Perspective: Quantum Hamiltonians for optical interactions

The multipolar Hamiltonian of quantum electrodynamics is extensively employed in chemical and optical physics to treat rigorously the interaction of electromagnetic fields with matter. It is also widely used to evaluate intermolecular interactions. The multipolar version of the Hamiltonian is commonly obtained by carrying out a unitary transformation of the Coulomb gauge Hamiltonian that goes by the name of Power-Zienau-Woolley (PZW). Not only does the formulation provide excellent agreement with experiment, and versatility in its predictive ability, but also superior physical insight. Recently, the foundations and validity of the PZW Hamiltonian have been questioned, raising a concern over issues of gauge transformation and invariance, and whether observable quantities obtained from unitarily equivalent Hamiltonians are identical. Here, an in-depth analysis of theoretical foundations clarifies the issues and enables misconceptions to be identified. Claims of non-physicality are refuted: the PZW transformation and ensuing Hamiltonian are shown to rest on solid physical principles and secure theoretical ground.

Expulsion of a Lacrimal Dacryolith by Sneezing: A Rare Event

Purpose

To describe the case of a man presenting with intermittent epiphora of the right eye and a low grade dacryocystitis due to a dacryolith.

Methods/Results

He was treated conservatively and was offered a Dacryocystorhinostomy. A few weeks before surgery, he developed swelling and pain over the right medial canthus followed by violent sneezing with spontaneous extrusion of the dacryolith.

Discussion

The authors propose that the dacryolith fragmented spontaneously and once it reached the nasal cavity, was expelled by violent sneezing to the nostril, a mechanism not previously reported.

Conclusions

Reformation of dacryolith is a likely possibility, and recurrence of symptoms in such cases may ultimately require a Dacryocystorhinostomy.

Outcomes for severe aponeurotic ptosis using posterior approach white-line advancement ptosis surgery

PurposeThe purpose of the study was to report the outcome of posterior approach white-line advancement surgery for severe involutional aponeurotic ptosis.Patients and methodsThis was a retrospective review of an interventional case series of all patients undergoing surgery for severe involutional aponeurotic ptosis during a 42-month period at a single center. The inclusion criteria were severe involutional ptosis (upper eyelid margin reflex distance (MRD) ≤1 mm) undergoing posterior approach surgery. There was minimum 3-month follow-up. The main outcome measures were type of ptosis (primary or recurrent), preoperative margin reflex distance, levator function and eyelid skin crease height, presence of visible iris sign (VIS), documented unusual intraoperative findings, postoperative complications, and follow-up time.ResultsOf the 836 procedures for ptosis, 122 procedures (76 patients) met the inclusion criteria for this study. Mean postoperative follow-up was 28 (median 18, range 12-98) weeks. Success rates were 80.3% (98/122) overall, 81.5% (66/81) in the non-VIS group, and 78% (32/41) in the VIS group. There was no significant difference between the two groups (P=0.411). Failures were due to undercorrection, with <2 mm MRD in 75% (18/24), overcorrection with >4.5 mm MRD in 16.7% (4/24), and inter-eyelid height asymmetry of >1 mm in 8.3% (2/122).ConclusionsOutcomes of ptosis surgery for severe aponeurotic ptosis using a posterior approach white-line advancement are comparable to, and possibly better than, anterior approach in eyelids with VIS.

Enhanced Chiral Discriminatory van der Waals Interactions Mediated by Chiral Surfaces

We predict a discriminatory interaction between a chiral molecule and an achiral molecule which is mediated by a chiral body. To achieve this, we generalize the van der Waals interaction potential between two ground-state molecules with electric, magnetic, and chiral response to nontrivial environments. The force is evaluated using second-order perturbation theory with an effective Hamiltonian. Chiral media enhance or reduce the free interaction via many-body interactions, making it possible to measure the chiral contributions to the van der Waals force with current technology. The van der Waals interaction is discriminatory with respect to enantiomers of different handedness and could be used to separate enantiomers. We also suggest a specific geometric configuration where the electric contribution to the van der Waals interaction is zero, making the chiral component the dominant effect.

Clinical and anthropological perspectives on chemical relaxing of afro-textured hair

The culturally engrained practice of 'relaxing' afro-textured hair has been linked with hair and scalp disorders. Herein, we discuss the evolution of human hair types, focusing in particular on afro-textured hair. We explore the biological features of this hair type, and discuss the different methods employed to straighten afro-textured hair, focusing in particular on chemical straightening. We also examine clinical, anthropological, and psychological issues associated with this latter practice. Examples of common scalp pathologies associated with chronic hair relaxing, such as alopecia, hair breakage, caustic burns and irritant contact dermatitis, are also highlighted. The data presented herein should enable clinicians to engage in culturally appropriate discussions with their patients about issues of appearance and conformity.

Whole-exome sequencing improves mutation detection in a diagnostic epidermolysis bullosa laboratory

BACKGROUND

Subtypes of inherited epidermolysis bullosa (EB) vary significantly in their clinical presentation and prognosis. Establishing an accurate diagnosis is important for genetic counselling and patient management. Current approaches in EB diagnostics involve skin biopsy for immunohistochemistry and transmission electron microscopy, and Sanger sequencing of candidate genes. Although informative in most cases, this approach can be expensive and laborious and may fail to identify pathogenic mutations in ~15% of cases.

OBJECTIVES

Next-generation DNA sequencing (NGS) technologies offer a fast and efficient complementary diagnostic strategy, but the value of NGS in EB diagnostics has yet to be explored. The aim of this study was to undertake whole-exome sequencing (WES) in nine cases of EB in which established diagnostic methods failed to make a genetic diagnosis.

METHODS

Whole-exome capture was performed using genomic DNA from each case of EB, followed by massively parallel sequencing. Resulting reads were mapped to the human genome reference hg19. Potentially pathogenic mutations were subsequently confirmed by Sanger sequencing.

RESULTS

Analysis of WES data disclosed biallelic pathogenic mutations in each case, with all mutations occurring in known EB genes (LAMB3, PLEC, FERMT1 and COL7A1). This study demonstrates that NGS can improve diagnostic sensitivity in EB compared with current laboratory practice.

CONCLUSIONS

With appropriate diagnostic platforms and bioinformatics support, WES is likely to increase mutation detection in cases of EB and improve EB diagnostic services, although skin biopsy remains an important diagnostic investigation in current clinical practice.

Abstract P1-06-11: Tumor-associated macrophages: CD206 expression and patient outcomes in locally advanced breast cancer

Introduction

The ability of a tumor to recur is related to the complex molecular biology of the tumor cells and the surrounding microenvironment. Tumor-associated macrophages (TAMs) account for up to 50% of the cell mass within a breast tumor, and the M2 macrophage phenotype has been reported to have pro-tumor activity. The mannose receptor, CD206, is a transmembrane receptor expressed predominantly in macrophages and shown in mouse studies to promote M2/TAM activity. This study evaluates CD206 expression in the tumor stroma with patient outcomes in locally advanced breast cancer.

Methods

The Scott & White tumor registry was queried for consecutive cases of women diagnosed with stage 3, HER-2 negative breast cancer between January 1999 and December 2006. To meet inclusion criteria, all biopsies must have been performed at S&W and patients must have had at least 5 years of follow up in our system documenting status of cancer (complete remission vs. metastatic recurrence). Archived formalin fixed and paraffin embedded tissue breast tissue from initial surgical biopsies was obtained from the Scott & White Pathology Department. Sections were cut at 4 microns thick and slides were stained for CD206. Two pathologists without knowledge of the patients’ clinical backgrounds reviewed each slide. The hot spot method was employed at 20x power to identify the 3 spots in tumor stroma that stained most heavily. The number of CD206+ cells in each of 3 hot spots was counted, and the mean number of CD206+ cells per hot spot reported by two independent pathologists was averaged for analysis.

Results

65 patients met inclusion criteria, of these 31 had a recurrence within 5 years of diagnosis. There was no correlation between likelihood of recurrence or overall survival and CD206 expression. In the 31 patients that had a recurrence, a high CD206 count of greater than or equal to 15 was associated with a shorter time to recurrence than a CD206 count of less than 15 (14.8 months vs. 22 months, respectively, p = 0.028). Mean age at diagnosis in the recurrence group was 59.6 vs. 60 years, and 15 (60%) vs. 2(33%) patients were ER positive in the low CD206 (&lt;15) vs. high CD206 ( = &gt;15) groups, respectively.

Conclusion

High expression of CD206 in the tumor stroma was associated with a shorter time to recurrence in patients with stage 3, HER-2 negative breast cancer; however, there were more ER negative tumors in the high CD 206 group. Our research supports in vitro data that high CD206 expression in macrophages may represent a more aggressive tumor phenotype. Future studies focusing on studying CD206 expression in HER-2 positive breast tumors along with histological stratification are needed to confirm this finding.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P1-06-11.

Assessment in Undergraduate Medical Education: Bangladesh Perspectives

Background: Medical education in Bangladesh is totally controlled by the Government and run a unique undergraduate curriculum throughout the country in both public and private sectors. This paper is aimed to briefly describe the medical education reform in Bangladesh and suggests further assessment changes. The present official form of undergraduate medical curriculum has first evolved in 1988 followed by revision in 2002 and 2012. Assessment and teaching are the two sides of the same coin. Assessment drives learning and learning drives practices. Following the curriculum reform since 2002, the assessment in undergraduate medical education has been greatly changed. There are a lot of in-course formative assessments which include item examination, card final and term final, designed to improve the quality of education. Ten percent marks of summative written examinations derive from formative assessment. Traditional oral examination has been changed to structured form to ensure greater reliability. Even then, teachers are not yet building up to conduct oral examination in such a structured way. Examiners differ in their personality, style and level of experience with variation of questioning and scoring from student to students. Weakness of reliability on oral examination still exists. Students also feel very stressful during the oral examinations. Moreover, to conduct such oral examination, three to four months times per year are lost by the faculties which can be efficiently utilised for teaching and research purposes. Worlds' leading medical schools now-a-days used oral examination only for borderline and distinction students. Bangladesh also must consider oral examination only for borderline and distinction students. DOI: http://dx.doi.org/10.3329/bjms.v12i4.16658 Bangladesh Journal of Medical Science Vol. 12 No. 04 October ’13 Page 357-363