Enhancing conductivity of metallic carbon nanotube networks by transition metal adsorption.

The conductivity of carbon nanotube thin films is mainly determined by carbon nanotube junctions, the resistance of which can be reduced by several different methods. We investigate electronic transport through carbon nanotube junctions in a four-terminal configuration, where two metallic single-wall carbon nanotubes are linked by a group 6 transition metal atom. The transport calculations are based on the Green's function method combined with the density-functional theory. The transition metal atom is found to enhance the transport through the junction near the Fermi level. However, the size of the nanotube affects the improvement in the conductivity. The enhancement is related to the hybridization of chromium and carbon atom orbitals, which is clearly reflected in the character of eigenstates near the Fermi level. The effects of chromium atoms and precursor molecules remaining adsorbed on the nanotubes outside the junctions are also examined.

Robust acceleration of self consistent field calculations for density functional theory.

We show that the type 2 Broyden secant method is a robust general purpose mixer for self consistent field problems in density functional theory. The Broyden method gives reliable convergence for a large class of problems and parameter choices. We directly mix the approximation of the electronic density to provide a basis independent mixing scheme. In particular, we show that a single set of parameters can be chosen that give good results for a large range of problems. We also introduce a spin transformation to simplify treatment of spin polarized problems. The spin transformation allows us to treat these systems with the same formalism as regular fixed point iterations.

Partial purification and some properties of a new papain inhibitor from psoriatic scales.

A new papain inhibitor was purified from psoriatic epidermal scales using gel chromatography and anion exchange chromatography. The purified protein inhibited papain and ficin but not cathepsin B, cathepsin H, trypsin, or chymotrypsin. Isoelectric focusing revealed 3 major inhibitor variants with pI's of 7.3, 6.9, and 6.5. A Mr of 38,000 was obtained by a gel chromatographic method for the crude inhibitor. After sodium dodecyl sulfate-polyacrylamide gel electrophoresis the Mr values of the isoelectric variants were: 43,000 for the variant pI 7.3, 43,000 and 35,000 for the variant pI 6.9, and 34,000-35,000 for the variant pI 6.5. An antiserum of the inhibitor was used to locate the inhibitor in the psoriatic and normal epidermis. In psoriatic epidermis, the inhibitor was found in the peripheral cytoplasm of spinous cells and in the scale. In normal epidermis, the staining was seen only in orifices of hair follicles. An inhibitor with similar size and antigenic properties to that isolated from the psoriatic scales was demonstrated in extracts made from the whole-thickness epidermis but not in extracts from the healthy epidermal scales, the dermis, the liver, the spleen, or the blood serum.

Antisense RNA inhibition of cathepsin L expression reduces tumorigenicity of malignant cells.

Several tumour-forming cell lines are known to overproduce the lysosomal cysteine peptidase cathepsin L. We have used an antisense approach to investigate whether inhibition of cathepsin L overexpression in two malignant cell lines (myeloma SP cells and L cells) reduces their tumorigenic potential. Two different cDNA fragments of murine cathepsin L were inserted in the antisense direction into the pcDNA3 vector, and SP and L cells were stably transfected with these plasmid constructs. Several of the selected clones expressing the antisense transcript showed specific reduction of the mRNA level and the intracellular activity of cathepsin L, and a greatly diminished amount of secreted procathepsin L. When tested in Balb/c nu/nu mice, the cell lines with low cathepsin L activity exhibited a significantly decreased potential for tumour growth when compared with control cells expressing wild-type levels of cathepsin L activity. This observation suggests that cathepsin L is a critical factor in tumour growth.

Detection of low molecular weight cysteine proteinase inhibitors by time-resolved fluoroimmunoassay.

A time-resolved fluoroimmunoassay was developed for the detection of 3 human low molecular weight cysteine proteinase inhibitors, ACPI (cystatin A), NCPI (cystatin B), and gamma-trace (cystatin C). Polystyrene tubes or polystyrene microtitration strips were used as solid phase. The rabbit anti-inhibitor immunoglobulins were used as the capture antibody, and, when labelled with europium, also as the detector antibody. The threshold sensitivity of the tests was 0.1 ng/ml for NCPI and 1 ng/ml for the others. All the 3 cysteine proteinase inhibitors, ACPI, NCPI, and gamma-trace, were detected in pooled serum samples of patients with kidney failure. gamma-Trace seemed to be quantitatively the major and ACPI the minor inhibitor. No other low molecular mass cysteine proteinase inhibitor was detected after isoelectric focusing of the 12 kDa area of gel filtered human serum.

Expression of the 43 kDa papain inhibitor during human fetal skin development.

The presence of the 43 kDa papain inhibitor protein in the skin of 40 fetuses with the gestational age varying from 9 to 40 weeks was studied. Immunohistochemistry showed the first evidence of the 43 kDa papain inhibitor in the acral parts, mostly in the nail bed, at the 14th week when the epidermis in all other sites was not stained. Staining of the follicular infundibulum as well as some parts of the uppermost epidermis and keratin layer was observed from 17 to 40 weeks. The staining was most intensive at 20-30 weeks gestational age, and later the intensity gradually decreased so that in the full-term newborn the 43 kDa papain inhibitor was hardly detectable or absent. It was concluded that the 43 kDa papain inhibitor is present in fetal skin at the stage of stratification (9-14 weeks) only in the nail region and its volar surroundings. It appears at the stage of interfollicular keratinization (14-24 weeks) in the uppermost epidermis, especially in the appendical openings and its amount seems the decrease during the stage of interfollicular keratinization (24 weeks--full-term). The expression of 43 kDa inhibitor protein is temporally related to that of filaggrin.

Failure of oral inosiplex treatment of recurrent herpes simplex virus infections.

A compound, a mixture of acedoben, dimepranol, and inosine (inosiplex) was used to treat recurrent local herpes simplex virus (HSV) infections in a double-blind placebo-controlled crossover study. Altogether, 58 patients with a history of frequently recurrent HSV infections were examined. Eighteen selected patients participated in the drug trial. Ten patients received both inosiplex and placebo, three received only inosiplex, and five received only the placebo. Three patients received both placebo and inosiplex twice. No substantial differences between the treatments with inosiplex or placebo could be seen in the frequency of occurrence or healing of the local lesions, nor in the results of these patients' immunologic studies. An evident placebo effect was observed, since only 15 (26%) of the 58 subjects examined continued to have an often relapsing form of the disease when followed up regularly.

Inactive cathepsin B-like enzyme in human melanoma culture medium.

An inactive cathepsin B-like enzyme with a molecular mass of 40 kD was found in a human melanoma culture medium. The inactive form of this enzyme was converted into an active form with a molecular mass of 28 kD by pepsin treatment. This activated cathepsin B-like enzyme had almost the same characteristics regarding molecular size, substrate specificity, dependence on chemical reagents, and Km values as intracellular cathepsin B. Sodium dodecylsulphate polyacrylamide gel electrophoresis followed by electroblotting with an antiserum against cathepsin B yielded inactive cathepsin B-like enzyme fractions which showed two immunoreactive bands with molecular masses of 40 and 28 kD, respectively. On the other hand, alkali treatment of the inactive cathepsin B-like enzyme fractions released a cysteine proteinase inhibitor with a molecular mass of 12 kD. These data suggest that these inactive cathepsin B-like enzymes in melanoma culture medium are present not only in the precursor form, but that they are also present as enzyme-inhibitor complexes, both of which can be activated enzymatically in vitro.

No evidence of human papillomavirus DNA in actinic keratosis.

Human papillomaviruses (HPVs) are involved in premalignant and malignant skin diseases as well as in a variety of benign cutaneous and mucosal lesion disease. Its association with HPV infection has recently been evaluated in a few studies, but the results are contradictory. For further assessment of the role of HPVs in AK, a series of 100 paraffin-embedded biopsy specimens taken from subjects with AK were studied for the presence of HPV types 1, 2, 3, 4, 5, 7, 12, 15, 26, 36, 37 and 59 DNA using in situ hybridization (ISH) under high stringency conditions (Tm -10 degrees C). All specimens were definitely negative for all bion specimens were definitely negative for all biotinylated HPV DNA probes tested. One fifth of the specimens were studied using the polymerase chain reaction (PCR) with general primers to confirm the negative results. All cases were also in the PCR. Our results suggest that HPVs are not directly involved in the aetiology of AK.

Known HPV types have no association with keratoacanthomas.

Certain HPV types have been linked to the genesis and development of premalignant and malignant skin diseases. There have been several contradictory reports on the role of HPV infections in the development of keratoacanthomas (KAs). To further study the involvement of HPVs in the aetiology of KAs, we investigated paraffin-embedded specimens of 80 biopsies of KAs for the presence of HPV 1, 2, 3, 4, 5, 7, 26, 37, 38, 47 and 59 DNA by in situ hybridization (ISH) with biotinylated probes under high stringency conditions (Tm-10 degrees C). Every fourth biopsy specimens was also examined by polymerase chain reaction (PCR) with consensus primers targeting the HPV E1 and L1 regions. The positive cases were further studied by direct DNA sequencing. All specimens proved to be negative for all HPV DNAs studied by ISH. Three out of 20 cases produced in positive PCR amplifications when consensus primers targeting the L1 region were used. However, the same samples remained negative with general primers targeting the E1 region. The DNA sequence analysis of the PCR-positive products showed a 76% homology with HPV type 17. Our results suggest that the known HPV types are unlikely to have any role in the aetiology of KAs.

Expression of PCNA is associated with the presence of HPV DNA in skin warts.

A series of 90 excised cutaneous warts (verrucae vulgaris) were studied for the presence of HPV (human papillomavirus) DNA using in situ hybridization (ISH) with biotinylated full genomic DNA probes of HPV types 1, 2, 3, and 4. The expression of PCNA (proliferating cell nuclear antigen) was examined using conventional immunohistochemistry. The aim was to test the hypothesis that HPV can reactivate PCNA, including in the host replication machinery. HPV DNA of the above types was detected in 60 of 90 verruca biopsies studied (66.7%): HPV 2 in 56 cases, HPV 1 in 2 cases, and HPV 3 in 2 cases. PCNA was expressed in all samples except two. The signal distribution of HPV DNA markedly differed from that of PCNA expression. ISH revealed strong HPV DNA signals in both the granular and the upper spinous cell layers, the most intense signals being detected in the upper epidermis. On the other hand, nuclear PCNA staining was present in the majority of parabasal and basal cells. Although strong PCNA signals within the wart lesions were found in the areas where HPV DNA was present, the PCNA positivity was almost invariably localized in the differentiated cells of the spinous cell layers, just below the HPV DNA-expressing cells. At the margins of the lesions, PCNA expression was still strong but disappeared abruptly towards the normal epidermis. HPV DNA-positive warts showed more intense expression of PCNA than did the HPV DNA-negative ones in this study. Our results indicate that PCNA induction is associated with the presence of HPV DNA, suggesting that HPV can reactivate PCNA, thus interfering with the host cell DNA replication machinery.

Failure to demonstrate human papillomavirus (HPV) involvement in Bowen's disease of the skin.

To assess the role of human papillomavirus (HPV) in the aetiology of extragenital Bowen's disease (EBD), a series of 91 cases were analysed using in situ hybridization (ISH) with whole genomic DNA probes of HPV types 1, 2, 4, 6, 7, 11, 12, 15, 16, 18, 26, 36, 37, 39, 42, 55 and 59. No HPV DNA was found in any of the samples tested. A polymerase chain reaction (PCR) was also used to analyse 37 of the 91 samples, using both the consensus primers MY09/MY11 which amplify a large number of HPV types from the L1 region and the degenerate primers CP65/CP70, which amplify the complete set of epidermodysplasia verruciformis (EV) HPV types. All the cases were also negative in the PCR. The results suggest that EBD is not HPV-related, at least in immunocompetent patients.

Separation and partial characterization of four cysteine proteinases from a human epidermal cell line.

Four different cysteine proteinases from a cultured human epidermal cell line (NCTC 2544) were partially purified and characterized. The biggest hydrolase was an endoaminopeptidase with the molecular weight of several hundred kilodaltons. It was a glycoprotein and had an almost neutral pH optimum. The three other hydrolases resembled lysosomal cathepsins B, H, and L in various respects except for somewhat higher molecular weight for cathepsin B (29 kDa) and the cathepsin H-like (70 kDa) hydrolase than those reported from most other tissues. Low molecular weight cysteine proteinase inhibitors ACPI (cystatin A) and NCPI (cystatin B) inhibited the cathepsins, but not the high molecular weight proteinase.

A 43-kDa papain inhibitor produced by a cultured human epidermal cell line.

Epidermis-derived cells (NCTC 2544) were cultured and the proteins of the culture medium, as well as of the cells, were fractionated by gel-chromatography. The fractions were analyzed for their papain-inhibitory capacity and for the presence of so-called 43-kDa papain inhibitor. A papain inhibitor was identified with molecular weight and immunological characteristics similar to the original 43-kDa inhibitor that was isolated from psoriatic scales. The result proves that NCTC-2544 cells can produce the so-called psoriasis inhibitor under culture conditions.

Cysteine proteinase inhibitors in psoriatic epidermis.

Human psoriatic epidermis and scales were demonstrated to contain two antigenically separate cysteine proteinase inhibitors, one acidic with an isoelectric point of 4.7-5.0 (ACPI) and one neutral with an isoelectric point of 6.0-6.5 (NCPI), while normal epidermis contains only ACPI. The total papain (cysteine proteinase) inhibiting activity of the psoriatic epidermis as calculated per mg protein was higher than that in normal epidermis. Both ACPI and NCPI were localized immunocytochemically, mainly in the highest spinous cell layers with less activity in the parakeratotic cells and lower layers of spinous cells. Basal cells were essentially negative.

Proteinase binding and enhancing factor from human skin.

Fresh human skin extract made in salt solution after a prior buffer extraction was shown to enhance the hydrolysis of N-alpha-benzoyl-DL-arginine beta-naphthylamide (BANA) by trypsin. This trypsin enhancing effect was further shown to be both stabilizing and activating. After chromatography on Sephadex G-100, the trypsin binding factor was found in fractions of void volume. Protease binding took place in physiological and hypotonic but not in hypertonic NaCl-solutions (0.5 mol/l). The proteinase binding factor was further purified by trypsin-Sepharose 4 B affinity chromatography. It was found to bind also chymotrypsin and elastase and to be thermostable (100 degrees C for 20 min), precipitable at acidic pH (3.5), and by acetone and ammonium sulphate (60% saturation). The bound proteinases were found to preserve their hydrolytic activity towards protein substrates. Bound trypsin and chymotrypsin could completely be inhibited by soybean trypsin inhibitor. The binding factor did not react with anti-human-alfa2-macroglobulin antiserum from rabbit.

Plasminogen activators of psoriatic scale extracts. Separation of two plasminogen activators by isoelectric focusing.

Psoriatic scale extracts were fractioned by using polyacrylamide gel isoelectric focusing (PAGIF) and preparative electrofocusing in granulated gel (PEGG). The largest protein fraction was found with Ip at pH 4.8--5.0, and the main protein bands within pH values 4.0--7.5. PEGG separated three main fractions with plasminogen activator or trypsin-like esterase activity with isoelectric points at pH 6.5--6.6, 5.4--6.2 and 4.9. The enzyme with Ip at pH 6.5--6.6 hydrolyzed trypsin substrates but lacked plasminogen activator capacity. The enzyme with Ip at pH 5.4--6.2 showed both activities but the third enzyme with plasminogen activator capacity with Ip at pH 4.9 was without detectable esterolytic activity towards substituted basic amino acid esters. The third enzyme was prominent in KCl-extract and the second in KSCN-extract. The first was equal in both extracts. The enzyme with Ip at pH 4.9 is possibly of bacterial origin while the plasminogen activator with Ip at pH 5.4--6.2 extracted in KSCN probably represents tissue activator of psoriatic scales.

Production of acid and neutral cysteine-proteinase inhibitors by a cultured human skin epithelium cell line.

Human skin epithelial-like cells (NCTC-strain 2544) were grown in RPMI-1640 medium supplemented with foetal calf serum for up to 2 weeks. The culture medium and extracts made from the cells were subjected to gel-filtration chromatography in a Sephacryl S-200 column for fractionation of the proteins. The fractions were assayed for acid and neutral cysteine-proteinase inhibitor (ACPI, NCPI) using time-resolved fluoroimmunoassay and radioimmunoassay, and the cysteine-proteinase-inhibiting activities were assayed using papain. Free NCPI, i.e. a molecule with isoelectric variants at pHs 6.0 and 6.5, which has an Mr of around 12,000 and is capable of inhibiting papain, was detected both in the culture medium and in the cells. Immunodiffusion studies revealed its immunological identity with human spleen-derived NCPI. The amount of NCPI increased during the incubation period. ACPI--characterized as a molecule having an isoelectric point of 4.9, an Mr of about 12,000, papain-inhibiting capacity and antigenic reactivity with spleen-derived ACPI--was not detected in the culture medium. It was, however, detected in the cells after 2 weeks in culture. These data prove that ACPI and NCPI are synthesized by the NCTC-2544 cells under the present culture conditions.

Purification and characterization of a cystatin-type cysteine proteinase inhibitor in the human hair shaft.

We found a cysteine proteinase inhibitor in human hair shaft extract treated with 0.01 M Tris HCl buffer, pH 8.0. A yield of 0.2 mg of purified cysteine proteinase inhibitor was obtained from 86 g of hair shaft. The cysteine proteinase inhibitor had a molecular mass of 13 kDa as determined by high-performance liquid chromatography and sodium dodecyl sulfate polyacrylamide gel electrophoresis. It was more stable to heat and pH than most proteins and had a pI of 4.7. Immunologically, its antigenicity was the same as that of cystatin A, but differed from that of cystatin B and C, and kininogen. The amino-acid sequence of the first 30 residues from the NH terminus of the inhibitor was identical to that of cystatin A from human epidermis. Hair shaft cysteine proteinase inhibitor is thus considered to be identical to epidermal cystatin A.

A method for the hyaluronic acid synthetase assay in human skin.

A method for the determination of hyaluronic acid synthetase activity of human skin is described. Skin samples were crush-homogenized, and incubated with UDP-14C-glucuronic acid and UDP-N-acetylglucosamine in Tris-HCl-buffer containing MgCl2. After papain digestion of the samples, the 14C-labeled hyaluronic acid was separated in Sephadex G 50 chromatography. The radioactivity incorporated into hyaluronic acid was an expression of the activity of hyaluronic acid synthetase. This activity was found to be increased in skin biopsies obtained from psoriatic lesions and decreased after local treatment with potent corticoids.