Post-translational transport into intact chloroplasts of a precursor to the small subunit of ribulose-1,5-bisphosphate carboxylase

A precursor to the small subunit of ribulose-1,5-bisphosphate carboxylase [3-phospho-D-glycerate carboxylyase (dimerizing), EC 4.1.1.39] has been identified among the products of cell-free translation of polyadenylated RNA from spinach and pea. In both cases, the precursor is larger than the mature protein by 4000-5000 daltons. Upon incubation of post-ribosomal supernatants of the in vitro protein synthesis mixtures with purified intact chloroplasts, the pea and spinach precursors are transported interchangeably into the chloroplasts and processed to the mature size and charge. Moreover, the newly transported small subunits are found to assemble with endogenous large subunits to form the holoenzyme. In contrast, a precursor to the Chlamydomonas reinhardtii small subunit is not taken up by higher plant chloroplasts, indicating the specificity of the transport events. Together, these results demonstrate that the in vitro reconstruction of the post-translational transport of the higher plant precursors is physiologically significant.     

A rapid procedure for selective enrichment of photosynthetic electron transport mutants.

Metronidazole (2-methyl-5-nitroimidazole-l-ethanol) is shown to be effective for the selective enrichment of mutants of Chlamydomonas reinhardtii that posses impaired photosynthetic electron transport. More than 99.9% of wild-type cells are killed when incubated in the presence of 6-10 mM metronidazole for 24 hr under illumination of 7500 lux. Survival of wild-type cells in darkness and of mutants that are blocked at different steps in photosynthetic electron transport is nearly 100% when incubated in the presence of the drug under identical conditions. The toxicity of metronidazole is demonstrated to depend upon its reduction by photosynthetic electron transport. Light-dependent oxygen uptake mediated by metronidazole is shown to require active photosystem l in vitro and in vivo. Ferredoxin is necessary for metronidazole reduction by thylakoid membrane fractions enriched in photosystem l activity. We propose that the toxicity of metronidazole is due to the formation of lethal derivatives of the drug or to the accumulation of hydrogen peroxide, which could occur upon autooxidation of metronidazole reduced by one electron. The results indicate that mutants of C. reinhardtii, and probably other photosynthetic organisms, with any lesion in photosynthetic electron transport from the oxidizing side of photosystem ll to ferredoxin can be isolated by metronidazole treatment of mutagenized cultures.     

Orbital Fracture in a Professional Diver: Issues and Management

Background

We present a case report of a professional diver who sustained a fracture of the left orbital medial wall as well as floor exceeding 50% with orbital fat herniation blocking the maxillary sinus ostium. This may result in a closed cavity within the maxillary sinus that could potentially result in barotraumas during future diving. The aim of his surgery consists of repairing the orbital fracture and to aerating the sinus at the same sitting.

Method

A transconjunctival approach was used combined with endoscopic sinus surgery approach to the maxillary sinus. The orbital floor fracture was repaired with a titanium plate. A wide middle meatal antrostomy was performed. A size eight Foley’s catheter was inserted into the maxillary sinus and the balloon inflated to elevate and support the displaced inferior orbital floor bone fragment. The balloon was left in situ for 4 weeks to support the mobile inferior orbital fragment till adequate bone healing and stability.

Results

Patient recovered well. At 3 months post-operatively, the maxillary antrostomy remained patent, and a hyperbaric oxygen challenge test was performed with success. A repeat orbital CT scan 1 day after hyperbaric challenge showed no signs of air leakage, and the bony inferior orbital floor fracture has healed completely with the titanium plate in situ.

Conclusion

This is the first case report of repair of orbital floor fracture with simultaneous aeration of the maxillary sinus in a professional diver using a combined approach. The patient was able to resume his occupation as a professional diver following surgery.

     

Design,Development, and Evaluation of a Novel Microneedle Array-based Continuous Glucose Monitor

The development of accurate, minimally invasive continuous glucose monitoring (CGM) devices has been the subject of much work by several groups, as it is believed that a less invasive and more user-friendly device will result in greater adoption of CGM by persons with insulin-dependent diabetes. This article presents the results of preliminary clinical studies in subjects with diabetes of a novel prototype microneedle-based continuous glucose monitor. In this device, an array of tiny hollow microneedles is applied into the epidermis from where glucose in interstitial fluid (ISF) is transported via passive diffusion to an amperometric glucose sensor external to the body. Comparison of 1396 paired device glucose measurements and fingerstick blood glucose readings for up to 72-hour wear in 10 diabetic subjects shows the device to be accurate and well tolerated by the subjects. Overall mean absolute relative difference (MARD) is 15% with 98.4% of paired points in the A+B region of the Clarke error grid. The prototype device has demonstrated clinically accurate glucose readings over 72 hours, the first time a microneedle-based device has achieved such performance.     

Admission hyperglycemia predicts poorer short‐ and long‐term outcomes after primary percutaneous coronary intervention for ST‐elevation myocardial infarction

Aims/Introduction

Admission hyperglycemia is associated with poor outcome in patients with myocardial infarction. The present study evaluated the relationship between admission glucose level and other clinical variables in patients with ST‐elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention (PCI).

Materials and Methods

The 959 consecutive STEMI patients undergoing primary PCI were divided into five groups based on admission glucose levels of <100, 100–139, 140–189, 190–249 and ≥250 mg/dL. Their short‐ and long‐term outcomes were compared.

Results

Higher admission glucose levels were associated with significantly higher in‐hospital morbidity and mortality, the overall mortality rate at follow up, and the incidence of reinfarction or heart failure requiring admission or leading to mortality at follow up. The odds ratios (95% confidence interval) for in‐hospital morbidity, in‐hospital mortality, mortality at follow up and re‐infarction or heart failure or mortality at follow up of patients with admission glucose levels ≥190 mg/dL, compared with those with admission glucose levels <190 mg/dL, were 2.12 (1.3–3.4, P = 0.001), 2.74 (1.4–5.5, P = 0.004), 2.52 (1.2–5.1, P = 0.01) and 1.70 (1.03–2.8, P = 0.04), respectively. Previously non‐diabetic patients with admission glucose levels ≥250 mg/dL had significantly higher in‐hospital morbidity or mortality (44 vs 70%, P = 0.03). Known diabetic patients had higher rates of reinfarction, heart failure or mortality at follow up in the 100–139 mg/dL (8 vs 27%, P = 0.04) and 140–189 mg/dL (11 vs 26%, P = 0.02) groups.

Conclusions

Admission hyperglycemia, especially at glucose levels ≥190 mg/dL, is a predictor of poor prognosis in STEMI patients undergoing primary PCI.     

Phosphorylation-regulated axonal dependent transport of syntaxin 1 is mediated by a Kinesin-1 adapter

Presynaptic nerve terminals are formed from preassembled vesicles that are delivered to the prospective synapse by kinesin-mediated axonal transport. However, precisely how the various cargoes are linked to the motor proteins remains unclear. Here, we report a transport complex linking syntaxin 1a (Stx) and Munc18, two proteins functioning in synaptic vesicle exocytosis at the presynaptic plasma membrane, to the motor protein Kinesin-1 via the kinesin adaptor FEZ1. Mutation of the FEZ1 ortholog UNC-76 in Caenorhabditis elegans causes defects in the axonal transport of Stx. We also show that binding of FEZ1 to Kinesin-1 and Munc18 is regulated by phosphorylation, with a conserved site (serine 58) being essential for binding. When expressed in C. elegans, wild-type but not phosphorylation-deficient FEZ1 (S58A) restored axonal transport of Stx. We conclude that FEZ1 operates as a kinesin adaptor for the transport of Stx, with cargo loading and unloading being regulated by protein kinases.     

The CD47-signal regulatory protein alpha (SIRPa) interaction is a therapeutic target for human solid tumors

CD47, a "don't eat me" signal for phagocytic cells, is expressed on the surface of all human solid tumor cells. Analysis of patient tumor and matched adjacent normal (nontumor) tissue revealed that CD47 is overexpressed on cancer cells. CD47 mRNA expression levels correlated with a decreased probability of survival for multiple types of cancer. CD47 is a ligand for SIRPα, a protein expressed on macrophages and dendritic cells. In vitro, blockade of CD47 signaling using targeted monoclonal antibodies enabled macrophage phagocytosis of tumor cells that were otherwise protected. Administration of anti-CD47 antibodies inhibited tumor growth in orthotopic immunodeficient mouse xenotransplantation models established with patient tumor cells and increased the survival of the mice over time. Anti-CD47 antibody therapy initiated on larger tumors inhibited tumor growth and prevented or treated metastasis, but initiation of the therapy on smaller tumors was potentially curative. The safety and efficacy of targeting CD47 was further tested and validated in immune competent hosts using an orthotopic mouse breast cancer model. These results suggest all human solid tumor cells require CD47 expression to suppress phagocytic innate immune surveillance and elimination. These data, taken together with similar findings with other human neoplasms, show that CD47 is a commonly expressed molecule on all cancers, its function to block phagocytosis is known, and blockade of its function leads to tumor cell phagocytosis and elimination. CD47 is therefore a validated target for cancer therapies.     

Implementation of the Risk–Need–Responsivity Framework across the Juvenile Justice Agencies in Singapore

The Risk–Need–Responsivity (RNR) framework is regarded as the forefront of offender rehabilitation in guiding youth offender risk assessment and interventions. This article discusses the juvenile justice system in Singapore and the local research that has been conducted in relation to the RNR framework and the associated Youth Level of Service (YLS) measures. It describes a journey that saw the implementation of the RNR framework across the juvenile justice agencies and highlights the challenges that were faced during the implementation process on the ground. Finally, the article concludes by providing future directions for the implementation of the RNR framework in Singapore.