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Compression and crevasses are common cutting artefacts in cryo-ultramicrotomy of vitreous sections. They can be reduced or suppressed under optimal cutting conditions. In the present study, compression and thickness were measured for different cutting speeds and knife angles. It was found that compression decreased with feed and that crevasses appeared only above a certain thickness. The optimal feed for vitreous sections was between 50 and 80 nm. The thickness, calculated by two independent methods, was quantitatively related to feed and compression.

Congenital transmission of T. spiralis infectio in BALB/c mice was studied. Pregnant mice were each infected with 300 larvae 5, 7, 15 and 17 days after fertilization. Newborn mice were examined by artificial digestion of muscles. Out of 6 offspring born to the mother-mouse infected 7 days after fertilization, two offspring were found to be infected, 7 and 24 larvae were recovered respectively. Other 7 female mice were first infected with T. spiralis larvae and then gestated, only the offspring born to the mother-mice fertilized 8 and 22 days after infection were found to be infected with a larval burden ranging from 1–3 larvae per animal. All of the larvae recovered from the offspring were the non-encapsulated larvae. The cross-fostering in which one-day old young born to healthy mother-mice were nursed by infected mothers for 21 days, showed that no young were found to be infected. These findings showed that tansplacental transmission of T. spiralis could occur in mice, if the female were infected during mid-pregnancy or fertilized in 1 month after infection (e.g., infected in one month before fertilization). The larvae transmitted from maternal-to-neonatal mice may be migrating. Transmammary transmission of T. spiralis was not observed.

Three calix[4]arene derivatives: 5, 11, 17, 23-tetra-tert-butyl-25, 27-dibutoxy-26, 28-diundecenyloxy calix[4]arene (C[4]B), 25, 27-dibutoxy-26, 28-diundecenyloxy calix[4]arene (p-H-C[4]B) and 5, 11, 17, 23-tetra (N, N-diethyl aminomethyl)-25, 26, 27, 28-tetra (ω-undecenoxy) calix[4]arene (p-DEAM-C[4]U) were used as gas chromatographic stationary phases mixed with OV-1701. All of them showed excellent selectivity to positional isomers especially aromatic isomers. The relationship between the structure and gas chromatographic properties of these calixarene stationary phases are discussed. It was found that the tert-butyl groups on the upper rim of calix[4]arene play important role in the recognition of solutes, which favor the inclusion of guest molecules by calix[4]arene during the retention process. Thermodynamic parameters were used to further the comprehension of the retention mechanism of solutes by these calix[4]arene derivatives.

Two new kinds of calix[4]arene derivatives, 5,11,17,23-tetra-tert-butyl-25,27-bis(isopropylcarbamoyl-methoxy)-26,28-diundecenyloxy calix[4]arene (C[4]A) and 25,27-dibutoxy-5,11,17,23-tetra-tert-butyl-26,28-diundecenyloxy calix[4]arene (C[4]B), have been synthesized for use as stationary phases in capillary gas chromatography with OV1701. These stationary phases demonstrate high column efficiencies, wide operating temperature ranges, good thermal stability and excellent selectivity for aromatic isomers, especially phenol compounds. Their inclusion properties are also discussed.

We have measured the magnetoresistance curves of a silver‐clad Bi (2223) tape below critical temperature Tc over a magnetic field range up to 8 T. At temperatures well below Tc the magnetoresistive transition can be well described by a thermally activated flux flow (TAFF) process. The activation energies inferred from such dissipation measurements are found to have the form U=U0+U’ (H,T), where U0 is magnetic field and temperature independent, U’ (H,T) is proportional to (1−T/Tc)n/H. At temperatures very close to Tc the TAFF dissipation can no longer be found and the magnetoresistance seems to be determined by the combination of viscous flux flow and thermal fluctuation.

Shoulder complaints are caused by suprascapular neuropathy in 1-2% of patients. This rare condition is characterised by slowly progressing shoulder pain, which has as a consequence restriction of movement and loss of strength. The most frequent causes are tear of the rotator cuff or a space occupying lesion.A 30-year-old man presented with slowly arising shoulder pain with subsequent also loss of strength and atrophy of the shoulder. A MRI scan of the shoulder showed a cyst in the glenoid cavity. Using EMG suprascapular neuropathy was diagnosed. The cyst was removed by operation and the patient recovered well.The diagnosis 'suprascapular neuropathy' was made using EMG. Space occupying lesions of the shoulder can be excluded by X-ray and MRI. The treatment is primarily conservative, with physiotherapy and pain management.

A 31-year-old sailor came to the hospital with a bursted wound of his left hallux. Earlier that day, he had cut his left hallux and the wound had already been stitched elsewhere. On physical examination a dangling left hallux was observed and a ruptured tendon of the M. extensor hallucis longus.

Detailed measurements of voltage‐current (V‐I) curves and magnetoresistance (R‐H) for Bi(2223) thick film were carried out for various temperatures and magnetic fields. The results indicate that a flux lattice melting transition takes place as the temperature and the field are raised. This transition boundary in the (H,T) phase diagram was found to follow the irreversibility line described by the function of H=H0(1−T/Tc)3/2. Above this line, the V‐I curves display a flux‐flow‐like character. Temperature and magnetic field dependencies of flow resistance Rf‐T and Rf‐H show a varied viscosity in different temperature and field ranges. Below this line, V‐I curves in the low voltage region present a thermally activated flux creep property. The R‐H measurements indicate that the fields at the onset and the midpoint of the magnetoresistive transition also follow a (1−T/Tc)3/2 dependence.

Two crown ethers, di(tert-butylbenzo)-propyl-15-crown-5 polysiloxane (PSO-DTB-15C5) and dibenzo-propyl-15-crown-5 polysiloxane (PSO-DB-15C5) have been synthesized and coated onto fused-silica capillary columns. The chromatographic characteristics, including column efficiency, polarity, phase transition temperature, operating temperature range and selectivity, were studied.

Compression and crevasses are common cutting artefacts in cryo-ultramicrotomy of vitreous sections. They can be reduced or suppressed under optimal cutting conditions. In the present study, compression and thickness were measured for different cutting speeds and knife angles. It was found that compression decreased with feed and that crevasses appeared only above a certain thickness. The optimal feed for vitreous sections was between 50 and 80 nm. The thickness, calculated by two independent methods, was quantitatively related to feed and compression.

The solid phase microextraction (SPME) has the advantages of high efficiency, high sensitivity, simple operation and solvent free operation for analyzing environmental samples. An optical fiber coated with mixed stationary phase of polysiloxane and polymeric fullerene (in ratio of 4:1) was used to extract 5 phthalic diesters by HS-SPME-GC. The operating conditions of SPME such as the extraction temperature, ionic strength of solution, adsorption time and desorption time have been studied. It was compared with commercial polymer coating PDMS fiber through headspace SPME combined with GC. The results indicated that OV-1/PSO-C60 was better than PDMS in extracting high boiling point and semi-volatile phthalic diesters. For phthalic diesters, the detection limits were in the range of 0.331 ng/L-12.5 micrograms/L, and relative standard deviations were below 12% except for dinonyl phthalate.

Carbon nanotubes (CNTs) have been successfully produced from 10 typical Chinese caking-coals using an arc plasma technique. For comparison, one caking coal from New Zealand is also tested. The results show that all coals tested can be used to produce significant quantities of CNTs with fullerenes as by-products. The CNTs are examined using scanning electron microscope and high resolution transmission electron microscope. It has been found that the yields of CNTs are closely related to coal properties. The CNT yield increases as the fixed carbon content in coal increases or as the volatile matter content in coal decreases. © 2002 Published by Elsevier Science Ltd.

We studied the effects of the neurotoxin, 6-hydroxydopamine (6-OHDA), on cultured fat-storing cells (FSCs) and hepatocytes. If either FSCs or hepatocytes were exposed to 6-OHDA for 4 hr, the neurotoxicant induced cell death in FSCs but not in hepatocytes. We decided to investigate why hepatocytes were refractile to injury from 6-OHDA while FSCs were labile. The activity of antioxidant enzymes within FSCs grown in vitro is remarkably lower than the activity in hepatocytes. Indeed, some specific antioxidant enzymes in FSCs were undetectable by our assays, but were easily detected in hepatocytes. Furthermore, the profile of antioxidant activity in FSCs was found to be almost identical to the profiles seen in cultured fibroblasts or myocytes. However, indirect immunolocalization of tyrosine hydroxylase in FSCs using anti-tyrosine hydroxylase antibodies was negative. Mazindol, a dopaminergic receptor antagonist, did not alleviate the toxicity of 6-OHDA suggesting that FSCs do not appear to possess a dopaminergic receptor. When the cell morphology of FSCs was examined by an indirect immunofluorescence technique, treatment of FSCs with 6-OHDA at a concentration of 200 microM for 2 hr modified the organization of alpha-smooth muscle actin into an irregular punctate pattern. Indeed, we found that the effects of 6-OHDA on cytoskeletal alterations and on the cell viability of FSCs were irreversible. These data suggest that : (1) 6-OHDA can cause irreparable injury to FSCs, but not hepatocytes; (2) hepatocytes are specially adapted to withstand an oxidative attack in contrast to FSCs. fibroblast and myocytes; (3) FSCs resemble other somatic cells in their low levels of antioxidant enzymes; and (4) this low profile of antioxidant activity may be responsible for the cell death and cytoskeletal alterations observed in FSCs in response to 6-OHDA.

Two distinct receptors, which bind both tumor necrosis factor-alpha and tumor necrosis factor-beta (TNF-alpha and TNF-beta), have been previously identified and cloned from transformed cells. The present study identifies a novel receptor subtype in normal human liver which binds TNF-alpha but not TNF-beta. TNF-alpha but not TNF-beta competes for 125I-TNF-alpha binding and incorporation into affinity-labeled complexes in human liver plasma membranes (HLPM). Antisera to the cloned receptors competed for 125I-TNF-alpha binding to plasma membranes isolated from various transformed cell lines but not to HLPM. However, mRNAs corresponding in size to both known TNF receptors were detected in liver RNA, making it likely that post-transcriptional modifications account for the TNF-alpha specificity of HLPM. These observations suggest that the effects of TNF-alpha and TNF-beta on some normal tissues may be more distinct than previously realized.

The initiation of mRNA translation is regulated by the reversible phosphorylation of several initiation factors. We report here that tumor necrosis factor-alpha (TNF) rapidly stimulates phosphorylation of one such factor, an mRNA cap binding protein, in several cell types which are important in vitro models of TNF action. This protein has been purified, sequenced, and identified as the proto-oncogene product eukaryotic initiation factor 4E. These data show that phosphorylation of a key component of the cellular translational machinery is a common early event in the various actions of TNF in diverse cell types.

A population of latent (cryptic) receptors for tumor necrosis factor-alpha (TNF) has been characterized in the rat liver plasma membrane (PM). 125I-TNF bound to high (Kd = 1.51 +/- 0.35 nM) and low (Kd = 13.58 +/- 1.45 nM) affinity receptors in PM. Solubilization of PM with 1% Triton X-100 prior to incubation with 125I-TNF increased both high affinity (from 0.33 +/- 0.04 to 1.67 +/- 0.05 pmol/mg of protein) and low affinity (from 1.92 +/- 0.16 to 7.57 +/- 0.50 pmol/mg of protein) TNF binding without affecting the affinities for TNF. Digestion of intact PM with chymotrypsin abolished most of the TNF binding capacity of PM. However, substantial binding activity was recovered by solubilization of chymotrypsin-treated PM with 1% Triton X-100, suggesting the presence of a large latent pool of TNF receptors. The affinities of the high and low affinity sites recovered from chymotrypsin-treated membranes were similar to those of intact PM. Affinity labeling of receptors whether from PM, solubilized PM, or membranes digested with chymotrypsin and then solubilized resulted in cross-linking of 125I-TNF into Mr 130,000, 90,000, and 66,000 complexes. Thus, the properties of the latent TNF receptors were similar to those initially accessible to TNF. To determine if exposure of latent receptors is regulated by TNF, 125I-TNF binding to control and TNF-pretreated membranes was assayed. Specific binding was increased by pretreatment with TNF (p less than 0.05), demonstrating that hepatic PM contains latent TNF receptors whose exposure is promoted by TNF. Homologous up-regulation of TNF receptors may, in part, be responsible for sustained hepatic responsiveness during chronic exposure to TNF.

During development, the cardiac alpha 1-adrenergic chronotropic response changes from positive in the neonate to negative in the adult. The negative chronotropic effect of alpha 1-adrenergic stimulation in the adult depends on maturation of sympathetic innervation and the presence of a pertussis toxin (PT)-sensitive guanine nucleotide-binding (G) protein. To examine the possibility of a developmental change in coupling of a PT-sensitive G protein to the alpha 1-adrenergic receptor, radioligand binding experiments with the iodinated alpha 1-selective radioligand [125I]-I-2-[beta-(4-hydroxyphenyl)ethylaminomethyl]tetralone ([ 125I]-IBE 2254) were performed on membranes prepared from control and PT-treated neonatal and adult rat hearts. Scatchard analysis showed fewer alpha 1-adrenergic receptors in the adult than in the neonate (168 +/- 10 fmol/mg protein in the neonate vs. 124 +/- 13 fmol/mg protein in the adult), but similar affinities (equilibrium dissociation constant 124 +/- 29 pM in the neonate vs. 140 +/- 34 pM in the adult). PT treatment did not alter the results. In both the neonate and adult, 5'-guanylylimidodiphosphate [Gpp(NH)p, 500 microM] shifted the l-epinephrine competition curve to the right and increased the slope factor toward unity. PT had no effect on the l-epinephrine competition curve in the neonate. However, in the adult PT itself caused a partial shift in the agonist competition curve, reducing but not eliminating the effect of Gpp(NH)p. Consistent with the results from the binding experiments, PT did not have any effect on the alpha 1-adrenergic-mediated positive chronotropic response in the neonate, whereas in the adult the alpha 1-adrenergic-mediated negative chronotropic response was completely converted to a positive one after PT treatment. These results indicate the presence of a PT-insensitive G protein in the neonatal and adult rat heart and the acquisition of a PT-sensitive G protein linked to the negative chronotropic response during development.