Transition of hemoglobin between two tertiary conformations: The transition constant differs significantly for the major and minor hemoglobins of the Japanese quail (Cortunix cortunix japonica)

Abstract We demonstrate that 5,5′-dithiobis(2-nitrobenzoate) -DTNB -reacts with only CysF9[93]β and CysB5[23]β among the multiple sulfhydryl groups of the major and minor hemoglobins of the Japanese quail (Cortunix cortunix japonica). K equ , the equilibrium constant for the reaction, does not differ very significantly between the two hemoglobins. It decreases 430-fold between pH ≈ 5.6 and pH ≈ 9: from a mean of 7 ± 1 to a mean of 0.016 ± 0.003. Quantitative analyses of the K equ data based on published X-ray and temperature-jump evidence for a tertiary structure transition in liganded hemoglobin enable the calculation of K rt , the equilibrium constant for the r ←→ t tertiary structure transition. K rt differs significantly between the two hemoglobins: 0.744 ± 0.04 for the major, 0.401 ± 0.01 for the minor hemoglobin. The mean pK a s of the two groups whose ionizations are coupled to the DTNB reaction are about the same as previously reported for mammalian hemoglobins

Detailed analysis of chick optic fissure closure reveals Netrin-1 as an essential mediator of epithelial fusion:.

Epithelial fusion underlies many vital organogenic processes during embryogenesis. Disruptions to these cause a significant number of human birth defects, including ocular coloboma. We provide robust spatial-temporal staging and unique anatomical detail of optic fissure closure (OFC) in the embryonic chick, including evidence for roles of apoptosis and epithelial remodelling. We performed complementary transcriptomic profiling and show that Netrin-1 (NTN1) is precisely expressed in the chick fissure margin during fusion but is immediately downregulated after fusion. We further provide a combination of protein localisation and phenotypic evidence in chick, humans, mice and zebrafish that Netrin-1 has an evolutionarily conserved and essential requirement for OFC, and is likely to have an important role in palate fusion. Our data suggest that NTN1 is a strong candidate locus for human coloboma and other multi-system developmental fusion defects, and show that chick OFC is a powerful model for epithelial fusion research

Progenitor cells of the rod-free area centralis originate in the anterior dorsal optic vesicle

<p>Abstract</p> <p>Background</p> <p>Nervous system development is dependent on early regional specification to create functionally distinct tissues within an initially undifferentiated zone. Within the retina, photoreceptors are topographically organized with rod free area centrales faithfully generated at the centre of gaze. How does the developing eye regulate this placement? Conventional wisdom indicates that the distal tip of the growing optic vesicle (OV) gives rise to the area centralis/fovea. Ectopic expression and ablation studies do not fully support this view, creating a controversy as to the origin of this region. In this study, the lineage of cells in the chicken OV was traced using DiI. The location of labelled cells was mapped onto the retina in relation to the rod-free zone at embryonic (E) 7 and E17.5. The ability to regenerate a rod free area after OV ablation was determined in conjunction with lineage tracing.</p> <p>Results</p> <p>Anterior OV gave rise to cells in nasal retina and posterior OV became temporal retina. The OV distal tip gave rise to cells above the optic nerve head. A dorsal and anterior region of the OV correlated with cells in the developing rod free area centralis. Only ablations including the dorsal anterior region gave rise to a retina lacking a rod free zone. DiI application after ablation indicated that cells movements were greater along the anterior/posterior axis compared with the dorsal/ventral axis.</p> <p>Conclusion</p> <p>Our data support the idea that the chicken rod free area centralis originates from cells located near, but not at the distal tip of the developing OV. Therefore, the hypothesis that the area centralis is derived from cells at the distal tip of the OV is not supported; rather, a region anterior and dorsal to the distal tip gives rise to the rod free region. When compared with other studies of retinal development, our results are supported on molecular, morphological and functional levels. Our data will lead to a better understanding of the mechanisms underlying the topographic organization of the retina, the origin of the rod free zone, and the general issue of compartmentalization of neural tissue before any indication of morphological differentiation.</p

General anaesthetic and airway management practice for obstetric surgery in England: a prospective, multi-centre observational study

There are no current descriptions of general anaesthesia characteristics for obstetric surgery, despite recent changes to patient baseline characteristics and airway management guidelines. This analysis of data from the direct reporting of awareness in maternity patients' (DREAMY) study of accidental awareness during obstetric anaesthesia aimed to describe practice for obstetric general anaesthesia in England and compare with earlier surveys and best-practice recommendations. Consenting patients who received general anaesthesia for obstetric surgery in 72 hospitals from May 2017 to August 2018 were included. Baseline characteristics, airway management, anaesthetic techniques and major complications were collected. Descriptive analysis, binary logistic regression modelling and comparisons with earlier data were conducted. Data were collected from 3117 procedures, including 2554 (81.9%) caesarean deliveries. Thiopental was the induction drug in 1649 (52.9%) patients, compared with propofol in 1419 (45.5%). Suxamethonium was the neuromuscular blocking drug for tracheal intubation in 2631 (86.1%), compared with rocuronium in 367 (11.8%). Difficult tracheal intubation was reported in 1 in 19 (95%CI 1 in 16-22) and failed intubation in 1 in 312 (95%CI 1 in 169-667). Obese patients were over-represented compared with national baselines and associated with difficult, but not failed intubation. There was more evidence of change in practice for induction drugs (increased use of propofol) than neuromuscular blocking drugs (suxamethonium remains the most popular). There was evidence of improvement in practice, with increased monitoring and reversal of neuromuscular blockade (although this remains suboptimal). Despite a high risk of difficult intubation in this population, videolaryngoscopy was rarely used (1.9%)

Intonation: Meaning and its Implication on Teaching

Several evidences of research into segmental phonology abound, but not much has been done on intonation. Jowitt opined that “… intonation has been hampered by insufficient investigation at the scholarly level …” (Jowitt, 2000). From researches, up to 70% of the problems associated with the lack of intelligibility in spoken communication are caused by inadequate knowledge of patterns of English intonation among non-native speakers. The aim of this paper is to investigate reasons responsible for relegation to the background the teaching of intonation patterns and investigate the connections between intonation and meaning. The model used for this research is that of Cruttenden (1986). In conclusion it was realized that intonation has great influence on meaning derivation and should be taught correctly by teachers of English who knows what it takes to teach phonology and its types. They are to introduce methods of teaching that will help learners develop interest and make deliberate efforts to acquire and use them correctly. The government and appropriate school authorities should ensure a conducive learning environment; provide training and retraining opportunities for teachers and world class language laboratories with state-of-the-art equipment. This will bring both learners and teachers of English to the attainment of Educated English

Benign subcutaneous emphysema: A case report with bite

Introduction: Subcutaneous emphysema is the presence of air/gas within the subcutaneous tissue plane. Though there are numerous causative factors, benign subcutaneous emphysema is rare. Case report: We report a very rare case of benign subcutaneous emphysema following an insect bite on the forearm of a 48-year old man. The puncture area was erythematous and the emphysema extended to the whole arm, axilla and superior mediastinum. Despite, conservative management, the patient had residual discomfort and erythema around the puncture site. Surgical debridement resulted in resolution of symptoms. Discussion: Subcutaneous emphysema affecting an isolated limb is extremely rare. It is vital to differentiate it from life-threatening soft-tissue infections secondary to a gas-forming organism. Immunodeficiency states are key factors in the development and the outcomes of patients with subcutaneous emphysema. Medical management successfully resolves symptoms in the majority of cases. However, surgical debridement of the puncture site and surrounding fibrotic tissue has been advocated for those with persistent symptoms. Conclusion: This case highlights a rare cause of benign subcutaneous emphysema, highlighting key issues surrounding its management for a successful outcome