Responses of mitochondrial superoxide dismutase, catalase and glutathione peroxidase activities to aging

The previous observation (Eur. J. Biochem., 82 (1978) 563--567) that age-dependent accumulation of lipid peroxides follows as a consequence of increased radical formation in mitochondria has prompted an examination of the response of a set of protective enzymes to the above situation. Levels of mitochondrial catalase activity as well as selenium-dependent glutathione peroxidase activity were found to be increased with age, while superoxide dismutase activity remained unchanged. No selenium-independent glutathione peroxidase activity could be detected either in preparations from young 3-month-old controls or in preparations from 2-year-old rats. Both the relatively high and unchanged levels of reduced glutathione and kinetic considerations suggest that glutathione peroxidase is preferentially involved in lipid peroxide metabolism, while catalase predominantly metabolizes mitochondrial H2O2.     

Abnormal serum factors in Guillain-Barré syndrome

The Guillain-Barré Syndrome (GBS) is generally considered to be a cell-mediated immunopathologic disease of the peripheral nervous system (PNS), although the evidence for this is indirect. Both in vitro and in vivo studies of sera from experimental animals with autoimmune demyelinating neuropathies suggest that serum factors, including antibodies to PNS myelin and/or Schwann cells, may be important in the pathogenesis of some of these disorders. More recently, similar in vitro and in vivo techniques, including the production of demyelination following intraneural injection in the rat have been employed to study sera from patients with GBS. The results of these studies demonstrate the presence of factor(s), as yet not fully characterized, that may be important in mediating demyelination. Moreover, in some patients with chronic or relapsing demyelinative inflammatory neuropathies and monoclonal gammopathy, there is evidence of antimyelin antibodies to PNS myelin. Further studies of serum from patients with acute GBS and these other neuropathies may clarify the role of serum factors in acquired inflammatory diseases of the PNS.     

An antibody targeting the N-terminal domain of SARS-CoV-2 disrupts the spike trimer

The protective human antibody response to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) focuses on the spike (S) protein, which decorates the virion surface and mediates cell binding and entry. Most SARS-CoV-2 protective antibodies target the receptor-binding domain or a single dominant epitope (“supersite”) on the N-terminal domain (NTD). Using the single B cell technology called linking B cell receptor to antigen specificity through sequencing (LIBRA-Seq), we isolated a large panel of NTD-reactive and SARS-CoV-2–neutralizing antibodies from an individual who had recovered from COVID-19. We found that neutralizing antibodies against the NTD supersite were commonly encoded by the IGHV1-24 gene, forming a genetic cluster representing a public B cell clonotype. However, we also discovered a rare human antibody, COV2-3434, that recognizes a site of vulnerability on the SARS-CoV-2 S protein in the trimer interface (TI) and possesses a distinct class of functional activity. COV2-3434 disrupted the integrity of S protein trimers, inhibited the cell-to-cell spread of the virus in culture, and conferred protection in human angiotensin-converting enzyme 2–transgenic (ACE2-transgenic) mice against the SARS-CoV-2 challenge. This study provides insight into antibody targeting of the S protein TI region, suggesting this region may be a site of virus vulnerability.     

Enhanced inflammatory hyperalgesia after recovery from burn injury

Severe burn induces severe pain. While chronic as well as acute pain syndromes are reported, the peripheral mechanisms of burn-induced chronic pain syndromes have not been studied. We tested the hypothesis that burn induces plastic changes in primary afferent nociceptors that predispose to chronic pain states. Mechanical nociceptive thresholds were measured using the Randall–Selitto paw-withdrawal test in male Sprague-Dawley rats, before and following a small (<1% total body surface area) partial-thickness thermal injury to the dorsal surface of one hind paw. This burn induced mechanical hyperalgesia, which lasted over 2 weeks. After recovery, local injection of prostaglandin E2 (PGE₂), to mimic re-injury, induced an enhanced and markedly prolonged mechanical hyperalgesia compared to the hyperalgesic effect of PGE₂ in the control contralateral paw. This prolonged PGE₂-induced hyperalgesia was reversed by a selective inhibitor of protein kinase C-epsilon (PKC). Our findings suggest PKC as a peripheral mechanism for burn-induced chronic pain syndromes.     

Toward Optimization of Imaging System and Lymphatic Tracer for Near-Infrared Fluorescent Sentinel Lymph Node Mapping in Breast Cancer

Background

Near-infrared (NIR) fluorescent sentinel lymph node (SLN) mapping in breast cancer requires optimized imaging systems and lymphatic tracers.

Materials and Methods

A small, portable version of the FLARE imaging system, termed Mini-FLARE, was developed for capturing color video and two semi-independent channels of NIR fluorescence (700 and 800 nm) in real time. Initial optimization of lymphatic tracer dose was performed using 35-kg Yorkshire pigs and a 6-patient pilot clinical trial. More refined optimization was performed in 24 consecutive breast cancer patients. All patients received the standard of care using ^99mTechnetium-nanocolloid and patent blue. In addition, 1.6 ml of indocyanine green adsorbed to human serum albumin (ICG:HSA) was injected directly after patent blue at the same location. Patients were allocated to 1 of 8 escalating ICG:HSA concentration groups from 50 to 1000 μM.

Results

The Mini-FLARE system was positioned easily in the operating room and could be used up to 13 in. from the patient. Mini-FLARE enabled visualization of lymphatic channels and SLNs in all patients. A total of 35 SLNs (mean = 1.45, range 1–3) were detected: 35 radioactive (100%), 30 blue (86%), and 35 NIR fluorescent (100%). Contrast agent quenching at the injection site and dilution within lymphatic channels were major contributors to signal strength of the SLN. Optimal injection dose of ICG:HSA ranged between 400 and 800 μM. No adverse reactions were observed.

Conclusions

We describe the clinical translation of a new NIR fluorescence imaging system and define the optimal ICG:HSA dose range for SLN mapping in breast cancer.