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Smectic blue phases ( BP(Sm)) are thermotropic liquid crystalline phases which exhibit both three-dimensional orientational order, such as classical blue phases, and smectic positional order. BP(Sm) appear as the three-dimensional counterpart of twist grain boundary phases. X-ray scattering and optical polarizing microscopy provide information on the hexagonal and cubic symmetries of these new phases.
We introduce the concept of degree of polarization for electromagnetic near fields. The approach is based on the generalized Stokes parameters that appear as expansion coefficients of the 3 x 3 coherence matrix in terms of the Gell-Mann matrices. The formalism is applied to optical near fields of thermally fluctuating half-space sources with particular interest in fields that are strongly polarized owing to resonant surface plasmons or phonons. This novel method is particularly useful when assessing the full vectorial characteristics of random evanescent fields, e.g., for near-field spectroscopy and polarization microscopy.
The formation of closed-compact multilamellar vesicles (referred to in the literature as the "onion texture") obtained upon shearing lamellar phases is studied using small-angle light scattering and cross-polarized microscopy. By varying the shear rate gamma;, the gap cell D, and the smectic distance d, we show that: (i) the formation of this structure occurs homogeneously in the cell at a well-defined wave vector q(i), via a strain-controlled process, and (ii) the value of q(i) varies as (dgamma;/D)(1/3). These results strongly suggest that formation of multilamellar vesicles may be monitored by an undulation (buckling) instability of the membranes, as expected from theory.
A hybrid-aligned cell of the smectic A liquid material 8CB gives two stable director configurations, one of which is periodic and gives strong diffraction of light. This photonic lattice director profile arises from "frustration" caused by conflicting constraints imposed by the boundary conditions and the constant amplitude smectic density wave. A model is proposed which accords well with the experiment results, predicting correctly the dependence of the periodicity on the cell thickness and reproducing optical polarization microscopy results.
We have synthesized liquid crystal (LC) mesogens based on a nonlinear oxadiazole unit that exhibit nematic phases near 200 degrees C. Polarized microscopy and conoscopy indicate that these LCs are biaxial nematics. Unambiguous and quantitative evidence for biaxiality is achieved using 2H NMR spectroscopy. "2D powder" spectra, obtained by rotating 2H-labeled samples about an axis perpendicular to the magnetic field at approximately 200 Hz, yield phase biaxiality parameters of approximately 0.1 when coupled with rigorous and proven simulations.
We study Bloch wall defects formed by quenching nematic thin films from planar anchoring to homeotropic anchoring through a temperature-driven anchoring transition. The director profiles of the walls are directly visualized using fluorescence confocal polarizing microscopy, and shown to agree well with the simulation based on the Frank elasticity theory. A pure twist wall exists if the ratio of sample thickness to surface extrapolation length p is smaller than or close to 1; while a diffuse Bloch wall is obtained if p is much greater than 1.
The effects of a temperature increase on monoclinic and tetragonal lysozyme single crystals were investigated by polarizing microscopy, X-ray diffraction and laser Raman spectroscopy. To prevent dissolution, the mother liquor was removed, and the crystals were covered by the oil poly-(chlorotrifluoroethylene). Upon heating, their macroscopic shape was stable beyond 453 K but a change (or loss) of birefringence was observed around 352 and 367 K for the tetragonal and monoclinic crystal forms, respectively, which is associated with tighter packing and higher crystal forces in monoclinic lysozyme. Raman spectral changes in the amide I and amide III regions indicated denaturation of the protein within the crystalline environment at temperature where birefringence changes, and differences in the S-S band suggest that in monoclinic lysozyme, denaturation is accompanied with disruption of some S-S bonds. Comparison with thermal denaturation and gel formation (beta-aggregation) of lysozyme in solution indicates that intermolecular interactions are mainly involved in the stabilization of the denatured lysozyme crystals. The behavior of ribonuclease A is very different. This protein unfolds and refolds reversibly in solution and its crystals melt at the unfolding temperature at 333 K, i.e. loss of structure induces breakdown of crystal lattice and macroscopic shape. Although the crystal lattice of proteins is stabilized by only few intermolecular contacts, its breakdown with increasing temperature is primarily a result of thermal unfolding of the polypeptide chains.
Trichothiodystrophy (TTD), an autosomal recessive disorder characterized by sulfur-deficient brittle hair, identifies a group of genetic disorders with an altered synthesis of high-sulfur matrix proteins and a defect in excision repair of ultraviolet damage in fibroblasts of most TTD patients. In contrast to patients with xeroderma pigmentosum (XP), TTD patients do not have an increased frequency of skin cancers. TTD patients may be grouped into four categories: 1) those without photosensitivity and without a defect in excision repair of UV damage; 2) those without photosensitivity and with an excision-repair defect in the same gene as in XP-D (complementation group D); 3) those with photosensitivity and with the XP-D repair defect; 4) those with photosensitivity and with a repair defect distinct from that in XP-D. We present a brother and sister in the third category of TTD. Clinically, the patients have brittle hair, short stature, ichthyosis, photosensitivity, nail and dental dysplasias, cataracts, mental retardation, and pyramidal tract abnormalities. Diagnosis was made by hair mount, which shows the characteristic banding pattern with polarizing microscopy, and by hair amino acid analysis, which demonstrated decreased high-sulfur matrix proteins. Fibroblasts cultured from skin biopsies had a marked DNA excision repair defect similar to the repair defect seen in XP-D. We have documented a unique dysmyelinating disorder on magnetic resonance imaging of the brain that might explain their mental retardation, marked hyperactivity, and neurologic deficits. Following the discovery that the human excision repair cross complementing rodent ultraviolet group 2 (ERCC2) gene is able to correct the ultraviolet sensitivity of XP-D cell strains, the ERCC2 cDNA from previous TTD patients was sequenced and shows frameshifts, deletions and point mutations in the ERCC2 gene. Molecular analysis of our patients is in progress. Molecular analysis of the defects in ERCC2 in clinically distinct patients with XP,XP/Cockayne's syndrome, and TTD may provide insight into the molecular mechanisms of these genetically related but clinically distinct disorders.
Our group has developed an ovine model of deep dermal, partial-thickness burn where the fetus heals scarlessly and the lamb heals with scar. The comparison of collagen structure between these two different mechanisms of healing may elucidate the process of scarless wound healing. Picrosirius staining followed by polarized light microscopy was used to visualize collagen fibers, with digital capture and analysis. Collagen deposition increased with fetal age and the fibers became thicker, changing from green (type III collagen) to yellow/red (type I collagen). The ratio of type III collagen to type I was high in the fetus (166), whereas the lamb had a much lower ratio (0.2). After burn, the ratios of type III to type I collagen did not differ from those in control skin for either fetus or lamb. The fetal tissue maintained normal tissue architecture after burn while the lamb tissue showed irregular collagen organization. In conclusion, the type or amount of collagen does not alter significantly after injury. Tissue architecture differed between fetal and lamb tissue, suggesting that scar development is related to collagen cross-linking or arrangement. This study indicates that healing in the scarless fetal wound is representative of the normal fetal growth pattern, rather than a "response" to burn injury.
Hyaline or colloid bodies (Civatte bodies) and amyloid are sometimes confused because of their similar appearance under the light microscope. A differentiation can be made by histochemical means (DMAB-Nitrite method) and by fluorescence or polarization microscopy. At the ultrastructural level hyaline or colloid bodies as well as amyloid exhibit a fibrillar structure, but can be differentiated by the diameter and arrangement of fibrils and the localization of the aggregations. A clearcut differentiation between hyaline or colloid bodies and amyloid seems of great importance in any dicussion of the epidermal origin of amyloid and the classification of fibrillar aggregations associated with skin tumours.
The light, polarization and electron microscopic changes in the liver of four cases of erythropoietic protoporphyria (EPP) are described. In one of these cases liver involvement resulted in death, whereas in the other three there were no symptoms of referable to hepatic disease. In two cases hepatic pigment was readily visible on light and polarization microscopy and corresponded to characteristic crystalline aggregates seen ultrastructurally. Pronounced micronodular cirrhosis and cholestasis were present in the fatal case, while in the other only mild periportal fibrosis and mononuclear inflammatory cell infiltrate occurred. The third and fourth cases showed no evidence of hepatic involvement on light microscopy. Electron microscopy, however, revealed characteristic crystal-containing vacuoles indicative of protoporphyrin deposition. The need for early detection of the hepatic lesion is emphasized.
We report a patient undergoing haemodialysis, who developed multiple subcutaneous nodules. Histology showed that the nodules were composed of deposits of crystals in the dermis, with an associated foreign-body reaction. The crystalline deposits were identified as calcium oxalate by histochemical staining, polarizing microscopy, and analytical electron microscopy.
INTRODUCTION: Previous investigations have demonstrated improved enamel caries resistance after laser irradiation. The purpose of this in vitro study was to assess the caries-preventive potential of 809 nm diode laser treatment of the enamel of primary teeth compared to topical fluoride application. METHODS: Eighty samples of sound primary teeth were embedded in plastic and stored in saline solution. The enamel surface of 80 samples was polished in an area of 2 x 2 mm. These tooth specimens were randomly assigned to one control and three test groups: (1) no treatment/control; (2) application of 0.1 mg of fluoride varnish (Duraphat) for 6 h; (3) diode laser application (809 nm, 140 mJ, 50 Hz, Ø 600 micro m fibre, contact mode, absorber, 1 min; ORA-LASER01 I.S.T.); and (4) combined application - laser/fluoride varnish. Caries-like lesions were created by pH-cycling. After lesion formation, longitudinal sections were taken and examined by polarized light microscopy. RESULTS: In the control group, all samples showed lesions up to 30 micro m in depth. After laser application, lesions could be identified in 15 out of 20 samples. Topical fluoride treatment in groups 2 (varnish) and 4 (laser/varnish) completely inhibited the development of caries-like lesions in all samples. CONCLUSION: In this in vitro investigation, topical fluoride treatment enhances the resistance of sound enamel of primary teeth more effectively than diode laser application.
BACKGROUND: The present study reports the incidence of trichocutaneous disorders studied in 500 patients infected with HIV 1 in a large university-based setting. Correlation of these findings with immunologic function at the time of diagnosis is presented. Unusual presentations and therapeutic interventions are discussed. Prognosis as related to various trichocutaneous disorders is elaborated. METHODS: All patients in this study were HIV 1 positive by Western blot assay. T-cell subsets were evaluated by monoclonal antibodies against T-cell surface markers. Hair disorders were analyzed by means of light hair pull test, hair mount, polarizing microscopy, trichogram, scalp biopsy, and cultures for bacteria, fungi, and mycobacteria as indicated. Trichologic manifestations were classified based upon immunologic correlation of absolute level of helper T cells/mm3. RESULTS: The majority of hair disorders in the study population occurred with helper T cell numbers of less than 150/mm3. Papulosquamous problems including seborrheic dermatitis and psoriasis were most commonly noted followed by disorders of cell growth cycle regulation and trichokeratinization, i.e., telogen effluvium and loose anagen syndrome. CONCLUSIONS: Multiple trichocutaneous disorders occur in the setting of retroviral infection. Most of these disorders occur in the setting of progressive immunoincompetence. The awareness of the disorders described here will aid the clinician in both the recognition and management of pilar aberrations in the appropriate clinical setting.
The phase equilibria in four lysophosphatidylcholine/water systems were investigated at different temperatures. Each of the 1-palmitoyl-, 1-stearoyl-, 1-oleoyl- and 1-linoleoyl-sn-glycero-3-phosphocholines was dispersed in heavy water at different concentrations. The phase structures were determined by 2H-, 14N- and 31P-NMR, polarization microscopy and low-angle X-ray diffraction. The phase diagrams of the oleoyl and linoleoyl systems were quite similar. At room temperature and with decreasing water content the isotropic micellar solution was followed by a hexagonal phase and then a cubic phase. Finally the lamellar phase appeared before the region of hydrated crystals. The same sequence of phases was observed in the stearoyl system at elevated temperatures. The palmitoyl system differed from the others: here a cubic phase followed after the micellar solution, then came a hexagonal phase and after this a lamellar phase. In general the lysophosphatidylcholines seem to behave similarly to the many soaps and detergents as they show the same sequence of isotropic micellar solution, hexagonal phase, lamellar phase with interspersed cubic phases. The presently established phase diagrams demonstrate that the major lysophosphatidylcholines which may be generated by phospholipase A2 in mammalian cell membranes, viz. 1-palmitoyl- and 1-stearoyl-glycerophosphocholines differ greatly in their packing properties. The extraordinary ability of 1-palmitoyl-glycerophosphocholine to form a cubic phase in equilibrium with a micellar solution is of particular interest with regard to the possible occurrence of cubic structures in biomembranes during the process of fusion.
Multinodular amyloid deposits localized in non-neoplastic adrenal glands were found incidentally at autopsy in an 83-year-old Japanese man. Clinically, the patient lacked evident deficiency of adrenal hormones. The nodules of the stromal amyloid deposits were scattered in the adrenal cortex, where the parenchymal cells were compressed and atrophic. The deposits were confirmed to be amyloid by Congo red staining and polarization microscopy. Amyloid fibrils were also demonstrated in the deposits by electron microscopy. The amyloid deposits were permanganate-sensitive and showed immunohistochemical staining for serum amyloid P component and serum amyloid A protein (SAA), implying that they were AA amyloid. There have been no reports describing localized amyloid deposits of the AA type in non-neoplastic adrenal glands. The pathogenesis and clinical significance of the amyloid deposition in the present case remain only speculative.
BACKGROUND: Although nephrotoxic in high doses, ethylene glycol (EG) has been used with ammonium chloride (NH(4)Cl) or vitamin D(3) to study calcium oxalate stone formation in rat models. In the present study we used EG alone or with NH(4)Cl to study hyperoxaluria, crystaluria, and crystal attachment to renal epithelial cells in rats with minimal renal damage. METHODS: Six-week-old male Sprague-Dawley (SD) rats were given food and special drinking water. In experiment 1 the drinking water contained 1.0% NH(4)Cl plus four different concentrations of EG (0.8%, 0.4%, 0.2%, 0.1%). In experiment 2 the drinking water contained EG alone (0.8%, 0.4%, 0.2%, 0.1%). Urine was collected for 24 h before the rats were sacrificed. In experiment 1 the rats were sacrificed 5-13 days after starting the special water. In experiment 2 the rats were sacrificed 7-21 days after starting the special water. Bladder urine was also obtained. Blood and urine were tested for calcium, phosphorus, and creatinine. In addition, urine was tested for pH, oxalate and N-acetyl-beta-D glucosaminidase (NAG). Kidney sections were stained with hematoxylin-eosin, von Kossa and Pizzolato stain. Crystal morphology was determined using polarizing microscopy, and composition was determined using high-resolution X-ray powder diffraction. RESULTS: Experiment 1: Aggravation of renal function, an increase in urinary oxalate and NAG excretion, and crystals observed in the kidneys all correlated with EG concentration and length of drinking time. In bladder urine, calcium oxalate monohydrate (COM) crystals exceeded calcium oxalate dihydrate (COD) crystals. Experiment 2: Renal function remained unchanged. Oxalate excretion increased and NAG increased slightly. Crystals occurred only in the papillary tip region. Crystals in bladder urine were mostly COD. CONCLUSION: In the current rat model, calcium oxalate crystaluria could be induced without severe renal damage in selected cases. Either and/or both COM and COD might form and interact with kidney epithelium. We propose different experimental conditions to study the various phases of calcium oxalate stone formation in young male SD rats.
We report a patient with trichothiodystrophy associated with autism, mental retardation, and seizures. The diagnosis was based on the presence of brittle hair, with a marked decrease in sulfur-rich amino acid content, and characteristic features such as "tiger tail" under polarizing microscopy and trichoschisis under scanning electron microscopy. Macroscopic alterations were mostly observed in the frontal and occipital hair, with only microscopic abnormalities in the occipital hair. We consider this an unusual expression of this disease.