[Computed tomography of the ethmoid labyrinth and adjacent structures]

In order to study the relation of ethmoid labyrinth to the adjacent structures, continuous axial CT scan of the ethmoid labyrinth was performed on 9 normal subjects. Meanwhile, coronal and axial CT scans of ethmoid labyrinth were obtained in 20 normal subjects. On an average, 22 scan sections were done on each subject. The relation of ethmoid labyrinth to adjacent structures was observed and the remarkable intersubject variations in this anatomic area were noted. The relation of posterior ethmoid cells or sphenoid sinus to the optic canal, and the relation of internal carotid artery to the sphenoid sinus were clearly demonstrated on axial scans. The detailed anatomic structure of the ostiomeatal complex and the anatomic relation of ethmoid labyrinth to orbit and anterior skull base were revealed by coronal CT scans. CT scan of the paranasal sinuses was of great importance in clinical practice for the purpose of etiological analysis of sinusitis, design of endoscopic sinus surgery and prevention of complication.

All-optical bistability in doped-polymer film waveguides

All-optical bistability was observed in thin-film waveguides made with acceptor-donor substituted azobenzene-doped poly(methyl methacrylate) polymer. Input-output curves with hysteresis characteristics were measured. The origin of the bistability was attributed to nonlinear coupling between a prism and a doped-polymer waveguide. An approximately theoretical analysis was introduced. Theoretical predictions were qualitatively consistent with experimental results.

Solution structure of the DNA-binding protein Sac7d from the hyperthermophile Sulfolobus acidocaldarius

The Sac7 proteins from the hyperthermophile Sulfolobus acidocaldarius are a heterogeneous mixture of small, thermostable, nonspecific DNA-binding proteins. One of these proteins, Sac7d, has been overexpressed in Escherichia coli to provide a homogeneous preparation for structure, stability, and function studies. We present here essentially complete sequence-specific 1H NMR assignments for Sac7d, a delineation of secondary structural elements, and the high-resolution solution structure obtained from a full relaxation matrix refinement. The final structure provides an excellent fit to the NMR data with an NOE R-factor of 0.27 for backbone NOEs. The structure has a compact globular fold with 82% of the sequence involved in regular secondary structure: an antiparallel two-stranded beta-ribbon with a tight turn, followed by a short 3(10) helix, an antiparallel three-stranded beta-sheet, another short 3(10) helix, and finally four turns of alpha-helix. The amphipathic alpha-helix packs across the hydrophobic face of the three-stranded beta-sheet in an open-faced sandwich arrangement with at least one turn of the helix exposed beyond the sheet. The hydrophobic face of the beta-ribbon packs against a corner of the twisted beta-sheet. The single tryptophan responsible for the 88% fluorescence quenching upon DNA binding is exposed on the surface of the three-stranded beta-sheet. Lysines 5 and 7, whose monomethylation may be associated with enhanced thermostability, are highly solvent exposed along the inner edge of the two-stranded ribbon. The structure of Sac7d differs in many respects from that reported for the homologous native Sso7d [Baumann et al. (1994) Nature Struct. Biol. 1, 808] with a backbone RMSD greater than 3.0 A, largely due to the packing and length of the C-terminal alpha-helix which may be important in Sac7d DNA binding.

Salicylate triggers heat shock factor differently than heat

Sodium salicylate has the unusual property of partially inducing the human heat shock response (Jurivich, D. A., Sistonen, L., Kroes, R., and Morimoto, R. I. (1992) Science 255, 1243-1245). Salicylate induces the DNA binding state of the human heat shock transcription factor (HSF), but this is insufficient to elevate heat shock gene expression. Because it is not known how HSF enhances heat shock gene expression, further analysis of the transcriptionally inert, salicylate-induced HSF was undertaken to potentially identify components of the heat shock response that are necessary for full transcriptional induction. Like thermal stress, exposure of HeLa cells to salicylate led to the induction of HSF1 into a DNA-bound state. Despite continued exposure of cells to salicylate, HSF1.DNA binding attenuated much more rapidly than a continuous heat shock. Western blot analysis revealed that the salicylate-induced form of HSF1 was not hyperphosphorylated like the heat-induced form. Furthermore, supershifts of the HSF1 bound to an heat shock element (HSE) oligonucleotide by monoclonal antibodies to phosphoamino acids revealed that salicylate induced threonine phosphorylation of HSF1, whereas heat led to a predominance of HSF1 serine phosphorylation. These data suggest that salicylate-independent signals are necessary to convert HSF1 into a transactivator of heat shock gene expression and that brief acquisition of DNA binding by this factor is insufficient to maximally enhance transcription.

Light-induced noncentrosymmetry in acceptor-donor-substituted azobenzene solutions

Light-induced noncentrosymmetry was achieved experimentally in acceptor-donor-substituted azobenzene solutions and observed by phase-matched nondegenerate six-wave mixing. The microscopic origin of the induced noncentrosymmetry was found to be orientational hole burning, which was distinguished directly with net orientation of molecules by experimental observations. The decay time of the induced noncentrosymmetry depended on the rotational orientation time of the sample's molecule, which varied linearly with the viscosity of the solvent.

Evidence for u.v. induction of CDKN2 mutations in melanoma cell lines

The CDKN2 gene, encoding the cyclin dependent kinase inhibitor p16, is a tumour suppressor gene involved in melanoma and maps to chromosome band 9p22. Mutations or interstitial deletions of this gene have been found both in the germline of familial melanoma cases and somatically in melanoma cell lines. Previous mutation analyses of melanoma cell lines have indicated a high frequency of C:G to T:A transitions, with all of these mutations occurring at dipyrimidine sites. Including three melanoma cell lines carrying tandem CC to TT mutations, the spectrum of mutations so far reported indicates a possible role for u.v. radiation in the mutagenesis of this gene in some tumours. To further examine this hypothesis we have characterised mutations of the CDKN2 gene in 30 melanoma cell lines. Nineteen lines carried complete or partial homozygous deletions of the gene. Of the remaining cell lines, eight were shown by direct sequencing of PCR products from exon 1 and exon 2 to carry a total of nine different mutations of CDKN2. Two cell lines carried tandem CC to TT mutations and a high rate of C:G to T:A transitions was observed. This study provides further evidence for the role of u.v. light in the genesis of melanoma, with one target being the CDKN2 tumour suppressor gene.

Low-power phase conjugation in push-pull azobenzene compounds

Push-pull azobenzene compounds were synthesized by the diazocoupling reaction, and low-power phase conjugation of azobenzene-compound-doped poly(methyl methacrylate) films was studied with a He-Ne laser at 632.8 nm. It is shown that this kind of polymer has appreciable third-order optical nonlinearity, with a chi((3)) of approximately 10(-4) esu in the tail of absorption.

The anatomy of the lateral cutaneous nerve of the thigh--a possible donor nerve for facial nerve repair

One hundred anterior branches of the lateral cutaneous nerve of the thigh were dissected and measured in 50 adult cadavers. The results show that this nerve was present in all sides, and the average length from the point of the nerve piercing the fascia lata to the point of its first branch was about 79 mm, the average width was 2.25 mm, and the average thickness was 0.79 mm. It was found that the nerve was approximately along the line between the anterior superior iliac spine and the midpoint of the upper margin of the patella. This study presents a simple method of locating this nerve for clinical reference. The results also reveal that this nerve is a possible donor for facial nerve repair.

[Tolerance of reconstructive flaps to postoperative irradiation in oral and maxillofacial regions]

Eighty-three reconstructive flaps in oral and maxillofacial regions irradiated with a dose of 4000 to 7200 cGy were observed for a 2 year follow-up period. It was found that the rates of acute side effects including redswelling erosion and ulceration in the flaps were lower significantly than in neighbor oral mucosa (P < 0.01-0.05). The late radiation side effects of the flaps were uncommon also. The result showed that free flaps were well tolerated to postoperative irradiation of routine dose. Our studies indicate that the preoperative irradiation deficiency of blood supply or purulency were main reasons of the late radiation side effects, e.g. atrophy of epithelia, cicatrization or necrosis of the flap. Base on the results we have designed preventive measures.

Immunofluorescence quantitation of stromelysin in human synovial fibroblasts by confocal laser scanning microscopy

BACKGROUND

Elevated levels of stromelysin have been reported in humans with osteoarthritis and rheumatoid arthritis, as well as in animal models of arthritis. However, a considerable amount of heterogeneity is observed in the expression of this enzyme in pathologic tissues as well as in in vitro systems. To analyze this variability, stromelysin expression was quantitated in individual human synovial fibroblasts (HSF) obtained from osteoarthritis patients.

EXPERIMENTAL DESIGN

HSF were incubated with interleukin-1 (40 units/ml), an agonist known to induce stromelysin, in the presence or absence of dexamethasone (0.01 to 100 nM), an inhibitor of stromelysin transcription. With a stromelysin-specific antibody and a tetramethyl-rhodamine 5-isothiocyanate-labeled secondary antibody, the enzyme was visualized and the fluorescence in individual cells was quantified with an ACAS 570 laser cytometer in confocal mode.

RESULTS

Stromelysin expression varied from one cell to another; however, on the basis of the magnitude of expression of stromelysin by each cell, the "nonresponders" within each treatment were identified. Approximately 34% of the cells showed a higher level of stromelysin expression in IL-1-treated HSF compared with controls. A dose-dependent inhibition in the expression of stromelysin was observed in response to increasing concentrations of dexamethasone. The dose-dependent changes in the accumulation of stromelysin protein correlated well with the stromelysin mRNA expression.

CONCLUSIONS

Confocal laser scanning microscopy can be effectively used to analyze cellular heterogeneity in stromelysin expression.

[Anatomical study of anterior branches of the lateral cutaneous nerve of the thigh]

100 anterior branches of the lateral cutaneous nerve of the thigh were dissected and measured in 50 adult cadavers. The results show that this nerve is present in all sides. The average length from the point of the nerve piercing fascia lata to the point of its first branch is about 79mm, the average width is 2.25 mm, and the average thickness is 0.79 mm respectively. It is found that the course of the nerve is approximately along the line between the anterior superior iliac spine and the midpoint of the patella. This study is benifit to the facial nerve grafting in clinic by providing data of the nerve.

Amplification of the Int-2 gene in head and neck squamous cell carcinoma

Cellular oncogenes have been implicated in head and neck cancer development since 1986. More recently interest has focused on chromosome 11q13; oncogenes therein undergoing ongoing investigation include Bcl-1/Prad-1, Hst-1 and Int-2. Our laboratory has studied the Int-2 oncogene for several years, primarily in the breast. This paper presents our investigations of Int-2 in the head and neck. Thirty-four paraffin-embedded primary squamous cell carcinomas were studied for Int-2 gene amplification using a carefully controlled method of sequence quantification by DNA dot blots. Amplification, mostly low level, was identified in 62 per cent of samples studied. No clinical correlation to amplification could be found. Further studies are underway looking for evidence of expression of Int-2 in fresh tissues and for amplification and expression of other oncogenes on this amplicon.

Dietary fat: gene expression and mammary tumorigenesis

Although discovered as an exogenous agent of mammary carcinoma, the mouse mammary tumor virus (MMTV) is also transmitted vertically as endogenous proviral DNA present in the germ line of all inbred mice. In the C3Hf mouse, which receives no exogenous virus, the initial event of mammary tumorigenesis is the transcription of the endogenous MMTV proviral DNA present at the Mtv-1 locus. Transcription occurs as a result of the hormonal effects of pregnancy, and Mtv-1 specific transcripts are seen in second-parity lactating mammary glands of these mice. As a means of studying the effects of diet on mammary carcinoma at the molecular/genetic level, we have studied the transcription of the Mtv-1 locus in C3Hf mice on a high-fat diet containing 46% fat in calories or a low-fat diet containing 10% fat in calories. We have detected an accelerated transcription of the Mtv-1 locus (first- vs. second-parity lactating mammary glands) in > 50% of the C3Hf mice on the high-fat diet. In addition, mice on the high-fat diet developed mammary tumors earlier (11 vs. 17.8 mos) and after fewer litters (2.1 vs. 4.2). Our results indicate that fat in the diet can affect gene expression related to mammary carcinoma.

Cholinergic neuronal differentiation factor (CDF)/leukemia inhibitory factor (LIF) binds to specific regions of the developing nervous system in vivo

The cholinergic neuronal differentiation factor (CDF)/leukemia inhibitory factor (LIF) promotes survival and/or differentiation of specific neuronal populations in vitro. To investigate the spatial and temporal distribution of CDF/LIF binding sites in the developing rat nervous system, we localized binding of iodinated native rat CDF/LIF by radioautography. We find that specific CDF/LIF binding sites are present in distinct regions of the nervous system at defined developmental stages. CDF/LIF binding is detectable in all sensory ganglia examined, both neural crest- and placode-derived, and in all sympathetic and parasympathetic ganglia examined. In the central nervous system, in contrast, binding is restricted to specific regions in the motor, sensory, and limbic systems. These in vivo results not only support culture studies which suggest CDF/LIF involvement in development of specific populations of neurons, but also suggest new roles played by CDF/LIF.

Homozygous deletion, rearrangement and hypermethylation implicate chromosome region 3p14.3-3p21.3 in sporadic breast-cancer development

DNAs from 19 malignant human breast tumors and 2 benign fibroadenomas were analyzed for heterozygosity at 5 polymorphic loci on the short arm of chromosome 3. One homozygous deletion and one rearrangement were identified using probe D3S2 which maps to 3p14.3-3p21.1. This probe also detected novel hybridizing fragments of 2.0 kb and/or 3.4 kb in 6/18 (33%) of the malignant tumor samples that hybridized with the D3S2 probe following digestion with the 5'-methylcytosine-insensitive enzyme MspI. Comparisons of HpaII and MspI digestion showed that all but one of the tumor DNAs analyzed were hypermethylated. The two fibroadenoma DNAs were not as highly methylated and had hybridizing fragments of 3.4 kb after HpaII digestion. These malignant breast-tumor DNAs exhibit 3 mechanisms by which a tumor-suppressor gene hypothesized to reside at 3p14-3p21 could be inactivated: homozygous deletion, rearrangement and hypermethylation, and strongly implicate this 3p chromosome region in breast-tumor development.

The C. elegans genome sequencing project: a beginning

The long-term goal of this project is the elucidation of the complete sequence of the Caenorhabditis elegans genome. During the first year methods have been developed and a strategy implemented that is amenable to large-scale sequencing. The three cosmids sequenced in this initial phase are surprisingly rich in genes, many of which have mammalian homologues.