Aphidicolin resistance in herpes simplex virus type I reveals features of the DNA polymerase dNTP binding site

We describe the mapping and sequencing of mutations within the DNA polymerase gene of herpes simplex virus type 1 which confer resistance to aphidicolin, a DNA polymerase inhibitor. The mutations occur near two regions which are highly conserved among DNA polymerases related to the herpes simplex enzyme. They also occur near other herpes simplex mutations which affect the interactions between the polymerase and deoxyribonucleoside triphosphate substrates. Consequently, we argue in favor of the idea that the aphidicolin binding site overlaps the substrate binding site and that the near-by conserved regions are functionally required for substrate binding. Our mutants also exhibit abnormal sensitivity to another DNA polymerase inhibitor, phosphonoacetic acid. This drug is thought to bind as an analogue of pyrophosphate. A second-site mutation which suppresses the hypersensitivity of one mutant to phosphonoacetic acid (but not its aphidicolin resistance) is described. This second mutation may represent a new class of mutations, which specifically affects pyrophosphate, but not substrate, binding.

Affinity labeling of chicken liver fatty acid synthase with chloroacetyl-CoA and bromopyruvate

Fatty acid synthase of chicken liver is inactivated rapidly and irreversibly by incubation with chloroacetyl-CoA or with bromopyruvate. Inactivation by both reagents follows saturation kinetics, indicating the formation of an E ... I complex (dissociation constants of 0.36 microM for chloroacetyl-CoA and 31 microM for bromopyruvate) prior to alkylation. The limiting rate constants are 0.15 s-1 for bromopyruvate and 0.041 s-1 for chloroacetyl-CoA. Inactivation by both reagents is protected by NADPH and 200 mM KCl, and by saturating amounts of thioester substrates which reduced the limiting rate constants 6.5-30-fold. Active-site-directed reaction of chloroacetyl-CoA is supported by the ability of this compound to form a kinetically viable complex with the enzyme as competitive inhibitor of acetyl-CoA. Chloroacetyl-CoA interacts initially at the CoA binding pocket, since the nucleotide afforded competitive protection of inactivation and caused a large decrease in its affinity. Subsequently, the phosphopantetheine prosthetic group is alkylated. Evidence is presented to show that bromopyruvate competes with chloroacetyl-CoA for the same target site.

Thyroid function during isoflurane anesthesia and valvular heart surgery

Proper thyroid function is essential for maintaining cardiovascular integrity during normal and stressful situations. In this study, the effects of isoflurane-O2 anesthesia and surgical stress on serum TSH, T4, free T4, T3, rT3, and cortisol were investigated in nine patients before, during, and after valve surgery. Compared with preoperative control values, serum TSH decreased in the postoperative period. Both T4 and free T4 had similar decreases after cardiopulmonary bypass (CPB) and remained depressed postoperatively. Both T3 and rT3 decreased at the start of cardiopulmonary bypass; T3 remained low in the postoperative period, while rT3 increased. Cortisol decreased during anesthesia and surgery in the prebypass period, but increased during cardiopulmonary bypass and in the postoperative period. The results suggest that isoflurane-O2 anesthesia during valve surgery produces a rapid decrease in T3, resulting in the low T3 syndrome postoperatively. Isoflurane, in the dose studied, similar to fentanyl, can suppress the cortisol response to anesthesia and surgery in the prebypass period, but not during and after CPB.

[Relationship between bacterial envelope barrier and resistance of E. coli, S. aureus to rifamdine]

The Rifamdine (RFD) resistant strains were obtained from wild types of S. aureus NCTC 6571, E. coli NCTC 10418 and Proteus vulgaris by drug concentration gradient plate. The experiment indicated that the growth inhibition of resistant cells induced by synergism of EDTA acting with RFD. Such results did not occur effectively if EDTA or RFD was added separately. The amount of 3H-RFD incorporated into cells of susceptible and resistant strains of E. coli and S. aureus was compared. The amount of 3H-RFD incorporated into susceptible cells was much greater than that of the resistant strains in E. coli cells. Ultrastructure comparison of sensitive and resistant cells showed that the surface of resistant cells was coarser and shorter, the outer membrane thickened and electron density increased. These results have shown that there is a close relationship between the resistance of bacteria induced by RFD and the decrease in the permeability of cell envelope barrier to the drug.

[Endocarditis after extracorporeal circulation surgery]

Between January, 1976 and April 1988, 1279 patients underwent open-heart operation in Ren Ji Hospital. Thirty three patients were complicated by infective endocarditis postoperatively, an incidence of 2.58%. Medical treatment was carried out in 29 cases and thirteen were cured. In another three patients of valve prosthetic endocarditis, replacement of prosthetic valve was necessary for their cure. In our series, Gram negative bacilli had been proved by blood culture, autopsy and arterial thrombi in thirteen patients and candida in four, mixed infection in five and staphylococcus aureus in only one case. One should not rely on positive blood culture for the diagnosis. Echocardiographic studies are helpful to early diagnosis and proper treatment. The presence of vegetation or signs of prosthetic valve failure are strong indication for reoperation. In prevention, in addition to strict aseptic technic in the operating room, special emphasis should be focused on the preventive administration of sensitive antibiotics against hospital borne pathogens. All indwelling catheters in arteries and veins, tracheal tubes and urethral catheters should be removed after 72 hours. Efforts to prevent infection after reoperation are important measures for the prevention of infective endocarditis after open-heart operation.

CT diagnosis of lacunae

Lacuna, a special small infarction in deep regions of the brain, is difficult to diagnose clinically. Of 182 stroke patients receiving CT scanning, 23 were diagnosed as having lacuna. 34 foci found on CT were distributed in the internal capsule, basal ganglia, thalamus and pons, with diameters varying from 3 to 22 mm. Combined CT and clinical findings showed that motor hemiplegia was present in 12 patients, pure sensory stroke in 1, sensory-motor stroke in 9, and the lock-in syndrome in 1.20 (87%) of the 23 patients partly or completely fulfilled the criteria for the lacuna syndrome. The detection of lacunae depends on the property of instrument, the method of scanning, and the thickness of slice. By showing some minor infarctions, CT has offered the possibility of diagnosis of lacunae.

Conformation and dynamics of Z-DNA oligomer duplex of d[(CG)3TATA(CG)3] in solution

The conformation and dynamics of a DNA oligomer, d[(CG)3TATA(CG)3], in 4M NaClO4 (Z-TATA 16 mer) have been studied by 1H NMR. The principal results of our investigation are: (i) at low temperature d[(CG)3TATA(CG)3] exists as duplexes in both low (0.1M NaCl) and high (4M NaClO4) ionic strength solutions; (ii) CGCGCG segments undergo the B-to-Z transition in 4M NaClO4; (iii) even in 4M NaClO4 the TATA box exhibits non-Z-structures and possesses multiple conformations which are slowly exchanging on the NMR chemical shift difference time scale; and, (iv) the Z-type structure of the CGCGCG segments induced in 4M NaClO4 is more conformationally mobile than its B-type counterpart in 0.1M NaCl on the nanosecond time scale.

Conformation and dynamics of a left-handed Z-DNA hairpin: studies of d(CGCGCGTTTTCGCGCG) in solution

The physical properties of the DNA oligomer d(CGCGCGTTTTCGCGCG) in solvents containing 4 M NaClO4 and 0.1 M NaCl were investigated by proton NMR, optical melting, and circular dichroism spectroscopy. Results of these investigations are as follows: (i) The DNA hexadecamer exists as a unimolecular hairpin in either high or low salt. (ii) In high salt the stem region of the hairpin is in the left-handed Z conformation. (iii) In either high or low salt, the duplex stem of the hairpin is stabilized against melting by approximately 40 degrees C compared to the linear core duplex. The added stability of the hairpin is entropic in origin. (iv) In high salt, as the temperature is elevated, the equilibrium structure of the duplex stem of the hairpin shifts from the Z to the B conformation before melting. (v) In low salt, when the DNA duplex exists in the B conformation, attachment of a T4 single-strand loop to one end only slightly decreases (by 14%) the correlation time of the CH5-CH6 interproton vector. In high salt, when the DNA duplex exists in the Z conformation, the correlation time of the CH5-CH6 interproton vector decreases by 51%. Since these viscosity-corrected correlation times are taken to be indicators of duplex motions on the nanosecond time scale, this result directly suggests a larger amplitude of these motions is present in the duplex stem of the hairpin when it exists in the Z conformation.

[Omnipaque (iohexol) CT myelography (CTM) in the diagnosis of cervical spondylotic myelopathy--correlative study of conventional myelography (a report of 100 cases)]

100 cases of cervical spondylotic myelopathy were studied with both CTM and conventional myelography and the results were compared. It was shown that CTM possesses more advantages over its counterpart as follows: (1) CTM can demonstrate with a higher degree of accuracy the size and configuration of the spinal cord, its internal composition and cystic necrosis, can pick up more herniations, hard and soft, up to 16% (39/252) and better define the position left, middle and right of the protrusion. (2) CTM is capable of making a correct diagnosis of cervical myelopathy and cystic necrosis in the cord. Analysis also showed that the degree of changes of spinal cord seen on CTM correlation closely with severity of the clinical picture. Atrophy and cystic necrosis of the cord are important factors accounting for clinical deterioration and operative failure.

Computed tomography of parotid masses

Fifty-six patients with parotid masses, benign tumors in 22, malignant tumors 26 and other diseases 8, were examined by CT scan, which can differentiate intrinsic from extrinsic parotid lesions, especially deep lobe from parapharyngeal tumors and typical benign tumors from malignant ones, but may fail to differentiate aggressive benign tumors from low-grade malignant ones. CT sialography was done to detect the relation between the trunk of the facial nerves and tumor according to the band of normal parotid tissue between the tumor and posterior border of the mandibular ramus, and incremental dynamic CT with intravenous bolus injection of contrast medium to detect the relation between the tumor and carotid sheath. We conclude that the images of CT sialography are much better than those of plain CT and intravenous enhancement CT.

[Studies on quantitative determination of total flavonoid in qingpi, zhiqiao and zhishi by TLC-densitometric methods]

A method for the determination of total flavonoid contents in Pericarpium Citri Reticulatae Viride (Qingpi), Fructus Aurantii (Zhiqiao) and Fructus Aurantii Immaturus (Zhishi) was established by the use of TLC-densitometry. The results show that the total flavonoid contents in Qingpi and Zhishi are higher than in Zhiqiao. The content in Zhiqiao is 9.81%-15.85%.

[A study on mechanism of skin penetration by cercaria of S. japonicum and screening of preventive drugs]

Mice pretreated with PG cyclo-oxygenase inhibitor aspirin, at 300 mg/kg/d x 5, and ibuprofen, at 100 mg/kg/d x 5 orally and 20 mg/kg/d x 3 intraperitoneally revealed moderate chemoprophylactic effects and the reduction of the penetration of worms by 23% when compared to controls. Daily oral administration of aspirin, at 300 mg/kg for 15 days the worms reduction increased to 41.7%. In estimation of PGE1 in cercariae of S. japonicum by radioimmunoassay, the PGE1 was 49 pg/100 cercariae. In normal mouse skin PGE1 has been measured to amount to 3105 +/- 691.7 pg/10 mg on average. In cercarial penetrated mouse skin, 1.5 hours after exposure the PGE1 assessed in 100 and 250 cercariae in the infected skin were 5506 +/- 1127.1 and 12085 +/- 2622.9 pg/10 mg respectively, which were significantly higher than that of the non-penetrated skin. These studies in conjunction with our previous work indicate that: 1.PGs, similar to S. mansoni, were probably necessary for cercarial penetration. 2.PG inhibitors could reduce cercarial penetration. Receptors antagonist etc. e.g. diphenhydramine, chlorpheniramine, atropine, practolol could not reduce cercarial penetration, but praziquantel in the pretreated mice could reduce cercarial penetration significantly. e.g. 400 mg/kg orally 2 hours prior to affection of cercariae about 100% reduction of the penetration, but if pretreated with praziquantel, 4, 8, 24, 36 hours prior to the affection the reduction penetration decreased to 51.7, 46.1, 9.4, 8.9% respectively.

[Efficacy of CT omnipaque myelography in the demonstration of intraspinal space-occupying diseases (report of 77 cases)]

The value of omnipaque myelography and CT myelography in 77 cases of intraspinal space-occupying lesions (51 extramedullary and 26 intramedullary confirmed by operation) was reviewed. In 69 cases the preoperative diagnosis was accurate, but not in the other 8 cases. It is not advisable according to the authors' experience to have both myelography and postmyelography CT scan done for all intraspinal space-occupying lesions. For most of the extramedullary tumors, myelography alone proved to be adequate. For intramedullary lesions the information obtained from myelography was inconclusive and postmyelography CT scan as a supplementary procedure was necessary.

N.m.r studies of internal mobility in a cyclic tetrapeptide

The conformation of cyclo(D-Phe-D-Pro-Ala-Pro) is reported. Measurements of spin-lattice relaxation in the rotating frame indicate that this peptide is conformationally less mobile on the microsecond time scale than larger cyclic peptides previously studied. Libration of the Pro-Ala and Pro-Phe peptide bond planes is suggested as the source of the small exchange contributions to 1/T1p.

[Gemfibrozil in the treatment of hyperlipidemia]

An elevated serum cholesterol level is a well known major risk factor for developing atherosclerosis in general, and for coronary heart disease in particular. There are many lipid lowering agents currently available. We used gemfibrozil in twenty hyperlipidemic cases who failed to response to diet control for three months. They were thirteen males and seven females with their ages ranging from thirty to eighty-one year-old. They included ten diabetes, one nephrotic syndrome and nine pure hyperlipidemic patients. All cases received gemfibrozil 600mg twice daily for 4-12 weeks. Gemfibrozil caused an increase in HDL cholesterol. The reductions in serum level of total cholesterol, total cholesterol/HDL cholesterol, and triglyceride were found. Only one case developed mild gastrointestinal side effect. There was no other major side effects.

Decline of chlorinated hydrocarbon insecticides residues in the tea-garden soils of Taiwan

Residues of chlorinated hydrocarbon insectidies and some of their metabolites, including p,p'-DDT, p,p'-DDD, p,p'-DDE, gamma-BHC, aldrin, dieldrin, heptachlor and heptachlor epoxide, were examined in the soils collected from 21 tea-gardens distributed in 15 countries of 6 prefectures in 1977, and from 100 locations distributed in 46 counties of 10 prefectures in 1984 in Taiwan. Although the use of these chlorinated hydrocarbon insecticides has been banned for many years, minor amounts of residues in the soils have still been detected. From 1977 to 1984, average residues of the chlorinated hydrocarbon insecticides and their metabolites in the soils of tea-gardens decreased from 5.64 to 0.06 ppb for gamma-BHC, 97 54 to 1.10 ppb for aldrin, 35.91 to 1.00 ppb for p,p'-DDE, 17.41 to 0.28 ppb for dieldrin, and 30.17 to 3.42 ppb for p,p'-DDT. But the number of positive cases increased for all chlorinated hydrocarbon insecticides tested, the residual levels were not significantly different among soils with different physiochemical properties or among soil layers. No significant amount of these insecticides was found in the processed tea.