Ontogenetic allometry and architectural properties of the paravertebral and hindlimb musculature in Eastern cottontail rabbits (Sylvilagus floridanus): functional implications for developmental changes in locomotor performance

Due to small body size, an immature musculoskeletal system, and other growth-related limits on performance, juvenile mammals frequently experience a greater risk of predation than their adult counterparts. As a result, behaviorally precocious juveniles are hypothesized to exhibit musculoskeletal advantages that permit them to accelerate rapidly and evade predation. This hypothesis was tested through detailed quantitative evaluation of muscle growth in wild Eastern cottontail rabbits (Sylvilagus floridanus). Cottontail rabbits experience high rates of mortality during the first year of life, suggesting that selection might act to improve performance in growing juveniles. Therefore, it was predicted that muscle properties associated with force and power capacity should be enhanced in juvenile rabbits to facilitate enhanced locomotor performance. We quantified muscle architecture from 24 paravertebral and hindlimb muscles across ontogeny in a sample of n = 29 rabbits and evaluated the body mass scaling of muscle mass (MM), physiological cross-sectional area (PCSA), isometric force (Fmax ), and instantaneous power (Pinst ), along with several dimensionless architectural indices. In contrast to our hypothesis, MM and PCSA for most muscles change with positive allometry during growth by scaling at M b 1.3 and M b 1.1 , respectively, whereas Fmax and Pinst generally scale indistinguishably from isometry, as do the architectural indices tested. However, scaling patterns indicate that the digital flexors and ankle extensors of juvenile S. floridanus have greater capacities for force and power, respectively, than those in adults, suggesting these muscle properties may be a part of several compensatory features that promote enhanced acceleration performance in young rabbits. Overall, our study implies that body size constraints place larger, more mature rabbits at a disadvantage during acceleration, and that adults must develop hypertrophied muscles in order to maintain mechanical similarity in force and power capacities across development. These findings challenge the accepted understanding that juvenile animals are at a performance detriment relative to adults. Instead, for prey-predator interactions necessitating short intervals of high force and power generation relative to body mass, as demonstrated by rapid acceleration of cottontail rabbits fleeing predators, it may be the adults that struggle to keep pace with juveniles.

Making effective use of task analysis to identify human factors issues in new rail technology

Task analysis is an important tool that enables designers to consider the human factors implications of a new technology. This paper details a task analysis for the task of driving long-haul freight trains in Australia and describes how this task analysis was used to evaluate a new in-cab information support technology. This paper then explores similarities and differences between this task analysis and one proposed by Roth and Multer (2009). It is argued that these two task analyses can form the basis for many future task analyses so that we can avoid 'reinventing the wheel,' allowing us to focus more on potential interesting differences between operations and geographical locations.

Conjugation of haloalkanes by bacterial and mammalian glutathione transferases: mono- and dihalomethanes

A primary route of metabolism of dihalomethanes occurs via glutathione (GSH) transferase-catalyzed conjugation. Mammalian theta class GSH transferases and a group of bacterial dichloromethane dehalogenases are able to catalyze the hydrolytic dehalogenation of dihalomethanes via GSH conjugation and subsequent formation of HCHO. Dihalomethanes have been shown to induce revertants in Salmonella typhimurium TA 1535 expressing theta class GSH transferases. Two mammalian theta class GSH transferases (rat GST 5-5 and human GST T1) and the bacterial dehalogenase DM11 were compared in the in vitro conjugation of CH(3)Cl and using in vitro assays (HCHO formation) and the S. typhimurium mutagenesis assay with the dihalomethanes CH(2)Cl(2), CH(2)Br(2), CH(2)BrCl, CH(2)ICl, CH(2)I(2), and CH(2)ClF. GSTs 5-5 and T1 had similar characteristics and exhibited first-order rather than Michaelis-Menten kinetics for HCHO formation over the range of dihalomethane concentrations tested. In contrast, the DM11 enzyme displayed typical hyperbolic Michaelis-Menten kinetics for all of the compounds tested. A similar pattern was observed for the conjugation of CH(3)Cl. The reversion tests with S. typhimurium expressing DM11 or GST 5-5 showed a concentration-dependent increase in revertants for most of the dihalomethanes, and DM11 produced revertants at dihalomethane concentrations lower than GST 5-5. Collectively, the results indicate that rates of conversion of dihalomethanes to HCHO are not correlated with mutagenicity and that GSH conjugates are genotoxic. The results are compared with the conjugation and genotoxicity of haloethanes in the preceding paper in this issue [Wheeler, J. B., Stourman, N. V., Armstrong, R. N., and Guengerich, F. P. (2001) Chem. Res. Toxicol. 14, 1107-1117]. The halide order appears most important in the dihalomethane conjugation reactions catalyzed by GST 5-5 and less so in GST T1 and DM11, probably due to changes in the rate-limiting steps.

Biallelic methylation and silencing of mouse Aprt in normal kidney cells

Heritable gene silencing is an important mechanism of tumor suppressor gene inactivation in a variety of human cancers. In the present study, we show that methylation-associated silencing of the autosomal adenine phosphoribosyltransferase (Aprt) locus occurs in primary mouse kidney cells. Aprt-deficient cells were isolated from mice that were heterozygous for Aprt, i.e., they contained one wild-type Aprt allele and one targeted allele bearing an insertion of the bacterial neo gene. Although silencing of the wild-type allele alone was sufficient for the cells to become completely Aprt-deficient, biallelic methylation of the promoter region was found to occur. Moreover, despite the absence of selective pressure against the targeted allele, phenotypic silencing of the inserted neo gene accompanied silencing of the wild-type Aprt allele. A potential role for allelic homology in these events is discussed.

Spectral Variations in Early-Type Galaxies as a Function of Mass

We report on the strengths of three spectral indicators-Mg(2), Hbeta, and Hn/Fe-in the integrated light of a sample of 100 field and cluster E/S0 galaxies. The measured indices are sensitive to age and/or metallicity variations within the galaxy sample. Using linear regression analysis for data with nonuniform errors, we determine the intrinsic scatter present among the spectral indices of our galaxy sample as a function of internal velocity dispersion. Our analysis demonstrates that there is significantly more intrinsic scatter in the two Balmer line indices than in the Mg(2) index, indicating that the Balmer indices provide more dynamic range in determining the age of a stellar population than does the Mg(2) index. Furthermore, the scatter is much larger for the low velocity dispersion galaxies, indicating that star formation has occurred more recently in the lower mass galaxies.

Treating acute stroke patients with intravenous tPA. The OSF stroke network experience

BACKGROUND AND PURPOSE

Since the FDA approved tissue plasminogen activator (tPA) in 1996 for acute ischemic stroke, few data have been obtained during the postmarketing phase, and applicability in rural hospitals does not exist. We attempt to examine the safety and outcome of intravenous tPA for acute ischemic stroke in the OSF Stroke Network.

METHODS

Fifty-seven consecutive patients treated with tPA were examined from June 1996 through December 1998. Admission and discharge National Institute of Health Stroke Scales (NIHSS), modified Rankin Scales (MRS), and discharge disposition, as well as intracerebral hemorrhage and mortality rates, were compared.

RESULTS

Of 20 network hospitals, 12 had the experience of administering tPA. No statistically significant differences in the variables recorded were observed for patients treated at the community hospitals versus those who received tPA at the tertiary medical center. In 35% of patients, tPA was initiated by an emergency room or primary care physician in consultation with an OSF neurologist. At discharge, 47% of the patients had minimal or no disability (MRS, 0 to 1), 44% had an NIHSS score of 0 or 1, 54% went home, 25% were transferred to in-patient rehabilitation, 12% went to a nursing or skilled-care facility, and 9% died. Intracerebral hemorrhage rate was 9%; 5% were symptomatic.

CONCLUSIONS

tPA can be administered safely with good outcome at community and rural hospitals. The OSF Stroke Network can serve as a model to assist small community hospitals to set up stroke programs and deliver up-to-date, acute stroke therapies.

Solid tissues removed from ATM homozygous deficient mice do not exhibit a mutator phenotype for second-step autosomal mutations

The presence of increased frequencies of blood-derived and solid tumors in ataxia-telangiectasia (A-T) patients, coupled with a role for the ATM (A-T mutation) protein in detecting specific forms of DNA damage, has led to the assumption of a mutator phenotype in A TM-deficient cells. Supporting this assumption are observations of increased rates of chromosomal aberrations and intrachromosomal homologous recombinational events in the cells of A-T patients. We have bred mice with knockout mutations for the selectable Aprt (adenine phosphoribosyltransferase) locus and the Atm locus to examine the frequency of second-step autosomal mutations in Atm-deficient cells. Two solid tissues were examined: (a) the ear, which yields predominately mesenchymal cells; and (b) the kidney, which yields predominately epithelial cells. We report here the lack of a mutator phenotype for inactivating autosomal mutations in solid tissues of the Atm-deficient mice.

A novel signature mutation for oxidative damage resembles a mutational pattern found commonly in human cancers

To determine the types of mutations induced by oxidative damage, a kidney cell line with a heterozygous deficiency for the autosomal Aprt (adenine phosphoribosyltransferase) gene was tested for its mutagenic response to hydrogen peroxide. Aprt-deficient cells were selected and scored for loss of heterozygosity (LOH) for 11 microsatellite loci on mouse chromosome 8. On the basis of the LOH analysis, spontaneous mutants (n = 38) were distributed into four classes: apparent point mutation, mitotic recombination, chromosome loss, and large interstitial deletion. However, 9 of 20 (45%) hydrogen peroxide-induced mutants exhibited a novel class of mutations characterized by "discontinuous LOH" for one or more of the microsatellite loci. Interestingly, mutations resembling discontinuous LOH are commonly observed in a wide variety of human cancers. Our data suggest that discontinuous LOH is a signature mutational pattern for oxidative damage and further suggest that such genetic damage is widespread in cancer.

Significance of peritoneal cytology in patients with potentially resectable adenocarcinoma of the pancreatic head

BACKGROUND

Recurrence in the peritoneum occurs in up to 50% of patients after a potentially curative pancreaticoduodenectomy. Previous authors have implicated preoperative fine-needle aspiration (FNA) as a cause of intraperitoneal tumor dissemination, although prior studies of peritoneal cytology findings have largely involved patients with locally advanced disease.

METHODS

A consecutive series of patients referred to our institution between 1991 and 1993 with suspected or biopsy-proven adenocarcinoma of the pancreatic head was studied prospectively. All patients fulfilled criteria for resectability as assessed by computed tomography: no metastatic disease, no encasement of the superior mesenteric or hepatic arteries, and a patent superior mesenteric-portal venous confluence. Peritoneal washings were obtained at the time of staging laparoscopy and/or at subsequent laparotomy. Data regarding peritoneal cytology results, previous FNA, preoperative chemoradiation, eventual resection, pattern of disease recurrence, and survival were collected.

RESULTS

A total of 80 peritoneal washings from 60 consecutive patients were prospectively examined. Forty-nine (82%) of 60 patients underwent FNA before peritoneal washings were obtained. A total of four patients (7%) had positive peritoneal cytology findings: three (6%) of 49 who underwent prior FNA and one (9%) of 11 with no prior FNA. Similarly, no differences in eventual peritoneal failure or short-term survival were observed for patients who underwent prior FNA compared with patients who did not. All four patients with positive peritoneal cytology findings had metastatic disease (liver, three; peritoneum, one) at a median of 4.8 months after diagnosis; three of the four died of disease at a median of 8 months.

CONCLUSIONS

Positive peritoneal cytology findings are rare in patients with radiologically resectable adenocarcinoma of the pancreas. When found, positive peritoneal washings are an indicator of advanced disease characterized by unresectability, early metastasis, and short survival. Computed tomographic-guided FNA does not appear to increase the risk for positive peritoneal washings and represents a valid approach to the pretreatment diagnosis of patients with suspected pancreatic malignancy.

Site-directed mutagenesis of adeno-associated virus type 2 structural protein initiation codons: effects on regulation of synthesis and biological activity

It has been shown that two of the three adeno-associated virus type 2 capsid proteins, B and C, are synthesized from a single spliced transcript. Protein C arises from an AUG codon at nucleotide 2810, whereas protein B is initiated by a unique eucaryotic initiation codon (ACG) that lies 65 triplets upstream from the C origin. The third capsid component, protein A, is synthesized from a second spliced transcript which uses an alternative 3' acceptor site. In this study we used oligonucleotide-directed mutagenesis to confirm the positions of the B initiation codon and the 3' acceptor sites for the alternatively spliced B/C and A protein messages. We also located definitively the protein A initiation codon, an AUG triplet mapping to nucleotide 2203. Mutagenesis of the B initiator permitted a direct test of the effect of increased B initiator strength on the translational efficiencies of the B and C proteins. It was found that conversion of the relatively inefficient protein B initiator (ACG) to an AUG enhanced the level of B synthesis while abolishing the synthesis of C from its downstream AUG initiator. Protein C synthesis thus depends on the strength of the B initiator, i.e., the relatively higher levels of C (approximately 20-fold greater than B) must result from frequent readthrough of the weak B initiator. Finally, we examined the abilities of mutants deficient in the synthesis of A, B, or C to produce infectious virions. We found that at least two of the structural proteins, B and C, are required for the production of infectious virions and that sequestration of single-stranded adeno-associated virus genomes from the pool of replicating DNA molecules does not occur in the absence of either of these proteins.

Arterial norepinephrine changes in patients with septic shock

Arterial, mixed venous (pulmonary arterial), and peripheral venous norepinephrine and epinephrine levels; hemodynamics; and blood lactate levels were measured in 28 patients with septic shock (16 men and 12 women). During hospital follow-up, 18 patients (64%) died of circulatory failure. There were no significant differences in hemodynamic parameters or initial blood lactate levels between survivors and nonsurvivors. Initial arterial, mixed venous, and peripheral venous norepinephrine levels were elevated above normal in both survivors and nonsurvivors. However, norepinephrine levels at all three sampling sites were significantly higher in nonsurvivors than in survivors. Arterial or mixed venous norepinephrine level was better than peripheral venous norepinephrine level in distinguishing survivors from nonsurvivors. In contrast, the differences in plasma epinephrine levels between survivors and nonsurvivors became significantly different only after 48 hr of follow-up. During 60 degrees head-up tilt, the increase in plasma norepinephrine level was significantly higher in survivors compared to non-survivors, suggesting a differential response in the sympathetic nervous system in the two groups of patients. These data suggest that measurement of arterial or mixed venous plasma norepinephrine levels may be a useful guide for assessing the clinical course of patients in septic shock. Moreover, the differences in the sympathetic nervous system response to a 60 degree tilt may predict a poor outcome in these patients.

Adeno-associated virus DNA replication is induced by genes that are essential for HSV-1 DNA synthesis

Adeno-associated virus (AAV) DNA replication is not detectable unless cells are coinfected with a helper adenovirus (Ad) or herpesvirus or unless AAV infection is carried out in certain established cell lines that have been treated with various metabolic inhibitors or uv irradiation. In helper-dependent infections, it has been shown that AAV DNA synthesis depends on one or more early Ad genes, whereas little is known concerning any herpesvirus gene that promotes AAV DNA synthesis. In this study we tested the ability of four cloned Xbal fragments of herpes simplex virus type 1 (HSV-1) DNA to induce AAV DNA synthesis in Vero cells. Cotransfections, which were carried out with pAV1 (an infectious AAV2 plasmid), revealed that AAV DNA synthesis could be optimally induced by three of these clones (C,D, and F) plus a clone of the HSV-1 ICP4 (IE 175) gene. ICP4, an immediate early gene, was presumably required to activate expression of other HSV genes. To help identify the additionally needed HSV genes, we tested Xbal C,D, and F subclones that contain genes previously found necessary for origin-dependent HSV DNA synthesis and found that at least five of these genes (UL 5, 8, 9, 29, and 30) contributed to the induction of AAV DNA synthesis. In contrast to their absolute requirement for HSV DNA synthesis, none of these genes were strictly necessary for AAV DNA replication. Because they are all known to specify proteins that are directly involved in HSV DNA synthesis, our results suggest that some or all of their products also may directly participate in the replication of AAV DNA.

Efficient synthesis of adeno-associated virus structural proteins requires both adenovirus DNA binding protein and VA I RNA

We have shown previously that replication of defective parvoviruses [adeno-associated viruses (AAV)] requires several early adenovirus (Ad) gene products [J. E. Janik, M. M. Huston, and J. A. Rose (1981) Proc. Natl. Acad. Sci. USA 78, 1925-1929]. To examine their possible roles in the transcription and translation of AAV mRNA, 293-31 cells, a human embryonic kidney cell line that constitutively expresses the Ad early region IA and IB gene products, were transfected with a pBR325 plasmid (pLH1) that contains a duplex AAV2 DNA segment (0.03-0.97 map units) which encompasses the promoters and coding sequences necessary for expression of all AAV polypeptides. When cells were transfected with pLH1 alone, both spliced and unspliced AAV-specific cytoplasmic RNAs accumulated. These transcripts were capable of directing synthesis of the three AAV capsid polypeptides in vitro, whereas in vivo synthesis of AAV protein was not detected by immunofluorescence or immunoprecipitation. When cells were cotransfected with pLH1 and intact Ad DNA, the level of cytoplasmic AAV RNA was enhanced and AAV protein was synthesized in vivo. Additional experiments demonstrated that in vivo AAV protein synthesis also could be induced when pLH1 was cotransfected with plasmids that contain the Ad DNA-binding protein (pDBP) and VA I RNA (p2BalM) genes; however, a low level of in vivo AAV capsid protein was occasionally detected in cotransfections with pLH1 and a plasmid that contains both VA I and VA II RNA coding sequences (p2SalC). Cotransfection of pLH1 and pDBP or pLH1 and p2SalC showed complex alterations in the steady-state patterns of AAV cytoplasmic transcripts. In both cases, increased levels of transcripts, particularly the 2.3-kb spliced species, were detected in comparison to levels seen in cells transfected with pLH1 alone. Despite these increases, however, there was little, if any, induction of AAV protein synthesis unless both the DNA-binding protein (DBP) and VA I RNA coding sequences were present in cotransfection with pLH1. We conclude that, in 293-31 cells, the Ad VA I RNA and DBP gene products regulate AAV capsid protein synthesis at least at two levels: (i) by increasing the steady-state levels of structural protein transcripts in the cytoplasm, especially the spliced species, and (ii) by enhancing the translation of these messages.

Synthesis of adeno-associated virus structural proteins requires both alternative mRNA splicing and alternative initiations from a single transcript

The three adeno-associated virus type 2 (AAV2) structural proteins (A, B, and C) are specified by transcripts generated from the most-rightward promoter (p40). Protein C (60 kilodaltons [kDa]), the most abundantly produced, is entirely contained within B (72 kDa) which, in turn, is contained within A (90 kDa). Although neither of the known structures of p40 transcripts, an unspliced 2.6-kilobase (kb) RNA and a spliced 2.3-kb RNA, possesses an AUG-initiated open reading frame that accounts for the synthesis of proteins A and B, recent evidence indicates that B is initiated by a unique eucaryotic initiation codon (ACG) (S.P. Becerra, J.A. Rose, M. Hardy, B. Baroudy, and C.W. Anderson, Proc. Natl. Acad. Sci. USA 82:7919-7923, 1985). In the present study, we analyzed the in vitro translation of AAV capsid proteins from synthetic transcripts and the in vivo expression of AAV mRNA and capsid proteins in 293 cells transfected with AAV DNA constructs. The results demonstrated that AAV transcripts contain only one functional 5' splice donor site, that synthesis of capsid proteins from the unspliced 2.6-kb transcript is very inefficient, that transcripts without the intervening sequence (IVS) (i.e., the 2.3-kb RNA) do not produce protein A but effectively synthesize proteins B and C, and that protein A is actively synthesized from transcripts which contain the last 34 bases of the IVS. Protein A initiates within this 34-base segment in reading frame 1, apparently with the AUG codon at nucleotide 2203, and then elongates into the B and C open reading frame. Because A is inefficiently synthesized from the 2.6-kb transcript, we conclude that an effective A transcript is generated by alternative splicing and that the alternative 3' acceptor site may lie at nucleotide 2200 within a context of...CAG]GTA. The levels of B and C produced by a synthetic transcript devoid of the IVS suggest that the known 2.3-kb RNA is the main source of these proteins and indicate that this single RNA species expresses both proteins by alternative use of their respective initiation codons.

Direct mapping of adeno-associated virus capsid proteins B and C: a possible ACG initiation codon

The three major capsid proteins of adeno-associated virus type 2 (AAV2) virions are designated A, B, and C and have molecular sizes of 90, 72, and 60 kDa, respectively. These proteins are related, and genetic studies have shown they are encoded by a long open reading frame located in the right half of the genome. The coding capacity distal to the first ATG in this reading frame is only 503 amino acids (i.e., a protein about the size of protein C), but an open frame sequence devoid of ATG codons extends upstream for an additional 184 codons. Although the amino terminus of the C capsid protein is blocked, partial amino acid sequence analyses of peptides from C have confirmed that it is encoded within the portion of the reading frame distal to the first ATG at nucleotide (nt) location 2810. The amino terminus of the B capsid protein is not blocked, and its sequence begins with alanine. The triplet encoding this alanine lies 64 codons upstream from the initiation site for protein C and is immediately preceded by the threonine codon, ACG, at nt 2615. This ACG codon lies in the most favorable sequence context for protein synthesis initiation. All three AAV2 capsid proteins are labeled in vitro with formyl[35S]methionyl-tRNAf, indicating that synthesis of each protein is initiated independently. Our data suggest that the nt 2615 ACG codon directs the methionyl-tRNA-dependent initiation of the AAV2 B capsid protein. Proteins B and C may be synthesized from the same mRNA species and their relative abundance could be determined by the efficiencies of their respective initiation codons.

Human cytomegalovirus completely helps adeno-associated virus replication

Coinfection of adeno-associated virus (AAV) with human cytomegalovirus (HCMV) strain Towne in human embryonic fibroblasts resulted in accumulation of AAV capsid antigen and production of infectious AAV with a lag of 24 hr compared to AAV replication in AAV-adenovirus coinfections. In contrast to previous observation, these findings demonstrated that HCMV is a competent helper virus for the complete replication of AAV. In addition, HCMV and AAV were synergistic in their cytopathic effects on cells, suggesting the possibility that AAV may play a role in the pathogenicity of HCMV infections.

Adeno-associated virus proteins: origin of the capsid components

The three primary capsid proteins (A, B, and C) of adeno-associated viruses have been shown previously to contain overlapping amino acid sequences (R. McPherson and J. Rose, J. Virol. 46:523-529, 1983). In the present study we demonstrate definitively that these proteins are encoded in the right half of the adeno-associated virus 2 genome, and one or both of the smallest adeno-associated RNA species (2.3- or 2.6-kilobase RNA) account for their synthesis. Protein A (90 kilodaltons) apparently initiates from a site within the intervening sequence, which is intact in the larger (unspliced) 2.6-kilobase mRNA, and may read through one or more termination codons, including a strong stop signal (UAA) that lies 31 bases downstream from the end of the intervening sequence. Proteins B (72 kilodaltons) and C (60 kilodaltons) are not derived from protein A but apparently originate from independent, in-frame initiations that lie downstream from the splice junction. It thus seems likely that production of the three adeno-associated virus capsid proteins involves at least two mRNA species. The B and C proteins presumably arise from the spliced 2.3-kilobase RNA, whereas protein A should be generated by the 2.6-kilobase RNA or a hitherto unidentified spliced RNA species.

Structural proteins of adenovirus-associated virus: subspecies and their relatedness

Capsids of adenovirus-associated virus (AAV) are known to contain three major structural proteins (A, B, and C). We have further resolved distinct subspecies of two of the major AAV proteins (two forms of protein A and four forms of protein C) which were found in both AAV1 and AAV2 serotypes. All subspecies were accurately synthesized in a cell-free translation system programmed with RNA isolated from infected cells. Analysis of virion proteins from the autonomous parvovirus H1 did not reveal a comparable array of subspecies of its major components. Staphylococcal V8 protease digestion of C proteins from AAV1 and AAV2 yielded very different electrophoretic patterns, indicating a considerable difference between the C proteins of these two serotypes, despite a high degree of genomic homology and an overall similarity in the number and relative proportions of analogous capsid proteins. On the other hand, staphylococcal V8 protease digestion of isolated proteins A, B, and C of AAV2 showed an extensive overlap among these proteins, possibly equivalent to all of protein C. In conjunction with other data, these findings suggest that proteins A, B, and C arise from different in-frame initiation sites contained in mRNA sequences that are transcribed from the right half of the AAV genome. The heterogeneity of subspecies may be explained by a partial read through of several tandem termination codons near the 3' end of AAV mRNA.

Adeno-associated virus helper activity of adenovirus DNA binding protein

The requirement for the adenovirus (Ad) single-stranded DNA binding protein (DBP) in the expression of adeno-associated virus (AAV) proteins was studied by specific immunofluorescent staining of infected cells and in vitro translation of RNA from infected cells. The Ad5 mutant ts125, which carries a mutation in the DBP gene, helped AAV as efficiently as the Ad5 wild type (WT) did at both the permissive (32 degrees C) and nonpermissive (40.5 degrees C) temperatures in HeLa and KB cells. Furthermore, at 40.5 degrees C ts125 was as efficient as Ad5WT was in inducing the expression of AAV proteins in a line of Detroit 6 cells which is latently infected with AAV. However, little if any AAV protein was synthesized when coinfections were carried out with Ad5WT in CV-C cells, a monkey cell line that is highly restrictive for human Ad replication unless the cells are also infected with simian virus 40. On the other hand, AAV protein was efficiently produced in CV-C cells in coinfections with the Ad5 mutant hr404, whose growth is unrestricted in CV-C cells and whose mutation also maps in the DBP gene. Finally, preparations of cytoplasmic RNA extracted from CV-C cells infected with AAV and Ad5WT or from CV-C cells infected with AAV, Ad5WT, and simian virus 40 were each capable of directing the in vitro synthesis of abundant amounts of AAV proteins in a rabbit reticulocyte lysate system. These results indicate that the abnormal DBP of ts125 still retains its helper function for AAV replication, but that the molecular feature of the DBP which relates to the monkey cell host range restriction of Ad's may also account for the observed block to AAV protein translation in CV-C cells.

Comparison of twice-daily ranitidine and placebo in the treatment of duodenal ulcer--a multicentre study in the United Kingdom

Treatment of duodenal ulcer with the H2-receptor antagonist ranitidine, 150 mg twice daily has been assessed in a double-blind, placebo controlled study at seven centres in the United Kingdom. One hundred-and-twenty-nine patients entered the trial with endoscopically confirmed duodenal ulcer. Five patients did not comply with the protocol and were excluded from the analysis. Nine patients (1 ranitidine, 8 placebo) did not complete the initial 4 weeks' treatment due to poor symptomatic response; one hundred-and-fifteen (58 ranitidine, 57 placebo) were endoscopically assessed after 4 weeks. The average 4-week healing rate among patients on ranitidine (83%) was significantly greater than that for the placebo group (32%, p less than 0.01). Forty-four patients whose ulcers had not healed received further treatment with ranitidine 150 mg b.d. on an open basis. After a total of up to 8 weeks' active treatment only three patients had not healed. Ulcer symptoms resolved or improved in a greater proportion of patients on ranitidine, and this was associated with a significantly lower antacid consumption. There was no serious unwanted effect associated with ranitidine treatment, and the twice daily dose of 150 mg is apparently a safe and effective short-term treatment for duodenal ulceration.

Herpes simplex virus types 1 and 2 completely help adenovirus-associated virus replication

In addition to adenoviruses, which are capable of completely helping adenovirus-associated virus (AAV) multiplication, only herpesviruses are known to provide any AAV helper activity, but this activity has been thought to be partial (i.e., AAV DNA, RNA, and protein syntheses are induced, but infectious particles are not assembled). In this study, however, we show that herpes simplex virus type 1 (HSV-1) and type 2 (HSV-2) are in fact complete AAV helpers and that AAV type 2 (AAV2) infectivity yields can approach those obtained when coinfections are carried out with a helper adenovirus. AAV helper activity was demonstrated in KB cells with two HSV-1 strains (11124 and 17MP) and an HSV-2 strain (HG52). Each herpesvirus supported AAV2 multiplication with comparable efficiency. AAV2 multiplication was similarly efficient in HSV-1 coinfections of HeLa cells, whereas lower yields were obtained in HEp-2 and primary human embryonic kidney cells. HSV-1 also supported AAV1 multiplication in HeLa cells but, at corresponding multiplicities of infection, AAV1 grew less efficiently than AAV2. Comparisons of the time courses of AAV2 DNA, RNA, and protein syntheses after coinfection with either adenovirus type 5 or HSV-1 revealed that, in each case, the onset of synthesis and attainment of maximal synthesis rate occurred earlier in coinfections with HSV-1. These findings demonstrate the linkage of AAV macromolecular synthesis to an event(s) in the helper virus cycle. Aside from this temporal association, helper-related differences in AAV macromolecular synthesis were not apparent.

Locations of adenovirus genes required for the replication of adenovirus-associated virus

We have used DNA transfection to identify several regions of the adenovirus genome needed to induce replication of the defective parvovirus, adenovirus-associated virus (AAV). Previous studies have indicated that only early adenovirus functions are needed to aid the replication of AAV. In this report, we demonstrate that three restriction endonuclease fragments of adenovirus DNA are necessary for production of infectious AAV in 293-31 cells (an adenovirus type 5-transformed human embryonic kidney cell line). These fragments map from 28.5 to 29.4, 59.5 to 75.9, and 89.7 to 100 map units on the adenovirus type 2 genome and correspond to the locations of the VAI RNA gene, early region 2, and early region 4, respectively. The 293-31 cell line, which has been found to express early region 1A and 1B proteins, alone is incapable of supporting AAV replication or even AAV DNA synthesis. Additional experiments with adenovirus type 5 host range mutants (group I, hr1 and group II, hr7) indicate, however, that early region 1A provides an essential function(s) for AAV replication, whereas early region 1B probably does not.

Deoxyribonucleic acid single-strand-specific endonucleases in human cells: partial purification of a salt-resistant endonuclease with an acidic isoelectric point

A second endonuclease with DNA single-strand specificity has been purified from KB cells, a continuous line of hunan epithelial cells. In contrast to other mammalian enzymes that cleave single-stranded DNA, this enzyme has an acidic isoelectric point (6.5 +/- 0.2). Its pH optimum is 9.5, it requires Mg2+ of Mn2+ for activity, and it has a sedimentation coefficient of 3.2 S, based on sucrose gradient centrifugation. The enzyme specifically catalyzes the endonucleolytic cleavage of synthetic DNA homopolymers and denatured viral DNA but does not attack linear duplex viral DNA. The rate of hydrolysis of poly(dT) is approximately 8-fold greater than that observed with denatured DNA. The relative rates of hydrolysis of homopolymers by the endonuclease are poly(dA) greater than poly(dT) greater than poly(dC) greater than poly(dG). Unlike other DNA single-strand-specific endonucleases isolated from human cells, this endonuclease is relatively insensitive to inhibition by KCl.

The characteristics of the binding of 12-alpha-[3H]-digoxin to the membranes of intact human erythrocytes: relevance to digoxin therapy

1 The characteristics of the binding of 12-alpha-[3H]-digoxin to the membranes of intact human erythrocytes are described. 2 Only one class of binding site can be demonstrated. Binding is time- and temperature-dependent, saturable and slowly reversible; it is inhibited by other cardiac glycosides and by potassium. 3 Pre-incubation with unlabelled digoxin reduces the subsequent binding of 12-alpha-[3H]-digoxin in stoichiometric fashion. 4 The possible application of the measurement of the binding of 12-alpha-[3H]-digoxin to the study of biochemical pharmacological events occurring during digoxin therapy is discussed.

Mechanism of host restriction of adenovirus-associated virus replication in African green monkey kidney cells

Human adenovirus (Ad) serotypes provide an early factor(s) that is necessary for adenovirus-associated virus (AAV) multiplication in human cell lines. However, little, if any, AAV production occurs in primary African green monkey kidney (AGMK) cells co-infected with AAV and a helper human Ad (non-permissive infection), unless cells are additionally infected with SV40 (permissive infection). To determine the basis of the host restriction of AAV replication in AGMK cells, AAV DNA, RNA and protein synthesis were analyzed under various conditions of infection. Hybridization reactions revealed no detectable AAV-specific DNA or RNA in infections with AAV alone or in combination with SV40. In co-infections with AAV and Ad5 or Ad7, the synthesis of both AAV- and Ad-specific DNA and RNA occurred without a significant rise in titre of either virus. During non-permissive infection, however, AAV DNA synthesis was abnormal in that an expected accumulation of single-stranded progeny molecules was not observed. Finally, although intact 20S AAV transcripts were present in the cytoplasm of AGMK cells during non-permissive infection (in amounts ranging from 50 to 80% of that found during permissive infection), AAV-specific polypeptides were not demonstrable by polyacrylamide gel electrophoresis. Taken together, these experiments indicate that the host restriction of AAV replication in AGMK cells is exerted at the level of translation of the single AAV messenger RNA. In addition, it appears that one or more of the AAV polypeptides specified by this message is required for the production of single-stranded AAV progeny DNA.

Purification and characterization of a DNA single strand specific endonculease from human cells

An endonuclease with DNA single-strand specificity has been purified from KB cells. The enzyme has a pH optimum at 9.2, requires Mg2+ for activity, and is inhibited by mono- or divalent cations. Its sedimentation coefficient of 4.6 S is based on sucrose gradient sedimentation, and it has a molecular weight of 54 000 as determined by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. The enzyme specifically catalyzes the endonucleolytic cleavage of denatured DNA, yielding acid-soluble oligonucleotides which contain 5'-phosphoryl termini. The rate of hydrolysis of poly(dT) is approximately eightfold greater than that observed with denatured DNA, although the Km for both substrates is 1.74 X 10(-5) M. The relative rates of hydrolysis of homopolymers by the endonuclease are: poly(dG) greater than poly(dT) greater than poly(dA) greater than poly (dC). Purified enzyme preparations also hydrolyze poly(U), releasing acid-soluble products. This activity cosediments in sucrose gradients with the DNA endonuclease activity, suggesting that both activities are contained in the same enzyme molecule.

Characterization of adenovirus-associated virus-induced polypeptides in KB cells

Electrophoretic analysis of KB cells coinfected with adenovirus-associated virus (AAV) type 2, a defective parvovirus, and adenovirus type 5 (as helper) have revealed the synthesis in vivo of at least five AAV-specific polypeptides. The three largest polypeptides, with molecular weights of 90,700, 71,600, and 60,000 comigrated in polyacrylamide gels with the three AAV structural polypeptides. The remaining two polypeptides had molecular weights of 24,900 and 15,800. The concentrations of the AAV-induced polypeptides relative to one another remained approximately constant during the infectious cycle, and the structural components were present in proportions similar to those found in purified virions. As determined by pulse-chase experiments, all polypeptides were generated at the level of protein synthesis and not by posttranslational proteolytic processing. Although inhibitors of proteolytic enzymes failed to influence the pattern of AAV-induced polypeptides, and amino acid analog, L-canavanine, blocked the appearances of both the major structural polypeptide (60,000 daltons) and the larger nonstructural polypeptide (24,900 daltons). Taken in conjunction with pulse-chase data, this result supports a model whereby the major virion polypeptide is produced by proteolytic cleavage of the nascent polypeptide chain.

Concatemers of alternating plus and minus strands are intermediates in adenovirus-associated virus DNA synthesis

Replicating DNA molecules of adenovirus-associated virus (AAV) were selectively extracted from KB cells coinfected at 39.5 detrees with a DNA minus, temperature-sensitive mutant of adenovirus 5 (ts125) as helper. Under these conditions AAV DNA replication proceeds normally, but there is little, if any, adenovirus DNA synthesis. An analysis of the replicating molecules in sucrose density gradients reveals that there are AAV DNA intermediates which consist of covalently linked plus and minus DNA strands. Under denaturing conditions, these concatemers are linear single strands whose lengths can reach at least four times the size of the AAV genome. The most abundant concatemeric species is a dimer which presumably exists in vivo as a unit length hairpin. Unit length linear duplexes appear to be immediate precursors of plus and minus progeny strands. These findings are compatible with a self-priming mechanism for the synthesis of AAV DNA.

DNA-minus temperature-sensitive mutants of adenovirus type 5 help adenovirus-associated virus replication

Efficient potentiation of adenovirus-associated viruses (AAV) replication occurs in coinfections with either of two DNA-minus temperature-sensitive mutants of adenovirus type 5 (Ad5), ts125 and ts149. The helper activity of these mutants does not result from leakiness. At the nonpermissive termperature (39.5 C) there was little or no detectable adenovirus DNA synthesis, and only a relatively low level of adenovirus transcription was observed. However, the synthesis of AAV DNA and RNA and the yield of infectious AAV were comparable in amounts to those found when wild-type Ad5 was the helper. Furthermore, an apparent lag in the initiation of AAV transcription after the onset of AAV DNA synthesis was seen in coinfections with both wild type or ts125. These findings strongly suggest that the adenovirus factor(s) required for AAV multiplication is produced early in the adenovirus DNA replication, this requirement does not include all factors directly needed for adenovirus DNA synthesis.

Penetration of C14-labelled rifampicin into primate peripheral nerve

The penetration of C14 Rifampicin into various tissues, but particularly peripheral nerve, has been studied in the monkey. Penetration into the substance of peripheral nerve internal to the epineurial covering was demonstrated and the significance of this in relation to the treatment of leprosy is discussed.

Arrangement of sequences in the inverted terminal repetition of adenovirus 18 DNA

In contrast to the single-stranded circular molecules produced with denatured DNA from other adenoviruses, there was associated with nearly all circular molecules of adenovirus type 18 a visible, duplex projection. These projections had a mean contour length of 0.31 +/- 0.12 mum, equivalent to approximately 3% of genome length. Individual projections ranged in size from 0.1 to 2 mum. Alkaline sucrose gradient purification of single-stranded molecules did not affect formation of these projections, and treatment of a preparation of circular molecules with Neurospora crassa single-strand specific nucleases yielded 0.34 +/- 0.09 mum duplex fragments. Single-stranded circles did not form if a limited number of nucleotides were removed from the 3' ends of native molecules by Escherichia coli exonuclease III digestion prior to denaturation and annealing. In addition, preformed single-stranded circles could be converted to linear molecules by similar treatment. Based on the formation of specific heteroduplex structures when preparations of native DNA were denatured and reannealed and the absence of branches on linear, single-stranded molecules, we conclude that projections are generated by unusually long, inverted terminal repetitions. The repetitious sequences occur in place of rather than in addition to regular sequences. These data provide direct, visual evidence for the arrangement of bases in the inverted terminal repetition of adenovirus DNA.

Self-complementarity of terminal sequences within plus or minus strands of adenovirus-associated virus DNA

At least 70% of plus or minus strands of adenovirus-associated virus DNA contain self-complementary sequences at or near their termini. Self-annealing of these sequences generates circular molecules that are closed by duplex, hydrogen-bonded segments. The self-annealed segments are sensitive to exonuclease III and have a thermal stability comparable to that of double-stranded DNA molecules. Length measurements of double-stranded adenovirus-associated virus DNA molecules show a bimodal distribution, with the larger component being 10% shorter than SV40 DNA. The presence of self-complementary terminal sequences in single-stranded molecules of viral DNA has been observed previously only with DNA from adenoviruses. It is thus especially notable that adenovirus-associated virus replication is unconditionally dependent on a helper adenovirus. A possible role for terminal self-complementary sequences in viral DNA replication is suggested.

Adenovirus-associated virus multiplication. IX. Extent of transcription of the viral genome in vivo

Nucleic acid hybridization procedures were used to measure the extent of transcription of adenovirus-associated virus (AAV) deoxyribonucleic acid (DNA) in KB cells in the presence of either adenovirus or herpes simplex virus as the helper. Annealing of AAV ribonucleic acid to AAV DNA was monitored by a hybridization inhibition assay on nitrocellulose filters or by hydroxyapatite chromatography. These experiments confirmed the previous observation that, in the presence of either type of helper virus, only one strand of AAV DNA (the thymidine-rich or "minus" strand) is transcribed in vivo. However, it was found that only 70 to 80% of this strand appears to be transcribed in vivo. Furthermore, studies with minus strands employing hydroxyapatite chromatography and nuclease S(1), which specifically degrades single-stranded DNA, indicated that up to 20% of the minus strand is self-complementary. It seems likely that these self-complementary sequences account for the bulk of that portion of the minus strand (20 to 30%) which is not transcribed in vivo.

A unique form of terminal redundancy in adenovirus DNA molecules

A unique form of terminal redundancy has been observed in DNA molecules extracted from several human adenovirus serotypes. Electron microscopic studies reveal that single-stranded circular molecules are formed when native DNA is denatured and then annealed. Temperatures approaching the T(m) of native DNA are required to convert circles to linear molecules, indicating a high degree of self-complementarity between terminal base sequences of DNA strands. Single-stranded circles are not generated if a limited number of nucleotides (2-4%) are removed from the 3' ends of native DNA by digestion with Escherichia coli exonuclease III before denaturation and annealing. The lenght of the redundant segment appears to differ among major serotypic groups, and a possible association between increased length of the redundant segment and increased oncogenic capability of virus serotype is suggested. Evidence for the configuration of the duplex closure region of circular molecules is also presented.

Adenovirus-associated virus multiplication. 8. Analysis of in vivo transcription induced by complete or partial helper viruses

We have analyzed ribonucleic acid (RNA) synthesized in KB cells co-infected with adenovirus-associated virus (AAV) type 2 and either adenovirus type 2 (Ad2) or herpes simplex virus type 1 (HSV-1). With either type of helper virus, synthesis of AAV RNA was readily detected by deoxyribonucleic acid (DNA)-RNA hybridization. As is the case for AAV RNA synthesized with helper Ad2, the AAV RNA synthesized with HSV-1 as helper annealed only to the thymidine-rich (minus) AAV DNA strand. In addition, AAV RNA synthesized with either type of helper (i) contained similar nucleotide sequences as determined by hybridization inhibition tests and (ii) had a mean molecular weight of approximately 7.5 x 10(5) based on sedimentation in dimethylsulfoxide-sucrose gradients. These experiments suggest that the restricted helper function of HSV-1 is not due to abnormal transcription of the AAV genome. Since the mean molecular weight of AAV RNA is equivalent to 40 to 50% of the AAV genome, as few as two or three AAV RNA species may be transcribed in vivo. In contrast to adenovirus RNA, cleavage of AAV RNA after transcription was not observed.

Adenovirus-associated virus multiplication. VII. Helper requirement for viral deoxyribonucleic acid and ribonucleic acid synthesis

The adsorption of adenovirus-associated virus (AAV) type 2 by KB cells and the subsequent penetration of the AAV genome to the cell nucleus was measured with and without helper adenovirus type 2 (Ad2). It was found that the helper virus did not enhance either process. On the other hand, a synthesis of AAV deoxyribonucleic acid (DNA) or ribonucleic acid (RNA) was not detected by nucleic acid hybridization after KB cells were infected with AAV type 2 alone, whereas both AAV DNA and RNA synthesis were readily detected when cells were additionally infected with Ad2 or herpes simplex virus type 1, a partial helper of AAV replication. AAV RNA synthesis was initially observed 10 to 11 hr after simultaneous infection with Ad2, but the interval between AAV infection and AAV transcription could be reduced to 4 to 5 hr when cells were first infected with Ad2 for 10 hr. It was estimated that AAV DNA synthesis accounted for 3% of the total DNA in cells after a simultaneous infection with Ad2. These findings, together with the previous observation that adenovirus provides a helper function(s) after AAV uncoating, suggest that AAV are defective only subsequent to the uncoating process, and that helper viruses may provide a factor(s) needed for initiating synthesis of AAV DNA, RNA, or both.

Adenovirus-associated virus multiplication. VI. Base compostion of the deoxyribonucleic acid strand species and strand-specific in vivo transcription

The two complementary strand species of 5-bromodeoxyuridine-substituted, adenovirus-associated virus type 2 (AAV-2) deoxyribonucleic acid were preparatively separated in CsCl density gradients and further purified by sedimentation through 5 to 20% sucrose. The base composition of each strand species was determined, and it was found that the species banding at a greater density in CsCl (heavy strands) had an expected higher thymidine content (26.5%) than that 21.7%) of the less dense species (light strands). Furthermore, the base composition of in vivo-synthesized, AAV-specific ribonucleic acid was similar to that of light-strand deoxyribonucleic acid, and this ribonucleic acid apparently hybridized only with heavy strands. These observations indicate that the heavy-strand species alone serves as the transcriptional template in vivo. This study represents the first instance in which the base composition and specificity of in vivo transcription have been determined for each of the complementary strands of an animal virus deoxyribonucleic acid.

Structural proteins of adenovirus-associated viruses

The structural proteins of adenovirus-associated virus (AAV) types 1, 2, and 3 were analyzed by acrylamide gel electrophoresis. In each case, one major protein (C) and two minor proteins (A and B) were identified. Component C had an estimated molecular weight of 62,000 daltons, and the molecular weights of components A and B were found to be 87,000 and 73,000 daltons, respectively. Coelectrophoresis of adenovirus and AAV proteins revealed an overlap only between the adenovirus fiber-penton component and the AAV C polypeptide. Among AAV serotypes, homologous components were electrophoretically identical, except that the C component of AAV-2 was of slightly lower molecular weight than the C components of AAV-1 and AAV-3. The relative incorporation of (14)C-arginine and (14)C-mixed amino acids into the three polypeptides of AAV-2 was similar, indicating an absence of an arginine-rich component. In addition, AAV-2 was found to have a substantially lower arginine content than helper adenoviruses.