Severe myocardial bridge presenting as paroxysmal atrioventricular block.

Chest pain complicated with electrocardiographic changes is not an uncommon scenario in emergency departments, which should be examined cautiously. We describe a 51-years-old man with a myocardial bridge of coronary artery presenting with simultaneous Mobitz type I atrioventricular block on electrocardiography. Echocardiography excluded valvular abnormality and systolic/diastolic dysfunction. Coronary angiography confirmed the diagnosis of a myocardial bridge at the middle segment of the left anterior descending artery, involving the most dominant septal perforator branch with marked systolic compression. The patient underwent coronary artery bypass grafting surgery and was followed up uneventfully at the outpatient department with medical treatment of diltiazem and clopidogrel. The present case is being reported to highlight that clinicians should be alert to such a congenital abnormality as a potential cause of repeated myocardial infarction and conduction abnormality.

High temperature oxidation of iron-iron oxide core-shell nanowires composed of iron nanoparticles.

This work describes an oxidation process of iron-iron oxide core-shell nanowires at temperatures between 100 °C and 800 °C. The studied nanomaterial was synthesized through a simple chemical reduction of iron trichloride in an external magnetic field under a constant flow of argon. The electron microscopy investigations allowed determining that the as-prepared nanowires were composed of self-assembled iron nanoparticles which were covered by a 3 nm thick oxide shell and separated from each other by a thin interface layer. Both these layers exhibited an amorphous or highly-disordered character which was traced by means of transmission electron microscopy and Mössbauer spectroscopy. The thermal oxidation was carried out under a constant flow of argon which contained the traces of oxygen. The first stage of process was related to slow transformations of amorphous Fe and amorphous iron oxides into crystalline phases and disappearance of interfaces between iron nanoparticles forming the studied nanomaterial (range: 25-300 °C). After that, the crystalline iron core and iron oxide shell became oxidized and signals for different compositions of iron oxide sheath were observed (range: 300-800 °C) using X-ray diffraction, Raman spectroscopy and Mössbauer spectroscopy. According to the thermal gravimetric analysis, the nanowires heated up to 800 °C under argon atmosphere gained 37% of mass with respect to their initial weight. The structure of the studied nanomaterial oxidized at 800 °C was mainly composed of α-Fe2O3 (∼ 93%). Moreover, iron nanowires treated above 600 °C lost their wire-like shape due to their shrinkage and collapse caused by the void coalescence.

Effect of phenylephrine on focal atrial fibrillation originating in the pulmonary veins and superior vena cava.

OBJECTIVES: This study was aimed at evaluating the effects of phenylephrine infusion on the occurrence of focal atrial fibrillation (AF). BACKGROUND: Paroxysmal AF can be initiated by ectopic atrial beats originating in the pulmonary vein (PV) or superior vena cava (SVC). The effect of change in autonomic tone on this focal AF is unknown. METHODS: This study included 12 patients with frequent bursts of AF documented by 24-h Holter monitoring. The number and coupling interval of spontaneous ectopic activity and bursts of AF were evaluated for 1 min before and after phenylephrine (2 to 3 microg/kg) injection. RESULTS: After detailed mapping, four patients had a focus located in the left superior PV, six in the right superior PV and two in the SVC. In 10 patients with AF foci originating in the PVs, the frequency of ectopic activity (19.5 +/- 27.4 vs. 11.4 +/- 22.9 beats/min, p = 0.059) was reduced as well as AF bursts (14 +/- 3 vs. 1.8 +/- 2.7 bursts/min, p = 0.005) before versus after phenylephrine injection; the minimal coupling interval of ectopic activity and AF bursts became longer compared with baseline. The maximal percent increase in sinus cycle length after phenylephrine injection was significantly greater in patients with complete suppression of AF compared with those with partial suppression (43 +/- 19 vs. 14 +/- 5%, p = 0.01). However, no significant effect of phenylephrine on AF originating in the SVC was found. CONCLUSIONS: Change in autonomic tone induced by phenylephrine injection was effective in suppressing focal AF originating in the PVs but not in the SVC.

Effect of suppression of TGF-beta1 expression on cell-cycle and gene expression of beta-1,4-galactosyltransferase 1 in human hepatocarcinoma cells.

beta-1,4-galactosyltransferase 1 (beta1,4-GT 1) is localized both in the Golgi complex where it catalyzes the transfer of galactose from UDP-galactose to terminal N-acetylglucosamine forming Galbeta1 --> 4GlcNAc structure, and on the cell surface where it serves as an adhesion molecule. It has previously been reported that the expression of beta1,4-GT 1 was cell-cycle-specific, regulated by cell growth. Transforming growth factor-beta1 (TGF-beta1) could regulate cell G1/S phase transition and modulate cell growth in many types of cells. In this study, we introduced the antisense-TGF-beta1 into SMMC-7721 cell, a human hepatocarcinoma cell line, for blocking its intrinsic TGF-beta1 expression, and changing its cell-cycle, and then analyzed the gene expression of beta1,4-GT 1 together with the beta1,4-GT activity. The result showed that the antisense-TGF-beta1 transfected SMMC-7721 cells (AST/7721) were growth enhanced, with more cells in S phase and less cells in G2/M phase compared with the mock transfected cells (pcDNA3/7721). At the same time, it was found that the gene expression of beta1,4-GT 1 in AST/7721 was decreased to one fifth that of pcDNA3/7721, and the cell surface beta1,4-GT activity was reduced to one fifth of the control, while the total activity of beta1,4-GT was decreased to one half that of the control. The results indicate that suppression of TGF-beta1 expression resulted in change of cell-cycle together with the decreased gene expression of beta1,4-GT 1 and beta1,4-GT activity in human hepatocarcinoma cells.

Accumulation of reactive oxygen species and oxidation of cytokinin in germinating soybean seeds.

Seed germination is an important developmental switch when quiescent seed cells initiate oxidative phosphorylation for further development and differentiation. During early imbibition of soybean seeds (Glycine max L. cv. Weber), a superoxide dismutase (SOD) activity peak was observed, in embryonic axes, after 6 h imbibition. Peroxidase activities, including catalase, were significantly increased after 12 h inhibition and during germination phase III. Catalase was the most efficient enzyme in catabolizing H2O2 in embryonic axes. When stored at 42 degrees C and 100% relative humidity, seeds were stressed and lost their viability in a time-dependent manner. A significant increase in the Cu, Zn-superoxide-dismutase activity, and to a lesser extent, Mn superoxide dismutase activity was observed during germination in low-viability (stressed) seeds as compared to high-viability (unstressed) seeds. Northern blot analysis confirmed that superoxide dismutase induction resulted from an accumulation of its transcripts in response to the production of O2-. The induction of catalase did not occur in low-viability seeds, resulting in dramatic accumulation of H2O2. Using capillary electrophoresis, HPLC and NMR we found that the endogenous cytokinin, zeatin riboside, was present in large quantities in the high-viability seeds, but it was oxidized into adenine in the low-viability seeds. In vitro superoxide anion could also oxidize the cytokinin. Zeatin riboside, but not adenine, was found to act as a scavenger of superoxide anions and may help to maintain seed viability by detoxifying reactive oxygen species. Germination of stressed seeds was partially restored by the addition of exogenous cytokinin (zeatin riboside). Protection against oxidative stress by cytokinin seemed to be a general phenomenon, as Escherichia coli cells were also protected against superoxide stress in the presence of cytokinin.

Transnasal endoscopic surgery of sphenoid sinus aspergillosis.

Aspergillus sp. are the most common contaminants of the paranasal sinuses with the maxillary sinus as the site most frequently involved. Fungal sphenoid sinusitis can be a life-threatening situation, thus aggressive therapy is indicated. The treatment is primarily surgical. The transnasal endoscopic technique offers excellent visualization and an atraumatic approach to the sphenoid sinus. Surgical exteriorization and aeration of the involved sinus, without using antifungal chemotherapeutic agents is curative. A rare case of sphenoid sinus aspergillosis which was successfully treated by transnasal endoscopic sphenoidotomy is reported.

[Clinical study of allergic rhinitis treated by "bu qi gu biao" therapy].

The authors summarized 500 cases of allergic rhinitis treated by "Bu Qi Gu Biao" therapy since 1980. After treatment, long term curative effect was 87%. Moreover, the authors had observed serum IgE, IgA and IgG, plasma cyclic nucleotides, blood flow in nasal mucosa, and ultrastructure of nasal mucosa before and after the treatment in 200 cases. The results indicated that "Bu Qi Gu Biao" therapy could adjust immune function and cyclic nucleotides metabolism in organism, improve blood flow in nasal mucosa tissue, restore or improve cell's shape and function and eliminate partial deposition of immune compound in vascular basement membrane. Therefore, it could control or eliminate the symptoms of allergic rhinitis.

Role of superoxide in radiation-killing of Escherichia coli and in thymine release from thymidine.

The role of superoxide and hydroxyl radicals in gamma-radiation-killing of Escherichia coli K12 was studied in aerated suspensions supplemented with formate, phosphate, superoxide dismutase, catalase and saturated with nitrous oxide. Nitrous oxide, which converts e-aq to .OH, caused decreased radiosensitivity. On the other hand, formate, which results in conversion of .OH to .O2-, resulted in an increased radiosensitivity. The results implicated .O2- as a major cause of radiation-mediated cell-killing. The addition of the enzymes, superoxide dismutase or catalase to the E. coli suspensions prior to and during irradiation had no effect on cell survival, indicating that the biologically significant site of generation and action of .O2- is an intracellular one. Further studies were undertaken to examine the role of superoxide in DNA damage. The release of thymine from the DNA base, thymidine was studied as a result of gamma-irradiation and of chemically generated superoxide (using KO2 in dimethyl sulfoxide). Thymine was identified by HPLC and mass spectrometry. C-13 NMR analysis of the reaction mixture of thymidine with KO2 in dimethyl sulfoxide provided evidence for attack of .O2 at the ribosyl Cl' atom.

Comparison of acute toxicities of deoxynivalenol (vomitoxin) and 15-acetyldeoxynivalenol in the B6C3F1 mouse.

The acute toxic effects of deoxynivalenol (DON) and 15-acetyldeoxynivalenol (15-ADON) were compared in the B6C3F1 female mouse after oral and intraperitoneal exposure. Using the abbreviated procedure of Lorke (Archs Toxicol. 1983, 54, 275), LD50 values for DON were estimated to be 78 mg/kg (oral) and 49 mg/kg (ip) whereas the LD50 values for 15-ADON were 34 mg/kg (oral) and 113 mg/kg (ip). Acute doses of these toxins resulted in extensive necrosis of the gastro-intestinal tract, bone marrow and lymphoid tissues, and focal lesions in kidney and cardiac tissue. The minimum doses required for these histopathological effects were consistent with LD50 estimations. The results indicate that 15-ADON was more or less toxic than DON depending on the route of administration. Risk assessments for DON should therefore consider the potential for 15-ADON occurrence and toxicity in food and feed.

Studies on the induction of aryl hydrocarbon(benzo[a]pyrene) hydroxylase in Neurospora crassa, and its suppression by sodium selenite.

Six fungal species were grown in the presence of benzo[a]pyrene (BP); four showed benzo[a]pyrene hydroxylase (aryl hydrocarbon hydroxylase, AHH) activity. Penicillium sp. and Neurospora crassa metabolized BP to a limited extent. N. crassa AHH activity was induced by BP, the major product of metabolism being 3-hydroxy-BP. Both induction of AHH activity and metabolism of BP were suppressed by sodium selenite in the growth medium. Two polypeptides, unique to BP-grown cells, were revealed by two-dimensional electrophoretic separation of [35S]methionine-labelled proteins in N. crassa cell extracts. In selenium-grown cells the synthesis of BP-specific polypeptides was severely inhibited.

Cigarette smoking among Beijing (Peking) high schoolers.

PIP: Students smoking at 2 key middle schools and 6 ordinary middle schools in Beijing, China were surveyed to determine the form in which high schoolers start smoking, and how long they have smoked. The patterns and causes of smoking were analyzed. The investigation was made from March to May 1981. 430 boys and 423 girls were selected from key schools and 1396 boys and 1394 girls from ordinary schools. Ages ranged from 13-17. All subjects completed a questionnaire in the classroom. To increase the reliability of the survey, names were kept secret. The students surveyed were classified into groups according to their smoking status: current regular smokers; occasional smokers; ex-smokers; and nonsmokers. In the key schools, there were only 4 smokers among 430 students, accounting for 0.9% of the total. Of these, 1 was Senior Class 2, 2 Senior Class 1, and 1 Junior Class 3. In the ordinary schools, 10% were smokers. 19.7% of the boys and 0.4% of the girls smoked. Among the boys, the higher the class, the more numerous the smokers. The smoking rate was 8.2% in the 1st year of junior high but rose to 34% in senior class 2; the difference was statistically significant. "Special occasion" smokers were few, only 5.5% of the students. In junior class, the number of regular smokers was about 2/3 to 4/5 that of occasional smokers. And by senior class 2 the number of regular smokers had risen to about 3 times that of the occasional smokers. In every grade, there were students who had given up smoking. Most had been occasional smokers. Some high schoolers had started to smoke in primary school and had a 4-5 year history of smoking, but most had only picked up smoking for 1-2 years after announcement of the Rules for High School Students prohibiting smoking. There were 3 smoking patterns: smoking without inhaling; inhaling the smoke deeply into the lungs, then expiring through the mouth or nostrils; and combining patterns 1 and 2. Of 265 students, 128 used the 1st pattern, 121 the second, and only 16 combined both patterns. The most common cause of smoking was curiosity. Next was lack of high ideals and dedication followed by boredom. The smoking rate in students whose parents were smokers was significantly higher than in those whose parents were nonsmokers. The difference was significant among all classes except junior class 1. To reduce smoking among high school students, it is necessary to go beyond the existing rules which prohibit smoking and emphasize political and ideologic education. Students must be taught about the dangers of smoking as early as possible, preferably in primary schools.^ieng

Hepatitis-B surface antigen and hepatocellular carcinoma in Taiwan. With special reference to types and localization of HBsAg in the tumor cells.

The relationship between hepatitis B virus (HBV) infection and hepatocellular carcinoma (HCC), with or without cirrhosis, was assessed immunopathologically through the detection of tissue hepatitis B surface antigen (HBsAg) on paraffin sections of 284 biopsy and surgical specimens of HCC, which were performed from 1970 to 1979, by the indirect immunoperoxidase technique. In 190 cases with nontumorous liver tissue available for histologic and etiologic analyses, cirrhosis was identified in 69.8% (37 of 53) in needle biopsy, 67.4% (31/46) in wedge, and 30.8% (28/91) in the resection or lobectomy group. HBsAg was detected in the nontumorous liver parenchyma in 85.7% in the whole series, and 90.6% in the cirrhotic cases (96.8% in wedge and 100% in resection cases). The HBsAg positivity in the noncirrhotic cases of the resection group was 84.1% (53/63), whereas the 10 negative cases in this group were all noncirrhotic. This clearly demonstrates a strong association of HBsAg and HCC in both cirrhotic and noncirrhotic patients in Taiwan, particularly in the cirrhotic group, as evidenced by the high prevalence of HBsAg in wedge and resection series. On the other hand, the etiology in the HBsAg-negative and noncirrhotic group, which also had a less evident male predominance (male:female = 3.3:1 versus 6-19.5:1) and significantly less liver cell dysplasia than HBsAg-positive or cirrhotic groups, remains to be explained. In 223 cases where tumor tissue met the minimal requirement for analysis, HBsAg was demonstrated in 27 cases (12.1%) in the tumor cells (15% in the resection group). This investigation indicates an important etiologic role of HBV in hepatocellular carcinogenesis, and the development of HCC does not depend on the coexistence of cirrhosis in Taiwan.

Regeneration of human liver after hepatic lobectomy studied by repeated liver scanning and repeated needle biopsy.

Regeneration of the residual lobe of the liver after hepatic lobectomy in humans was studied by repeated liver scanning in seven noncirrhotic and three cirrhotic patients. Each patient was studied for several months during the study which lasted from 1-12 years. Regeneration was apparent in noncirrhotic liver remnants following hepatic lobectomy. In the case of a long standing, space occupying lesions such as benign giant cysts, the liver remnant would complete its regeneration process rather early, usually within a few months of hepatic lobectomy. In hepatoma cases, however, regeneration of the residual lobe after hepatic resection usually took five or six months for completion. On the contrary, no definite increase in the size of the liver remnant was seen on repeated liver scanning in cirrhotic patients. Histologic study of the residual lobe was repeated on needle biopsy specimens in two noncirrhotic and four cirrhotic patients. Regenerative hyperplasia of liver cells with large hyperchromatic, or double nuclei never seen in the preresection liver appeared in the liver remnant five, 11, and 27 days after hepatic lobectomy in noncirrhotic patients. In cirrhotics, however, there were no histologic changes between the preresection liver and the postresection remnant studied three, five, 15, 40 days or even two years and 8 months after hepatic lobectomy.

Purification and studies of some physicochemical properties of glutamine synthetase of Neurospora crassa.

Glutamine synthetase (EC 6.3.1.2) of Neurospora crassa was purified to near homogeneity by chromatography on a glutamate-Sepharose affinity column. Its properties, including molecular weight, subunit structure, amino acid composition, and approximate alpha-helix content, have been examined. In the native state, this enzyme has been demonstrated by gel filtration to be an octamer of molecular weight 360,000 and as having a sedimetation coefficient of 13.2 S by sedimentation velocity measurements. Circular dichroism spectra in the far ultraviolet range suggest an approximate alpha-helix content of 23-24%. The subunit generated by treatment with urea was found to be 45,000 daltons by gel filtration methods and a molecular weight of 46,000 was calculated for the monomer obtained by sodium dodecyl sulphate (SDS) treatment and electrophoresis in SDS-polyacrylamide gels. Interprotomeric cross-linking experiments, using diimidoesters, suggest the presence of two noncovalently linked tetramers comprising the native octameric structure. Amino acid analyses revealed the presence of six tryptophans, four half cystines, and nine methionine residues per monomer of 45,000 daltons.