The search for a unifying diagnosis involving neurological, endocrine and immune dysfunction: a case report of a novel presentation of DAVID syndrome.

BACKGROUND: We report a novel presentation of deficit in anterior pituitary function with variable immune deficiency (DAVID) syndrome in a healthy young girl presenting in Addisonian crisis with raised intracranial pressure. Nearly all cases of DAVID syndrome described in the literature have presented with recurrent infections and variable immunodeficiency. Pseudotumour cerebri has not been reported in DAVID syndrome to date. CASE PRESENTATION: A four-year-old girl represented to hospital with vomiting, confusion and diplopia after ten days of tiredness, neck and abdominal pain, and headache. Her cranial nerve examination demonstrated a right abducens nerve palsy and papilloedema, and she was found to have ketotic hypoglycaemia and hypocortisolaemia secondary to adrenocorticotrophic hormone (ACTH) deficiency. Her neuroimaging was consistent with pseudotumour cerebri, and her lumbar puncture opening pressure confirmed raised intracranial pressure (30-40 cmH2O). Cerebrospinal fluid analysis was normal. The patient's symptoms improved with hydrocortisone replacement and acetazolamide, but the raised intracranial pressure recurred after acetazolamide was discontinued. She was subsequently found to have panhypogammaglobulinaemia, and DAVID syndrome was diagnosed. Genetic testing demonstrated a truncating mutation in the NFKB2 gene c.2557C > T, p.(Arg853*). CONCLUSIONS: This case demonstrates pseudotumour cerebri as a novel neurological presentation of DAVID syndrome, highlights the rare association between adrenal insufficiency and intracranial hypertension, and shows the challenges in diagnosing isolated ACTH deficiency. We emphasise that cortisol should be checked in pre-pubertal children with pseudotumour cerebri and a diagnosis of DAVID syndrome considered in those presenting with low cortisol and neurological symptoms.

Analysis of unidirectional non-paraxial invisibility of purely reflective PT-symmetric volume gratings.

We study the diffraction produced by a slab of purely reflective PT-symmetric volume Bragg grating that combines modulations of refractive index and gain/loss of the same periodicity with a quarter-period shift between them. Such a complex grating has a directional coupling between the different diffraction orders, which allows us to find an analytic solution for the first three orders of the full Maxwell equations without resorting to the paraxial approximation. This is important, because only with the full equations can the boundary conditions, allowing for the reflections, be properly implemented. Using our solution we analyze unidirectional invisibility of such a grating in a wide variety of configurations.

Analysis of PT-symmetric volume gratings beyond the paraxial approximation.

We study the diffraction produced by a PT -symmetric volume Bragg grating that combines modulation of refractive index and gain/loss of the same periodicity with a quarter-period shift between them. Such a complex grating has a directional coupling between the different diffraction orders, which allows us to find an analytic solution for the first three orders of the full Maxwell equations without resorting to the paraxial approximation. This is important, because only with the full equations can the boundary conditions, allowing for reflections, be properly implemented. Using our solution we analyze the properties of such a grating in a wide variety of configurations.

Novel optical characteristics of a Fabry-Perot resonator with embedded PT-symmetrical grating.

We explore the optical properties of a Fabry-Perot resonator with an embedded Parity-Time (PT) symmetrical grating. This PT-symmetrical grating is non diffractive (transparent) when illuminated from one side and diffracting (Bragg reflection) when illuminated from the other side, thus providing a unidirectional reflective functionality. The incorporated PT-symmetrical grating forms a resonator with two embedded cavities. We analyze the transmission and reflection properties of these new structures through a transfer matrix approach. Depending on the resonator geometry these cavities can interact with different degrees of coherency: fully constructive interaction, partially constructive interaction, partially destructive interaction, and finally their interaction can be completely destructive. A number of very unusual (exotic) nonsymmetrical absorption and amplification behaviors are observed. The proposed structure also exhibits unusual lasing performance. Due to the PT-symmetrical grating, there is no chance of mode hopping; it can lase with only a single longitudinal mode for any distance between the distributed reflectors.

Sucrose octabenzoate: assignment of 13C and 1H resonances of the sucrose moiety and the 13C resonances of the carbonyl carbons. Use of 13C-n.m.r. spectroscopy for the study of selective deacylation.

Assignment of the 1H and 13C signals arising from the carbohydrate portion of sucrose octabenzoate has been achieved using homonuclear shift correlation experiments (COSY) and one-bond 1H-13C heteronuclear shift correlation measurements, respectively. The 13C resonances of the carbonyl carbon atoms of the eight benzoyl groups are readily distinguished for solutions in benzene-d6-pyridine-d5 (1:1), and have been assigned by means of three-bond 1H-13C shift correlation studies coupled with measurement of the 13C-n.m.r. spectrum of a sucrose octabenzoate specifically labelled with 13C in some of the carbonyl groups. With this assignment, products of partial deacylation of the octabenzoate may readily be identified by treatment with excess of benzoyl-carbonyl-13C chloride followed by measurement of the 13C-n.m.r. spectrum of the labelled sucrose octabenzoate, so prepared, in the carbonyl region.