[Carcinoma arising from postburn scars (report of 5 cases)]

Carcinoma arising from postburn scars is rare. We have encountered 5 patients suffering from this late complication of scars, accounting for 0.32% of 1563 admissions for late surgery after burn injuries. They were all males, with a mean age of 56 years. The mean latent period was 43.2 years, and it was apparently longer when the acute burn injury occurred earlier in life. The site of predilection was the lower extremity, and multiple biopsies of various sites of the lesion remained to be the measure of confirmation. Pathologically, they were all squamoon cell carcinoma, grade I in 4 cases and grade II in 1. Immunohistochemical staining with anti-proliferation cell nuclear antigen (PCNA) showed that PCNA positive nuclei of squamous cell carcinoma were more numerous, as compared with that in the neighboring pseudo -epitheliomatous hyperplasia (PEH) and in normal skin, denoting markedly augmented assimilation of DNA in malignant degeneration. On the contrary, the number of Langerhan's cells were smallest in cancer area, as compared with PEH and normal skin. The diagnosis, treatment and prevention of such malignant degeneration in postburn scars have been discussed.

[Long-term efficacy of hepatitis B vaccine in newborn and revaccination study]

Two-hundred and sixty-nine newborns were followed up for 4 and 5 years after completion of vaccination (10 micrograms x 3). The anti-HBs positive rates remained 82.54% and 72.03%, respectively. The low-level titer (> or = 10-99 mIU/ml) made up 44.61%, and the medium-level titer (> or = 100-99mIU/ml) 32.34%. The highest titer was 857 mIU/ml. A 10 micrograms dose of hepatitis B vaccine was given to these children. The anti-HBs level went up greatly in the first month after revaccination, but started to drop in the third month, decreased rapidly in the sixth month, and in the twelveth month the level trended to restore the level before revaccination. This paper indicated that the home-made hepatitis B vaccine was effective. Revaccination was not necessary within 5-7 years after initial vaccination. Revaccination to children whose anti-HBs level was < 10mIU/ml was beneficial but the anti-HBs persistence was short.

[Effects of ligustrazine and nitroglycerine on acute hypoxic pulmonary hypertension in anesthetized dogs]

The effects of ligustrazine and nitroglycerine on acute hypoxic pulmonary hypertension were observed in 10 anesthetized dogs. The results showed that ligustrazine (40 mg/kg) significantly reduced the hypoxic mean pulmonary artery pressure (PAPm) and pulmonary vascular resistance (PVR) the 10th and 15th minute after its injection into the right atrium, respectively. Its action was blocked by the continuous intravenous injection of methylene blue (1 mg/kg/min). It was suggested that the action of ligustrazine could be mediated by endothelium-derived relaxing factor. It was also discovered that nitroglycerine (40 micrograms/kg) could quickly decrease PAPm and PVR, indicating that nitroglycerine can be used to treat acute pulmonary hypertension and the aggravation of chronic cor pulmonale.

Comparison of time-frequency distribution techniques for analysis of simulated Doppler ultrasound signals of the femoral artery

The time-frequency distribution of the Doppler ultrasound blood flow signal is normally computed by using the short-time Fourier transform or autoregressive modeling. These two techniques require stationarity of the signal during a finite interval. This requirement imposes some limitations on the distribution estimate. In the present study, three new techniques for nonstationary signal analysis (the Choi-Williams distribution, a reduced interference distribution, and the Bessel distribution) were tested to determine their advantages and limitations for analysis of the Doppler blood flow signal of the femoral artery. For the purpose of comparison, a model stimulating the quadrature Doppler signal was developed, and the parameters of each technique were optimized based on the theoretical distribution. Distributions computed using these new techniques were assessed and compared with those computed using the short-time Fourier transform and autoregressive modeling. Three indexes, the correlation coefficient, the integrated squared error, and the normalized root-mean-squared error of the mean frequency waveform, were used to evaluate the performance of each technique. The results showed that the Bessel distribution performed the best, but the Choi-Williams distribution and autoregressive modeling are also techniques which can generate good time-frequency distributions of Doppler signals.

Measurement of fractional lipid synthesis using deuterated water (2H2O) and mass isotopomer analysis

Fractional biosynthesis of palmitate, stearate, and cholesterol was determined with deuterated water (2H2O) using mass isotopomer analysis in Hep G2 and MCA sarcoma cells in culture. The method employed differs from previous ones in that the number of deuterium atoms from 2H2O incorporated into newly synthesized molecules was determined and not assumed. After correction for background natural abundances, the isotopomer distribution due to deuterium incorporation in fatty acids and cholesterol was shown to follow a simple binomial distribution depending on the deuterium enrichment in water (p) and the maximum number of deuterium atoms incorporated per molecule (N). Under a wide range of 2H2O enrichments, N could be determined to be 17 for palmitate, 20 for stearate, and 20 for cholesterol by regression analysis or from a series of consecutive mass isotopomer ratios. The fraction derived from de novo synthesis was given by the ratio of the observed to the theoretical deuterium enrichment, which is the product (N x p). The new synthesized fraction of palmitate and stearate by Hep G2 cells for the length of the experiment was found to be 77 and 65%, respectively. These values were confirmed by experiments with [U-13C]glucose as the precursor. In MCA sarcoma cells grown in lipid-poor medium, the average values for fractional synthesis of palmitate, stearate, and cholesterol were 70, 35, and 70%, respectively. This approach should be generally applicable to the simultaneous determined of fractional synthesis of a number of compounds with either deuterium or 13C tracers. Its application is only limited by the accuracy of mass spectrometric analysis.

Expression of modified human cytochrome P450 1A2 in Escherichia coli: stabilization, purification, spectral characterization, and catalytic activities of the enzyme

A full-length human cytochrome P450 (P450) 1A2 cDNA clone and four derivatives in which the 5'-terminus was modified were inserted into the pCW vector and used to transform Escherichia coli cells. Low levels of expression were seen with most of the constructs but high expression levels (245 nmol membrane-bound P450 recovered per liter culture) were achieved when the N-terminus was MALLLAVFL, as reported earlier by Fisher et al. (C. W. Fisher, D. L. Caudle, C. Martin-Wixtrom, L. C. Quattrochi, R. H. Tukey, M. R. Waterman, and R. W. Estabrook, 1992, FASEB J. 6, 759-764). The expressed human P450 1A2 in bacterial membranes was rapidly denatured to cytochrome P420 in the presence of detergents. This denaturation was blocked by the inhibitory ligand alpha-naphthoflavone (alpha NF, 7,8-benzoflavone). Human P450 1A2 was solubilized using high concentrations of sodium cholate and Triton N-101 and could be purified to near homogeneity in high yield in two steps. alpha NF was included in the buffer in the first step and then removed in the second chromatography step along with the detergent. The purified human P450 1A2 was found to be almost completely in the high spin iron configuration, in contrast to P450 1A2 enzymes isolated from rats and rabbits. The enzyme was catalytically active toward the known substrates 7-ethoxyresorufin and phenacetin. The N-terminal appears to be blocked, as is the case for other P450s we have expressed that contain the sequence MALLLAVFL in E. coli. Previously this human P450 has only been available in limited amounts; the methods presented here should facilitate further biochemical and practical studies on this interesting enzyme.

Biosynthesis of the diterpene cis-abienol in cell-free extracts of tobacco trichomes

Biosynthesis of the hydroxylated labdane diterpene, cis-abienol, 9 alpha H-[(12Z)-labda-12,14-dien-8 alpha-ol] from geranylgeranyl pyrophosphate was observed in cell-free extracts prepared from trichome-bearing tissues of the experimental tobacco, Nicotiana tabacum L. c.v. T.I. 1068. Synthetic activity was observed with extracts of trichome glands, but not subepidermal tissue or epidermis from which glands had been removed. The activity was soluble, Mg2+ stimulated, had a pH optimum near 7.0, and was unaffected by conditions which inhibit cytochrome P450 oxygenase. These results indicate the occurrence in trichome glands of T.I. 1068, a cyclase activity which yields the cyclized hydroxylated labdanoid cis-abienol directly.

Classification of lower limb arterial stenoses from Doppler blood flow signal analysis with time-frequency representation and pattern recognition techniques

A pattern recognition system was used to classify Doppler blood flow signals for the determination of lower limb arterial stenoses. The diagnostic features were extracted from time-frequency representations of Doppler signals. Three techniques were tested to estimate time-frequency representations: the short-time Fourier transform, the autoregressive (AR) modeling, and the Bessel distribution. A boundary tracking algorithm was proposed to extract the frequency contour of the Doppler time-frequency representations. Based on the characteristics of the Doppler frequency contour, shape descriptors from an autoregressive analysis were proposed as diagnostic features. Simple algorithms were proposed to normalize these autoregressive shape descriptors. Amplitude distribution of the Doppler time-frequency representation was also found useful for stenosis classification. A total of 379 arterial segments from the aorta to the popliteal artery were classified by the pattern recognition system into three categories of diameter reduction (0-19%, 20-49%, and 50-99%). The short-time Fourier transform provided an overall accuracy of 80% (kappa = 0.38); AR modeling, 81% (kappa = 0.42); and the Bessel distribution, 82% (kappa = 0.43). All these results are better than those based on visual interpretation (accuracy = 76%, kappa = 0.29) performed by a trained technologist. The AR modeling and the Bessel distribution improved the performance of the pattern recognition system in comparison with the short-time Fourier transform. It is likely that with further improvement, the pattern recognition approach will be a useful clinical tool to quantify stenoses and to follow the disease progression with more reliability and less bias than visual interpretation as done currently in clinical practice.

A new hypothesis about the relationship between free radical reactions and hemorheological properties in vivo

This paper is concerned with a hypothesis that disturbance of free radical reactions may lead to abnormality of hemorheological properties in vivo, and so the free radicals generated in vivo may damage certain tissue cells indirectly by reducing the supply of oxygen and nutrients to these cells through slowing the circulation of blood. This hypothesis is based on the following evidence: A. We have found that the whole blood viscosity at low shear rate correlates to the lipid peroxidation in the patients suffering from certain cardio- or cerebrovascular diseases, and in dogs during liver ischemia reperfusion or hemorrhagic pancreatitis. B. Reports have shown that several alterations of hemorheological properties may take place as a result of free radical reactions, such as lipid peroxidation. For instance, lipid peroxidation may lead to decrease of deformability of red cells, increase of aggregation of red cells, formation of liquid thrombin, etc. C. We have demonstrated that some alterations of hemorheological properties involve the role of free radicals in rats suffering from intestinal ischemia/reperfusion. As evidence for this conclusion, superoxide dismutase (SOD) used as a specific scavenger of superoxide anion radical (O2-) can significantly prevent the intestinal ischemia/reperfusion induced changes of lipid peroxidation, red cell aggregation, Cassion's viscosity and whole blood viscosity at low shear rate in rats.

Signals that produce 3' termini in CYC1 mRNA of the yeast Saccharomyces cerevisiae

The cyc1-512 mutant was previously shown to contain a 38-bp deletion, 8 nucleotides upstream from the major wild-type poly(A) site, in the CYC1 gene, which encodes iso-1-cytochrome c of the yeast Saccharomyces cerevisiae. This 38-bp deletion caused a 90% reduction in the CYC1 transcripts, which were heterogeneous in size, aberrantly long, and presumably labile (K. S. Zaret and F. Sherman, Cell 28:563-573, 1982). Site-directed mutagenesis in and adjacent to the 38-bp region was used to identify signals involved in the formation and positioning of CYC1 mRNA 3' ends. In addition, combinations of various putative 3' end-forming signals were introduced by in vitro mutagenesis into the 3' region of the cyc1-512 mutant. The combined results from both studies suggest that 3' end formation in yeast cells involves signals having the following three distinct but integrated elements acting in concert: (i) the upstream element, including sequences TATATA, TAG ... TATGTA, and TTTTTATA, which function by enhancing the efficiency of downstream elements; (ii) downstream elements, such as TTAAGAAC and AAGAA, which position the poly(A) site; and (iii) the actual site of polyadenylation, which often occurs after cytidine residues that are 3' to the so-called downstream element. While the upstream element is required for efficient 3' end formation, alterations of the downstream element and poly(A) sites generally do not affect the efficiency of 3' end formation but appear to alter the positions of poly(A) sites. In addition, we have better defined the upstream elements by examining various derivatives of TATATA and TAG ... TATGTA, and we have examined the spatial requirements of the three elements by systematically introducing or deleting upstream and downstream elements and cytidine poly(A) sites.

Mechanisms of inhibition of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone bioactivation in mouse by dietary phenethyl isothiocyanate

The tobacco-specific nitrosamine, 4-(methylnitrosamino)-1-(3-pyridyl)-1- butanone (NNK), induces lung tumors in mice, rats, and hamsters. Phenethyl isothiocyanate (PEITC), which occurs as gluconasturtiin in cruciferous vegetables, is a potent inhibitor of NNK-induced carcinogenesis. The present study investigated the enzymatic basis for the bioactivation of NNK and the mechanisms of the inhibition of this process by dietary PEITC in mice. The apparent Km for the formation of keto aldehyde, keto alcohol, and NNK-N-oxide in lung microsomes was 4.9, 2.6, and 1.8 microM and, in liver microsomes, 5.5, 5.1, and 8.8 microM, respectively. Immunoinhibition studies suggested that cytochrome P450s (P450s) 2A1 and 2B1 or related forms are the major enzymes involved in the oxidative metabolism of NNK in mouse lung microsomes. When female A/J mice were fed diets containing 0, 1, or 3 mumol of PEITC/g of diet for 4 wk, the dietary PEITC had no significant effects on the food consumption and body weight of the mice. NNK oxidation in the lung microsomes of mice consuming the 1 or 3 mumol of PEITC/g of diet was decreased by 13 to 27% or 30 to 50%, respectively. In liver microsomes, whose NNK oxidative metabolism rates were about twice those of lung microsomes on a per mg of protein basis, the activities were decreased by 14 to 31% by the 3 mumol of PEITC/g of diet. The apparent Km remained unchanged, and the apparent Vmax decreased in the lung and liver microsomes of PEITC-fed mice, suggesting a noncompetitive nature of the inhibition. When added to the incubation mixture, PEITC decreased NNK metabolism in a concentration-dependent manner and exhibited a competitive inhibition with apparent Ki values of 51 to 93 nM. Dietary PEITC decreased the hepatic P450 content by 25%, but increased (2-fold) the O-dealkylase activities of 7-pentoxyresorufin (indicative of P450 2B1) and 7-ethoxyresorufin (indicative of P450 1A) in the liver microsomes of mice consuming the 3 mumol of PEITC/g of diet. The P450 2B level was increased in liver microsomes but slightly decreased in the lung microsomes. The p450 2E1 level was increased by dietary PEITC by 1.2- and 1.6-fold in the liver and lung microsomes, respectively. The activities of glutathione S-transferase and NAD(P)H-quinone oxidoreductase in liver and lung microsomes were not affected appreciably by the dietary PEITC treatment. The results suggest that chronic consumption of PEITC decreases the rate of metabolic activation of NNK by chemical inactivation and competitive inhibition of the enzyme(s) responsible for NNK oxidation.

M(r) 6,400 aurin tricarboxylic acid directly activates platelets

ATA is a novel anticoagulant polymeric anionic aromatic compound that inhibits von Willebrand factor binding to platelet glycoprotein Ib and thereby prevents ristocetin- and shear stress-induced platelet aggregation. To investigate its mechanism of action, ATA fractions of homogeneous M(r) have been prepared by size exclusion chromatography. ATA fractions of M(r) > or = 2,500 are most effective at inhibiting vWF-mediated platelet aggregation, and ATA of M(r) = 2,500 also inhibits thrombin-induced platelet activation. Paradoxical results were observed in studies of ATA with M(r) = 6,400. This fraction of ATA stimulates aggregation of washed platelets or platelet-rich-plasma. The dose/response of aggregation shows a bell-shaped curve with maximal aggregation at approximately 2 micrograms/ml. Platelet aggregation is associated with phosphoinositide turnover and protein kinase C- and calcium-dependent protein phosphorylation. Platelet signalling responses to ATA are inhibited by platelet pretreatment with PGI2 or dibutyryl-cyclic AMP, but are unaffected by inhibiting platelet cyclooxygenase with aspirin. These results suggest that M(r) 6,400 ATA directly activates platelet phospholipase C to initiate platelet aggregation. This effect, unique to M(r) 6,400 ATA, could potentially mitigate ATA's beneficial anti-thrombotic effect on vWF-mediated platelet responses, and should be considered when analyzing results of experiments that utilize unfractionated ATA.

Structure-activity relationships of arylalkyl isothiocyanates for the inhibition of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone metabolism and the modulation of xenobiotic-metabolizing enzymes in rats and mice

Many arylalkyl isothiocyanates are potent inhibitors of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK)-induced lung tumorigenesis in rats and mice. In the mouse, 4-phenylbutyl isothiocyanate (PBITC) and 6-phenylhexyl isothiocyanate (PHITC) exhibited greater inhibition than benzyl isothiocyanate (BITC) and phenethyl isothiocyanate (PEITC). The present study was conducted to investigate the structure-activity relationships of these four arylalkyl isothiocyanates for their inhibition of NNK oxidation and effects on xenobiotic-metabolizing enzymes in rats and mice. A single dose (0.25 or 1.00 mmol/kg) of each isothiocyanate was given to F344 rats 6 or 24 h before death. The rates of NNK oxidation were decreased in microsomes from the liver, lung and nasal mucosa of rats. Generally, PEITC was more potent than BITC but less potent than PBITC and PHITC. The rates in rat liver microsomes were decreased at 6 h but recovered or increased at 24 h; the rates in rat lung microsomes were markedly decreased at both 6 and 24 h; and the rates in rat nasal mucosa microsomes were also significantly decreased. The same treatment decreased the rat liver N-nitrosodimethylamine demethylase activity dramatically and ethoxyresorufin O-dealkylase and erythromycin N-demethylase activities moderately. However, the rat liver microsomal pentoxy-resorufin O-dealkylase activity was decreased at 6 h but increased at 24 h, with PEITC showing the most marked induction. The rat liver NAD(P)H:quinone oxidoreductase activity was increased 1.4- to 3.3-fold, with PEITC being most effective; and the glutathione S-transferase activity was increased slightly. Similarly, at a single dose of 0.25 mmol/kg (5 mumol/mouse) 24 h before death, PEITC, PBITC, PHITC but not BITC, decreased NNK oxidation in mouse lung microsomes by 40-85%, with PBITC and PHITC showing greater inhibition. Furthermore, all four isothiocyanates extensively inhibited NNK oxidation in rat lung and nasal mucosa microsomes as well as mouse lung microsomes in vitro, with PEITC (IC50 of 120-300 nM) being more potent than BITC (IC50 of 500-1400 nM) but less potent than PBITC and PHITC (IC50 of 15-180 nM). PHITC was a very potent competitive inhibitor of NNK oxidation in mouse lung microsomes with apparent K(i) values of 11-16 nM. These results indicate that PBITC and PHITC are more potent inhibitors of NNK bioactivation in rats and mice than PEITC. In addition, these arylalkyl isothiocyanates could be effective in protecting against the actions of a broad spectrum of carcinogenic or toxic compounds.

[Inhibitory effect of intraventricular administration of morphine on the hyperviscosity and elevation of blood pressure induced by stress in the rat]

Experiments were performed on 99 Wistar rats. It was found that hyperviscosity and elevation of blood pressure (BP) could be induced by hanging and restraining conscious rats with their four limbs tied on a frame. These effects were unaffected by bilateral vagotomy. By intravenous injection of propranolol or phentolamine, elevation of BP could be reduced, while stress-induced hyperviscosity could only be reduced by propranolol (i.v.). Stress-induced hyperviscosity and elevation of BP could be inhibited by electroacupuncture applied to the right hind leg or microinjection of morphine into 4th ventricle of the brain. On the other hand, if opiate receptor antagonist naloxone was given into the 4th-ventricle, the stress-induced hyperviscosity and elevation of BP could no longer be inhibited by electroacupuncture. It is suggested that the hyperviscosity and elevation of BP induced by hanging and restraining are mediated by excitatory cardiovascular sympathetic outflow with the result of activation of adrenoreceptors. Activation of the opiate receptors in the hindbrain may be responsible for decrease in stress-induced hyperviscosity and elevation of BP and for the inhibitory effect of electroacupuncture of the right hind leg on stress-induced hyperviscosity and elevation of BP.

Cardiac Doppler blood-flow signal analysis. Part 1. Evaluation of the normality and stationarity of the temporal signal

The normality (Gaussian property) and stationarity of the cardiac Doppler blood-flow signal were evaluated on short-time segments distributed over the cardiac cycle. The basic approaches used to perform statistical tests on the nonstationary and quasiperiodic cardiac Doppler signal are presented. The results obtained from the data of ten patients having a normal aortic valve and ten patients having a stenotic valve indicate that a complex Gaussian random process is an acceptable approximation for the clinical cardiac Doppler signal. For segments of 10 ms or less, 82 per cent of them were accepted to be stationary with a significance level of 0.05, whereas for durations greater than 40 ms, the percentage of stationary segments was less than 75 per cent. It was concluded that the 10 ms window generally used in practice is a good choice for Doppler spectrogram estimation, but a shorter time interval would be preferable.

Comparison of spectral techniques for computer-assisted classification of spectra of heart sounds in patients with porcine bioprosthetic valves

The diagnostic performance of two spectral techniques (the fast Fourier transform, FFT, and autoregressive modelling, ARM) combined with four windowing functions (rectangular, Hanning, Hamming, and sine-cosine) and two classifiers (Bayes and nearest neighbour) to detect valvular degeneration was evaluated in a group of 95 patients. Forty-seven patients had a porcine bioprosthetic valve inserted in the aortic position and 48 patients had a porcine bioprosthetic valve inserted in the mitral position. Among the aortic valves, 24 were normal and 23 were degenerated whereas among the mitral valves, 19 were normal and 29 were degenerated. The aortic and mitral valves were analysed separately. For each type of valve, 21 features were extracted from the spectra of the valve closure sounds to train and test the performance of four pattern recognition systems by using the leave-one-out method. The discriminant properties of all feature combinations between two and five among the 21 features selected were evaluated. Results show that the FFT combined to the nearest neighbour classifier provided the best performances: 87 per cent of correct classifications (CCs) for aortic valves when using the Hanning or the Hamming window and 94 per cent of CCs for mitral valves when using the rectangular window. The best performances obtained with the ARM were 81 per cent of CCs for the aortic valves (nearest neighbour classifier and the Hanning or the Hamming window) and 92 per cent of CCs for the mitral valves (nearest neighbour classifier and the Hamming window or the Bayes classifier and the Hanning or the Hamming window).

Cardiac Doppler blood-flow signal analysis. Part 2. Time/frequency representation based on autoregressive modelling

Doppler spectrograms obtained by using autoregressive (AR) modelling based on the Yule-Walker equations were investigated. A complex AR model using the in-phase and the quadrature components of the Doppler signal was used to provide blood-flow directions. The effect of model orders on the spectrogram estimation was studied using cardiac Doppler blood flow signals taken from 20 patients. The 'final prediction error' (FPE) and the 'Akaike's information criterion' (AIC) provided almost identical results in model-order selection. An index, the spectral envelope area (SEA), was used to evaluate the effect of window duration and sampling frequency on AR Doppler spectrogram estimation. The statistical analysis revealed that the SEA obtained from AR modelling was not sensitive to window duration and sampling frequency. This result verified the consistency of the AR Doppler spectrogram. The white-noise characteristics of the AR modelling error signal indicated that the Doppler blood-flow signal can be adequately modelled as a complex AR process. With appropriate model orders, AR modelling provided better Doppler spectrogram estimates than the periodogram.

In vitro granuloma formation by spleen cells treated with psoralen plus long-wave ultraviolet radiation

In vitro granulomas are induced by culturing murine spleen cells with artificial microparticles, dextran beads. In the presence of 0.5 microgram/mL 8-methoxypsoralen, UVA radiation (0.2-2.0 J/cm2) suppressed granuloma formation in a UVA dose-dependent manner. The doses of PUVA did not affect the cell viability as assessed by trypan blue exclusion. The time course of granuloma formation in 0.5 J/cm2 PUVA-treated cells was similar to that of normal spleen cells, with a maximum granuloma index at day 3 of culture, although a 49-63% suppression of granuloma formation was observed. PUVA-treated, nonadherent cells produced the same granuloma index when cultured with normal adherent cells. In contrast, a smaller granuloma index was observed in PUVA-treated adherent cells even when they were cultured with normal nonadherent cells. These data suggest that PUVA alters macrophages, resulting in the suppression of granuloma formation in vitro.

Protein kinase C is activated in platelets subjected to pathological shear stress

High levels of fluid shear stress at the blood vessel wall directly stimulate von Willebrand factor (vWF)-mediated platelet adhesion and aggregation and thereby contribute to the pathogenesis of arterial thrombosis. We have found that a pathological level of arterial wall shear stress (90 dynes/cm2) induces platelet aggregation that is associated with the phosphorylation of pleckstrin, a M(r) 47,000 protein kinase C substrate (p47). Shear-induced p47 phosphorylation depends entirely on vWF binding to platelet glycoprotein (Gp) Ib and GpIIb-IIIa, and the specific inhibition of protein kinase C with the staurosporine analogue Ro 31-7549 inhibits the full aggregation response to shear. Shear stress-induced platelet p47 phosphorylation occurs independent of any measurable change in diacylglycerol mass or hydrolysis of phosphatidylinositol 4,5-bisphosphate. These results indicate that mechanical shear stress induces vWF to bind to platelet GpIb and GpIIb-IIIa, stimulating a diacylglycerol-independent pathway of protein kinase C activation that contributes to platelet aggregation in response to shear.

Effects of phenethyl isothiocyanate, a carcinogenesis inhibitor, on xenobiotic-metabolizing enzymes and nitrosamine metabolism in rats

Phenethyl isothiocyanate (PEITC), a constituent of cruciferous vegetables, has been shown to inhibit chemical carcinogenesis, possibly due to its ability to block the activation or to enhance the detoxification of chemical carcinogens. The present study was conducted to elucidate the biochemical mechanisms involved by characterizing the effects of PEITC on phase I and phase II xenobiotic-metabolizing enzymes. A single dose of PEITC to F344 rats (1 mmol/kg) decreased the liver N-nitrosodimethylamine demethylase (NDMAd) activity (mainly due to P450 2E1) by 80% at 2 h and the activity of NDMAd remained decreased by 40% at 48 h after treatment. The liver pentoxyresorufin O-dealkylase (PROD) activity and P450 2B1 protein level were elevated 10- and 7-fold at 24 h after treatment respectively. The liver microsomal ethoxyresorufin O-dealkylase (EROD) (mainly due to P450 1A) and erythromycin N-demethylase (mainly due to P450 3A) activities were decreased at 2-12 h after treatment and recovered afterwards. The lung microsomal PROD and EROD activities were not significantly affected; whereas, the nasal microsomal PROD and EROD activities were decreased by 40-50%. After a treatment with PEITC, the rates of oxidative metabolism of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) were decreased in liver microsomes by 40-60% at 2 h and recovered gradually; the rates in lung microsomes were markedly decreased by 60-70% at 2 h and remained at the decreased level at 24 h; and the rates in nasal mucosa microsomes were decreased gradually with the lowest activities observed at 18 h (50%) followed by a gradual recovery. Furthermore, the treatment with PEITC resulted in a maximal 5-fold increase of NAD(P)H:quinone oxidoreductase and 1.5-fold increase of glutathione S-transferase activities in the liver, but the activities of these two enzymes were not significantly affected in the lung and nasal mucosa. The sulfotransferase activity in the liver was decreased by 32-48% at 24-48 h after treatment; the nasal activity was increased by 1.8- to 2.5-fold, but the lung activity was not significantly changed. The hepatic UDP glucuronosyltransferase activity was slightly decreased at 2 h but slightly increased at 48 h after treatment, but no changes were observed for the lung and nasal activities. The study demonstrates that PEITC selectively affects xenobiotic-metabolizing enzymes in the liver, lung and nasal mucosa and it is especially effective in inhibiting the P450-dependent oxidation of NNK in the lung and of NDMA in the liver.

Metabolism of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone by inducible and constitutive cytochrome P450 enzymes in rats

The tobacco-specific nitrosamine, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) induces tumor formation in the liver, lung, nasal cavity, and pancreas of rats. Metabolic activation is required for the tumorigenicity of this compound. The involvement of cytochrome P450 enzymes in NNK bioactivation was investigated in rats by studies with chemical inducers and antibodies against P450s. Liver microsomal enzymes catalyzed the formation of 4-oxo-1-(3-pyridyl)-1-butanone (keto aldehyde), 4-hydroxy-1-(3-pyridyl)-1-butanone (keto alcohol), 4-(methylnitrosamino)-1-(3-pyridyl-N-oxide)-1-butanone (NNK-N-oxide), and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) from NNK. When the activity was expressed on a per nanomole P450 basis, treatments of rats with 3-methylcholanthrene (MC), phenobarbital (PB), pregnenolone 16-alpha-carbonitrile (PCN), Aroclor 1254 (AR), safrole (SA), and isosafrole (ISA) increased the keto aldehyde formation in liver microsomes 2.0-, 2.4-, 3.8-, 2.5-, 2.1-, and 1.8-fold, respectively; PB, AR, SA, and ISA increased the keto alcohol formation 1.7-, 1.3-, 2.0-, and 1.3-fold, respectively. The extents of induction were more pronounced when expressed on a per milligram protein basis, due to the higher microsomal P450 contents in the induced microsomes. The formation of NNK-N-oxide was markedly increased by PB and PCN and slightly increased by AR, SA, and ISA. However, the formation of NNAL, the major metabolite due to carbonyl reduction, was not increased by the treatments but was decreased by AR, ISA, and acetone (AC). The kinetic parameters of NNK metabolism by control, MC-, PB-, and PCN-induced liver microsomes were obtained. A panel of monoclonal (anti-1A1, -2B1, -2C11, and -2E1) and polyclonal (anti-1A2, -2A1, and -3A) antibodies were used to assess the involvement of constitutive hepatic P450 enzymes in NNK metabolism. Keto aldehyde formation was inhibited by anti-1A2 and anti-3A (about 15%) but not by others; the formation of keto alcohol was inhibited by anti-1A2, anti-2A1, and anti-3A (by 13-26%). In incubations with lung microsomes, the formation of keto aldehyde, keto alcohol, NNK-N-oxide, and NNAL were observed. With nasal mucosa microsomes, however, only keto aldehyde and keto alcohol formation were appreciable. SA and AC significantly decreased NNK metabolism in lung and nasal mucosa microsomes.(ABSTRACT TRUNCATED AT 400 WORDS)

Kinetics and enzyme involvement in the metabolism of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) in microsomes of rat lung and nasal mucosa

The rat lung and nasal cavity are two target organs for carcinogenesis by 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK). In order to characterize further the enzymes involved in the bioactivation of NNK, detailed kinetic and inhibitory studies were conducted with rat lung and nasal mucosa microsomes, and the results were compared with previous studies. The enzymes in rat lung microsomes catalyzed the alpha-hydroxylation, pyridine N-oxidation and carbonyl reduction of NNK. The apparent Km for the formation of the NNK-derived keto aldehyde, NNK-N-oxide, the NNK-derived keto alcohol and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol were 28.8, 10.4, 7.0 and 178.1 microM respectively. In rat nasal microsomes, alpha-hydroxylation was the predominant pathway and the rate was approximately 200 times higher than that in lung microsomes. The apparent Kms for keto aldehyde and keto alcohol formation in rat nasal microsomes were 9.6 and 10.1 microM respectively. The cytochrome P450 inhibitors metyrapone and carbon monoxide markedly inhibited the metabolism of NNK in both rat lung and nasal microsomes. In rat lung microsomes, alpha-naphthoflavone and monospecific antibodies against P450s 1A2, 2A1 and 2B1 inhibited the formation of keto aldehyde by 39, 46, 64 and 23% respectively. In rat nasal microsomes, alpha-naphthoflavone and antibodies against P450s 1A2, 2A1 and 3A inhibited the metabolism of NNK by 80, 35, 20 and 14% respectively. The results indicate that cytochromes P450 play a major role in the metabolic activation of NNK in rat lung and nasal microsomes, and that there are tissue-related differences in NNK metabolism.

Quantitative structure-activity relationships of benzamide derivatives for anti-leukotriene activities

To determine the structural requirements of the benzamide derivatives reported by Nakai et al. (J. Med. Chem. 1988, 31, 84-91) for antileukotriene activity, we studied their conformational characteristics in comparison with those of leukotriene. By superimpositions of the conformations of antagonists on that of leukotriene, we found that the conformations of the conjugated benzamide moiety, tetrazole ring, and benzopyran or benzodioxan ring of the antagonists correspond to the triene moiety, peptide carboxylic acid residue, and cysteine residue of leukotriene, respectively, but that no moiety of the antagonists corresponds to the terminal aliphatic carboxylic acid moiety of leukotriene. Furthermore, the stable conformations of alkyl and alkoxy groups of the antagonists were quite different from that of the omega-chain of leukotriene. However, conformational analyses taking all the possible rotations of these flexible chains into consideration showed that antagonists in which these flexible chains can most feasibly adopt the same lengths as those of the omega-chain exhibit potent antagonist activity. From these results, we deduced the structural features of benzamide derivatives necessary for potent antileukotriene activity.

[A case-control study on the relationship between smoking and genetic background and lung cancer]

A case-control study on the relationship between smoking and genetic background and lung cancer was carried out. The cases (probund) were death cases of lung cancer diagnosed between 1984 and 1986 in Quanshan County, and the controls were healthy people at the same period. Cases and controls were 1:1 in match with sex, age and residence. 196 pairs were so matched. The results were adjusted for smoking habit and family history of lung cancer using conditionally logistic regression model. There were significant differences shown in quantity of smoking (packet/year) (beta = 0.070 9) and age to start (years) (beta = -0.055 6) between cases and controls. There were also significant differences in history of lung cancer of first and second relatives (living together or not) between cases and controls. The positive interaction between smoking habit and genetic background of lung cancer was also found.

Metabolism of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone in human lung and liver microsomes and cytochromes P-450 expressed in hepatoma cells

4-(Methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), a potent tobacco-specific carcinogen in animals, has been linked to tobacco-related cancers in humans. The cytochrome(s) P-450 (P-450) responsible for the metabolic activation of NNK in humans has not been identified. The present work investigated the ability of human lung and liver microsomes and 12 forms of human P-450, expressed in Hep G2 (hepatoma) cells, to metabolize NNK. Of the 12 P-450 forms, P-450 1A2 had the highest activity in catalyzing the conversion of NNK to the keto alcohol, 4-hydroxy-1-(3-pyridyl)-1-butanone. P-450s 2A6, 2B7, 2E1, 2F1, and 3A5 also had measurable activities in the formation of keto alcohol. The apparent Km and Vmax for the formation of keto alcohol in the P-450 1A2-expressed Hep G2 cell lysate were 309 microM and 55 pmol/min/mg protein, respectively. 4-(Methylnitrosamino)-1-(3-pyridyl)-1-butanol, a reductive product, was the major metabolite formed, whereas the formation of keto alcohol and its aldehyde and acid derivatives (all alpha-hydroxylation products) constituted approximately 1% of the initial amount of NNK in P450-expressed Hep G2 cell lysate. A similar metabolite pattern was observed with human lung or liver microsomes. In human lung microsomes, the apparent Kms for the formation of 4-hydroxy-4-(3-pyridyl)butyric acid, 4-oxo-1-(3-pyridyl)-1-butanone, NNK-N-oxide, and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol were 526, 653, 531, and 573 microM, respectively; the formation of keto alcohol was not observed. For human lung microsomes, there was no sex-related difference in NNK metabolism. Carbon monoxide (90% atmosphere) significantly inhibited the metabolism of NNK in human lung and liver microsomes. 7,8-Benzoflavone, an inhibitor of P-450s 1A1 and 1A2, had no effect on NNK metabolism in human lung microsomes but decreased the formation of keto alcohol by 47% in human liver microsomes. Similarly, antibodies against human P-450s 1A2 and 2E1 decreased keto alcohol formation by 42% and 53%, respectively, in human liver microsomes but did not affect NNK metabolism in lung microsomes. Inhibitory antibodies against P-450s 2A1, 2C8, 2D1, or 3A4 had little or no effect on the metabolism of NNK in human liver or lung microsomes.(ABSTRACT TRUNCATED AT 400 WORDS)

[Electrophysiological effects of neferine against ischemic ventricular tachyarrhythmias]

The electrophysiological effects of neferine (Nef, 8mg/kg,i.v.) on ischemic ventricular tachyarrhythmias in both normal and ischemic myocardium were studied in open-chest dogs by programmed electrical stimulation (PES) with intimal surface anodal direct current at the circumflex coronary artery during 5-8 days after acute myocardial infarction. Its effects were compared with procainamide (PA). Both drugs lengthened the QTc interval and the effective refractory period (ERP) of normal and infarcted myocardium in both ventricles and decreased the dispersion of ERP in infarcted myocardium (IDR) as well as in left ventricle (VDR), increased the diastolic excitability threshold (DET) of normal and infarcted myocardium in both ventricles remarkably. The PES-induced VT or VF was prevented in all of Nef treated dogs and in 5 out of 6 PA treated dogs, Nef prevented spontaneous VF in 5 dogs (n = 6), PA prevented spontaneous VF in 4 dogs (n = 6). The results indicated that Nef may be effective in preventing the onset of reentrant ventricular tachycardias and sudden cardiac death after myocardial ischemic damage.

[Estimation of glucocorticoid membrane binding sites in synaptic plasma membrane isolated from porcine brain]

Using radioligand binding assay, we measured the Bmax and Kd of glucocorticoid membrane binding sites (GCMBS) in the synaptic plasma membranes isolated from different regions of porcine brain. The Kds of GCMBS in cerebrum, cerebellum, midbrain, thalamus, nuclei caudatus and hypothalamus are all around 200 nmol/L. The Bmax of GCMBS in the mentioned brain regions ranges from 218.98 fmol/mg to 486.95 fmol/mg protein.

The effect of averaging cardiac Doppler spectrograms on the reduction of their amplitude variability

The effect of averaging cardiac Doppler spectrograms on the reduction of their amplitude variability was investigated in 30 patients. Beat-to-beat variations in the amplitude of Doppler spectrograms were also analysed. The quantification of amplitude variability was based on the computation of the area under the absolute value of the derivative function of each spectrum composing mean spectrograms. Fast Fourier transform using a Hanning window was used to compute Doppler spectra. Results obtained over systolic and diastolic periods showed that the reduction of amplitude variability followed an exponentially decreasing curve characterised by the equation f (r) = 100 e-beta(r-1), where r is the number of cardiac cycles, beta the exponentially decreasing rate, and 100 the normalised variability for r = 1. In systole, the decreasing rate beta was 0.165, whereas in diastole it was 0.225. Reductions of the variability in systole for a number of cardiac cycles of 5, 10, 15, and 20 were 48, 77, 90 and 96 per cent, respectively. In diastole, reductions of the variability for the same numbers of cardiac cycles were 59, 87, 96 and 99 per cent, respectively. Based on these results, it can be concluded that no significant improvement in the reduction of amplitude variability may be obtained by averaging more than 20 cardiac cycles.

The effects of non-interval PUVA treatment on Langerhans cells and contact hypersensitivity

Although application of topical psoralen followed immediately by ultraviolet-A irradiation (non-interval PUVA) was reported to be effective in the treatment of psoriasis, its precise mechanisms of action have not yet been explored. Since regular topical PUVA therapy, consisting of the topical application of psoralen followed by UVA exposure 1-2 h later, can change the number and morphology of Langerhans cells (LCs) and inhibit contact hypersensitivity (CHS), we investigated whether these same effects may be induced by non-interval PUVA. Our results showed that no differences exist between these two types of PUVA treatment. Non-interval PUVA treatments of 3 J/cm2 produced no erythematous reactions and resulted in changes in the number and morphology of LCs. The non-interval regimen also inhibited CHS to dinitrofluorobenzene applied to the treated skin by inducing the suppressor lymphocytes. These results suggest that there might be a link between the observed changes of the LCs and the effectiveness of non-interval PUVA therapy in the treatment of psoriasis, through a mechanism other than the inhibition of DNA synthesis of psoriatic keratinocytes.

[Effect of sodium 18 beta-glycyrrhetate on experimental arrhythmia]

The effect of sodium 18 beta-glycyrrhetate (SGA) on experimental arrhythmia was investigated. The result shows that SGA strongly counteracts arrhythmia induced by chloroform of chloroform adrenaline, lengthens the appearance time of arrhythmia induced by CaCl2, slightly retards the heart rate of rats and rabbits, and partly antagonizes the acceleration effect of isoproterenol on rabbit hearts.

The catalytic consequences of experimental evolution. Studies on the subunit structure of the second (ebg) beta-galactosidase of Escherichia coli, and on catalysis by ebgab, an experimental evolvant containing two amino acid substitutions

1. The ratio of ebgA-gene product of ebgC-gene product in the functional aggregate of ebg beta-galactosidases was determined to be 1:1 by isolation of the enzyme from bacteria grown on uniformly radiolabelled amino acids and separation of the subunits by gel-permeation chromatography under denaturing conditions. 2. This datum, taken together with a recalculation of the previous ultracentrifuge data [Hall (1976) J. Mol. Biol. 107, 71-84], analytical gel-permeation chromatography and electron microscopy, strongly suggests an alpha 4 beta 4 quaternary structure for the enzyme. 3. The second chemical step in the enzyme turnover sequence, hydrolysis of the galactosyl-enzyme intermediate, is markedly slower for ebgab, having both Asp-97----Asn and Trp-977----Cys changes in the large subunit, than for ebga (having only the first change) and ebgb (having only the second), and is so slow as to be rate-determining even for an S-glycoside, beta-D-galactopyranosyl thiopicrate, as is shown by nucleophilic competition with methanol. 4. The selectivity of galactosyl-ebgab between water and methanol on a molar basis is 57, similar to the value for galactosyl-ebgb. 5. The equilibrium constant for the hydrolysis of lactose at 37 degrees C is 152 +/- 19 M, that for hydrolysis of allolactose is approx. 44 M and that for hydrolysis of lactulose is approx. 40 M. 6. A comparison of the free-energy profiles for the hydrolyses of lactose catalysed by the double mutant with those for the wild-type and the single mutants reveals that free-energy changes from the two mutations are not in general independently additive, but that the changes generally are in the direction predicted by the theory of Burbaum, Raines, Albery & Knowles [(1989) Biochemistry 28, 9283-9305] for an enzyme catalysing a thermodynamically irreversible reaction. 7. Michaelis-Menten parameters for the hydrolysis of six beta-D-galactopyranosylpyridinium ions and ten aryl beta-galactosides by ebgab were measured. 8. The derived beta 1g values are the same as those for ebgb (which has only the Trp-977----Cys change) and significantly different from those for ebgo (the wild-type enzyme) and ebga. 9. The alpha- and beta-deuterium secondary isotope effects on the hydrolysis of the galactosyl-enzyme of 1.08 and 1.00 are difficult to reconcile with the pyranose ring in this intermediate being in the 4C1 conformation.

Dinucleotide repeat polymorphism at the D11S436 locus

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Localization of the highly polymorphic microsatellite DXS456 on the genetic linkage map of the human X chromosome

The CA repeat microsatellite DXS456, with a heterozygosity of 77%, has been localized by multipoint linkage analysis in relation to 20 other genetic markers. DXS456 mapped to a 4.2-cM interval defined by the flanking markers DXS178 and DXS287. The maximum likelihood order of markers, cen-(DXYS1X/DXYS13X/DXYS2X/DXYS12X)-DXS366 -DXS178-DXS456-DXS287-DXS358-DXS267- qter, is favored by odds greater than 1000:1 over the subset of most likely alternative orders. Linkage of DXS456 can be inferred for at least six disease genes that are known to be linked to markers in the region Xq21.31-Xq25 and the marker will serve as an important index point for orienting these and other disease and marker loci in the region.

Studies on monoclonal antibody against recombinant human granulocyte colony-stimulating factor

Three hybridoma cell lines producing monoclonal antibodies (McAb) against recombinant human granulocyte colony-stimulating factor (rhG-CSF) have been established by fusing mouse myeloma cell line SP2/0 cells with spleen cells from a BALB/c mouse immunized with rhG-CSF. Ascites was obtained from BALB/c mice by injecting the hybridoma cells intraperitoneally. Three McAbs were purified by the caprylic acid-ammonium sulfate method. For each, the IgG subclass, valence and activity, molecular weight, specificity and affinity were determined. The applications of McAbs against rhG-CSF in the clinic and laboratory are discussed.

Metabolism of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) by cytochrome P450IIB1 in a reconstituted system

Several previous studies have suggested that cytochrome P450IIB1 is involved in the bioactivation of the tobacco-specific carcinogen, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), in rats as well as in mouse lung microsomes. The present investigation was undertaken to study the metabolism of NNK by purified cytochrome P450IIB1 in a reconstituted system. The metabolites 4-hydroxy-4-(3-pyridyl) butyric acid (hydroxy acid), 4-oxo-4-(3-pyridyl) butyric acid (keto acid), 4-oxo-4-(3-pyridyl) butanol (keto aldehyde), 4-(methylnitrosamino)-1-(3-pyridyl-N-oxide)-1-butanone (NNK-N-oxide) and 4-oxo-4-(3-pyridyl)-1-butanol (keto alcohol) were quantitated by HPLC. The results showed that, in addition to alpha-hydroxylations, cytochrome P450IIB1 also catalyzed the formation of NNK-N-oxide efficiently, and to a certain extent, the conversion of NNK primary hydroxylation metabolites (keto aldehyde and keto alcohol) to secondary metabolites (keto acid and hydroxy acid). Cytochrome b5 at a ratio of 1:1 or 2:1 to P450IIB1 had no significant effect on the metabolic activities and profiles of NNK. The apparent Km values for the formation of keto aldehyde, NNK-N-oxide and keto alcohol were respectively 191.2, 131.4 and 318.0 microM with corresponding apparent Vmax values of 89.7, 295.5 and 333.3 pmol/min/nmol P450, indicating that hydroxylation at the alpha-methyl position is preferred over the alpha-methylene position. Measurement of formaldehyde, a product derived from the alpha-methyl hydroxylation, was developed as a convenient method to study NNK metabolism. Thiourea activated cytochrome P450IIB1-catalyzed NNK metabolism significantly. Phenethyl isothiocyanate, an inhibitor of NNK-induced lung carcinogenesis, inhibited P450IIB1-catalyzed NNK demethylation in a concentration-dependent manner. This work demonstrates that purified P450IIB1 can catalyze the conversion of NNK to most of its oxidative metabolites.

Metabolic activation of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone as measured by DNA alkylation in vitro and its inhibition by isothiocyanates

The bioactivation of the tobacco-specific nitrosamine, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), by microsomes from target organs was studied with an in vitro microsome-mediated DNA alkylation system. Mouse lung, rat lung, and rat nasal microsomes catalyzed a time- and protein-dependent DNA methylation by [methyl-3H]NNK with activities of 4.11, 0.95, and 137.4 pmol/mg DNA/mg protein/h, respectively. The DNA methylation of NNK catalyzed by all three microsomal systems was inhibited by cytochrome P-450 inhibitors, such as carbon monoxide and metyrapone, but not by the cyclooxygenase inhibitor, aspirin, or by prolonged preincubation in the absence of NADPH. The possible involvement of specific P450 isozymes was assessed by specific inhibitory antibodies. An anti-P450IIB1&2 antibody significantly inhibited the DNA methylation by 45 and 32% in mouse lung and rat lung, respectively, whereas anti-P450IA1 and anti-P450IIE1 antibodies failed to show significant inhibition. All antibodies showed no inhibition in rat nasal microsomes. Glutathione inhibited the DNA methylation in a concentration-dependent manner in all three microsomal systems. Phenethyl isothiocyanate (PEITC), at doses of 0.25 and 1.00 mmol/kg body weight, was given intragastrically 2 h before sacrifice to mice and 24 h before sacrifice to rats, respectively; both mouse and rat lung microsomal activities were inhibited by about 40 and 90% by the low- and high-dose PEITC treatments, respectively. The rat nasal microsomes were only inhibited by the high-dose PEITC treatment by about 40%. PEITC, 4-phenylbutyl isothiocyanate, and 6-phenylhexyl isothiocyanate all inhibited the microsome-mediated DNA methylation of NNK in vitro, with 4-phenylbutyl isothiocyanate and 6-phenylhexyl isothiocyanate being more potent than PEITC and the mouse lung microsomes more sensitive than the rat lung and nasal microsomes. All three microsomal systems were shown to catalyze the in vitro DNA pyridyloxobutylation by [5-3H]NNK. On an equal protein basis, the rat nasal microsomes were much more active in catalyzing the DNA pyridyloxobutylation.

Effects of excess iodine in chick embryo thyroid follicles: initial inhibition and subsequent hypertrophy

The effects of excess iodine on the development of the thyroid gland of chick embryos was assessed following injections of potassium iodide prior to incubation. Iodide injection resulted in a significantly greater thyroid gland weight (goitre) on Day 18 of incubation and a delay in hatching. Histological studies of the thyroid gland on Day 12 of incubation revealed that iodide injection had inhibited thyroid follicle development. On Day 14, however, the thyroid glands of the iodide-treated embryos were indistinguishable from controls and on Day 18 the thyroid follicles of the iodide-injected embryos were clearly hypertrophied. In agreement with these light microscopical observations, electron microscopical examination showed conspicuous development of rough endoplasmic reticulum in the follicle cells of both iodide-treated 14 and 18 days old embryos and in those of the corresponding controls. Immunocytochemical studies of the pituitary of 18 days old embryos revealed a depletion of immunoreactive TSH suggesting that the iodide-induced hypertrophy of the thyroid was mediated by an activation of the thyrotropes. Iodide treatment was without effect on plasma levels of T3 and T4 for Day 18 embryos suggesting that the compensatory hypertrophy of the thyroid gland was sufficient to maintain circulating levels of thyroid hormones. The present results demonstrate that, in the embryonic chick thyroid, excess iodine produces effects which occur in two phases. The first phase consists of a transitory inhibition of the formation of follicles; it is followed by a second phase of compensatory hypertrophy resulting in goitre. The first phase probably results from a direct inhibitory effect of iodine on the developing thyroid whereas the second phase probably reflects a stimulation of the thyroid by TSH.

Studies on antipeptic ulcer agents: the quantitative structure-activity relationship analysis of heterocyclic aldehyde N4-substituted phenyl (thio) semicarbazones

Forty-five condensation products of furan-, pyrrole- and N-methyl pyrrole-alpha-carboaldehyde with N4-3- or N4-4-substituted phenyl semicarbazones and thiosemicarbazones were designed to optimize the antiulcer activity of a previously derived lead structure, formula II. Quantitative structure-activity relationships revealed that among the series of semicarbazones, increasing hydrophobicity and the introduction of electron-donating groups into the phenyl ring raise the antiulcer activity. Generally, semicarbazones are more active than the corresponding thiosemicarbazones. The wide gulf between the activity and toxicity of two derivatives (Compounds III and IV) necessitates further investigation of their pharmacological effects.

Polymorphisms in the human X-linked pyruvate dehydrogenase E1 alpha gene

Pyruvate dehydrogenase E1 alpha deficiency is an X-chromosome-linked disorder, often with fatal consequences. We have searched for genetically useful polymorphisms in or near this gene. No restriction fragment length polymorphisms were detected using a battery of 36 different restriction enzymes and probing with a full-length cDNA fragment, or two single-copy genomic fragments located within intron 8, and 15 kb 3' of the coding region, respectively. The chemical cleavage method was then applied to the detection of base changes in or near the gene. One polymorphism was found in exon 8 of the coding region. However, no base changes were detected in intron 3 or in the part of intron 8 covered by fragment gB2. Three blocks of microsatellite DNA containing variable numbers of CA-repeats were isolated from the 5' end of the gene and characterized. Length polymorphisms in these microsatellite DNAs were analysed using the polymerase chain reaction. Although the three loci are tightly linked, the polymorphisms appear not to be in disequilibrium, making them useful markers in linkage studies of the pyruvate dehydrogenase E1 alpha gene. Of 31 females analysed 12(39%) were heterozygous for at least one length polymorphism of the three (CA)n alleles.

[Study of the mechanism of gastrodin and derivatives of gastrodigenin]

The tritiated alpha-isobutylhydroxybenzyl alcohol (3H-G018) was found to be able to bind benzodiazepine (BZ) receptor on the rat brain membrane. The 125I labeled G-018 also had the similar binding activity with this receptor. In the present investigation, we observed that gastrodigenin and its derivatives inhibited the 125I-G018 binding of BZ receptor competitively, but no inhibition was observed with gastrodin. The results suggested that Gastrodigenin was bound to BZ receptor, and otherwise, gastrodin would have no direct interaction with BZ receptor. Probably, it might metabolize into gastrodigenin in vivo, and then got through the blood brain barrier and bound to BZ receptor, which mediated its pharmacological effects on the central nervous system.

Delayed radiation encephalopathy after radiotherapy for nasopharyngeal cancer: a CT study of 45 cases

The CT features of 45 cases of delayed radiation encephalopathy (including radiation necrosis) following radiotherapy for nasopharyngeal carcinoma are reported. The brain lesions were uni- or bilateral and involved mainly the white matter and subsequently the gray matter of the lower portion of the brain included within the portals of irradiation and its vicinity. The lesions were edematous and hypodense on CT and showed postcontrast enhancement in 50% of the cases. Within the period of follow-up (1-5 years), the lesions showed remissions and exacerbations and in some cases stabilized. In addition, there was progressive cerebral atrophy, manifesting itself mainly as dilatation of the temporal horns, the neighboring cisterns, and sylvian fissures. In some cases that were followed for a long time, the cerebral lesions showed either foci of calcification or encephalomalacia and/or porencephaly.

Somatic embryogenesis and plant regeneration in Acanthopanax senticosus

Mature embryos of Acanthopanax senticosus explanted on Murashige and Skoog (MS) medium with 0.5 mg/1 2,4-D developed somatic embryos directly from swollen cotyledon and embryo axes within one to two months. When the somatic embryos were transferred to medium supplemented with 2,4-D (0.5 mg/1) or IAA (1-3 mg/1) or Zeatin (0.5 mg/1) and NAA (0.2 mg/1), additional somatic embryos developed. Most (93%) embryos germinated on the above medium without 2,4-D. Sixty-two percent of the plantlets survived in soil. Histological observations revealed that the somatic embryos originated from cell masses of epidermal and sub-epidermal origin. There was no cytological separation zone between the somatic embryos and cultured expiants. Consequently, embryos were difficult to separate from their expiant tissue.