[A pilot study on trihalomethane formation in water treated by chlorine dioxide]

Trihalomethane (THM) formation was determined by gas chromatography in water disinfected with chlorine dioxide (ClO2) only or ClO2 combined with chlorine (Cl2), to lay a basis for water disinfected with ClO2. Results showed no THM was produced in water disinfected with ClO2 only if without existence of bromine (Br) ion in it; certain amount of bromoform could be formed with existence of bromine ion, and THM formation could be inhibited by ClO2 and Cl2, with a ratio of greater than 1 between them. Light irradiation could decrease the amount of THM produced whether in disinfection with ClO2 or combination with ClO2 and Cl2. No significant effect of pH value of water on THM formation was observed, but pH should be controlled under neutral or slightly acidic to ensure the concentration of ClO2 in water.

Two closely related cDNAs encoding starch branching enzyme from Arabidopsis thaliana

Two starch branching enzyme (SBE) cDNAs were identified in an Arabidopsis seedling hypocotyl library using maize Sbe1 and Sbe2 cDNAs as probes. The two cDNAs have diverged 5' and 3' ends, but encode proteins which share 90% identity over an extensive region with 70% identity to maize SBE IIb [12]. Genomic Southern blots suggest that the two cDNAs are the products of single, independent genes, and that additional, more distantly related SBE genes may exist in the Arabidopsis genome. The two cDNAs hybridize to transcripts which show similar expression patterns in Arabidopsis vegetative and reproductive tissues, including seedlings, inflorescence rachis, mature leaves, and flowers. This is the first report of the identification of cDNAs encoding two closely related starch branching enzymes from the same species.

Release of the catalytic domain N(o) from the herpes simplex virus type 1 protease is required for viral growth

The herpes simplex virus type 1 (HSV-1) protease and its substrate, ICP35, are involved in the assembly of viral capsids and required for efficient viral growth. The full-length protease (Pra) consists of 635 amino acid (aa) residues and is autoproteolytically processed at the release (R) site and the maturation (M) site, releasing the catalytic domain No (VP24), Nb (VP21), and a 25-aa peptide. To understand the biological importance of cleavage at these sites, we constructed several mutations in the cloned protease gene. Transfection assays were performed to determine the functional properties of these mutant proteins by their abilities to complement the growth of the protease deletion mutant m100. Our results indicate that (i) expression of full-length protease is not required for viral replication, since a 514-aa protease molecule lacking the M site could support viral growth; and that (ii) elimination of the R site by changing the residue Ala-247 to Ser abolished viral replication. To better understand the functions that are mediated by proteolytic processing at the R site of the protease, we engineered an HSV-1 recombinant virus containing a mutation at this site. Analysis of the mutant A247S virus demonstrated that (i) the mutant protease retained the ability to cleave at the M site and to trans process ICP35 but failed to support viral growth on Vero cells, demonstrating that release of the catalytic domain No from Pra is required for viral replication; and that (ii) only empty capsid structures were observed by electron microscopy in thin sections of A247S-infected Vero cells, indicating that viral DNA was not encapsidated. Our results demonstrate that processing of ICP35 is not sufficient to support viral replication and provide genetic evidence that the HSV-1 protease has nuclear functions other than enzymatic activity.

The C-terminal 25 amino acids of the protease and its substrate ICP35 of herpes simplex virus type 1 are involved in the formation of sealed capsids

The herpes simplex virus type 1 protease and its substrate, ICP35, are involved in the assembly of viral capsids. Both proteins are encoded by a single open reading frame from overlapping mRNAs. The protease is autoproteolytically processed at two sites. The protease cleaves itself at the C-terminal site (maturation site) and also cleaves ICP35 at an identical site, releasing a 25-amino-acid (aa) peptide from each protein. To determine whether these 25 aa play a role in capsid assembly, we constructed a mutant virus expressing only Prb, the protease without the C-terminal 25 aa. Phenotypic analysis of the Prb virus in the presence and absence of ICP35 shows the following: (i) Prb retains the functional activity of the wild-type protease which supports virus growth in the presence of ICP35; (ii) in contrast to the ICP35 null mutant delta ICP35 virus, the Prb virus fails to grow in the absence of ICP35; and (iii) trans-complementation experiments indicated that full-length ICP35 (ICP35 c,d), but not the cleaved form (ICP35 e,f), complements the growth of the Prb virus. The most striking phenotype of the Prb virus is that only unsealed aberrant capsid structures are observed by electron microscopy in mutant-infected Vero cells. Our results demonstrate that the growth of herpes simplex virus type 1 requires the C-terminal 25 aa of either the protease or its substrate, ICP35, and that the C-terminal 25 aa are involved in the formation of sealed capsids.

Multiple protein-DNA interactions over the yeast HSC82 heat shock gene promoter

We have utilized DNase I and micrococcal nuclease (MNase) to map the chromatin structure of the HSC82 heat shock gene of Saccharomyces cerevisiae. The gene is expressed at a high basal level which is enhanced 2-3-fold by thermal stress. A single, heat-shock invariant DNase I hypersensitive domain is found within the HSC82 chromosomal locus; it maps to the gene's 5' end and spans 250 bp of promoter sequence. DNase I genomic footprinting reveals that within this hypersensitive region are four constitutive protein-DNA interactions. These map to the transcription initiation site, the TATA box, the promoter-distal heat shock element (HSE1) and a consensus GRF2 (REB1/Factor Y) sequence. However, two other potential regulatory sites, the promoter-proximal heat shock element (HSE0) and a consensus upstream repressor sequence (URS1), are not detectably occupied under either transcriptional state. In contrast to its sensitivity to DNAase I, the nucleosome-free promoter region is relatively protected from MNase; the enzyme excises a stable nucleoprotein fragment of approximately 210 bp. As detected by MNase, there are at least two sequence-positioned nucleosomes arrayed 5' of the promoter; regularly spaced nucleosomes exhibiting an average repeat length of 160-170 bp span several kilobases of both upstream and downstream regions. Similarly, the body of the gene, which exhibits heightened sensitivity to DNase I, displays a nucleosomal organization under both basal and induced states, but these nucleosomes are not detectably positioned with respect to the underlying DNA sequence and may be irregularly spaced and/or structurally altered. We present a model of the chromatin structure of HSC82 and compare it to one previously derived for the closely related, but differentially regulated, HSP82 heat shock gene.

[A clinicopathological study of cor pulmonale with coronary heart disease]

The necropsy findings of 18 patients with cor pulmonale and coronary heart disease (CHD) were compared with those of a control group of 30 patients with cor pulmonale alone. The results showed that there was no significant statistical difference between the two groups on average heart weight and average left and right ventricular thickness (P > 0.05). The results suggest that at the end stage of cor pulmonale left ventricule may be involved whether there are complicating left ventricular disease or not. In this study, cor pulmonale and CHD were both accurately diagnosed in 33.3%, CHD failed to be diagnosed in 38.9% and cor pulmonale failed to be diagnosed in 27.8% of the patients. Single diagnostic factor analysis for cor pulmonale with CHD indicated that age, history of hypertension, history of angina pectoris, history of MI, accentuation A2, presence of bundle branch block, abnormal Q wave and left axis or normal deviation, Cheng Xiansheng diagostic criteria and Selvester MI screening criteria are of significance (P < 0.05). Multiple factor logistic regression analysis indicated that independent prognostic factors including history of angina pectoris, Selvester MI screening criteria and Cheng Xiansheng diagnostic criteria are of help for diagnosis (P < 0.03-0.000). The above-mentioned diagnostic methods are, however, not so specific. At present the best method for diagnosis of CHD is coronary arteriography.

Altered oxidative stress responses in nickel-resistant mammalian cells

BALB 3T3 cells exposed to NiCl2 acquired resistance to concentrations as high as 200 microM and retain resistance for many generations in the absence of nickel. This resistance was not due to alterations in uptake or to metallothionein overexpression. The nickel-resistant B200 cell line was found to also exhibit cross-resistance to hydrogen peroxide and menadione. These nickel-resistant cells had 1.8 times higher basal levels of glutathione compared to wild-type cells. Studies with the glutathione synthesis inhibitor buthionine sulfoximine showed that while glutathione turnover was more rapid in the nickel-resistant cells, its depletion following NiCl2 treatment of the parental BALB 3T3 cell line was greater than in the nickel-resistant B200 cells. The reduced level of binding of NFkB and AP-1 transcription factors to their DNA consensus sequences in B200 cells compared to wild-type cells, and their more reactive response following treatment of resistant cells with H2O2 or buthionine sulfoximine, strengthens the hypothesis that nickel resistance is closely allied to oxidative stress responses.

Use of molecular epidemiological techniques in a pilot study on workers exposed to chromium

OBJECTIVES

Molecular epidemiological techniques, capable of detecting damage to DNA, were used to see if such damage occurred in the lymphocytes of a group of workers exposed to chromium. The two aims of this pilot study were to see if these new techniques might make useful biological monitoring tools for workers exposed to chromium and also, to help assess whether the current occupational exposure limit for chromium (VI) was sufficiently protective in this specific working situation.

METHODS

Volunteer groups of 10 workers exposed to chromium and 10 non-exposed workers provided urine and blood samples towards the end of the working week. Chromium concentrations were measured in whole blood, plasma, lymphocytes, and urine. Lymphocytes were used to examine two forms of DNA damage in the two groups; these were the level of DNA strand breakage and, the production of 8-hydroxydeoxyguanosine.

RESULTS

Chromium concentration in whole blood, plasma, and urine of workers exposed to chromium was significantly raised (P < 0.01) compared with non-exposed controls, but in isolated lymphocytes, there was only a modest but significant (P < 0.05) increase in chromium in the group exposed to chromium. There was no difference in the levels of DNA strand breaks or 8-hydroxydeoxyguanosine between the groups. Air monitoring for chromium was not undertaken but current levels for the group exposed to chromium were reported to be around 0.01 mg/m3, which is 20% of the current United Kingdom occupational exposure limit.

CONCLUSIONS

We were unable to detect any damage in lymphocytic DNA due to exposure to chromium. This may have been due to the low chromium exposure (< 20% of the United Kingdom occupational exposure limit), the ability of plasma to detoxify chromium (VI) to chromium (III) before it reached the lymphocytes, or perhaps the insensitivity of the molecular techniques used. It is now important to test these and other such techniques on groups exposed to levels closer to the United Kingdom occupational exposure limit.

Phenotype of the herpes simplex virus type 1 protease substrate ICP35 mutant virus

The herpes simplex virus type 1 ICP35 assembly protein is involved in the formation of viral capsids. ICP35 is encoded by the UL26.5 gene and is specifically processed by the herpes simplex virus type 1 protease encoded by the UL26 gene. To better understand the functions of ICP35 in infected cells, we have isolated and characterized an ICP35 mutant virus, delta ICP35. The mutant virus was propagated in complementing 35J cells, which express wild-type ICP35. Phenotypic analysis of delta ICP35 shows that (i) mutant virus growth in Vero cells was severely restricted, although small amounts of progeny virus was produced; (ii) full-length ICP35 protein was not produced, although autoproteolysis of the protease still occurred in mutant-infected nonpermissive cells; (iii) viral DNA replication of the mutant proceeded at wild-type levels, but only a very small portion of the replicated DNA was processed to unit length and encapsidated; (iv) capsid structures were observed in delta ICP35-infected Vero cells by electron microscopy and by sucrose sedimentation analysis; (v) assembly of VP5 into hexons of the capsids was conformationally altered; and (vi) ICP35 has a novel function which is involved in the nuclear transport of VP5.

The protease of herpes simplex virus type 1 is essential for functional capsid formation and viral growth

The herpes simplex virus type 1 protease and related proteins are involved in the assembly of viral capsids. The protease encoded by the UL26 gene can process itself and its substrate ICP35, encoded by the UL26.5 gene. To better understand the functions of the protease in infected cells, we have isolated a complementing cell line (BMS-MG22) and constructed and characterized a null UL26 mutant virus, m100. The mutant virus failed to grow on Vero cells and required a complementing cell line for its propagation, confirming that the UL26 gene product is essential for viral growth. Phenotypic analysis of m100 shows that (i) normal amounts of the c and d forms of ICP35 were produced, but they failed to be processed to the cleaved forms, e and f; (ii) viral DNA replication of the mutant proceeded at near wild-type levels, but DNA was not processed to unit length or encapsidated; (iii) capsid structures were observed in thin sections of m100-infected Vero cells by electron microscopy, but assembly of VP5 into hexons of the capsid structure was conformationally altered; and (iv) nuclear localizations of the protease and ICP35 are independent of each other, and the function(s) of Na, at least in part, is to direct the catalytic domain N(o) to the nucleus.

Involvement of mu opioid receptors of periaqueductal gary (PAG) in acupuncture inhibition of noxious blood pressure response in rabbits

Strong electric shock stimulation of the rabbit front paw elicited a pressor blood pressure response regarded as noxious response. Ligands of mu opioid receptors were microinjected into the PAG to observe their effects on acupunture inhibition of the pressor response. (1) Ohmefentanyl (OMF), a mu agonist, significantly attenuated the pressor response. Mu antagonist TCTAP greatly enhanced the pressor response. (2) Electroacupuncture (EA) significantly inhibited the pressor response, the inhibition being readily reversed by TCTAP. The response after TCTAP was significantly greater than that of the control before EA. The results suggest that noxious stimulation is able to activate the mu opioid receptor of the PAG to modulate the noxious response and EA is able to enhance the activation.

Preliminary report on cardiovascular responses to urapidil during intubation and extubation

Urapidil (Ebrantil), a new antihypertensive agent with central and peripheral sites of action, has proven effective in the management of both chronic and acute hypertension. This study investigates its effects on cardiovascular responses during intubation and extubation under general anesthesia. Thirty normotensive patients (ASA I-II) were randomized into control (I, without urapidil, n = 10); lower dose (II, 0.4 mg/kg, n = 10); and higher dose (III, 0.6 mg/kg, n = 10) groups. A significant fall of blood pressure was observed in all patients within 1 min after urapidil administration (P < 0.05), and the magnitude of the decrease was related to blood pressure before treatment. However, no transient drop of blood pressure to hypotensive values was observed. The results suggest that urapidil could be used under general anesthesia in patients to control fluctuating blood pressure during intubation and extubation. The increased heart rate (P < 0.05) seen for several minutes after urapidil administration may have been due to the patients' hypovolemic state.

Monitoring of total chromium in rat fluids and lymphocytes following intratracheal administration of soluble trivalent or hexavalent chromium compounds

1. Intratracheal instillation of sodium dichromate (CrVI) and chromium acetate hydroxide (CrIII) to male Wistar rats gave rise to increased chromium concentrations in whole blood, plasma and urine up to 72 h post exposure; peak concentrations were reached at 6 h after exposure. 2. The ratio of whole blood chromium to plasma chromium concentrations was significantly different for Cr(VI) and Cr(III) treatments. Both blood chromium and plasma chromium assays should therefore be used for the assessment of chromium exposure. 3. Chromium was also detected in peripheral lymphocytes. Cr(VI), but not Cr(III) accumulated significantly in the lymphocytes after treatment. These cells have potential to be used for biomarkers of the assessment of exposure to chromium compounds.

The C-terminal third of UL42, a HSV-1 DNA replication protein, is dispensable for viral growth

UL42 is the herpes simplex virus type 1 DNA polymerase (Pol) accessory protein and is required for viral DNA replication and growth. Previous results from this laboratory demonstrated that the N-terminal two thirds of the protein contains all of the biochemical activities of the protein which can be measured in vitro. These activities include dsDNA-binding, association with DNA polymerase, and stimulation of polymerase activity. To better understand the functions of UL42 in infected cells, we have isolated and characterized two viral recombinants, UL42lacZ and n338. In the mutant virus UL42lacZ, the UL42 gene was disrupted by insertion of the Escherichia coli lacZ gene, while in the mutant virus n338, a termination codon was introduced after amino acid position 338. Analysis of the mutant phenotypes suggest that (1) the first 338 residues of UL42 retain all the functions necessary for viral DNA replication and growth in lytic infection, (2) localization of UL42 to the cell nucleus is independent of Pol, and (3) localization of ICP8 (ssDNA-binding protein) to prereplication sites is independent of functional UL42.

Intragenic complementation of herpes simplex virus ICP8 DNA-binding protein mutants

The major DNA-binding protein, or infected-cell protein 8 (ICP8), of herpes simplex virus is required for viral DNA synthesis and normal regulation of viral gene expression. Previous genetic analysis has indicated that the carboxyl-terminal 28 residues are the only portion of ICP8 capable of acting independently as a nuclear localization signal. In this study, we constructed a mutant virus (n11SV) in which the carboxyl-terminal 28 residues of ICP8 were replaced by the simian virus 40 large-T-antigen nuclear localization signal. The n11SV ICP8 localized into the nucleus and bound to single-stranded DNA in vitro as tightly as wild-type ICP8 did but was defective for viral DNA synthesis and viral growth in Vero cells. Two mutant ICP8 proteins (TL4 and TL5) containing amino-terminal alterations could complement the n11SV mutant but not ICP8 gene deletion mutants. Cell lines expressing TL4 and TL5 ICP8 were isolated, and in these cells, complementation of n11SV was observed at the levels of both viral DNA replication and viral growth. Therefore, complementation between n11SV ICP8 and TL4 or TL5 ICP8 reconstituted wild-type ICP8 functions. Our results demonstrate that (i) the carboxyl-terminal 28 residues of ICP8 are required for a function(s) involved in viral DNA replication, (ii) this function can be supplied in trans by another mutant ICP8, and (iii) ICP8 has multiple domains possessing different functions, and at least some of these functions can complement in trans.

Hexavalent chromium produces DNA strand breakage but not unscheduled DNA synthesis at sub-cytotoxic concentrations in hepatocytes

Rat hepatocytes were used to investigate the possible induction of unscheduled DNA synthesis (UDS) and the extent of DNA strand breaks induced by sodium dichromate (a representative chromium(VI) compound) and chromium acetate hydroxide (chromium(III)) in vitro. Cytotoxicity, measured using tetrazolium salt (MTT) reduction assay, was found at a much higher dose of chromium(III), (> 50 microM), compared to that of chromium(VI), (> 2.5 microM), in cultured hepatocytes over 20 h treatment at 37 degrees C. Chromium(VI), but not chromium(III), stimulated minimal UDS in hepatocytes at sub-cytotoxic concentrations. A positive UDS response was only observed at cytotoxic concentration. DNA strand breaks in hepatocytes were induced by chromium(VI) following incubation at 37 degrees C for 1 h at doses of 10, 20 and 40 microM sodium dichromate. The subsequent ligation of such strand breaks in hepatocytes treated with 40 microM chromium(VI) for 1 h at 37 degrees C was demonstrated. The majority of strand breaks was repaired within 30 min following removal of the chromate. In conclusion, chromate-induced DNA strand breakage, possibly involving the formation of oxygen radicals and lack of significant UDS have some analogy to those produced by ionizing radiation.

Microvascular geometry of the rat heart. Arteriolar and venular capillary regions

The importance of realistic data regarding microvascular geometry for the understanding of oxygen transport to tissue cannot be underestimated. The purpose of the present investigation was therefore to determine the pattern of capillarization in rat myocardium. The histochemical method used in this study was novel in that it allowed for the discrimination of arteriolar capillary (AC) and venular capillary (VC) regions on the basis of color. Our preeminent finding was that systematic differences exist in microvascular geometry from arteriolar to venular capillary regions in normal rat myocardium. Specifically, VC regions are characterized by greater capillary density; more uniform capillary spacing; shorter segment lengths; and increased capillary diameter. These differences translate to significantly greater capillary length, surface and volume densities on the venular side of the capillary bed. In the face of lower PO2 values towards venules, this distinctive geometry would serve to provide advantageous geometric conditions for oxygen diffusion.

Production of 8-hydroxydeoxyguanosine in isolated DNA by chromium(VI) and chromium(V)

Chromium(VI) and Cr(V) compounds increased the concentration of 8-hydroxydeoxyguanosine (oh8dG) in isolated DNA, whereas no such increase was seen with Cr(III). Furthermore, incubating DNA with H2O2 and Cr(VI) or Cr(V) potentiated the formation of oh8dG above levels observed with either chromium compound alone. In the presence of catalase, the increase in DNA oxidation observed with Cr(VI) was inhibited, the base oxidation observed being equivalent to background levels, and this indicated involvement of H2O2 in the mechanism. Glutathione did not enhance chromium-induced formation of this oxidized base. These results help to explain a mechanism of chromium-induced DNA oxidation involving H2O2 via a Fenton-type reaction.

Distal protein sequences can affect the function of a nuclear localization signal

The major DNA-binding protein, or infected-cell protein 8 (ICP8), encoded by herpes simplex virus can localize to the cell nucleus independently of other viral proteins. To define the nuclear localization signals within ICP8, we performed several forms of mutagenesis on the cloned ICP8 gene. Deletion analysis of the ICP8 gene showed that several portions of ICP8 are involved in its nuclear localization. To determine whether these regions were independent localization signals, we introduced various portions of the ICP8 gene into a series of cassette plasmids which allowed expression of fusion proteins containing pyruvate kinase, normally a cytoplasmic protein, fused to various portions of ICP8. These results showed that the carboxyl-terminal 28 residues are the only portion of ICP8 capable of targeting protein kinase into the nucleus. However, inclusion of certain additional regions of ICP8 into the fusion protein led to an inhibition of nuclear localization. Therefore, the carboxyl-terminal 28 residues of ICP8 can act independently as a nuclear localization signal, but certain conformational constraints or folding or assembly requirements in the remainder of the protein can affect the nuclear localization of the protein. Our results demonstrate that sequences distant from a nuclear localization signal can affect its ability to function. A set of fusion vectors has been isolated which should be of general use for making 5' or 3' fusions in any reading frame to rapidly map localization signals.

Induction of DNA strand breaks in peripheral lymphocytes by soluble chromium compounds

1. Incubation of human lymphocytes with sodium dichromate (CrVI) at 37 degrees C for 3 h resulted in a dose-dependent increase in DNA strand breaks without concurrent cytotoxicity. In contrast, chromium acetate hydroxide (CrIII) failed to induce DNA strand breaks at sub-cytotoxic concentrations. 2. DNA strand breaks were also detected in the peripheral lymphocytes of Wistar rats, 24 h after intratracheal instillation of sodium dichromate (1.3 and 2.5 mg kg-1). Instillation of chromium acetate hydroxide (up to 21.8 mg kg-1) failed to induce DNA strand breaks in peripheral lymphocytes. In accord with previous studies, hexavalent chromium was found to be more readily absorbed from the lungs into the peripheral blood than chromium in its trivalent form. 3. The results of this study indicate that fluorometric analysis of DNA unwinding (FADU) in peripheral lymphocytes might be a convenient method of measuring an important biological effect of chromium in occupationally-exposed workers.

Association between the herpes simplex virus major DNA-binding protein and alkaline nuclease

Herpes simplex virus encodes seven proteins which have been shown to be both necessary and sufficient for in vitro replication of origin-containing plasmids. We have shown previously that one of these proteins, the major DNA-binding protein mDBP, forms a complex with alkaline nuclease, which is not one of the seven essential proteins. In this study, we have employed immunological reagents and a series of deletion mutants to investigate this complex further. We have determined the regions of mDBP which are important in the formation of this complex, and we have shown that the intranuclear locations of alkaline nuclease and major DNA-binding protein overlap.

EXPRESSION OF C-fos PROTEIN IN SEROTONERGIC NEURONS OF RAT BRAINSTEM FOLLOWING ELECTRO-ACUPUNCTURE

The c-fos proto-oncogene encodes a nuclear phosphoprotein, Fos which has been proposed to be a "third messenger" coupling short term extracellular signals to long term alteration in cell function. Using double labeling immunocytochemistry, the present work demonstrated the co-localization of Fos protein and serotonin in the nucleus raphe dorsalis, nucleus raphe centralis superior and rostral ventromedial medulla. The results pose an interesting problem, the possible relation of Fos protein to the biosynthesis of serotonin, awaiting further investigation.

Photodynamic therapy for 50 patients with skin cancers or precancerous lesions

Hematoporphyrin photodynamic therapy (HpD-PDT) was used to treat 50 patients (51 lesions) with skin cancers or precancerous lesions. The preliminary results were satisfactory, with 44 cases (45 lesions) obtaining excellent results, 4 cases good, 1 case fair, and 1 case poor. The effective rate was 98%, the significant remission rate 96%, and the complete remission rate 88.2%. Exposure to sunlight should be avoided after HpD injection, since it produces photosensitivity. A follow-up for 1 to 3 years confirmed that HpD-PDT is a good new adjuvant therapy for selected cases. It brings a hopeful future to the treatment of skin cancers.

Potential role for herpes simplex virus ICP8 DNA replication protein in stimulation of late gene expression

We have identified a trans-dominant mutant form of the herpes simplex virus (HSV) DNA-binding protein ICP8 which inhibits viral replication. When expressed by the V2.6 cell line, the mutant gene product inhibited wild-type HSV production by 50- to 150-fold when the multiplicity of infection was less than 5. Production of HSV types 1 and 2 but not production of pseudorabies virus was inhibited in V2.6 cells. The inhibitory effect was not due solely to the high levels of expression, because the levels of expression were comparable to those in the permissive wild-type ICP8-expressing S-2 cell line. Experiments designed to define the block in viral production in V2.6 cells demonstrated (i) that viral alpha and beta gene expression was comparable in the different cell lines, (ii) that viral DNA replication proceeded but was reduced to approximately 20% of the control cell level, and (iii) that late gene expression was similar to that in cells in which viral DNA replication was completely blocked. Genetic experiments indicated that the mutant gene product inhibits normal functions of ICP8. Thus, ICP8 may play distinct roles in replication of viral DNA and in stimulation of late gene expression. The dual roles of ICP8 in these two processes could provide a mechanism for controlling the transition from viral DNA synthesis to late gene expression during the viral growth cycle.

Correct intranuclear localization of herpes simplex virus DNA polymerase requires the viral ICP8 DNA-binding protein

We used indirect immunofluorescence to examine the factors determining the intranuclear location of herpes simplex virus (HSV) DNA polymerase (Pol) in infected cells. In the absence of viral DNA replication, HSV Pol colocalized with the HSV DNA-binding protein ICP8 in nuclear framework-associated structures called prereplicative sites. In the presence of viral DNA replication, HSV Pol colocalized with ICP8 in globular intranuclear structures called replication compartments. In cells infected with mutant viruses encoding defective ICP8 molecules, Pol localized within the cell nucleus but showed a general diffuse intranuclear distribution. In uninfected cells transfected with a plasmid expressing Pol, Pol similarly showed a diffuse intranuclear distribution. Therefore, Pol can localize to the cell nucleus without other viral proteins, but functional ICP8 is required for Pol to localize to prereplicative sites. In cells infected with mutant viruses encoding defective Pol molecules, ICP8 localized to prereplicative sites. Thus, Pol or the portions of Pol not expressed by the mutant viruses are not essential for the formation of prereplicative sites or the localization of ICP8 to these structures. These results demonstrate that a specific nuclear protein can influence the intranuclear location of another nuclear protein.

Simplified fluorometric assay of total selenium in plasma and urine

We describe here a single-tube assay that may be applied to the whole range of selenium status in adult and pediatric patients, including depletion during parenteral or other nutrition. A specimen or aqueous standard, 100 microL, is digested with 0.5 mL of HNO3/HCIO4 (4/1 by vol, at 190 degrees C for 90 min), reduced with 0.5 mL of concentrated HCI (150 degrees C, 30 min), and complexed with 0.5 mL of 6.3 mmol/L 2,3-diaminonaphthalene (DAN) reagent in the presence of EDTA (60 degrees C, 30 min). The resulting fluorophore is extracted into cyclohexane and its fluorescence measured (excitation at 366 nm; emission at 544 nm). It is not necessary to control pH during the complexing step or to protect the DAN from light. The limit of detection of selenium is 10 micrograms/L (0.126 mumol/L); linearity of results extends to 2000 micrograms/L (25.3 mumol/L). Between-batch precision is 5%, analytical recovery 90%-96%. Performance is good as tested against Reference Materials and by participation in a National Quality Assurance Scheme.

Simplified fluorometric assay of total selenium in plasma and urine

We describe here a single-tube assay that may be applied to the whole range of selenium status in adult and pediatric patients, including depletion during parenteral or other nutrition. A specimen or aqueous standard, 100 microL, is digested with 0.5 mL of HNO3/HCIO4 (4/1 by vol, at 190 degrees C for 90 min), reduced with 0.5 mL of concentrated HCI (150 degrees C, 30 min), and complexed with 0.5 mL of 6.3 mmol/L 2,3-diaminonaphthalene (DAN) reagent in the presence of EDTA (60 degrees C, 30 min). The resulting fluorophore is extracted into cyclohexane and its fluorescence measured (excitation at 366 nm; emission at 544 nm). It is not necessary to control pH during the complexing step or to protect the DAN from light. The limit of detection of selenium is 10 micrograms/L (0.126 mumol/L); linearity of results extends to 2000 micrograms/L (25.3 mumol/L). Between-batch precision is 5%, analytical recovery 90%-96%. Performance is good as tested against Reference Materials and by participation in a National Quality Assurance Scheme.

Guinea pig cytomegalovirus immediate-early transcription

Guinea pig cytomegalovirus (GPCMV) immediate-early (IE) gene expression was analyzed. GPCMV IE RNA was defined as RNA obtained from GPCMV-infected guinea pig cells treated with cycloheximide for 1 h before infection and for 4 h postinfection. Mapping studies showed that GPCMV IE genes are located at several distinct sites on the GPCMV genome. A total of 17 GPCMV IE transcripts were identified, and 9 IE transcripts coded for by three specific regions of the genome (regions I, II, and III) were characterized in detail. A series of recombinant DNA clones were generated to identify the nine IE transcripts. Three of the IE transcripts from region I and three from region III were transcribed in the same direction from overlapping sequences. The 2.0-kilobase (kb) transcript encoded by the EcoRI E DNA fragment (region II) was the most abundant IE GPCMV transcript. The cloned GPCMV DNA subfragment that was used to identify the region II EcoRI E 2.0-kb transcript did not hybridize to GPCMV early or late RNA, indicating that this transcript is expressed only under IE conditions. Expression of RNAs from the IE genes was also measured during a natural GPCMV infection in the absence of cycloheximide. During the natural infection, the transcripts previously identified under IE cycloheximide block conditions were expressed, and the region II EcoRI E 2.0-kb transcript was the most abundant transcript at 1 h postinfection. In addition, a rise and fall in RNA levels was observed during the natural infection, demonstrating the transient nature of expression of these transcripts. We conclude that GPCMV IE gene expression is complex, involving a reasonably large number of genes, and demonstrates some similarities with IE transcription by other CMVs.

[Observations of the incidence of metastases form forestomach carcinoma following fractioned laser hyperthermia]

In order to evaluate the effect of local tumor hyperthermia on the incidence of distant metastases, transplantable forestomach carcinomas in 615-strain mice were treated by YAG laser hyperthermia in two trials. The results showed that the increased incidences of metastases following treatment at heating conditions of 41 degrees C/10 min, 41 degrees C/20 min, 45 degrees C/10 min and 45 degrees C/20 min were not statistically significant. Tumor growth inhibition laser hyperthermia at 45 degrees C/20 min was more effective than that under other heating conditions.

Genetic evidence for multiple nuclear functions of the herpes simplex virus ICP8 DNA-binding protein

We have isolated several mutant herpes simplex viruses, specifically mutated in the infected cell protein 8 (ICP8) gene, to define the functional domains of ICP8, the major viral DNA-binding protein. To facilitate the isolation of these mutants, we first isolated a mutant virus, HD-2, with the lacZ gene fused to the ICP8 gene so that an ICP8-beta-galactosidase fusion protein was expressed. This virus formed blue plaques on ICP8-expressing cell lines in the presence of 5-bromo-4-chloro-3-indolyl-beta-D-galactopyranoside. Mutated ICP8 gene plasmids cotransfected with HD-2 DNA yielded recombinant viruses with the mutant ICP8 gene incorporated into the viral genome. These recombinants were identified by formation of white plaques. Four classes of mutants were defined: (i) some expressed ICP8 that could bind to DNA but could not localize to the cell nucleus; (ii) some expressed ICP8 that did not bind to DNA but localized to the nucleus; (iii) some expressed ICP8 that neither bound to DNA nor localized to the nucleus; and (iv) one expressed ICP8 that localized to the cell nucleus and bound to DNA in vitro, but the mutant virus did not replicate its DNA. These classes of mutants provide genetic evidence that DNA binding and nuclear localization are distinct functions of ICP8 and that ICP8 has nuclear functions other than binding to DNA. Furthermore, the portion of ICP8 needed for a nuclear function(s) distinct from DNA binding is the part of ICP8 showing sequence similarity to that of the cellular protein cyclin or proliferating cell nuclear antigen.