Monitoring cerebral oxygenation in a pediatric patient undergoing surgery for vascular ring

Regional cerebral oxygenation can be monitored using near-infrared spectroscopy (NIRS). Inadequacy of collateral cerebral circulation and regional cerebral ischemia during cardiac and vascular surgery may be detected by the use of NIRS monitoring. We report a 2-year-old child who underwent surgical repair of vascular ring and subclavian reimplantation, where use of NIRS helped in early detection and timely intervention to prevent prolonged cerebral ischemia.

Neighboring cysteine residues in human fucosyltransferase VII are engaged in disulfide bridges, forming small loop structures

Among alpha 3-fucosyltransferases (alpha3-FucTs) from most species, four cysteine residues appear to be highly conserved. Two of these cysteines are located at the N-terminus and two at the C-terminus of the catalytic domain. FucT VII possesses two additional cysteines in close proximity to each other located in the middle of the catalytic domain. We identified the disulfide bridges in a recombinant, soluble form of human FucT VII. Potential free cysteines were modified with a biotinylated alkylating reagent, disulfide bonds were reduced and alkylated with iodoacetamide, and the protein was digested with either trypsin or chymotrypsin, before characterization by high-performance liquid chromatography/electrospray ionization mass spectrometry. More than 98% of the amino acid sequence for the truncated enzyme (beginning at amino acid 53) was verified. Mass spectrometry analysis also demonstrated that both potential N-linked sites are occupied. All six cysteines in the FucT VII sequence were shown to be disulfide-linked. The pairing of the cysteines was determined by proteolytic cleavage of nonreduced protein and subsequent analysis by mass spectrometry. The results demonstrated that Cys(68)-Cys(76), Cys(211)-Cys(214), and Cys(318)-Cys(321) are disulfide-linked. We have used this information, together with a method of fold recognition and homology modeling, using the (alpha/beta)(8)-barrel fold of Escherichia coli dihydrodipicolinate synthase as a template to propose a model for FucT VII.

Disulfide bonds of GM2 synthase homodimers. Antiparallel orientation of the catalytic domains

GM2 synthase is a homodimer in which the subunits are joined by lumenal domain disulfide bond(s). To define the disulfide bond pattern of this enzyme, we analyzed a soluble form by chemical fragmentation, enzymatic digestion, and mass spectrometry and a full-length form by site-directed mutagenesis. All Cys residues of the lumenal domain of GM2 synthase are disulfide bonded with Cys(429) and Cys(476) forming a disulfide-bonded pair while Cys(80) and Cys(82) are disulfide bonded in combination with Cys(412) and Cys(529). Partial reduction to produce monomers converted Cys(80) and Cys(82) to free thiols while the Cys(429) to Cys(476) disulfide remained intact. CNBr cleavage at amino acid 330 produced a monomer-sized band under nonreducing conditions which was converted upon reduction to a 40-kDa fragment and a 24-kDa myc-positive fragment. Double mutation of Cys(80) and Cys(82) to Ser produced monomers but not dimers. In summary these results demonstrate that Cys(429) and Cys(476) form an intrasubunit disulfide while the intersubunit disulfides formed by both Cys(80) and Cys(82) with Cys(412) and Cys(529) are responsible for formation of the homodimer. This disulfide bond arrangement results in an antiparallel orientation of the catalytic domains of the GM2 synthase homodimer.

Characterization of cysteine residues and disulfide bonds in proteins by liquid chromatography/electrospray ionization tandem mass spectrometry

Cysteine residues and disulfide bonds are important for protein structure and function. We have developed a simple and sensitive method for determining the presence of free cysteine (Cys) residues and disulfide bonded Cys residues in proteins (<100 pmol) by liquid chromatography/electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS) in combination with protein database searching using the program Sequest. Free Cys residues in a protein were labeled with PEO-maleimide biotin immediately followed by denaturation with 8 M urea. Subsequently, the protein was digested with trypsin or chymotrypsin and the resulting products were analyzed by capillary LC/ESI-MS/MS for peptides containing modified Cys and/or disulfide bonded Cys residues. Although the MS method for identifying disulfide bonds has been routinely employed, methods to prevent thiol-disulfide exchange have not been well documented. Our protocol was found to minimize the occurrence of the thiol-disulfide exchange reaction. The method was validated using well-characterized proteins such as aldolase, ovalbumin, and beta-lactoglobulin A. We also applied this method to characterize Cys residues and disulfide bonds of beta 1,4-galactosyltransferase (five Cys), and human blood group A and B glycosyltransferases (four Cys). Our results demonstrate that beta 1,4-galactosyltransferase contains one free Cys residue and two disulfide bonds, which is in contrast to work previously reported using chemical methods for the characterization of free Cys residues, but is consistent with recently published results from x-ray crystallography. In contrast to the results obtained for beta 1,4-galactosyltransferase, none of the Cys residues in A and B glycosyltransferases were found to be involved in disulfide bonds.

trkA, trkB, and trkC messenger RNA expression by bulbospinal cells of the rat

Previous research has shown that corticospinal as well as rubrospinal neurons express the high-affinity trkB and trkC receptors but not the high-affinity trkA receptor. To determine if bulbospinal neurons in other brainstem areas show the same pattern of trk receptor expression, bulbospinal cells were labelled via the injection of the retrograde tracer FluoroGold into the spinal cord. Brainstem sections were then processed for in situ hybridization using oligonucleotide probes to the trkA, trkB, and trkC receptors. The results indicated that, although trkA expression occurred in brainstem areas that contain bulbospinal neurons (e.g., the vestibular nuclei, and the pontine reticular formation), very few FluoroGold-labelled cells expressed the trkA receptor. In contrast, at least 90% of bulbospinal cells in each brainstem area examined expressed the trkB receptor. Quantitative analysis indicated differences in the level of trkB labelling between bulbospinal cells in different brainstem areas, with the highest levels seen in the locus coeruleus and magnocellular portion of the red nucleus, and the lowest levels seen in the medial and superior vestibular nuclei and the raphe obscurus. With the exception of the accessory trigeminal nucleus, over 84% of bulbospinal cells in each brainstem area also expressed the trkC receptor. TrkC receptor expression was greatest in the locus coeruleus and subcoeruleus and lowest in the accessory trigeminal nucleus, the raphe magnus, and the vestibular nuclei. Results indicate that, as with other descending pathways, virtually all bulbospinal pathways should be amenable to treatment with brain-derived neurotrophic factor, neurotrophin-4/5 or neurotrophin-3, but not nerve growth factor, following spinal cord damage.

Organ culture of chicken bursa as a model to study the pathogenicity of infectious bursal disease virus isolates

In vitro study with chicken bursal organ culture was attempted to assess the pathogenicity of locally isolated infectious bursal disease virus (IBDV) initially isolated from the bursa of naturally infected birds. In bursal organ culture, lymphoblastic transformation was noticed as early as 24 hr postinoculation and reached maximum at 72 hr postinoculation. The other microscopic changes were increased number of macrophages and formation of plasma cells. The IBDV antigen was detected 24 hr onward by coagglutination test with antibody coated Staphylococcus aureus strain Cowan I. On the basis of lesion score, the three isolates of IBDV (A, B, and C) were graded as virulent (B isolate) and moderately virulent (A and C isolates). A similar pattern of pathogenicity was also observed in the in vivo pathogenicity studies in chicken based on bursa: body weight ratio and histopathologic lesion score. The bursal organ culture thus provides a useful experimental model to differentiate the IBDV isolates on the basis of their virulence.

An A-type proanthocyanidin from Prunus armeniaca

Roots of Prunus armeniaca yielded a new A-type proanthocyanidin whose structure was assigned as ent-epiafzelechin-3-O-p-hydroxybenzoate-(4alpha-->8, 2alpha-->O-->7)-epiafzelechin (1). The structure of 1 was determined through extensive 1D and 2D NMR studies.

Rapid diagnosis of fowl pox with coagglutination assay

The coagglutination test was standardised for detection of fowl pox antigen in infected scabs and chorioallontoic membrane of chicken embryos. The Staphylococcus aureus Cowan I strain, containing large amounts of Protein A in their cell wall, coated with fowl pox antibodies was found specific and sensitive for detection of fowl pox antigen. The test is easy to perform and rapid as the positive results can be read within 15 seconds.

A new quantum chemical approach in QSAR-analysis. Parametrisation of conformational energies into molecular descriptors JMn (steric) and JSn (electronic)

Two new types of structure-related molecular descriptors, JMn and JSn, have been developed using conformational energies from quantum chemical calculations. For this purpose propipocaine (CAS 3670-68-6) was chosen as a model and 42 analogues were studied. The quantum chemical calculations were performed applying AM1 and PCILO approximation methods. Appropriate mathematical models were designed to calculate steric parameter log JM1 and electronic parameters JS1 to JS6. The values obtained for these parameters were used in multiple linear regression analysis for the evaluation of the structure-activity relationship. Furthermore, a comparison between electronic parameters JSn and sigma (Hammett) was made. The results show, that these parameters can be used successfully in predicting the biological activity of compounds in this model. Although, JS5 values are comparable to sigma-Hammett, the electronic parameter JS2 gives a better correlation in QSAR-analysis involving two parameters JS2 and log JM1.

Dyskeratosis congenita in a female

We report a 9-year-old Saudi girl with dyskeratosis congenita. In addition to the known manifestations of this disease, she also had the additional features of tufts of hairs on the limbs, and an early onset of keratinized basal cell papillomas on her trunk.

Autosomal recessive epidermolysis bullosa simplex. A case report

We report a male child with autosomal recessive epidermolysis bullosa simplex presenting at birth. The patient subsequently developed cutaneous atrophy, nail dystrophy, milia and alopecia. He had growth retardation and anaemia, but there were no other associated abnormalities. Electron microscopy showed epidermolytic cleavage. The family history indicated an autosomal recessive mode of inheritance.

Cutaneous granuloma with ataxia telangiectasia--a case report and review of literature

A patient is reported who had ataxia telangiectasia with multiple cutaneous lesions mainly on the limbs, which showed atrophy and scarring. Histopathology of these skin lesions showed tuberculoid granulomas without frank collagen necrobiosis in the dermis. Chromosomal analysis revealed a translocation between 7 and 14 as well as deletion of chromosomes 4 and 6.

Successful treatment of Sweet's syndrome with doxycycline

Two patients with Sweet's syndrome are described, both of whom were treated with doxycycline 200 mg daily, and responded well to therapy. Doxycycline appears to be an effective alternative to corticosteroids for the treatment of Sweet's syndrome.

Etretinate in the treatment of ulcerative lichen planus

Ulcerative lichen planus (ULP) is a rare variant of lichen planus. It is resistant to all therapeutic modalities, and most of the patients with this disorder described in the literature have been successfully treated only by surgical skin grafting. We report a case with ULP successfully treated with etretinate.

Subcorneal pustular dermatosis and IgA myeloma

A case of subcorneal pustular dermatosis (SCPD), as a presenting feature in a patient with multiple myeloma, is described. This is the seventh case report of this association and the first from the Middle East. Five of these cases, including the present report, have been of the IgA paraprotein type, IgA intraepidermal deposits have been described in a few patients with SCPD associated with IgA paraproteinaemias but have not been detected in our patient.

White fibrous papulosis of the neck

We report two middle-aged women who presented with multiple, discrete, non-follicular, oval, pale, asymptomatic lesions on the neck. Clinical and histopathological features were compatible with the entity of white fibrous papulosis of the neck.

Mycetoma: comparison of MR imaging with CT

Magnetic resonance (MR) images obtained in 18 patients with pathologically confirmed mycetoma in the body (n = 4) or lower extremity (n = 14) were retrospectively reviewed and compared with computed tomographic (CT) scans in 15 patients and surgical findings in 10. T1-weighted images showed an infiltrating mass (same signal intensity as muscle) involving skin, subcutaneous fat, muscles, tendons, and other tissues. On T2-weighted images, the mass and affected structures showed moderately increased signal intensity. Bone marrow involvement was detected in seven patients and was best visualized on T1-weighted images. CT showed moderate enhancement of the infiltrative process in all patients. Bone changes, seen in nine, included coarse trabeculation, periosteal reaction, endosteal proliferation, and patchy destruction. MR imaging and CT were comparable and correlated well with surgery in showing the extent of soft-tissue involvement. Early bone changes (important for therapy planning for pedal mycetoma) were seen only at CT. The study showed that MR imaging is sensitive for assessing the extent of mycetoma in the soft tissues. CT should be the method of choice for staging pedal lesions because it can be used to detect early bone involvement.