One-disulfide intermediates of apamin exhibit native-like structure

The conformations of three peptide models of the one-disulfide and fully reduced forms of apamin were characterized by using nuclear magnetic resonance (NMR) spectroscopy. Apa-2 contains the native disulfide bond between Cys3 and Cys15 in apamin with the other two cysteines replaced by alanines. Apa-1 contains the native disulfide bond between Cys1 and Cys11. Apa-S has all cysteines replaced with serines, mimicking fully reduced apamin. Comparing NOESY cross peaks and coupling constants for amide protons in the peptide analogs with those in native apamin indicates that a significant portion of Apa-2 possesses native-like structural elements of apamin in addition to some random coil conformations. Apa-1 contains a short helical structure from Ala9 to Arg13, corresponding to the N-terminal portion of the alpha-helix observed in the native structure, along with some local and probably flexible secondary structures corresponding to the reverse turn region in native apamin. A larger portion of Apa-1 exists in the form of random coil conformations compared to Apa-2. Apa-S displays mainly random coil conformations with some localized helical structures from Glu7 to Arg14 which are similar to the "nascent helices" proposed by Wright et al. [Wright, P. E., Dyson, H. J., & Lerner, R. A. (1988) Biochemistry 27, 7167-7175]. Formation of the first disulfide bond in apamin seems to be important in the folding process by stabilizing native-like structure, presumably by reducing the conformational freedom and initiating formation of structure.(ABSTRACT TRUNCATED AT 250 WORDS)

Characterization of the ATP-inhibited K+ current in canine coronary smooth muscle cells

Intracellular adenosine triphosphate (ATP)-inhibited K+ currents (IK, ATP) in canine coronary artery smooth muscle cells were characterized in the whole-cell configuration using the suction pipette method. Cells dialysed internally with solutions containing 5 mM ATP (ATPi) showed little detectable whole-cell current at potentials more negative than -30 mV. However, cells dialysed with ATPi-free solutions developed a time- and voltage-independent current which reached a maximum of 132 +/- 25 pA at -40 mV about 10 min following patch rupture. After "run-up", the current showed little "run-down". Concentration-dependent inhibition by ATPi yielded an inhibition constant (Ki) of 350 microM and a Hill coefficient of 2.3. In ATPi-free solutions, the large current at -40 mV was reduced by glibenclamide with a Ki of 20 nM and a Hill coefficient of 0.95. Conversely, in 1 mM ATPi solutions, the small current at -40 mV was increased by P-1075 from 8 +/- 2 pA to 143 +/- 33 pA, with a dissociation constant (Kd) of 0.16 microM and a Hill coefficient of 1.7. The effect of P-1075 was antagonized by glibenclamide. Maximal current density elicited by either ATPi depletion or external application of the channel opener P-1075 was similar with slope conductances of 81 +/- 10 pS/pF and 76 +/- 13 pS/pF respectively in the potential range of -90 to -40 mV. External Ca2+ had no effect on this current. Finally, in 1 mM ATPi, 20 and 50 microM adenosine increased the current slope conductance by 36 +/- 15% and 73 +/- 10% respectively between -90 to -40 mV. The IK, ATP, although very small in these cells, was extremely effective in causing membrane potential hyperpolarization.

Increased methotrexate resistance and dhfr gene amplification as a consequence of induced Ha-ras expression in NIH 3T3 cells

Oncogene activation and loss of tumor suppressor genes are known to play a role in tumor initiation as well as its progression. The potential roles of these genes in perturbation of genome stability has become a major interest. To better understand the relationship between expression of an oncogene and genetic instability, we have studied a cell line expressing an activated human Ha-ras under the control of bacterial lactose operon regulatory elements for changes in methotrexate resistance and dihydrofolate reductase (dhfr) gene amplification following mutant Ha-ras induction. In these cells mutant Ha-ras is directed by an inducible SV40 promoter containing a bacterial lac operator sequence which is repressed due to constitutive expression of bacterial lac repressor gene. The expression of this Ha-ras is specifically induced by the addition of isopropyl-1-thio-beta-D-galactopyranoside (IPTG), a lactose analogue, to the culture medium. During single-step methotrexate selection, these cells showed an increased frequency of methotrexate resistance in the presence of IPTG. More than 60% of the methotrexate-resistant colonies showed a 2-6-fold amplification of the dhfr gene. One clone with rearranged dhfr had about 100-fold amplification of the gene. The increased capacity to amplify DNA in response to mutant Ha-ras induction was not locus specific since cells also displayed an increased frequency of resistance to N-(phosphonacetyl)-L-aspartic acid in the presence of ITPG. Four of the methotrexate-resistant clones with amplified dhfr gene were cultured further in the presence or absence of IPTG and subsequently compared for their ability to grow in soft agar as a measure of transformation. In medium containing methotrexate but no IPTG, the clones were unable to grow in soft agar, indicating that methotrexate resistance due to gene amplification is separable from transformation.

[An experimental model of electric injury by high voltage]

A standardized 10,000-volt, 2 + 0.15-A, 5-s electric burn rabbit model was established. Microscopic examination revealed that there was patchy cellular necrosis intermingled with viable cells in the muscle in the burn area. Grossly, there was a distinct interface between viable and nonviable tissues. The resulted injury correlated well with clinical features of electric burn.

Separation of subcellular compartments containing distinct functional forms of MHC class II

Antigen processing in B lymphocytes entails initial binding of antigen to the surface Ig and internalization of the antigen into acidic compartments where the antigen is degraded, releasing peptides for binding to major histocompatibility complex class II molecules. Using subcellular fractionation techniques we show that functional, processed antigen-class II complexes capable of activating antigen-specific T cells in vitro are first formed in dense vesicles cosedimenting with lysosomes which are distinct from early endosomes and the bulk of late endosomes. With time, processed antigen-class II complexes appear in vesicles sedimenting with early endosomes and finally cofractionate with plasma membrane. A separate compartment is identified which contains major histocompatibility complex class II receptive to peptide binding but which does not have access to processed antigen in the B cell. These class II molecules are in the so-called "floppy" form in contrast to the class II molecules in the very dense vesicles which are in the "compact" form. These results demonstrate a correlation between the floppy and compact forms of class II molecules and their association with processed antigen and show that floppy and compact forms of class II reside in distinct and physically separable subcellular compartments.

Depletion of intracellular Ca2+ stores activates nitric-oxide synthase to generate cGMP and regulate Ca2+ influx

The mechanism of activation of the agonist-stimulated Ca2+ entry pathway in the plasma membrane is not known. To determine the role of nitric-oxide synthase (NOS) and cGMP in the regulation of this pathway, we used intact and streptolysin O (SLO)-permeable pancreatic acini and measured the relationship between Ca2+ release from internal stores, the NO metabolic pathway, generation of cGMP, and activation of Ca2+ entry. We found that agonist- or thapsigargin (Tg)-activated Ca2+ entry is inhibited by L-NA, a specific inhibitor of NOS, and by LY83583, an inhibitor of guanylyl cyclase. Inhibition of Ca2+ entry by inhibition of NOS was reversed by the NO releasing molecules NO2- and sodium nitroprusside (SNP) and by Bt2cGMP. Inhibition of Ca2+ entry by inhibition of guanylyl cyclase was reversed by Bt2cGMP, but not by the NO releasing agents. The use of L-NA-treated cells and different concentrations of SNP revealed that cGMP has a dual effect on Ca2+ entry. Increasing cGMP up to 10-fold above control activated Ca2+ entry. Further increase in cGMP up to 80-fold above control inhibited Ca2+ entry in a concentration-dependent manner. Measurement of cellular cGMP in intact cells showed that carbachol, Tg, and NO2- increased cGMP to similar levels. The effects of carbachol and Tg were inhibited by L-NA and LY83586, whereas the effect of NO2- was inhibited only by LY83583. SLO-permeabilized cells were shown to be agonist-competent in that the agonist induced Ca2+ release from the inositol 1,4,5-trisphosphate (IP3) pool and activated a NO-dependent generation of cGMP. These cells were used to study the regulation of NOS by Ca2+ and by Ca2+ content of the internal stores. When internal stores were maintained loaded with Ca2+, increasing medium [Ca2+] up to 2.5 microM only modestly increased NOS activity. In contrast, the depletion of Ca2+ from internal stores markedly increased NOS activity independent of medium [Ca2+]. Thus, NOS senses both cytosolic [Ca2+]i and internal store Ca2+ load. We propose that activation of Ca2+ entry involves an agonist-mediated Ca2+ release from internal stores which activates a cellular pool of NOS to generate cGMP, which then modulates Ca2+ entry pathway in the plasma membrane. This mechanism can explain the capacitative nature of Ca2+ entry. The biphasic effect of cGMP provides the cells with a negative feedback mechanism which inhibits Ca2+ entry during periods of high cell [Ca2+]i. This could allow oscillatory behavior of Ca2+ entry.

Prolonged inhibition of brain nitric oxide synthase by short-term systemic administration of nitro-L-arginine methyl ester

We studied the dose-response characteristics and the temporal profile of inhibition of brain nitric oxide (NO) synthase (NOS) elicited by i.v. administration of the NOS inhibitor nitro-L-arginine methyl ester (L-NAME). L-NAME was administered i.v. in awake rats equipped with a venous cannula. L-NAME was injected in cumulative doses of 5, 10, 20 and 40 mg/kg and rats were sacrificed 30 min after the last dose. NOS catalytic activity was assayed in forebrain cytosol as the conversion of [3H]L-arginine into [3H]L-citrulline. L-NAME attenuated brain NOS activity in a dose-dependent manner but enzyme activity could not be inhibited by more than approximately 50%. After a single 20 mg/kg injection of L-NAME the inhibition of brain NOS activity was time dependent and reached a stable level at 2 hrs (52% of vehicle). Inhibition after a single injection was still present at 96 hrs, albeit to a lower magnitude. We conclude that intravenous administration of L-NAME in rats at concentrations commonly used in physiological experiments leads to a dose and time-dependent but partial inhibition of brain NOS catalytic activity. The finding that the inhibition persists for several days after a single administration is consistent with the hypothesis that nitro-L-arginine, the active principle of L-NAME, binds to NOS irreversibly.

An influenza A (H1N1) virus, closely related to swine influenza virus, responsible for a fatal case of human influenza

In July 1991, an influenza A virus, designated A/Maryland/12/91 (A/MD), was isolated from the bronchial secretions of a 27-year-old animal caretaker. He had been admitted to the hospital with bilateral pneumonia and died of acute respiratory distress syndrome 13 days later. Antigenic analyses with postinfection ferret antisera and monoclonal antibodies to recent H1 swine hemagglutinins indicated that the hemagglutinin of this virus was antigenically related to, but distinguishable from, those of other influenza A (H1N1) viruses currently circulating in swine. Oligonucleotide mapping of total viral RNAs revealed differences between A/MD and other contemporary swine viruses. However, partial sequencing of each RNA segment of A/MD demonstrated that all segments were related to those of currently circulating swine viruses. Sequence analysis of the entire hemagglutinin, nucleoprotein, and matrix genes of A/MD revealed a high level of identity with other contemporary swine viruses. Our studies on A/MD emphasize that H1N1 viruses in pigs obviously continue to cross species barriers and infect humans.

Messenger RNA of G-proteins alpha-subunit in rat brown adipose tissue

The present study was addressed to quantify the steady-state mRNA levels for the alpha subunit of stimulatory (Gs) and inhibitory (Gi-1 and Gi-2) G-proteins in brown (interscapular) male rat adipose tissue (n = 6 rats). The quantification of specific mRNA, estimated using a solution hybridization RNAse protection assay, showed that the amounts of G alpha i-1, G alpha i-2 and G alpha s mRNA were 0.88 +/- 0.28 amol/microgram DNA, 76 +/- 4 amol/micrograms DNA and 460 +/- 16 amol/micrograms DNA, respectively. When the amounts of G alpha i-1 and G alpha i-2 and G alpha s mRNA in brown adipose tissue were compared with those in epididymal white adipose tissue (obtained from the same rats), G alpha i-1 and G alpha i-2 mRNA levels were very similar between brown and white adipose tissue, whereas the level of G alpha s mRNA was significantly higher in brown than in white fat tissue (P < 0.001). In conclusion, the present study shows the steady-state levels of mRNA for the alpha subunit of Gs, Gi-1 and Gi-2 in rat brown fat and suggests that the quantity of G alpha s mRNA is higher in brown than in white adipose tissue. Further studies are needed to explain the possible physiological importance of these findings.

Control of communicable diseases in the People's Republic of China

Communicable diseases were rampant in old China. Since the new China was founded, the Government has assigned high priority to the prevention of infectious diseases. A series of measures were adopted, such as instituting health policies in the vein of "Prevention First" as well as health laws and regulations, coordinating department participation and setting up the network of prevention and control of diseases. The incidence of leading infectious diseases has declined dramatically. Although great success has been achieved, infectious diseases still form one of the major public health problems in China. There are some existing problems which hinder the progress of infectious disease control. This situation is being addressed by the government and the slogan "Health for All in 2000" has become the focus of the nation.

Risk factors for oesophageal cancer in northeast China

A hospital-based case-control study of oesophageal cancer was carried out in the Heilongjiang Province, a low-risk area for oesophageal cancer in China. From May 1985 to May 1989, 196 histologically confirmed cases and 392 controls with other (non-neoplastic) diseases were personally interviewed in the wards of 5 major hospitals. Information was obtained about usual consumption in the early 1980s of 32 major contributors to the diet in the province, socio-demographic status, smoking and alcohol consumption. Odds ratios (OR) were obtained from logistic regression models, and confounding was controlled by means of multivariate models. Smoking and alcohol consumption were major risk factors for oesophageal cancer in this population. Smokers of handmade cigarettes exhibited a particularly high risk. A near multiplicative synergism was found between smoking and alcohol consumption. There was a significant inverse dose-risk trend for combined consumption of vegetables and fruits; a 300-g increase per day lowered risk by 35%. Vitamin C intake was negatively associated with risk; a 100-mg increase per day lowered risk by 39%. Our data suggest a modifying effect of vitamin C and beta-carotene on risk associated with smoking, but the power of analyses was low. Salt, salt-preserved foods and pickled vegetables were not associated with increased risk. High temperature of meals and drinks was a strong risk indicator in this population. The strength of tea and overall tea consumption were independent determinants of the risk.

[Detection of messenger RNA coding for BNP precursor in rat brain by in situ hybridization]

Messenger RNA coding for BNP precursor has been detected and mapped in histological sections of rat brain by in situ hybridization using specific rat BNP DNA probes labelled with 32P. The results showed that areas of highest concentration of BNP gene expression were located in the hypothalamus and in the verge area of the thalamus. Successively decreased concentration could also be found in amydaloid nuclei, olfactory bulb, hippocampus and cerebral cortex. While practically no BNP gene expression could be found in cerebellum and medulla oblongata.

Gender difference in smoking effects on adult pulmonary function

Data on 1,618 male and 1,669 female adults aged 40-69 yrs, from China in the Beijing Respiratory Health Study, were analysed to investigate the gender differences in effects of smoking on pulmonary function. Smoking was characterized by total smoking-years, smoking status (former, transitional and constant), smoking type (cigarette, cigar and others). The effects of smoking on height-standardized forced vital capacity (FVC) and forced expiratory volume in one second (FEV1) were assessed by multiple regressions adjusting for age, education level, use of an indoor coal stove for heating, passive smoking, occupational dust and gas/fume exposure, and residence. Prediction equations were derived from nonsmoking asymptomatic subjects. As compared to women, men had a much higher smoking prevalence (78 vs 35%) but a lower quitting rate (14 vs 23%). Female lifetime nonsmokers had greater mean percentage predicted lung function values than male lifetime nonsmokers, whilst female cigarette smokers had lower values than their male counterparts. In both sexes, the highest mean percentage predicted lung function values were found in lifetime nonsmokers, whilst the lowest values were found among former smokers, the second lowest among transitional smokers, and constant smokers actually had greater values than both former and transitional smokers. These findings were confirmed by sex-specific regression analyses. A global test on the interactions between smoking and sex was highly significant. This study suggests that adverse smoking effects on pulmonary function were greater in women than in men.(ABSTRACT TRUNCATED AT 250 WORDS)

[Study on the apical sealability of warm lateral condensation techniques]

An apical leakage test and a visible light spectrophotmetric analysis were performed to compare the apical sealability of warm lateral condensation and conventional lateral condensation techniques.The results showed that warm lateral with sealer delivered best sealability.It was superior to warm lateral without sealer(P<0.05) and conventional lateral condensation technique(P<0.01).Because of its inconvenient operation causing by native-made putta-percha,it is difficult to use warm lateral condensation technique widely in our country.

Probing the role of histidine-372 in zinc binding and the catalytic mechanism of Escherichia coli alkaline phosphatase by site-specific mutagenesis

In the X-ray structure of Escherichia coli alkaline phosphatase at 2.0-A resolution, His-372 was found only 3.8 A away from the zinc and forms a hydrogen-bonding interaction with Asp-327, a bidentate ligand of the zinc at the M1 site. However, His-372 does not directly interact with the zinc atom at the M1 site. In order to investigate the role of the side chain of His-372 in zinc binding and the catalytic mechanism of Escherichia coli alkaline phosphatase, site-directed mutagenesis was used to convert His-372 to alanine. The fact that the His-372-->Ala enzyme has similar zinc binding affinity as the wild-type enzyme indicates that His-372 is not involved in zinc binding at the M1 site. However, the altered kinetic behavior of the mutant enzyme compared to the wild-type enzyme suggests that the imidazole ring of His-372 plays an indirect role in the catalytic mechanism of the enzyme. The hydrolysis activity of the His-372-->Ala enzyme at pH 8.0 is 10-fold lower than that of the wild-type enzyme. In the presence of a phosphate acceptor at pH 8.0, the mutant enzyme is approximately 80% as active as the wild-type enzyme. Therefore, the His-372-->Ala mutation selectively enhances the transphosphorylation activity of the enzyme. The His-372-->Ala enzyme also exhibits 4- and 30-fold decreases in Km as compared to the wild-type enzyme in 0.1 M MOPS buffer and 1.0 M Tris, buffer at pH 8.0, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Phencyclidine-induced behavioral sensitization

Chronic administration of a psychomotor stimulant has been shown to produce progressively enhanced effects, a phenomenon called "reverse tolerance" or sensitization. The present study reexamined the effects of the daily injection of phencyclidine on locomotor activity and stereotypy in rats, and investigated whether drug-environment conditioning was necessary for the development of behavioral sensitization and whether (5R,10S)-(+)-5-methyl-10,11-dihydro-5H-dibenzo[a,b]cyclohepten-5,1 0-imine hydrogen maleate (MK-801, dizocilpine) blocked behavioral sensitization to phencyclidine. Female Sprague-Dawley rats were used. Locomotor activity and stereotypy were measured automatically with the Digiscan system. The results confirmed an earlier finding that four daily injections of phencyclidine induced sensitization to both locomotor activity and stereotypy. The development of behavioral sensitization did not require drug-environment conditioning. Moreover, MK-801 did not block behavioral sensitization to phencyclidine. The results of the present study suggest that the neuronal mechanisms underlying sensitization to phencyclidine are different from those underlying sensitization to amphetamine and cocaine.

Inversions and deletions generated by a mini-gamma delta (Tn1000) transposon

Intramolecular transposition by an engineered derivative of the transposon gamma delta (Tn1000) is described. This 1-kb element contains inverted repeats of the 40 bp of the delta end of gamma delta, bracketing a kan gene, but it contains no resolution site. Transposition was analyzed in two plasmids; one contained two contraselectable (conditional lethal) genes (thyA and sacB) adjacent to the mini-gamma delta element in a 13.0-kb pBR322/pUC-based two-component plasmid (a heterodimer), and the other contained a different contraselectable gene (strA [rpsL]) in a 13.2-kb three-component plasmid (a heterotrimer). Selection for loss of function of a single contraselectable gene yielded inversions and deletions. Each inversion plasmid was 1 kb larger than the parent plasmid: it had a second copy of mini-gamma delta inserted in the contraselected gene, with that copy plus the intervening segment inverted, and the 5-bp target site duplicated. Each deletion plasmid was smaller than the parent plasmid and had a deletion that extended from one transposon end into or through the contraselected gene for distances of up to 9.4 kb. The frequencies of deletions versus inversions ending in a single target gene were similar, although overall, deletions outnumbered inversions because deletions, but not inversions, into sites beyond the contraselected gene inactivate it. This work also demonstrates that thyA (which encodes thymidylate synthetase) is a useful contraselectable marker.

A selective blocker for rested T-type Ca++ channels in guinea pig atrial cells

The T-type Ca++ channel is widely distributed. Its physiological roles have not been well established because of the lack of a selective T-channel blocker. By using the suction pipette method, the authors describe (7-[[4-[bis(4-fluorophenyl)methyl]-1-piperazinyl]methyl]-2-[(2- hydroxyethyl)amino]4-(1-methylethyl)-2,4,6-cycloheptatrien-1-one) or U-92032, which selectively blocks rested closed T-type Ca++ channels (T channel). After a 3-min exposure to external U-92032 (1 microM), a 50% resting block of the T channel was observed on the first step depolarization from -90 to -40 mV; subsequent stimulations at 0.1 Hz produced little further block. The L-type Ca++ current (L channel) was not affected. At 10 microM, U-92032 produced about 100% resting block of the T and 20% block of the L channels. Subsequent stimulations at 0.1 Hz increased the block of L channel to 56% at the sixth pulse, which indicated strong use dependence at negative potentials and low stimulation rates. Blockade of the T channel did not alter channel steady-state activation and inactivation or current inactivation time courses. By contrast, blockade of the L channel shifted the midpoint of its steady-state inactivation curve from -20.6 mV to -27.8 mV and accelerated its slow inactivation time course, from 171 +/- 16 msec to 79.8 +/- 9.3 msec. Moreover, the 90% recovery time from inactivation was increased from 0.12 to 60 sec. Because U-92032 is ionized at pH 7, its inability to affect the T channel gating property may suggest external drug binding sites.(ABSTRACT TRUNCATED AT 250 WORDS)

Generator mechanism of pain-related evoked potentials following CO2 laser stimulation of the hand: scalp topography and effect of predictive warning signal

In order to clarify the generator mechanism of pain-related evoked potentials (pain EPs), we studied the scalp topography of the pain EPs following CO2 laser stimulation of hand dorsum by using balanced sternovertebral electrodes as the noncephalic reference in 11 normal volunteers. We also examined the effects of predictive warning signal (light-emitting diode) on the pain EPs. In both the warned and unwarned conditions, all of the 22 hand stimulations showed a large negative component (N2) at the peak latency of about 213 ms followed by a large positive component (P2) at the peak latency of about 329 ms. A preceding small negative component (N1) at the peak latency of about 148 ms was detected in 12 of the 22 hand stimulations in the warned condition and in 13 of the 22 hand stimulations in the unwarned condition. P2 was significantly larger and occurred earlier in the warned condition than in the unwarned condition, whereas other components did not differ between the two conditions, suggesting that an increased attention of the subject to the stimulus influenced the generator mechanism of the P2 component. With regards to the scalp topography, N2 was maximal at Cz and widespread transversely to both sides, whereas P2 was maximal at Cz or Pz and spread more posteriorly than N2. These findings suggest that P2 is generated by a different mechanism from N2 and is most likely associated with pain-related cognitive function. N1 was localized to the contralateral central and midtemporal areas, confirming that the nociceptive inputs are perceived in the sensory cortex in humans. The question as to whether the N1 component is generated in the hand area of the primary somatosensory cortex or in the secondary somatosensory cortex, or in both areas, remains to be solved.

Hypertonic saline improves cerebral oxidative metabolism and cytochrome aa3 redox state during hemorrhagic hypotension in dogs

Hypertonic saline used in the treatment of hemorrhagic shock dramatically improves cardiovascular performance. In the present study, our focus was on whether it would improve disturbances of cerebral oxidative metabolism induced by hemorrhagic hypotension. Fourteen dogs were bled over a period of 15 min so that the mean arterial blood pressure of seven dogs (group H) fell to 65 mmHg and that of the other seven (group L), to 45 mmHg. These pressures were maintained for 30 min, and then 20% hypertonic saline (1.5 ml/kg body weight) was injected intravenously. Cerebral oxyhemoglobin, deoxyhemoglobin, cerebral blood volume, and oxidized cytochrome aa3 were continuously monitored by near-infrared spectroscopy throughout the experiment. The experimental results showed that 45 min of hemorrhagic hypotension led to decreases in cerebral oxyhemoglobin (from control level 0 to -25.5 +/- 7.5 microM/liter brain tissue in group H and to -32.3 +/- 7.5 microM/liter brain tissue in group L), in total hemoglobin (from control level 0 to -7.2 +/- 1.8 microM/liter brain tissue in group H and to -6.5 +/- 1.7 microM/liter brain tissue in group L), and in oxidized cytochrome aa3 in group L (from control level 0 to -0.8 +/- 0.4 microM/liter brain tissue), but to increases in deoxyhemoglobin (from control level 0 to 15.5 +/- 5.0 microM/liter brain tissue in group H and to 25.8 +/- 3.4 microM/liter brain tissue in group L) and in oxidized cytochrome aa3 in group H (from control level 0 to 0.6 +/- 0.3 microM/liter brain tissue.(ABSTRACT TRUNCATED AT 250 WORDS)

Radioimmunoguided surgery in gastric cancer using 131-I labeled monoclonal antibody 3H11

A clinical trial of radioimmunoguided surgery (RIGS) using 131-I labeled monoclonal antibody (MAb) 3H11 was performed on 25 cases with gastric cancer in this study. The results showed that the route of the administration of radiolabeled MAb is the key point of successful RIGS for gastric cancer. The RIGS in 19 cases in the group of submucosal injection via endoscope was very satisfying. For the detection of metastatic lymph nodes, the sensitivity rate of RIGS was 99.2% (118/119), the specificity, 97.7% (43/44), and the accuracy 98.8% (161/163). The accuracy rate in detecting tumor infiltration of the gastric wall was 95.9% (94/98), the sensitivity 94.6% (35/37), and the specificity 96.7% (59/61). Thus, the use of RIGS may improve the radical resectability rate and possibly the overall survival rate in patients with gastric cancer.

A maternal homeobox gene, Bombyx caudal, forms both mRNA and protein concentration gradients spanning anteroposterior axis during gastrulation

We have isolated a caudal (cad) homologue from a cDNA library of Bombyx mori embryos. The Bombyx cad cDNA encodes a protein of 244 amino acids. The homology between Drosophila and Bombyx homeodomains is 80%. Similar to Drosophila cad, there is no YPWM peptide sequence along the upstream of homeodomain. Northern blot hybridization with a Bombyx cad probe revealed the presence of single maternal transcript of 2.3 kb. A stronger signal of the transcripts was detected in unfertilized eggs and in eggs up to 36 hours after deposition. The transcripts decreased rapidly by 2 days and a weak signal was maintained until hatching. To analyse its spatial expression pattern, we have established a novel frozen sectioning method for in situ hybridization and immunohistochemistry experiments. The results showed that Bombyx cad transcripts accumulated first in the nurse cells and transferred into the oocyte at a defined time during oogenesis. The maternal transcripts of Bombyx cad formed a concentration gradient spanning the anteroposterior axis during the gastrulation stage and were restricted to the anal pad, the most posterior domain, after 2 days of embryogenesis; the Drosophila cad mRNA revealed the corresponding expression profile during the syncytial blastoderm stage. The Bombyx cad protein was not detected in the ovary and the first 9 hours of eggs, but was first detected evenly during cellular blastoderm stage. During gastrulation, Bombyx cad protein concentration gradients shifted along the anteroposterior axis coinciding with the shifting of the mRNA concentration gradients.(ABSTRACT TRUNCATED AT 250 WORDS)

Nitro-L-arginine attenuates hypercapnic cerebrovasodilation without affecting cerebral metabolism

We have previously demonstrated that topical cortical application of nitro-L-arginine (L-NA), a potent inhibitor of nitric oxide (NO) synthesis, attenuates resting cerebral blood flow (CBF) and the cerebrovasodilation elicited by hypercapnia. In this study, we sought to determine whether these cerebrovascular effects of L-NA are secondary to a depression in cerebral metabolism. Rats were anesthetized (chloralose, 80 mg/kg) and artificially ventilated. Arterial pressure and blood gases were monitored. The frontal cortex was exposed and superfused with normal Ringer (pH 7.3-7.4; 37 degrees C) or with Ringer containing L- or D-NA. CBF or cerebral glucose utilization (CGU) was measured autoradiographically using the [14C]iodoantipyrine or 2-[14C]deoxy-D-glucose method, respectively. Application of normal Ringer did not affect CBF at the site of superfusion (n = 5; P > 0.05, paired t test). Application of L-NA (1 mM; n = 5), but not D-NA (1 mM; n = 6), attenuated resting CBF by 33 +/- 5% (P < 0.05; analysis of variance). During hypercapnia (partial pressure of CO2 = 55-60 mmHg), L-NA attenuated the CBF increase by 78 +/- 6% (n = 5/group; P < 0.05 from Ringer), whereas D-NA had no effect (P > 0.05). Resting CBF and the CBF response to hypercapnia were largely unaffected in brain regions outside the field of superfusion. In contrast to hypercapnia, L-NA (1 mM) did not attenuate the increases in CBF elicited by topical application of papaverine (10-1,000 microM; n = 8).(ABSTRACT TRUNCATED AT 250 WORDS)

Estradiol regulation of mRNA expression of stimulatory G-protein alpha-subunit in white adipose tissue from female rats

Adipose tissue has been recognized as a major peripheral metabolic target of estrogens. The present study was addressed to examine in female rats whether differences in the adipose tissue mRNA expression of alpha-subunit of stimulatory (Gs) and/or inhibitory (Gi) G-proteins exist between intact and ovariectomized rats, the latter with or without estradiol or testosterone treatment. The fat cell membrane protein amount of Gs and Gi alpha-subunit also was examined. All these parameters were evaluated in parametrial fat tissue samples obtained from 40 female Sprague-Dawley rats. A group of rats (N = 20) was investigated for evaluation of mRNA expression and another group (N = 20) for quantification of the protein amount of Gs and Gi alpha-subunit. Each group was represented by five control rats (sham-operated), five ovariectomized (OVX) rats, five ovariectomized rats treated with estradiol (OVXE) and five ovariectomized rats treated with testosterone (OVXT). Ribonucleic acid extracted from adipose tissue and analyzed by northern blot with G alpha s, G alpha i-3 cRNA probes revealed three major bands with estimated sizes of 1.9, 3.5 and 2.35 kb, respectively. Messenger RNA quantitative analysis, by a solution of hybridization RNAase protection assay on total nucleic acid samples, showed that the amount of G alpha i-1 and G alpha i-2 mRNA was similar within the different groups, whereas the G alpha s mRNA was significantly less abundant (p < 0.01) in OVX and OVXT rats than in control or OVXE rats. No difference in G alpha s mRNA content was found between control and OVXE rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Promoter of the POU-M1/SGF-3 gene involved in the expression of Bombyx silk genes

To characterize the transcription regulation of the POU-M1/SGF-3 gene, we have cloned a genomic DNA fragment encompassing the whole coding region and its flanking sequences. This gene does not contain any intron. The 5'-flanking region of the gene contains several interesting motifs, such as homeodomain-binding motifs, sequences resembling the transcriptional factor Sp1-binding site, and TGTTT motifs, but lacks some of the typical transcriptional regulatory sequences, such as TATA and CCAAT boxes. Transcriptional analysis of a series of deletion mutants of the gene in the nuclear extracts prepared from the middle silk gland of 2-day-old fifth instar larvae revealed the presence of multiple cis-regulatory elements located both upstream and downstream of the initiation site. One of these elements, the homeodomain-binding element, was identified to mediate negative regulation. By mobility shift assay using the POU-M1 specific antibodies, we found that this negative element interacts with the POU-M1/SGF-3. Transcription analysis in vitro using templates mutagenized in the PB region and one of the POU-M1 antibodies indicated that the PB region is an autoregulatory element responsible for SGF-3-dependent transcriptional repression.

Fertile transgenic Indica rice plants obtained by electroporation of the seed embryo cells

We have obtained fertile transgenic plants of Indica rice variety IR36, by using electroporation to transfer the neomycin phosphotransferase II (nptII) gene into cells of mature embryos. Resistant calli were selected in the presence of 30 μg/ml G418. Nearly thirty transgenic plants were regenerated within three months after transformation. Many of them yielded seeds following self-pollination. Data from molecular analysis and enzyme assay proved that the foreign gene was stably integrated into the genome of resistant calli, R0 and R1 plants, and also expressed. Mendelian segregation of the nptII gene was observed in R1 progeny plants.

Establishing a resuscitation model in rabbits with closed-thoracic cardiopulmonary by-pass

This study aims to establish an animal model of resuscitation in rabbits by using closed-thoracic cardiopulmonary by-pass (CTCPB). The rabbits were randomly divided into four groups according to cardiac arrest times which were 8, 10, 12, and 15 min. Neurologic outcome and blood lactate were determined within 150 min after resuscitation. It was indicated that the rabbits' neurologic functions were progressively injured with prolonged cardiac arrest time. The threshold of circulatory arrest time that induced a vegetative state in the rabbits was between 10 and 12 min. There were no significant differences in cardiac resuscitability among the four groups, as was so for plasma lactate, although it increased significantly from the control levels. The establishment of a small-animal model of resuscitation by using CTCPB, and the problems in dealing with it are also described and discussed in detail in this paper. Our experience indicated that this is a simple, convenient, and economical animal model for the study of resuscitation.

Salicylamide sulfate cell entry in perfused rat liver: a multiple-indicator dilution study

The hepatocellular entry of salicylamide sulfate conjugate, which binds to both red blood cells and albumin, was examined with the multiple-indicator dilution technique in the perfused rat liver, with medium containing both 20% red cells and 1% albumin (set A), red cells only (set B), albumin only (set C) and neither red cells nor albumin (set D). [14C]Salicylamide sulfate, 51Cr-labeled red cells (a vascular reference), 125I-labeled albumin, [3H]sucrose or [58Co] ethylenediaminetetraacetic acid (EDTA) (high and low molecular weight interstitial references, respectively) and 3H2O or D2O (a cellular reference) were injected as a bolus into the portal vein. Among all sets of outflow data, the earliest immediate vascular recoveries for the [14C] salicylamide sulfate were lower than those for the vascular reference. For sets A and B, the upslopes precessed those for the 58Co-EDTA curve, then crossed over the 58Co-EDTA curves, with lower magnitude peaks occurring at the same time as those for labeled albumin, whereas for sets C and D, in which red cells were absent, the upslopes of [14C]salicylamide sulfate lagged behind those for labeled albumin and [3H]sucrose, reaching lower magnitude peaks coincidental in time with those for labeled sucrose. The precession of the [14C]salicylamide sulfate curve over 58Co-EDTA or [3H]sucrose in the presence (sets A and B) but not in the absence (sets C and D) of red cells and the absence of precession with albumin alone (set C) suggest that a red cell effect on the upslope is more evident than that for albumin. For all experiments, the downslopes of the sulfate curve crossed over those of the labeled red cells, albumin, 58Co-EDTA and sucrose curves and then the water curve at around the peak. The downslopes of the [14C]salicylamide sulfate were similar to those for labeled water, suggesting rapid cellular influx and efflux of salicylamide sulfate. Quantitative evaluation with a barrier-limited space-variable transit-time model for rapidly equilibrating red cell and albumin binding accounted for the upslope effects on [14C]salicylamide sulfate behavior and demonstrated its relatively high liver cell permeability. Values for the unbound permeability surface area product (0.029 to 0.036 ml sec-1.gm-1) were not different, regardless of the presence or absence of red cells and albumin, and slightly exceeded values for hepatic blood flow (0.0186 +/- 0.0016 ml sec-1.gm-1). Comparable influx (0.083 to 0.14 sec-1) and efflux (0.10 to 0.18 sec-1) coefficients were obtained, suggesting rapid cellular entry and efflux of salicylamide sulfate.(ABSTRACT TRUNCATED AT 400 WORDS)

An association between air pollution and mortality in six U.S. cities

BACKGROUND

Recent studies have reported associations between particulate air pollution and daily mortality rates. Population-based, cross-sectional studies of metropolitan areas in the United States have also found associations between particulate air pollution and annual mortality rates, but these studies have been criticized, in part because they did not directly control for cigarette smoking and other health risks.

METHODS

In this prospective cohort study, we estimated the effects of air pollution on mortality, while controlling for individual risk factors. Survival analysis, including Cox proportional-hazards regression modeling, was conducted with data from a 14-to-16-year mortality follow-up of 8111 adults in six U.S. cities.

RESULTS

Mortality rates were most strongly associated with cigarette smoking. After adjusting for smoking and other risk factors, we observed statistically significant and robust associations between air pollution and mortality. The adjusted mortality-rate ratio for the most polluted of the cities as compared with the least polluted was 1.26 (95 percent confidence interval, 1.08 to 1.47). Air pollution was positively associated with death from lung cancer and cardiopulmonary disease but not with death from other causes considered together. Mortality was most strongly associated with air pollution with fine particulates, including sulfates.

CONCLUSIONS

Although the effects of other, unmeasured risk factors cannot be excluded with certainty, these results suggest that fine-particulate air pollution, or a more complex pollution mixture associated with fine particulate matter, contributes to excess mortality in certain U.S. cities.

Association of indoor and outdoor particulate level with chronic respiratory illness

The effect of indoor and outdoor particulate level on respiratory health was examined in 1,576 never smokers, 40 to 69 yr of age residing in industrial, residential, and suburban areas. The health outcomes of interest in this report were physician-diagnosed bronchitis, asthma, and six respiratory symptoms including chronic cough, chronic phlegm, bouts of cough and phlegm, shortness of breath (SOB), wheeze, and wheeze with SOB. Households with coal stoves had substantially higher indoor particulate levels than those with gas stoves. Subjects were grouped into three exposure categories according to the indoor use of coal stoves for both cooking and heating (B), either cooking or heating (E), or neither (N). The adjusted odds ratios for chronic phlegm, bouts of cough and phlegm, wheeze, and wheeze with SOB were significantly higher in the B than in the N group; the odds ratios for chronic cough and SOB were also higher for B than N, although these were not significant. The odds ratios in the E group were significantly greater for wheeze with SOB than in the N group but not for the other symptoms. The global estimates of the odds ratios for the six symptoms were 1.4 and 2.0, respectively, for the E and B groups. The particulate level was highest in the industrial area and lowest in the suburban area. There was an excess risk of all respiratory symptoms among subjects residing in industrial and residential areas, with an increase in symptom prevalence with outdoor particulate levels.(ABSTRACT TRUNCATED AT 250 WORDS)

A comprehensive analysis of peripheral blood lymphocytes in healthy aged humans by flow cytometry

This study used a panel of mAb and multiparameter flow cytometry to assess the composition of PBL from healthy aged individuals. The results showed that while total lymphocyte numbers altered only marginally in the aged (> or = 70 years) there were significant changes in the distribution of various sub-populations; for example, there were lower numbers of CD3+ and CD8+ cells, and higher numbers of CD16+ (NK) cells. As a direct result of these changes the numbers of CD2+ cells remained unchanged in the aged compared with young adult controls (18-25 years). The number of CD4+ T cells expressing CD45RO isoform (memory cells) exceeded the number of CD4+CD45RA+ (naive) cells in aged donors, whereas the converse was true for young donors. In addition, associated with this increase in CD45RO+ cells, the aged showed an expanded population of CD45RO+ T cells displaying low surface levels of CD45RO. These data suggest that shifts in the distribution of regulatory T cell subsets may play a role in age-related changes in immune response.

[Relation between traditional Chinese medicinal syndrome differentiation and blood platelet function in 310 cases of blood stasis]

310 patients (153 male, 157 female) of Blood Stasis were divided into various groups by Syndrome Differentiation of TCM and 35 healthy subjects were taken as control. The relationship of TCM Syndrome and function of blood platelet were studied with blood platelet counting, its volume, adherence and aggregation, plasma thromboxane B2 (TXB2) and 6-keto-prostaglandin F1 alpha(6k-PGF1 alpha) as indices of observation. The results were: (1) Blood platelet aggregation of Blood Stasis patients was higher than that in control (P > 0.001). (2) There were some differences of platelet aggregation among different TCM Syndromes. Platelet aggregation of Blood Stasis patients with Qi Deficiency was higher than that with other Syndromes significantly, and the aggregating rate in those patients was higher than that in control (P < 0.05). (3) The platelet aggregation and TXB2 of patient with Heart Qi Deficiency were significantly higher than those of the control (P < 0.05, P < 0.001), and they were also higher than of other groups of blood stasis patient with Spleen, Lung or Kidney Qi Deficiency.

Parkinsonism induced with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) in cats: behavioral, biochemical and pathological studies

Intraperitoneal injection of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) in four cats produced akinesia, bradykinesia, crouched posture, feeding difficulty, and so on, lasting for two weeks. Madopar therapy ameliorated these motor impairments. Reduction of the concentration of dopamine and its metabolites was determined in the substantia nigra and putamen by high performance liquid chromatography (HPLC). Depletion of noradrenaline, serotonin and their metabolites was also seen. Loss of nerve cells and proliferation of glial cells in the substantia nigra were observed under the light microscope. The results indicate that MPTP-induced Parkinsonism in the cat provides an animal model that can be used for basic and therapeutic research on Parkinson's disease.

Reconstitution of wild type viral DNA in simian cells transfected with early and late SV40 defective genomes

The DNAs of polyomaviruses ordinarily exist as a single circular molecule of approximately 5000 base pairs. Variants of SV40, BKV and JCV have been described which contain two complementing defective DNA molecules. These defectives, which form a bipartite genome structure, contain either the viral early region or the late region. The defectives have the unique property of being able to tolerate variable sized reiterations of regulatory and terminus region sequences, and portions of the coding region. They can also exchange coding region sequences with other polyomaviruses. It has been suggested that the bipartite genome structure might be a stage in the evolution of polyomaviruses which can uniquely sustain genome and sequence diversity. However, it is not known if the regulatory and terminus region sequences are highly mutable. Also, it is not known if the bipartite genome structure is reversible and what the conditions might be which would favor restoration of the monomolecular genome structure. We addressed the first question by sequencing the reiterated regulatory and terminus regions of E- and L-SV40 DNAs. This revealed a large number of mutations in the regulatory regions of the defective genomes, including deletions, insertions, rearrangements and base substitutions. We also detected insertions and base substitutions in the T-antigen gene. We addressed the second question by introducing into permissive simian cells, E- and L-SV40 genomes which had been engineered to contain only a single regulatory region. Analysis of viral DNA from transfected cells demonstrated recombined genomes containing a wild type monomolecular DNA structure. However, the complete defectives, containing reiterated regulatory regions, could often compete away the wild type genomes. The recombinant monomolecular genomes were isolated, cloned and found to be infectious. All of the DNA alterations identified in one of the regulatory regions of E-SV40 DNA were present in the recombinant monomolecular genomes. These and other findings indicate that the bipartite genome state can sustain many mutations which wtSV40 cannot directly sustain. However, the mutations can later be introduced into the wild type genomes when the E- and L-SV40 DNAs recombine to generate a new monomolecular genome structure.

Functional interaction of the v-Rel and c-Rel oncoproteins with the TATA-binding protein and association with transcription factor IIB

Rel family proteins regulate the expression of genes linked to kappa B-binding motifs. Little is known, however, of the mechanism by which they enhance transcription. We have investigated the ability of the v-Rel and c-Rel oncoproteins to interact with components of the basal transcription machinery. Here we report that both the acidic transcription activation domain mapping to the unique C terminus of chicken c-Rel and the F9 cell-specific activation region common to both v-Rel and c-Rel interact with the TATA-binding protein (TBP) and transcription factor IIB (TFIIB) in vitro and in vivo. We also demonstrate that TPB interaction with Rel activation regions leads to synergistic activation of transcription of a kappa B-linked reporter gene. Combined with the observation that the mouse c-Rel and human RelA proteins also interact with TBP and TFIIB in vitro, these results suggest that association with basal transcription factors is important for the transcriptional activities of Rel family proteins.

Comparison of 10 influenza A (H1N1 and H3N2) haemagglutinin sequences obtained directly from clinical specimens to those of MDCK cell- and egg-grown viruses

PCR was used to amplify and sequence the complete HA1 region of the haemagglutinin (HA)-encoding genes of 10 clinical isolates of influenza virus of the H1N1 or H3N2 subtypes. These sequences were compared to those obtained from viruses isolated from the same specimens after passage in eggs and MDCK cells. Amino acid substitutions in the egg-derived HA sequences were found in nine out of the 10 specimens analysed, whereas seven out of eight of the MDCK-derived HA sequences were identical to those in the corresponding original specimens. Changes in the H1 HA occurred at residues 77a, 196 (also found in the corresponding HA from the MDCK isolate), 225, 226 and 227; changes in the H3 HA occurred at residues 137, 156, 186, 248 and 276. In addition, we have shown that an amino acid change at residue 145 in the HA of the H3 subtype that was previously demonstrated to be egg-selected is now present in circulating strains.

Occupational exposures and physician-diagnosed asthma

Data from a community-based random sample of 3,606 adults 40 to 69 years of age residing in Beijing, China, were used to examine the relationship between occupational exposures to dusts and gases/fumes and physician-diagnosed asthma. The prevalence of asthma was 3.9 percent for men and 3.8 percent for women. After adjusting for sex, age, education, residential areas, indoor coal combustion, and smoking status, the attributable risks of asthma were 1.7 percent and 1.2 percent for dust and gas/fume exposure, respectively. The adjusted odds ratios of asthma for dust and gas/fume exposed groups were 1.6 (95 percent confidence interval [CI], 1.1 to 2.2) and 1.4 (95 percent CI, 0.9 to 2.1), which were independent of sex and smoking status. When subjects were classified into none, dust-only, gas/fume-only, and both-exposure groups, the estimated odds ratios of asthma were 1.3 (95 percent CI, 0.9 to 2.1) in dust-only group, 0.9 (95 percent CI, 0.5 to 1.9) in fume-only group, and 2.1 (95 percent CI, 1.2 to 3.6) in both-exposure group, suggesting a combining effect of the two agents. There was an exposure-response relationship between dust and gas/fume exposures and asthma. In analysis of specific occupational agents, our findings are consistent with previously reported airway effects of organic dusts, but they also suggest that exposure to organic solvents may result in asthma, particularly when combined with dust.

Conversion of a magnesium binding site into a zinc binding site by a single amino acid substitution in Escherichia coli alkaline phosphatase

The replacement of aspartic acid by histidine at position 153 in Escherichia coli alkaline phosphatase results in a mutant enzyme that is remarkably similar to certain mammalian alkaline phosphatases that are activated by magnesium in a time-dependent fashion. These mammalian alkaline phosphatases have histidine at the position corresponding to 153 of the E. coli sequence. Here we report the three-dimensional structure of the mutant E. coli alkaline phosphatase with histidine at position 153. The structure reveals that the octahedral magnesium binding site has been converted to a tetrahedral zinc binding site with an imidazole ring nitrogen of His-153 as one of the ligands to the zinc. The alteration in metal binding caused by the mutation could explain the origin of the magnesium activation observed with the mammalian alkaline phosphatases. The structure also reveals differences in the mode of phosphate binding, explaining the enhanced phosphate affinity and the reduced activity of the mutant enzyme in the presence of zinc.

Binding of magnesium in a mutant Escherichia coli alkaline phosphatase changes the rate-determining step in the reaction mechanism

To investigate the role of magnesium at the M3 site in Escherichia coli alkaline phosphatase, site-specific mutagenesis was used to substitute Glu-322, a ligand of the Mg2+ with either aspartic acid (E322D) or alanine (E322A). The residual Mg2+ content of the E322D enzyme is about 16-fold lower than that of the wild-type enzyme, and both mutant enzymes exhibit extremely poor catalytic activity compared to the wild-type enzyme. Mg2+ is a strong activator of the E322D enzyme. The hydrolysis activity of the E322D enzyme maximally stimulated by Mg2+ is 60% of that of the wild-type enzyme. Under conditions that measure the sum of hydrolysis and transphosphorylation activities, the kcat of the E322D enzyme in the presence of 500 mM Mg2+ is 2.6-fold higher than the kcat observed for the wild-type enzyme. Zn2+ also activates the E322D enzyme, although it is not as strong an activator as Mg2+. Competition experiments suggest that the activation of the E322D enzyme by Mg2+ and Zn2+ results from binding of either of these metals to the same site on the enzyme. High concentrations of the substrate p-nitrophenyl phosphate inhibit the activity of the E322D enzyme; however, high concentrations of Mg2+ can overcome this inhibition. Stopped-flow experiments indicate that the rate-limiting step of the nonstimulated E322D enzyme at pH 8.0 differs from that of the wild-type enzyme and involves the breaking of the covalent bond between the enzyme and phosphate.(ABSTRACT TRUNCATED AT 250 WORDS)

Amount of G-protein alpha-subunit in rat white adipocytes: lack of difference between subcutaneous and visceral fat

It has been the purpose of this study to examine possible differences in the amount of stimulatory (Gs) and inhibitory (Gi) G-protein alpha-subunits (measured with a quantitative enzyme-linked immunosorbent assay in fat cell membrane preparation) between subcutaneous and intra-abdominal regions in rats. The lipolytic response to isoproterenol and the number of beta-adrenergic binding sites were also examined. These parameters were all evaluated simultaneously in subcutaneous (inguinal), epididymal and perirenal fat samples collected from six male Sprague-Dawley rats. The membrane contents of the Gs and Gi alpha-subunits were similar in the three depots. Moreover, no difference was found among the different regions with regard to isoproterenol-stimulated glycerol release and beta-adrenoceptor number, expressed per cell number. In conclusion, the present study shows for the first time in rats that the abundance of inhibitory and stimulatory G-protein alpha-subunits is similar in subcutaneous and in visceral adipocytes. Moreover, the number of beta-adrenoceptors and the lipolytic response to isoproterenol do not show significant variations with the anatomical site. As the present results are apparently in contrast with those obtained previously in human adipocytes, there is a possibility that the different results observed in rat and in human fat cells could be explained by species differences.

Solution structure of tertiapin determined using nuclear magnetic resonance and distance geometry

The solution structure of tertiapin, a 21-residue bee venom peptide, has been characterized by circular dichroism (CD), two-dimensional nuclear magnetic resonance (NMR) spectroscopy, and distance geometry. A total of 21 lowest error structures were obtained from distance geometry calculations. Superimposition of these structures shows that the backbone of tertiapin is very well defined. One type-I reverse turn from residue 4 to 7 and an alpha-helix from residue 12 to 19 exist in the structure of tertiapin. The alpha-helical region is best defined from both conformational analysis and structural superimposition. The overall three-dimensional structure of tertiapin is highly compact resulting from side chain interactions. The structural information obtained from CD and NMR are compared for both tertiapin and apamin (ref. 3), another bee venom peptide. Tertiapin and apamin have some similar secondary structure, but display different tertiary structures.

Passive cigarette smoke, coal heating, and respiratory symptoms of nonsmoking women in China

In this study we evaluated data from a sample of 973 never-smoking women, ages 20-40, who worked in three similar textile mills in Anhui Province, China. We compared prevalence rates of respiratory symptoms across homes with and without coal heating and homes with different numbers of smokers. Multiple logistic regression models that controlled for age, job title, and mill of employment were also estimated. Respiratory symptoms were associated with combined exposure to passive cigarette smoke and coal heating. Effects of passive cigarette smoke and coal heating on respiratory symptoms appeared to be nearly additive, suggesting a dose-response relationship between respiratory symptoms and home indoor air pollution from these two sources. The prevalence of chest illness, cough, phlegm, and shortness of breath (but not wheeze) was significantly elevated for women living in homes with both smokers and coal heating.

Programmable drug delivery from an erodible association polymer system

An erodible association polymer system based on blends of cellulose acetate phthalate (CAP) and Pluronic F127, a block copolymer of poly(ethylene oxide) and poly(propylene oxide), has been investigated for its applicability to rate-programmed drug delivery. The compatibility and thermal properties were characterized by DSC and FTIR. Results from the thermal analysis indicate that the blends are compatible above 50% CAP, as revealed by a single composition-dependent glass transition temperature (Tg). The existence of molecular association through intermolecular hydrogen bonding between the carboxylic acid and the ether oxygen groups is supported by the observation of an upward shift in the IR carbonyl stretching frequency at increasing Pluronic F127 concentrations. Using theophylline as a model drug, the in vitro polymer erosion and drug release characteristics of the present polymer system were evaluated at different buffer pH's on a rotating-disk apparatus. The results show that the rates of both polymer erosion and drug release increase with the Pluronic F127 concentration in the blend. Further, at pH 4, the polymer erosion is minimal and the theophylline release appears to be governed mainly by diffusion through the polymer matrix. In contrast, at pH 7.4, the theophylline release is controlled primarily by the polymer surface erosion. To demonstrate the unique approach to programmed drug release based on the concept of nonuniform initial drug distribution, pulsatile patterns of drug release have been achieved successfully from the present surface-erodible polymer system using a multilaminate sample design with alternating drug-loaded layers.(ABSTRACT TRUNCATED AT 250 WORDS)

A specific activator of the ATP-inhibited K+ channels in guinea pig ventricular cells

The specific activity of a pyridylcyanoguanidine, P-1075, on cardiac potassium current inhibited by internal ATP (KATP) was examined using whole-cell and single-channel recording techniques. At 10 microM, the compound markedly abbreviated ventricular cell action potentials. The effect was reversible by 1 microM glyburide. Whole-cell current experiments showed that the compound elicited a time-independent outward current which had a linear current-voltage relationship between -70 to 0 mV. This current was inhibited by glyburide. Elevation of intracellular ATP from 1 to 5 mM strongly reduced the effect of P-1075 (50 microM) on the current, from 25.5 +/- 1.8 to 3.4 +/- 0.6 pA/pF. Removal of internal ATP, which caused KATP channel to "rundown", markedly diminished the drug effect, suggesting phosphorylation of the channel may be necessary for drug action. Dose-response effect of P-1075 on KATP channel had a Kd of 34.5 microM and a Hill coefficient of 2.0 for the 1 mM ATP experiment and a corresponding 36.6 microM and 2.2 for the 5 mM ATP experiment, implying probably two drug receptor sites. Single-channel recordings indicated that P-1075 increased KATP channel open probability. The complex interaction of ATP and P-1075 with the whole-cell current can be explained by a scheme developed by other investigators based on single-channel results. The compound, at doses of up to 25 microM, did not affect the inwardly and outwardly rectifying K+ currents nor the L-type Ca++ current. We conclude that P-1075 is a specific activator of phosphorylated KATP channels.

Influenza A virus haemagglutinin polymorphism: pleiotropic antigenic variants of A/Shanghai/11/87 (H3N2) virus selected as high yield reassortants

Genetic reassortment of the A/Shanghai/11/87 (H3N2) variant of influenza A virus with A/PR8/34 (H1N1) virus [the standard donor of high yield (hy) genes for influenza vaccine viruses] resulted in the isolation of two reassortants with differing H3 haemagglutinin (HA) phenotypes, X-99 and X-99a. The two HA phenotypes were derived from individual subpopulations of the H3N2 wild-type virus during the reassortment event. The HA mutants and their respectively derived reassortants (identical in RNA genotype) differed in antigenicity, replication characteristics, yield in chick embryos and haemagglutinin gene sequence. Despite antigenic differences in reactions to polyclonal rabbit antisera of 60%, both X-99 and X-99a, the hy reassortants, were equally immunogenic and protective in BALB/c mice to challenge by parental wild-type virus. Differences in HA phenotype were related to a Ser to Ile change at amino acid position 186. These findings emphasize the polymorphism of influenza virus strains as well as the need for caution in selection of vaccine strains from among antigenically distinct viral subpopulations.

Effects of acupuncture on somatosensory evoked potentials: a review

Although acupuncture has a long history of analgesic effects, the mechanisms underlying its effects are still unclear. Somatosensory evoked potential (SEP) methodology has been adopted in the research of acupuncture since the 1970s. In research on the effects of acupuncture on the conventional SEP, variable results have been observed, and two different opinions concerning the presence or absence of acupuncture effects on the conventional SEP are discussed. Since the conventional SEP is mediated mainly by fast conducting sensory nerve fibers, the conventional SEP methodology, especially that for recording short-latency SEP, may be inadequate for studying acupuncture mechanisms. In the case of the long-latency cortical SEP, there are too few data available to judge the effects of acupuncture analgesia (AA). Studies on the effects of AA on pain SEPs demonstrated that AA has a suppressive effect on amplitude of the pain SEP (and affecting the latency as well in some experiments) in both animals and humans, being accompanied by increased pain threshold. Thus, acupuncture seems to have analgesic effects that are probably related to activation of the antinociceptive system, and application of the pain SEP methodology to the study of mechanisms of AA may be promising.