High Risk Prognostic Factors Predictive of Outcome Following Stereotactic Body Radiation Therapy (SBRT) for Early-Stage Lung Cancer

PURPOSE/OBJECTIVE(S)

High risk prognostic factors for outcomes following SBRT for early-stage lung cancer per SWOG/NRG 1914 include: tumor size > 2cm; moderately/poorly/undifferentiated histology; or high metabolic activity on PET/CT defined as SUV > 6.2. The purpose of this IRB approved retrospective study is to assess outcome for stage I lung cancer and to validate SWOG risk stratification in a single community-based radiation department.

MATERIALS/METHODS

A total of 132 patients with 139 tumors treated with SBRT between 2014 and 2019 were stratified by SWOG risk group (high vs. low). To assess differences by risk group in estimated overall survival (OS) at the patient level, as well as Freedom from Local Failure (FFLF), Freedom from Regional Failure (FFRF) and Freedom from Distant Failure (FFDF) at the tumor level, Kaplan-Meier methodology and Cox proportional hazards (PH) modeling for correlated data were used. Statistical significance was concluded at the 0.05 level.

RESULTS

Median follow-up for the entire group is 56 months. 77% of patients had high risk tumors. The median patient age was 75 years with 57% female. Patients with high-risk tumors were older (p = 0.023) compared to patients with low-risk tumors. At the tumor level, high risk tumors were more likely to have biopsies performed (91% vs 57% p = 0.002) and more likely to experience regional failure (28% vs 7% p = 0.005). High risk tumors were more likely to experience local failure (8% vs 0% p = NS) and distant failure (27% vs 14% p = NS). Median survival was 49 months for the whole group (46.0 months high risk, 65.1 months low risk). Actuarial OS at 5 years is 38% (35% high risk, 51% low risk). Actuarial FFLF at 5 years is 94% (93% high risk, 100% low risk). Actuarial FFRF at 5 years is 77% (72% high risk, 93% low risk). Actuarial FFDF at 5 years is 74% (70% high risk, 88% low risk). Cox PH models revealed no statistically significant differences in FFRF by risk group (p = 0.08).

CONCLUSION

Excellent local control but higher regional and distant failure was demonstrated for high-risk lung tumors as defined by SWOG/NRG 1914. Clinically important decrement in outcomes were consistently noted for high-risk tumors in this sample which did not demonstrate statistical significance due to lack of events and statistical power. However, our data supports the prognostic importance of tumor size/grade and SUV for identifying patients at high risk. Further validation with larger sample sizes would contribute to our knowledge regarding risk stratification for early-stage lung cancer treated with SBRT.

Contamination of organic nutrient sources with potentially toxic elements, antibiotics and pathogen microorganisms in relation to P fertilizer potential and treatment options for the production of sustainable fertilizers: A review

Organic nutrient sources such as farmyard manure, sewage sludge, their biogas digestates or other animal by-products can be valuable fertilizers delivering organic matter to the soil. Currently, especially phosphorus (P) is in the focus of research since it is an essential plant nutrient with finite resources, estimated to last only for some more decades. Efficient utilization of organic P sources in agriculture will help to preserve P resources and thereby has the potential to close nutrient cycles and prevent unwanted P-losses to the environment, one of the major causes for eutrophication of water bodies. Unfortunately, organic P sources usually contain also various detrimental substances, such as potentially toxic elements or organic contaminants like pharmaceuticals as well as pathogenic microorganisms. Additionally, the utilization of some of these substrates such as sewage sludge or animal by-products is legally limited in agriculture because of the potential risk to contaminate sites with potentially toxic elements and organic contaminants. Thus, to close nutrient cycles it is important to develop solutions for the responsible use of organic nutrient sources. The aim of this review is to give an overview of the contamination of the most important organic nutrient sources with potentially toxic elements, antibiotics (as one important organic contaminant) and pathogenic microorganisms. Changes in manure and sewage sludge management as well as the increasing trend to use such substrates in biogas plants will be discussed with respect to potential risks posed to soils and water bodies. Some examples for abatement options by which contamination can be reduced to produce P fertilizers with high amounts of plant available P forms are presented.

Beyond knockouts: the International Knockout Mouse Consortium delivers modular and evolving tools for investigating mammalian genes

The International Knockout Mouse Consortium (IKMC; http://www.mousephenotype.org ) has generated mutations in almost every protein-coding mouse gene and is completing the companion Cre driver resource to expand tissue-specific conditional mutagenesis. Accordingly, the IKMC has carried out high-throughput gene trapping and targeting producing conditional mutations in murine embryonic stem cells in more than 18,500 genes, from which at least 4900 mutant mouse lines have been established to date. This resource is currently being upgraded with more powerful tools, such as visualization and manipulation cassettes that can be easily introduced into IKMC alleles for multifaceted functional studies. In addition, we discuss how existing IKMC products can be used in combination with CRISPR technology to accelerate genome engineering projects. All information and materials from this extraordinary biological resource together with coordinated phenotyping efforts can be retrieved at www.mousephenotype.org . The comprehensive IKMC knockout resource in combination with an extensive set of modular gene cassettes will continue to enhance functional gene annotation in the future and solidify its impact on biomedical research.

Die Isolierung phototroph negativer Mutanten von Rhodospirillum rubrum

Mutants of Rhodospirillum rubrum have been isolated that cannot grow photosynthetically but grow aerobically in the dark. The number of mutants in relation to the preculture and the operation of the tetrapyrrole biosynthesis in the mutants have been determined

Gene expression profiling of human ovarian tumours

There is currently a lack of reliable diagnostic and prognostic markers for ovarian cancer. We established gene expression profiles for 120 human ovarian tumours to identify determinants of histologic subtype, grade and degree of malignancy. Unsupervised cluster analysis of the most variable set of expression data resulted in three major tumour groups. One consisted predominantly of benign tumours, one contained mostly malignant tumours, and one was comprised of a mixture of borderline and malignant tumours. Using two supervised approaches, we identified a set of genes that distinguished the benign, borderline and malignant phenotypes. These algorithms were unable to establish profiles for histologic subtype or grade. To validate these findings, the expression of 21 candidate genes selected from these analyses was measured by quantitative RT–PCR using an independent set of tumour samples. Hierarchical clustering of these data resulted in two major groups, one benign and one malignant, with the borderline tumours interspersed between the two groups. These results indicate that borderline ovarian tumours may be classified as either benign or malignant, and that this classifier could be useful for predicting the clinical course of borderline tumours. Immunohistochemical analysis also demonstrated increased expression of CD24 antigen in malignant versus benign tumour tissue. The data that we have generated will contribute to a growing body of expression data that more accurately define the biologic and clinical characteristics of ovarian cancers.

Modes de prescription et de consommation des triptans en Alsace : un mésusage fréquent mais évitable

AIMS

To analyze use of triptans in the Alsace region of France: patients, disorders motivating, doses, analgesics and migraine prophylactics associated treatments, contra-indications. To study major consumers (more than 144 intakes per year) and to determine among them the proportion who suffering from chronic headache.

METHOD

Data concerning all prescriptions of triptans and analgesics as well as migraine prophylaxis prescriptions were obtained from the computer databases of five of the French National Health's local health agencies in Alsace, recorded between April 1, 2003 and March 31, 2004. Data about motivating disorders and the clinical context were obtained using a questionnaire sent to prescribers. Data about patients with more than 144 intakes per year were provided by medical advisors of French Health insurance.

RESULTS

We founded 20686 users: 92.1 percent used between 0 and 6 intakes per month. 11.5 percent of disorders motivating the prescription that were mentioned by prescribers were for off-label use: tension-type headache 2.7 percent, mixed headache, 8.8 percent. Prescribers declared at least one contra-indication for triptan use for 7.8 percent of patients. Over all, prescriptions were off-label for 16.1 percent of patients. Patients who used more than 144 intakes per year accounted for 1.9 percent of the total number and self-medication accounted for 19.2 percent of all triptan intakes. Half of the patients were suffering from daily chronic headache (chronic migraine in 66 percent). 15.6 percent of these patients presented at least one contraindication (high blood pressure or ischemic disease). All in all we estimate that use of triptan is a misuse for 25 percent to 30 percent of the intakes. Quantities of other analgesics used increased simultaneously with triptan use: on average 65, 119 and 244 Defined Daily Doses (DDD)/person/year for patients who used between 1 and 72, 73 and 144 and more than 144 intakes respectively. On average 35.4 percent (in DDD) of analgesics used were opiates (dextropropoxyphene, codeine, tramadol). This proportion increased simultaneously with triptan use: 58.9 percent for major users. Prophylactic treatment for migraine was used by 27.9 percent of the patients: lack of prophylaxis was a prescriber's choice in 90 percent of the cases.

CONCLUSIONS

The high rate of triptan misuse emphasizes the importance of improving prescription of these drugs.

Identification of genes associated with platinum drug sensitivity and resistance in human ovarian cancer cells

Platinum-based chemotherapeutic regimens are ultimately unsuccessful due to intrinsic or acquired drug resistance. Understanding the molecular basis for platinum drug sensitivity/resistance is necessary for the development of new drugs and therapeutic regimens. In an effort to identify such determinants, we evaluated the expression of approximately 4000 genes using cDNA microarray screening in a panel of 14 unrelated human ovarian cancer cell lines derived from patients who were either untreated or treated with platinum-based chemotherapy. These data were analysed relative to the sensitivities of the cells to four platinum drugs (cis-diamminedichloroplatinum (cisplatin), carboplatin, DACH-(oxalato)platinum (II) (oxaliplatin) and cis-diamminedichloro (2-methylpyridine) platinum (II) (AMD473)) as well as the proliferation rate of the cells. Correlation analysis of the microarray data with respect to drug sensitivity and resistance revealed a significant association of Stat1 expression with decreased sensitivity to cisplatin (r=0.65) and AMD473 (r=0.76). These results were confirmed by quantitative RT–PCR and Western blot analyses. To study the functional significance of these findings, the full-length Stat1 cDNA was transfected into drug-sensitive A2780 human ovarian cancer cells. The resulting clones that exhibited increased Stat1 expression were three- to five-fold resistant to cisplatin and AMD473 as compared to the parental cells. The effect of inhibiting Jak/Stat signalling on platinum drug sensitivity was investigated using the Janus kinase inhibitor, AG490. Pretreatment of platinum-resistant cells with AG490 resulted in significant increased sensitivity to AMD473, but not to cisplatin or oxaliplatin. Overall, the results indicate that cDNA microarray analysis may be used successfully to identify determinants of drug sensitivity/resistance and future functional studies of other candidate genes from this database may lead to an increased understanding of the drug resistance phenotype.

The Outcome of In-Vitro Fertilization/Intracytoplasmic Sperm Injection (IVF/ICSI) Cycles Complicated by Moderate-Severe Ovarian Hyperstimulation Syndrome (OHSS)

A retrospective study was used in the Fertility Clinic of the Department of Obstetrics & Gynecology, Tawam Hospital, Al Ain, Abu Dhabi, United Arab Emirates to determine the outcome of IVF/ICSI cycles complicated by OHSS.

Materials & Methods: In the period between January 1994 and August 2000, 3174 IVF/ICSI cycles were performed and 2918 cycles had reached embryo transfer, 564 women achieved pregnancy (19.33%). 92 women (3.15%) developed moderate-severe OHSS and were hospitalized and their medical and IVF records were reviewed. Supportive management whilst waiting for the condition to resolve spontaneously together with follow-up by ultrasound scan and blood tests was applied to all patients included in the study. Pregnancy test was performed 17 days after ovum pick-up.

Results: Ninety-two women developed moderate-severe OHSS, 37 women of them had a clinical pregnancy (40.2%). 51.4% were singletons and 48.6% were multiple pregnancies; including 13 sets of twins, 4 sets of triplets and one set of quadruplets. The miscarriage rate was 32.4% and the spontaneous fetal reduction rate was 16.6%. 25 women continued pregnancy (67.6%); eleven women had preterm delivery (44%), low birth weight rate was 44% and take home baby rate was 59.4%. The Cesarean section rate was 24%. Pregnancy-induced hypertension rate was only 8% and gestational diabetes 4%. There were no cases of ectopic pregnancy or placental abruption.

Conclusion: The pregnancy rate and the rate of multiple pregnancy, miscarriage, prematurity, low birth weight and Cesarean section rate are significantly higher than those reported previously for pregnancies conceived with the use of assisted reproductive techniques without the development of OHSS. The incidence of other obstetric complications such as pregnancy-induced hypertension, gestational diabetes, abruptio placentae and ectopic pregnancy are not significantly different.

Characterization of pepR1, a gene coding for a potential transcriptional regulator of Lactobacillus delbrueckii subsp. lactis DSM7290

The gene designated pepR1, encoding a potential transcription regulator of Lactobacillus delbrueckii subsp. lactis DSM7290, was identified by sequence similarity of an open reading frame located upstream of the prolidase pepQ orientated in opposite direction. pepQ and pepR1 coding regions are spaced by 152 nucleotides. Upstream of the -35 region of pepQ, a 14-bp palindromic sequence, homologous to the catabolite responsive element, could be identified. The pepRl gene has the potential to encode a protein of 333 amino acids with a calculated molecular mass of 36955 Da and a calculated pl of 5.5. The deduced protein sequence shows significant identity to the catabolite control protein of Bacillus. Co-expression in Escherichia coli was studied with the pepR1-pepQ intergenic region fused to the promoterless beta-galactosidase reporter gene. The pepQ-beta-galactosidase hybrid displayed an enhanced expression in the presence of cloned pepR1.

Molecular cloning and DNA sequence analysis of pepL, a leucyl aminopeptidase gene from Lactobacillus delbrueckii subsp. lactis DSM7290

A genomic library of Lactobacillus delbrueckii subsp. lactis DSM7290 DNA fragments from a Sau3A partial digestion in the low-copy-number vector pLG339, was used to screen Escherichia coli for the presence of peptidases. Using the chromogenic substrate leucine-beta-naphthylamide (Leu-NH-Nap) and E. coli strain CM89 lacking the corresponding enzyme activity in an enzymic plate assay, allowed the isolation of two peptidase genes; the newly described pepL and the recently cloned and sequenced pepN. Clones could be distinguished not only by the restriction pattern of isolated plasmids but also by the rate and intensity of their colour reaction with Leu-NH-Nap. Three out of five clones were identified to express the Lactobacillus pepN gene; the others were shown to express a second aminopeptidase gene, designated pepL. This gene, together with 200 bp upstream of the proposed AUG initiation codon, was further subcloned and sequenced. The corresponding open reading frame of 897 nucleotides is predicted to encode a protein of 299 amino acids (34,541 Da). Searching the EMBL database revealed similarity to the prolinase of Lactobacillus helveticus (45.8% identity), to the iminopeptidases of Lb. delbrueckii subsp. lactis and Lb. delbrueckii subsp. bulgaricus (25.5%), and to the Bacillus coagulans prolinase (21.5%). Minor similarities were detected for hydrolytic enzymes with serine active sites. The product encoded by the pepL gene was functional but could not be visualized on Coomassie-blue-stained polyacrylamide gels. High level expression of peptidase L in E. coli was achieved by placing the gene under the control of the T7 promoter.

Two distinct adaptive responses in the synthesis of exocrine pancreatic enzymes to inverse changes in protein and carbohydrate in the diet

Rates of synthesis of 16 individual pancreatic exocrine proteins; tissue concentrations of amylase, trypsinogen, and chymotrypsinogen; and morphological assessment of pancreatic acinar cells were studied in the exocrine pancreas in response to inverse changes in protein and carbohydrate in the diet, administered for 12 days. Two distinct patterns of response were observed. During adaptation to diets containing normal protein (22%) or increased levels of protein (30, 45, 64, and 82% protein) and correspondingly decreased levels of carbohydrate, amylase and the majority of protease zymogens were synthesized in direct proportion to the nutritional substrates carbohydrate and protein, respectively, in the diet. With increases in dietary protein, anticoordinate patterns of response in the synthesis of exocrine isoenzymes were observed: 0.4- to 2.0-fold increases in trypsinogen forms 1 and 2, chymotrypsinogen forms 1 and 2, proelastase 1, and procarboxypeptidases A and B; 5- to 7-fold decreases in amylase forms 1 and 2; and insignificant changes in trypsinogen 3, proelastase 2, lipase, and ribonuclease. During adaptation to diets containing normal protein (22%) or decreased levels of protein (0 or 10% protein) and correspondingly increased levels of carbohydrate, amylase and the majority of protease zymogens were synthesized in inverse proportion to nutritional substrates in the diet.(ABSTRACT TRUNCATED AT 250 WORDS)

Hormonal stimulation in the exocrine pancreas results in coordinate and anticoordinate regulation of protein synthesis

24-h intravenous caerulein infusion studies in the rat were combined with in vitro amino acid incorporation studies followed by high-resolution separation of proteins by two-dimensional isoelectric focusing and SDS gel electrophoresis to study the extent to which persistent changes in the biosynthesis of exocrine pancreatic proteins are regulated by cholecystokinin-like peptides. Beginning in the third hour of optimal hormone infusion at 0.25 microgram kg-1 h-1, changes were observed in the synthetic rates of 12 proteins, which progressed over the course of the 24-h study. Based on coordinate response patterns, exocrine proteins could be classified into four distinct groups. Group I (trypsinogen forms 1 and 2) showed progressive increases in synthetic rates reaching a combined 4.3-fold increase over control levels. Group II (amylase forms 1 and 2) showed progressive decreases in synthesis to levels 7.1- and 14.3-fold lower than control levels, respectively. Group III proteins (ribonuclease, chymotrypsinogen forms 1 and 2, procarboxypeptidase forms A and B, and proelastase 1) showed moderate increases in synthesis, 1.4-2.8-fold, and group IV proteins (trypsinogen 3, lipase, proelastase 2, and unidentified proteins 1-4) did not show changes in synthesis with hormone stimulation. Regulation of protein synthesis in response to caerulein infusion was specific for individual isoenzymic forms in the case of both trypsinogen and proelastase. The ratio of biosynthetic rates of trypsinogen forms 1 + 2 to amylase forms 1 + 2 increased from a control value of 0.56 to 24.4 after 24 h of hormonal stimulation (43.5-fold increase). Biosynthetic rates for an unidentified protein (P23) with an Mr = 23,000 and isoelectric point of 6.2 increased 14.2-fold, and the ratio of synthesis of P23 to amylase 2 increased 200-fold during caerulein infusion. During hormone stimulation the anticoordinate response in the synthesis of pancreatic glycosidases (decreased synthesis) and serine protease zymogens (increased synthesis) explain previous observations that showed little change in rates of total protein synthesis under similar conditions.

Effects of in vivo cholinergic stimulation of rat exocrine pancreas

Peptide and cholinergic secretagogues both produce biphasic dose-response curves for pancreatic enzyme secretion in vitro: supraoptimal doses result in submaximal secretory responses. We compared the effects of maximal and supramaximal doses of a cholinergic agent (carbachol) on rat exocrine pancreas in vivo. In conscious rats, volume and enzyme output were measured from the cannulated pancreatic duct during infusion of carbachol for 3 h. Infusion of 5 X 10(-7) mol . kg-1 . h-1 carbachol caused optimal stimulation, whereas a supraoptimal dose (5 X 10(-6) mol . kg-1 . h-1) resulted in submaximal response. Similar results were achieved when discharge of amylase and protein synthesis was determined in vitro after carbachol in vivo. Supraoptimal doses of carbachol increased serum amylase and enhanced acinar cell lysosomal activity in the Golgi area. The latter appeared to induce fusion of zymogen granules, which resulted in cytoplasmic vacuoles. The in vivo results corroborate in vitro findings of a biphasic dose-response relationship for carbachol and demonstrate destructive effects of supraoptimal concentrations on target cells.

Clinical results and pharmacokinetics of high-dose cytosine arabinoside (HD ARA-C)

Four patients with acute nonlymphoblastic leukemia and one malignant teratoma refractory to conventional chemotherapy were treated with high doses of cytosine arabinoside (HD ARA-C). They received up to 12 cycles of 1.8 to 3 g/m2 every 12 hours applied by 2-hour infusions. A total of 55 HD ARA-C infusions was performed. All leukemic patients responded. A complete clearance of blasts from the bone marrow was observed in two patients following 8-12 cycles of 3 g/m2. However, relapses occurred after three and seven weeks, in one case with resistance to HD ARA-C. The patient with malignant teratoma did not respond. No severe toxicity emerged even after repeated applications. Adverse reactions included moderate nausea and vomiting (4 patients), diarrhea (2 patients), hepatic dysfunction (1 patient), bone pain (1 patient), blurred vision (1 patient), conjunctivitis (1 patient), and exanthema with partial epidermiolysis (1 patient). Granulocytopenia occurring between 3-8 days after having started the therapy, subsided within 4-25 days. Plasma levels of ARA-C and the metabolite uracil arabinoside (ARA-U) were monitored. At steady state plasma concentrations of ARA-C were 32-97 microM (8-24 micrograms/ml). ARA-C disappeared from the plasma mono- or biphasic with a terminal half-life (t50%) of 7.8-12.6 minutes. The total clearance (Cl) of ARA-C varied between 1.7 and 2.9 liters/kg . h, and the distribution volume (Vss) between 0.44 and 0.86 liters/kg. Cerebrospinal fluid (CSF) levels of ARA-C reached 10-15% of steady state concentrations in plasma.

Determination of cytarabine and uracil arabinoside in human plasma and cerebrospinal fluid by high-performance liquid chromatography

A high-performance liquid chromatographic method for the determination of the antineoplastic agent cytarabine and its main metabolite uracil arabinoside in human plasma and cerebrospinal fluid is described. Complete separation from endogenous constituents was achieved by isocratic reversed-phase chromatography using phosphate buffer (0.05 M, pH 7.0) as the eluent. The limit of detection was 50 ng/ml. Day-to-day coefficients of variation were below 10%. The applicability of this rapid, simple and specific method for pharmacokinetic studies and monitoring of therapy was demonstrated.

High molecular weight virus DNA in KB cells infected with ts mutants of adenovirus type 2 under permissive and non-permissive conditions

Temperature-sensitive (ts) mutants of adenovirus type 2 (Ad2), which are deficient in virus DNA synthesis at the non-permissive temperature, have been used to investigate whether virus DNA replication is required for the occurrence of high mol. wt. Ad2 DNA (greater than 100S, 50 to 90S) in human cells productively infected with Ad2. The high mol. wt. virus DNA has been previously shown to consist of virus and cellular DNA molecules covalently linked. The present data indicate that after infection with DNA-ts mutants, the production of high mol.wt. virus DNA is much less sensitive to restrictive conditions than the synthesis of unit length (34S) Ad2 DNA. This finding lends further support to the idea that the occurrence of high mol. wt. virus DNA is independent of the synthesis of unit length virus DNA.

Studies on secretory glycoproteins in the rat exocrine pancreas. III. Intracellular transport of fucose-labeled proteins as studied by cell fractionation

The transcellular movement of fucosylated glycoproteins has been studied in vitro using rat pancreatic lobules and cell fractionation procedures, and has been compared with the well established pathway of secretory proteins. Using tritiated leucine as pulse label for the latter, their translocation from the rough endoplasmatic reticulum into the Golgi complex and finally into zymogen granules could be followed. In the case of glycoproteins, 14C-fucose was incorporated mainly into the smooth microsomal fraction (representative of the Golgi complex) and only one third of this specific activity was transported into the zymogen granule fraction. A detailed analysis of this fraction after separation of the content of zymogen granules from their membranes revealed a predominant labeling of membrane glycoproteins by 14C-fucose. In comparison, leucine-labeled bulk proteins were found almost exclusively in the zymogen granule content fraction, with little radioactivity in the membrane fraction. The data indicate a concomitant synthesis of fucosylated glycoproteins destined in part for the zymogen granule membrane and to a greater amount associated with the smooth microsomal fraction. The results are discussed in the light of recent findings indicating that about 40% of the proteins in the zymogen granule membrane are made up of one major glycoprotein which could be involved in the mechanism of exocytosis.

Integration of adenovirus type 2 DNA in productively infected cells: results of sequential hybridization experiments

In human KB cells permissively infected with adenovirus type 2, the high mol. wt. forms of virus DNA have been characterized. These size classes of virus DNA sediment at greater than 100S and 40 to 90S in alkaline sucrose density gradients. Considerable evidence from a series of earlier communications supports the notion that the high mol. wt. forms of virus DNA represent virus DNA sequences covalently linked to cellular DNA. 3H-labelled high mol. wt. adenovirus type 2 DNA from productively infected cells can be shown to hybridize to virus DNA fixed to filters. In the present paper we demonstrate that on alkali elution of the DNA from the filters used in the first step of the hybridization experiment, the labelled DNA re-hybridizes to cellular DNA in the second step of a sequential hybridization experiment. The order of performing the two successive hybridization experiments can be reversed and very similar results are obtained. These data provide conclusive evidence for the covalent linkage of virus and cellular DNA sequences in KB cells productively infected with adenovirus type 2.

Isolation and characterization of temperature-sensitive mutants of adenovirus type2

Fourteen temperature-sensitive mutants of human adenovirus type2, which differed in their plaquing efficiencies at at the permissive and nonpermissive temperatures by 4 to 5 orders of magnitude, were isolated. These mutants, which could be assigned to seven complementation groups, were tested for their capacity to synthesize adenovirus DNA at the nonpermissive temperature. Three mutants in three different complementation groups proved deficient in viral DNA synthesis. The DNA-negative mutant H2ts206 complemented the DNA-negative mutants H5ts36 and H5ts125, whereas mutant H2ts201 complemented H5ts36 only. Among the DNA-negative mutants, H2ts206 synthesized the smallest amount of viral DNA at the nonpermissive temperature (39.5 C). Data obtained in temperature shift experiments indicated that a very early function was involved in temperature sensitivity. In keeping with this observation, early virus-specific mRNA was not detected in cells infected with H2ts206 and maintained at 39.5 C. Prolonged (52 h) incubation of cells infected with H2ts206 at the nonpermissive temperature led to the synthesis of a high-molecular-weight form of viral DNA.

Intracellular forms of adenovirus DNA: integrated form of adenovirus DNA appears early in productive infection

In KB cells productively infected with adenovirus type 2, alkali-stable greater than 100S and 40-100S viral DNAs are synthesized starting 2-4 hr postinfection, i.e., before unit length (34 S) viral DNA is made. The amount of greater than 100S and 40-100S viral DNA increases when 34S viral DNA synthesis begins, and at 16-18 hr postinfection, the 40-100S viral DNA represents 5-20% of the total intracellular viral DNA. The 40-100S viral DNA is synthesized throughout infection. Part of the 40-100S DNA synthesized 5-8 hr postinfection has a density in alkaline CsCl gradients intermediate between those of viral and cellular DNAs. This finding indicates that newly synthesized viral DNA is covalently linked to cellular DNA. Viral sequences can be excised from the cellular DNA of infected cells with the EcoRI restriction endonuclease. Fragments of viral DNA are detected in polyacrylamide-agarose gels by DNA-DNA hybridization, and these fragments correspond in size to most of the known EcoRI fragments of adenovirus 2 DNA. Viral DNA sequences in size-classes between the EcoRI-A and -C fragments are also found and probably represent viral DNA linked to cellular sequences.