotic core area. Likewise, we did not find changes in the relative aortic arch lesion size. However, late atherosclerotic GF Ldlr^?/- mice had altered inflammatory plasma protein markers and reduced smooth muscle cell content in their atherosclerotic root plaques relative to CONV-R Ldlr^?/- mice. Neither absolute nor relative aortic root or aortic arch plaque size correlated with age. Our analyses on GF Ldlr^?/- mice did not reveal a significant contribution of the microbiota in late aortic atherosclerosis.     

Mechanical Properties of the Human Tibial and Peroneal Nerves Following Stretch With Histological Correlations

Despite the extensive literature regarding peripheral nerve stretch injuries, there are few studies that compare the nerve histology with the mechanical properties in humans. There is clinical evidence suggesting that the peroneal nerve is at greater risk for injury compared to the tibial nerve following total hip arthroplasty and hip trauma. We examined the two nerves from fresh human cadavers with or without controlled stretch. The mechanical properties, stiffness, and strain were compared with light microscopic preparations in longitudinal sections stained by the trichrome method for collagen and showing the effects of structural deformation. The tibial nerve had an average failure load 1.7× that for the peroneal nerve (P = 0.0001). Although the corresponding average stiffness showed a trend toward being larger (4.39 vs. 3.81 N/mm), the difference was not significant (P = 0.126). Histologically, the perineurium along with the underlying nerve fascicle was undulated in the control specimens and straightened out in the stretched specimens. Peroneal nerves went on to failure at lower loads and exhibited a wavy pattern on pathologic slides after failure, which shows that peroneal nerves fail mechanically before they can unfold. The tibial nerve has a biomechanical and histological advantage compared to the peroneal nerve during tensile testing, which could be the reason why it is less commonly damaged. We conclude that the perineurium is especially protective against deformation changes in human nerves relative to the respective nerve size and number of fascicles. Anat Rec, 302:2030–2039, 2019. © 2019 American Association for Anatomy     

Revision total hip arthroplasty in the United States: national trends and in-hospital outcomes

Purpose

With the increasing number of primary total hip arthroplasties (THA) being performed, the frequency of revision surgery is also expected to increase. We analysed the immediate in-hospital complications and epidemiologic data of 3,469 revision and 18,186 primary THA cases.

Methods

The National Hospital Discharge Survey (NHDS) was evaluated between 2001 and 2010 for patients who underwent revision and primary THA. Patients were identified and included in our retrospective study based on ICD-9 procedure codes.

Results

The number of primary and revision THAs increased steadily from 2001 to 2010. The revision burden decreased for the same studied period (r?=?–0.92) to reach 13.9 % in 2010. The South region had higher revision burden of 17.4 % (p?<?0.001). The primary THA group was more likely to be obese, morbidly obese, and have hypertension (p?<?0.001). The revision THA group had an increased rate of blood transfusions (p?<?0.001), deep venous thrombosis (p?=?0.008), post-operative sepsis (p?<?0.001), and wound complications (p?<?0.001). The in-hospital mortality rate was also higher for the revision THA group (0.6 % versus 0.2 %, p?<?0.001).

Conclusions

The revision burden has undergone a steady decrease over the ten years studied and the reason for this is likely multifactorial. The South region had a significantly higher revision burden when compared to the rest of the United States. Larger hospitals tend to perform relatively more revisions. Revision THA patients are associated with longer hospital stay, higher complications rate, and higher in-hospital mortality rate.

     

Modified Lapidus arthrodesis with plantar plate and compression screw for treatment of hallux valgus with hypermobility of the first ray: A preliminary report

BackgroundTMT-1 arthrodesis is an established method in hallux valgus surgery, but it is technically demanding and typically calls for a period of postoperative immobilization.MethodsIn this cohort study, initial experience with a plantar plate is described. 58 patients (59 arthrodesis) were included.ResultsThe mean duration of protected full weight bearing was 7 weeks. 94.12% patients were satisfied with the results, bony union was achieved in 98.31%. The Foot Function Index improved by 33 to a mean of 8 (p < .001). The postoperative Mayo Clinic Forefoot Score was excellent in 47.04 and good in 47.04%. The mean hallux valgus angle improved by 24.4–13.2° (p < .001). The mean first intermetatarsal angle improved by 11.2–5.2° (p < .001).ConclusionInitial experience with this form of fixation appears to provide suitable stability, allow early-protected weight bearing, with an acceptable level of complications.     

Clinical Doppler ultrasound for the assessment of plaque ulceration in the stenosed carotid bifurcation by detection of distal turbulence intensity: a matched model study

The assessment of flow disturbances due to carotid plaque ulceration may provide added diagnostic information to Doppler ultrasound (DUS) of the carotid stenosis, and indicate whether the associated hemodynamics are a potential thromboembolic source. We evaluated the effect of ulceration in a moderately stenosed carotid bifurcation on distal turbulence intensity (TI) measured using clinical DUS in matched anthropomorphic models. Several physiologically relevant ulcer geometries (hemispherical, mushroom-shaped, and ellipsoidal pointing distally and proximally) and sizes (2-mm, 3-mm and 4-mm diameter hemispheres) were investigated. An offline analysis was performed to determine several velocity-based parameters from ensemble-averaged spectral data, including TI. Significant elevations in TI were observed in the post-stenotic flow field of the stenosed carotid bifurcation by the inclusion of ulceration (P < 0.001) in a region two common carotid artery diameters distal to the site of ulceration during the systolic peak and the diastolic phase of the cardiac cycle. Both the size and shape of ulceration had a significant effect on TI in the distal region (P < 0.001). Due to the use of a clinical system, this method provides the means to evaluate for plaque ulcerations in patients with carotid atherosclerosis using DUS.