Establishment and characterization of two cell lines derived from human transitional cell carcinoma

Two continuous cell lines derived from the neoplastic urothelium had been maintained in culture for more than two years. The first cell line derived from the urothelium of a fusion papillocarcinoma on the left lateral wall of the bladder was designated as TBC-1 and grown in vitro for more than 150 generations. The second cell line derived from the urothelium of a papillocarcinoma in the left renal pelvis was designated as TPC-1 and grown in vitro for more than 100 generations. Characterization studies made on both cell lines showed that the cells had a rapid doubling time, exhibited multilayering and produced tumors in sc of BALB/c. Tumor nodules that produced sc of BALB/c kept similar cellular and pathological features to those of the primary biopsy specimens under light and electron microscopes. TPC-1 cell line exhibited a three-dimensional structure of transitional epithelium on the nylon-mesh disk which was coated with a layer of rat tail collagen. Both TBC-1 and TPC-1 cell lines formed colonies in soft agar. Their forming rates were 35% and 28%, respectively. The chromosome number of TBC-1 cells ranged from 17 to 84, with a modal number of 54; whereas that of TPC-1 cells ranged from 28 to 139, with a modal number of 49. The TBC-1 cells showed mutant p53 and ras p21 protein expression and expressed weakly ABH blood group isoantigens. Analysis of lactic dehydrogenase (LDH) isozymes showed the highest levels of LDH isozyme 4 sonicated cell lysates of TBC-1 and TPC-1 respectively.

New triterpenoid saponins, asterbatanoside D and E, from Aster batangensis

Two new triterpenoid saponins named asterbatanoside D and E have been isolated from Aster batangensis and their structures elucidated as 3-O-beta- D-glucopyranosyl-bayogenin-28-O-beta-D-glucopyranosyl-(1-->6)-beta -D- glucopyranoside and 3-O-6'-acetyl-beta-D-glucopyranosyl-bayogenin-28-O-beta-D- glucopyranosyl-(1-->6)-beta-D-glucopyranoside by means of MS, 1D and 2D NMR techniques (COSY, TOCSY, ROESY, HMQC, and HMBC), and chemical reactions.

Comparative mapping of YRRM- and TSPY-related cosmids in man and hominoid apes

Using chromosomal in situ hybridization it has been demonstrated that specific members of the YRRM and the TSPY families are multicopy and Y chromosome specific in hominoids. After hybridization with the YRRM-related cosmid A5F and the TSPY-related cosmids cos36 and cY91, a reverse and complementary pattern of main and secondary signals is detected on the Y chromosomes of the human, the pygmy chimpanzee and the gorilla, while the location of signals coincides on the Y chromosomes of the chimpanzee, both orang-utan subspecies and the white hand gibbon. This complementary distribution of YRRM and TSPY sequences on the hominoid Y chromosomes possibly originates from a similar sequence motif that is shared by and evolutionarily conserved between certain members of both gene families and/or repeated elements flanking those genes. Otherwise this complementary distribution could go back to a common organization of these genes next to each other on an ancient Y chromosome which was disrupted by chromosomal rearrangements and amplification of one or other of the genes at each of the locations.

Changes of gastric acid secretion and somatostatin after Roux-en-Y cholangiojejunostomy

The authors studied the changes of gastric acid secretion and determined the levels of somatostatin (SS) and gastrin (Gn) in blood, gastric juice and pyloric antrum in 28 patients Roux-en-Y with cholangiojejunostomy (CJR-Y). Gastric acid hypersecretion was identified, and the level of SS was found dropped while the content of Gn increased in these specimens. It was considered that the reduction of SS synthesis and secretion might have a key effect on the mechanism of secondary gastric acid hypersecretion in patients after CJR-Y.

Triterpenoid saponins from Clematis chinensis

From the roots of Clematis chinensis, two new triterpenoid saponins, named clematichinenoside A and B, were isolated and their structures were elucidated as 3-O-beta-D-ribopyranosyl-(1-3)-alpha-L-rhamnopyranosyl-(1-2)-alpha -L- arabinopyranosyl oleanolic acid 28-O-beta-D-glucopyranosyl ester and 3-O-beta-D-glucopyranosyl-(1-4)-beta-D-ribopyranosyl-(1-3)-alpha-L - rhamnopyranosyl-(1-2)-alpha-L-arabinopyranosyl hederagenin 28-O-alpha-L-rhamnopyranosyl-(1-4)-beta-D-glucopyranosyl-(1-6)- beta-D-glucopyranosyl ester, respectively. In addition oleanolic acid, hederagenin and seven known saponins were obtained.

[Treatment of severe burn of knee joint with fasciocutaneous flap of the lower leg]

Burn of knee joint often happens on the extended side surface and hurts the articular capsule and cavity. Five patients with severe burn of knee joint were successfully treated with fasciocutaneous flap of the lower leg. After the operation, all the flaps survived. Three patients' articular cavity got initial sealing-up. Except two patients' joints merging, joint movement was normal or near normal, and with satisfactory appearance. The timing, key points, and advantages of this operation were discussed. The fasciocutaneous flap of the lower leg is a good selection for severe burn of knee joint.

[Promoting effects of rhizoma Drynariae on the calcification of cultivated chick embryo bone primordium]

It has been discovered by tissue cultivation and isotope tracing that the injection of Rhizoma Drynariae significantly promotes the calcification of chick embryo bone primordium in vitro, increases the ALP activity of cultivated tissues and accelerates the synthesis of proteoglycan. It has also been proved that the promotion of the synthesis of proteoglycan is an important factor of the promotion of calcification.

Sulfide dehydrogenase from the hyperthermophilic archaeon Pyrococcus furiosus: a new multifunctional enzyme involved in the reduction of elemental sulfur

Pyrococcus furiosus is an anaerobic archaeon that grows optimally at 100 degrees C by the fermentation of carbohydrates yielding acetate, CO2, and H2 as the primary products. If elemental sulfur (S0) or polysulfide is added to the growth medium, H2S is also produced. The cytoplasmic hydrogenase of P. furiosus, which is responsible for H2 production with ferredoxin as the electron donor, has been shown to also catalyze the reduction of polysulfide to H2S (K. Ma, R. N. Schicho, R. M. Kelly, and M. W. W. Adams, Proc. Natl. Acad. Sci. USA 90:5341-5344, 1993). From the cytoplasm of this organism, we have now purified an enzyme, sulfide dehydrogenase (SuDH), which catalyzes the reduction of polysulfide to H2S with NADPH as the electron donor. SuDH is a heterodimer with subunits of 52,000 and 29,000 Da. SuDH contains flavin and approximately 11 iron and 6 acid-labile sulfide atoms per mol, but no other metals were detected. Analysis of the enzyme by electron paramagnetic resonance spectroscopy indicated the presence of four iron-sulfur centers, one of which was specifically reduced by NADPH. SuDH has a half-life at 95 degrees C of about 12 h and shows a 50% increase in activity after 12 h at 82 degrees C. The pure enzyme has a specific activity of 7 mumol of H2S produced.min-1.mg of protein-1 at 80 degrees C with polysulfide (1.2 mM) and NADPH (0.4 mM) as substrates. The apparent Km values were 1.25 mM and 11 microM, respectively. NADH was not utilized as an electron donor for polysulfide reduction. P. furiosus rubredoxin (K(m) = 1.6 microM) also functioned as an electron acceptor for SuDH, and SuDH catalyzed the reduction of NADP with reduced P. furiosus ferredoxin (K(m) = 0.7 microM) as an electron donor. The multiple activities of SuDH and its proposed role in the metabolism of S(o) and polysulfide are discussed.

Purification and characterization of NADP-specific alcohol dehydrogenase and glutamate dehydrogenase from the hyperthermophilic archaeon Thermococcus litoralis

Thermococcus litoralis is a strictly anaerobic archaeon that grows at temperatures up to 98 degrees C by fermenting peptides. Little is known about the primary metabolic pathways of this organism and, in particular, the role of enzymes that are dependent on thermolabile nicotinamide nucleotides. In this paper we show that the cytoplasmic fraction of cell extracts contained NADP-specific glutamate dehydrogenase (GDH) and NADP-specific alcohol dehydrogenase (ADH) activities, neither of which utilized NAD as a cofactor. The GDH is composed of identical subunits having an M(r) of 45,000 and had an optimal pH and optimal temperature for glutamate oxidation of 8.0 and > 95 degrees C, respectively. Potassium phosphate (60 mM), KCl (300 mM), and NaCl (300 mM) each stimulated the rate of glutamate oxidation activity between two- and threefold. For glutamate oxidation the apparent Km values at 80 degrees C for glutamate and NADP were 0.22 and 0.029 mM, respectively, and for 2-ketoglutarate reduction the apparent Km values for 2-ketoglutarate, NADPH, and NH4+ were 0.16, 0.14, and 0.63 mM, respectively. This enzyme is the first NADP-specific GDH purified form a hyperthermophilic organism. T. litoralis ADH is a tetrameric protein composed of identical subunits having an M(r) of 48,000; the optimal pH and optimal temperature for ethanol oxidation were 8.8 and 80 degrees C, respectively. In contrast to GDH activity, potassium phosphate (60 mM), KCl (0.1 M), and NaCl (0.3 M) inhibited ADH activity, whereas (NH4)2SO4 (0.1 M) had a slight stimulating effect. This enzyme exhibited broad substrate specificity for primary alcohols, but secondary alcohols were not oxidized.(ABSTRACT TRUNCATED AT 250 WORDS)

A Y chromosome gene family with RNA-binding protein homology: candidates for the azoospermia factor AZF controlling human spermatogenesis

We have previously mapped the human azoospermia factor to a deletion in Y chromosome interval 6 (subinterval XII-XIV). We now report the isolation and characterization of a gene family located within this deletion. Analysis of the predicted protein products suggests a possible role in RNA processing or translational control during early spermatogenesis. The Y chromosome RNA recognition motif (YRRM) family includes a minimum of three members expressed specifically in the testis. Interphase in situ results and Southern blot analysis indicate that several further YRRM sequences map within interval 6. Several mammalian species show Y chromosome conservation of YRRM sequences. We have detected deletions of YRRM sequences in two oligospermic patients with no previously detectable mutation.

Hydrogenase of the hyperthermophile Pyrococcus furiosus is an elemental sulfur reductase or sulfhydrogenase: evidence for a sulfur-reducing hydrogenase ancestor

Microorganisms growing near and above 100 degrees C have recently been discovered near shallow and deep sea hydrothermal vents. Most are obligately dependent upon the reduction of elemental sulfur (S0) to hydrogen sulfide (H2S) for optimal growth, even though S0 reduction readily occurs abiotically at their growth temperatures. The sulfur reductase activity of the anaerobic archaeon Pyrococcus furiosus, which grows optimally at 100 degrees C by a metabolism that produces H2S if S0 is present, was found in the cytoplasm. It was purified anaerobically and was shown to be identical to the hydrogenase that had been previously purified from this organism. Both S0 and polysulfide served as substrates for H2S production, and the S0 reduction activity but not the H2-oxidation activity was enhanced by the redox protein rubredoxin. The H2-oxidizing and S0-reduction activities of the enzyme also showed different responses to pH, temperature, and inhibitors. This bifunctional "sulfhydrogenase" enzyme can, therefore, dispose of the excess reductant generated during fermentation using either protons or polysulfides as the electron acceptor. In addition, purified hydrogenases from both hyperthermophilic and mesophilic representatives of the archaeal and bacterial domains were shown to reduce S0 to H2S. It is suggested that the function of some form of ancestral hydrogenase was S0 reduction rather than, or in addition to, the reduction of protons.

Loss of the 'azoospermia factor' (AZF) on Yq in man is not associated with loss of HYA

We have typed 9 EBV cell lines from azoospermic or severely oligospermic patients for the expression of H-Y antigen, in order to test the hypothesis of the coincidence of AZF and HYA genes. Of nine patients with cytogenetically normal Y chromosomes, 7 could be tested for HYA expression and of these 6 were H-Y positive. Of the three patients showing Yq structural abnormalities, two could be tested for H-Y expression and one was negative, the other positive. These results therefore show no correlation between spermatogenic failure and the absence of HYA, thus separating the AZF locus from HYA.

Bioenergetics of sulfur reduction in the hyperthermophilic archaeon Pyrococcus furiosus

The bioenergetic role of the reduction of elemental sulfur (S0) in the hyperthermophilic archaeon (formerly archaebacterium) Pyrococcus furiosus was investigated with chemostat cultures with maltose as the limiting carbon source. The maximal yield coefficient was 99.8 g (dry weight) of cells (cdw) per mol of maltose in the presence of S0 but only 51.3 g (cdw) per mol of maltose if S0 was omitted. However, the corresponding maintenance coefficients were not found to be significantly different. The primary fermentation products detected were H2, CO2, and acetate, together with H2S, when S0 was also added to the growth medium. If H2S was summed with H2 to represent total reducing equivalents released during fermentation, the presence of S0 had no significant effect on the pattern of fermentation products. In addition, the presence of S0 did not significantly affect the specific activities in cell extracts of hydrogenase, sulfur reductase, alpha-glucosidase, or protease. These results suggest either that S0 reduction is an energy-conserving reaction, i.e., S0 respiration, or that S0 has a stimulatory effect on or helps overcome a process that is yield limiting. A modification of the Entner-Doudoroff glycolytic pathway has been proposed as the primary route of glucose catabolism in P. furiosus (S. Mukund and M. W. W. Adams, J. Biol. Chem. 266:14208-14216, 1991). Operation of this pathway should yield 4 mol of ATP per mol of maltose oxidized, from which one can calculate a value of 12.9 g (cdw) per mol of ATP for non-S0 growth. Comparison of this value to the yield data for growth in the presence of S0 reduction is equivalent to an ATP yield of 0.5 mol of ATP per mol of S0 reduced. Possible mechanism to account for this apparent energy conservation are discussed.

Microdeletions in interval 6 of the Y chromosome of males with idiopathic sterility point to disruption of AZF, a human spermatogenesis gene

For males with idiopathic sterility, a molecular screen specific for small lesions (microdeletions) in interval 6 of the Y chromosome was set up using 29 Y-DNA probes. A "de novo" microdeletion in Y interval 6 was detected in 2 out of 19 "chromosomally normal" sterile males. The first microdeletion includes the Y-DNA probes pY6HP35 and 12f3; the second microdeletion includes the Y-DNA probes pY6HP52, 49f, FR15-II and the subinterval "C" of probe 50f2. A probe of the pY6H sequence family is present in both deletions. Sequences of this family cross-hybridize to dhMiF1, a DNA sequence of a fertility gene structure on the Y chromosome of Drosophila hydei. It was possible to map the position of the Y-deletion of one patient to the distal part of Yq11.22 or the proximal part of Yq11.23, and the deletion of the second patient to the distal part of Yq11.23. These microdeletions probably do not overlap. Since AZF, a human spermatogenesis gene, has been mapped to Y interval 6, we postulate that the microdeletions detected in this chromosome region affect the functional DNA structure of the AZF gene. If this holds true, it is possible that the AZF locus, cytogenetically mapped to distal Yq11, contains two spermatogenesis genes (AZFa and AZFb) or a large gene structure comparable to the Y fertility genes of Drosophila.

Towards the molecular localisation of the AZF locus: mapping of microdeletions in azoospermic men within 14 subintervals of interval 6 of the human Y chromosome

We have used a series of 30 DNA probes previously mapped to the long arm of the human Y chromosome, to screen a panel of 21 patients with structural abnormalities in Yq, by genomic blot hybridisation. The results have allowed us to construct a detailed map of interval 6 of the Y chromosome, in which 28 of the probes could be assigned to 14 sub-intervals within interval 6. Some probes detect two or more loci within this region, each of which has been localised. The same set of probes has been used to screen a panel of 19 chromosomally normal azoospermic men, two of whom have been found to carry microdeletions within this region. With the completion of this map we have been able accurately to localise these microdeletions within interval 6 and show that they do not overlap. We believe these microdeletions may disrupt the azoospermia factor (AZF) involved in spermatogenesis, and which is known to lie in this region. These results are an important step towards the localisation of the AZF locus.

The use of the polymerase chain reaction to identify porcine isolates of Trichinella

A method was developed to identify domestic isolates of Trichinella using the polymerase chain reaction. Oligonucleotide primers, based on the repetitive DNA sequence (pPRA) from the P1 isolate of Trichinella, were used to amplify genomic DNA from 13 domestic isolates and tested against sylvatic isolates of Trichinella. Pattern differences were observed among domestic isolates, indicating divergence of this repetitive sequence. The primers were specific for domestic Trichinella as no amplification was detected for sylvatic isolates or Trichinella pseudospiralis. It was possible to identify an isolate from a single larva following digestion or in situ in muscle tissue.

N5, N10-methylenetetrahydromethanopterin dehydrogenase (H2-forming) from the extreme thermophile Methanopyrus kandleri

Methanopyrus kandleri is a novel abyssal methanogenic archaebacterium growing at 110 degrees C on H2 and CO2. The N5, N10-methylenetetrahydromethanopterin dehydrogenase, an enzyme involved in methanogenesis from CO2 and H2, was purified from this hyperthermophile and characterized. The dehydrogenase was found to be composed of only one polypeptide of apparent molecular mass 44 kDa. The UV/Vis spectrum was similar to that of albumin. The protein catalyzed the reversible dehydrogenation of N5, N10-methylenetetrahydromethanopterin (CH2 = H4MPT) to N5, N10-methenyltetrahydromethanopterin (CH identical to H4MPT+) and molecular hydrogen: CH2 = H4MPT H+ in equilibrium CH identical to H4MPT+ +H2. The rate of CH2 = H4MPT dehydrogenation (apparent Vmax) at 65 degrees C and pH 5.8 was 1500 U/mg, the apparent Km for CH2 = H4MPT was 50 microM, the Arrhenius activation energy was 52 kJ/mol, and the Q10 between 30 degrees C and 70 degrees C was 2.0. The specific activity increased hyperbolically with the proton concentration between pH 7 and pH 4.5. The purified dehydrogenase did not catalyze the reduction of viologen dyes, of coenzyme F420, and of pyridine nucleotides with either CH2 = H4MPT or H2. For activity the CH2 = H4MPT dehydrogenase required the presence of salts. Fifty percent of maximal activity was reached at salt concentrations of 100 mM, potassium phosphate, potassium chloride, and sodium chloride being almost equally effective in stimulating the enzyme activity. Cell extracts of M. kandleri did not loose CH2 = H4MPT dehydrogenase activity when incubated at 90 degrees C for 60 min. The purified enzyme, however, proved very thermolabile. The purified enzyme, however, proved very thermolabile.(ABSTRACT TRUNCATED AT 250 WORDS)

Methyl-coenzyme M reductase and other enzymes involved in methanogenesis from CO2 and H2 in the extreme thermophile Methanopyrus kandleri

Methanopyrus kandleri belongs to a novel group of abyssal methanogenic archaebacteria that can grow at 110 degrees C on H2 and CO2 and that shows no close phylogenetic relationship to any methanogen known so far. Methyl-coenzyme M reductase, the enzyme catalyzing the methane forming step in the energy metabolism of methanogens, was purified from this hyperthermophile. The yellow protein with an absorption maximum at 425 nm was found to be similar to the methyl-coenzyme M reductase from other methanogenic bacteria in that it was composed each of two alpha-, beta- and gamma-subunits and that it contained the nickel porphinoid coenzyme F430 as prosthetic group. The purified reductase was inactive. The N-terminal amino acid sequence of the gamma-subunit was determined. A comparison with the N-terminal sequences of the gamma-subunit of methyl-coenzyme M reductases from other methanogenic bacteria revealed a high degree of similarity. Besides methyl-coenzyme M reductase cell extracts of M. kandleri were shown to contain the following enzyme activities involved in methanogenesis from CO2 (apparent Vmax at 65 degrees C): formylmethanofuran dehydrogenase, 0.3 U/mg protein; formyl-methanofuran:tetrahydro-methanopterin formyltransferase, 13 U/mg; N5,N10-methylenetetrahydromethanopterin cyclohydrolase, 14U/mg; N5,N10-methenyltetrahydromethanopterin dehydrogenase (H2-forming), 33 U/mg; N5,N10-methylenetetrahydromethanopterin reductase (coenzyme F420 dependent), 4 U/mg; heterodisulfide reductase, 2 U/mg; coenzyme F420-reducing hydrogenase, 0.01 U/mg; and methylviologen-reducing hydrogenase, 2.5 U/mg. Apparent Km values for these enzymes and the effect of salts on their activities were determined. The coenzyme F420 present in M. kandleri was identified as coenzyme F420-2 with 2-gamma-glutamyl residues.

Purification and properties of N5,N10-methylenetetrahydromethanopterin reductase (coenzyme F420-dependent) from the extreme thermophile Methanopyrus kandleri

Methanopyrus kandleri belongs to a novel group of abyssal methanogenic archaebacteria that can grow at 110 degrees C on H2 and CO2 and that shows no close phylogenetic relationship to any methanogens known so far. N5,N10-Methylenetetrahydromethanopterin reductase, an enzyme involved in methanogenesis from CO2, was purified from this hyperthermophile. The apparent molecular mass of the native enzyme was found to be 300 kDa. Sodium dodecylsulfate/polyacrylamide gel electrophoresis revealed the presence of only one polypeptide of apparent molecular mass 38 kDa. The ultraviolet/visible spectrum of the enzyme was almost identical to that of albumin indicating the absence of a chromophoric prosthetic group. The reductase was specific for reduced coenzyme F420 as electron donor; NADH, NADPH or reduced dyes could not substitute for the 5-deazaflavin. The catalytic mechanism was found to be of the ternary complex type as deduced from initial velocity plots. Vmax at 65 degrees C and pH 6.8 was 435 U/mg (kcat = 275 s-1) and the Km for methylenetetrahydromethanopterin and for reduced F420 were 6 microM and 4 microM, respectively. From Arrhenius plots an activation energy of 34 kJ/mol was determined. The Q10 between 40 degrees C and 90 degrees C was 1.5. The reductase activity was found to be stimulated over 100-fold by sulfate and by phosphate. Maximal stimulation (100-fold) was observed at a sulfate concentration of 2.2 M and at a phosphate concentration of 2.5 M. Sodium-, potassium-, and ammonium salts of these anions were equally effective. Chloride, however, could not substitute for sulfate or phosphate in stimulating the enzyme activity. The thermostability of the reductase was found to be very low in the absence of salts. In their presence, however, the reductase was highly thermostable. Salt concentrations between 0.1 M and 1.5 M were required for maximal stability. Potassium salts proved more effective than ammonium salts, and the latter more effective than sodium salts in stabilizing the enzyme activity. The anion was of less importance. The N-terminal amino acid sequence of the reductase from M. kandleri was determined and compared with that of the enzyme from Methanobacterium thermoautotrophicum and Methanosarcina barkeri. Significant similarity was found.

[A study on the problems of the radiologic manifestations in sarcoidosis]

Unilateral hilar adenopathy, which is considered as an atypical manifestation of sarcoidosis, appeared only on the initial stage, and eventually became bilateral. The adenopathy may occur in all groups of the mediastinal lymph nodes. The roentgenological findings of the pulmonary parenchymal lesions include interstitial, alveolar, miliary and fibrous lesions. The alveolar involvement, and the pathological consideration of pseudoalveolar manifestations in X-ray film were discussed.

[Clinical application of 3-dimensional image reconstruction of the left ventricle by echocardiography]

In this report is introduced a method of 3 D reconstruction of the LV by echocardiography. It was verified that 3 D image reconstruction could evaluate the function of the LV quantitatively in various cardiac disorders. And according to the specific display features of colored 3 D segmental shortening, it could also make diagnosis for certain heart diseases such as ischemic heart disease; hypertrophic or congestive cardiomyopathy, myocarditis, rheumatic heart disease; etc.

Single step purification of methylenetetrahydromethanopterin reductase from Methanobacterium thermoautotrophicum by specific binding to blue sepharose CL-6B

Methylenetetrahydromethanopterin reductase from metanogenic archaebacteria catalyzes the reversible reduction of N5,N10-methylenetetrahydromethanopterin to N5-methyltetrahydromethanopterin with reduced coenzyme F420 as electron donor. The enzyme is involved in methane formation from CO2 and in methanol disproportionation to CO2 and CH4. We report here that the reductase from Methanobacterium thermoautotrophicum specifically binds to Blue Sepharose CL-6B. Binding was competitive with coenzyme F420 rather than with NAD, NADP, FAD, FMN, AMP, ADP and ATP. The reductase could also be desorbed with salt. Based on this property an affinity chromatographic procedure for the purification of the enzyme was developed.

Purification and properties of N5, N10-methylenetetrahydromethanopterin reductase from Methanobacterium thermoautotrophicum (strain Marburg)

The reduction of N5,N10-methylenetrahydromethanopterin (CH2 = H4MPT) to N5-methyltetrahydromethanopterin (CH3-H4MPT) is an intermediate step in methanogenesis from CO2 and H2. The reaction is catalyzed by CH2 = H4MPT reductase. The enzyme from Methanobacterium thermoautotrophicum (strain Marburg) was found to be specific for reduced coenzyme F420 as electron donor; neither NADH or NADPH nor reduced viologen dyes could substitute for the reduced 5-deazaflavin. The reductase was purified over 100-fold to apparent homogeneity. Sodium dodecyl sulfate/polyacrylamide gel electrophoresis revealed only one protein band at the 36-kDa position. The apparent molecular mass of the native enzyme was determined by gel filtration to be in the order of 150 kDa. The purified enzyme was colourless. It did not contain flavin or iron. The ultraviolet visible spectrum was almost identical to that of albumin, suggesting the absence of a chromophoric prosthetic group. Reciprocal plots of the enzyme activity versus the substrate concentration at different constant concentrations of the second substrate yielded straight lines intersecting at one point on the abscissa to the left of the vertical axis. This intersecting pattern is characteristic of a ternary complex catalytic mechanism. The Km for CH2 = H4MPT and for the reduced coenzyme F420 were determined to be 0.3 mM and 3 microM, respectively. Vmax was 6000 mumol.min-1.mg protein-1 (kcat = 3600 s-1). The CH2 = H4MPT reductase was stable in the presence of air; at 4 C less than 10% activity was lost within 24 h.

[Assessment of the diagnostic significance of the pleural indentation sign]

Varying manifestations of the pleural indentation sign as well as their pathologic basis were discussed. It was found that the opacity shadow standing for this kind of sign on radiograph was attributed to not only pleural indentation, but also pleural adhesion, and sometimes, lobular collapse around the lesion. Both its occurrence and morphology showed no significant difference between the lung cancer and the tuberculoma. In the light of pulmonary connective tissue theory, any lesion located at periphery of the lung and accompanied by remarkable desmoplasia and cicatricial contraction, no matter whether malignant or benign, may cause pleural shrinkage or indentation. Therefore, the pleural indentation sign does not exclusively appear in the lung cancer. It would lead us onto a wrong path if differentiation is made by overemphasizing its value. It may be radiologically helpful only in identifying the types of the lung cancer owing to its high occurrence rate in adenocarcinoma and bronchioalveolar carcinoma.