Homeless patients' experience of satisfaction with care

This article explores homeless individuals' experiences of satisfaction with health care, and explores the interrelationship among experiences of being homeless, health perceptions of participants, and experiences of satisfaction with health care. It presents the findings of a phenomenological study that was conducted using participants selected from five sites in one southeastern state. Participant interviews were conducted at a nurse-managed primary health care clinic for homeless, at a night time soup-kitchen, and at three private, not-for-profit, homeless shelters in two different towns. The study was part of a larger study designed to develop and validate a reliable measure of client satisfaction with primary health care among homeless individuals. Face-to-face in-depth interviews with 17 homeless individuals were conducted, with the semistructured interview constituting the primary data source. Common themes were identified and the interrelationship of theme clusters was explored. Analysis of the data yielded five distinct themes that represent the lived experiences of satisfaction with health care. These themes were mediated and directly informed by five themes of homelessness and three themes of health identified in the shared experiences of the participants. The themes identified suggest that satisfaction with health care for homeless persons differs from currently identified dimensions of satisfaction with care, and that some aspects of homelessness are seen by participants as positive and health promoting.

Complex expression patterns of lymphocyte-specific genes during the development of cartilaginous fish implicate unique lymphoid tissues in generating an immune repertoire

Cartilaginous fish express canonical B and T cell recognition genes, but their lymphoid organs and lymphocyte development have been poorly defined. Here, the expression of Ig, TCR, recombination-activating gene (Rag)-1 and terminal deoxynucleosidase (TdT) genes has been used to identify roles of various lymphoid tissues throughout development in the cartilaginous fish, Raja eglanteria (clearnose skate). In embryogenesis, Ig and TCR genes are sharply up-regulated at 8 weeks of development. At this stage TCR and TdT expression is limited to the thymus; later, TCR gene expression appears in peripheral sites in hatchlings and adults, suggesting that the thymus is a source of T cells as in mammals. B cell gene expression indicates more complex roles for the spleen and two special organs of cartilaginous fish-the Leydig and epigonal (gonad-associated) organs. In the adult, the Leydig organ is the site of the highest IgM and IgX expression. However, the spleen is the first site of IgM expression, while IgX is expressed first in gonad, liver, Leydig and even thymus. Distinctive spatiotemporal patterns of Ig light chain gene expression also are seen. A subset of Ig genes is pre-rearranged in the germline of the cartilaginous fish, making expression possible without rearrangement. To assess whether this allows differential developmental regulation, IgM and IgX heavy chain cDNA sequences from specific tissues and developmental stages have been compared with known germline-joined genomic sequences. Both non-productively rearranged genes and germline-joined genes are transcribed in the embryo and hatchling, but not in the adult.

Evolution of hematopoiesis: Three members of the PU.1 transcription factor family in a cartilaginous fish, Raja eglanteria

T lymphocytes and B lymphocytes are present in jawed vertebrates, including cartilaginous fishes, but not in jawless vertebrates or invertebrates. The origins of these lineages may be understood in terms of evolutionary changes in the structure and regulation of transcription factors that control lymphocyte development, such as PU.1. The identification and characterization of three members of the PU.1 family of transcription factors in a cartilaginous fish, Raja eglanteria, are described here. Two of these genes are orthologs of mammalian PU.1 and Spi-C, respectively, whereas the third gene, Spi-D, is a different family member. In addition, a PU.1-like gene has been identified in a jawless vertebrate, Petromyzon marinus (sea lamprey). Both DNA-binding and transactivation domains are highly conserved between mammalian and skate PU.1, in marked contrast to lamprey Spi, in which similarity is evident only in the DNA-binding domain. Phylogenetic analysis of sequence data suggests that the appearance of Spi-C may predate the divergence of the jawed and jawless vertebrates and that Spi-D arose before the divergence of the cartilaginous fish from the lineage leading to the mammals. The tissue-specific expression patterns of skate PU.1 and Spi-C suggest that these genes share regulatory as well as structural properties with their mammalian orthologs.

31P-MRS-based determination of brain intracellular and interstitial pH: its application to in vivo H+ compartmentation and cellular regulation during hypoxic/ischemic conditions

In the last decade, significant progress has been made in the characterization of pH regulation in nervous tissue in vitro. However, little work has been directed at understanding how pH regulatory mechanisms function in vivo. We are interested in how ischemic acidosis can effect pH regulation and modulate the extent of post-ischemic brain damage. We used 31P-MRS to determine normal in vivo pH(i) and pH(e) simultaneously in both the isolated canine brain and the intact rat brain. We observed that the 31P(i) peak in the 31P-MRS spectrum is heterogeneous and can be deconvoluted into a number of discrete constituent peaks. In a series of experiments, we identified these peaks as arising from either extracellular or intracellular sources. In particular, we identified the peak representing the neurons and astrocytes and showed that they maintain different basal pH (6.95 and 7.05, respectively) and behave differently during hypoxic/ischemic episodes.

Hypercholesterolemia causes mechanical weakening of rabbit atheroma : local collagen loss as a prerequisite of plaque rupture

Hypercholesterolemia may render atherosclerotic plaques prone to rupture. To test this hypothesis, catheters with matrix-covered balloons were implanted into the aorta of rabbits fed standard or 0. 5% cholesterol chow (n=70). In 1 month, fibrous plaques developed around the balloon. Time-dependent accumulation of cholesteryl esters and free cholesterol was detected in the plaques of the cholesterol-fed group only. The pressure needed to rupture the plaque by balloon inflation was used as an index of plaque strength. Three months after the catheter implantation, the breaking pressure was 2.1 times lower (P<0.05) in cholesterol-fed rabbits. It was accompanied by collagen loss, as measured by plaque hydroxyproline content, but not with deficiency of collagen cross-linking. Sirius red staining showed preservation of collagen originally covering the balloon and accumulation of nascent collagen in the lesions of standard chow-fed rabbits. In the cholesterol-fed group, both mature and new collagen underwent degradation predominantly in the plaque shoulders. Collagen breakdown was associated with local accumulation of foamy macrophages. Gel zymography demonstrated relative enhancement of gelatinolytic activity at 92 and 72 kDa, as well as caseinolytic activity at 57, 45, and 19 kDa in the lipid-laden plaques. Lipid accumulation in the plaque was also associated with a loss of smooth muscle cells, the cellular source of the collagen fibers. The remaining smooth muscle cells showed increased collagen synthesis, although it was insufficient to counterbalance collagen degradation and cell loss. Thus, we have obtained direct evidence that hypercholesterolemia is accompanied by enhanced local collagen degradation, which is potentially responsible for plaque weakening.

Transcriptional regulation of lymphocyte lineage commitment

The development of T cells and B cells from pluripotent hematopoietic precursors occurs through a stepwise narrowing of developmental potential that ends in lineage commitment. During this process, lineage-specific genes are activated asynchronously, and lineage-inappropriate genes, although initially expressed, are asynchronously turned off. These complex gene expression events are the outcome of the changes in expression of multiple transcription factors with partially overlapping roles in early lymphocyte and myeloid cell development. Key transcription factors promoting B-cell development and candidates for this role in T-cell development are discussed in terms of their possible modes of action in fate determination. We discuss how a robust, stable, cell-type-specific gene expression pattern may be established in part by the interplay between endogenous transcription factors and signals transduced by cytokine receptors, and in part by the network of effects of particular transcription factors on each other.

Evidence for medullary projections of the intercostal nerve-elicited inspiratory termination

This study hypothesized that the ICN-elicited inspiratory termination reflex required synaptic activation in two distinct regions of the ventral respiratory group (VRG): (1) transitional (tVRG), and (2) pre-Bötzinger complex (pre-BötC). Data from adult cats indicate that axons of passage associated with the ICN-elicited termination reflex traverse tVRG, but that relevant synaptic processing does not occur in this region. Furthermore, data indicate that neither synaptic nor axonal transmission within the pre-BötC is required for the SLN- or ICN-elicited termination reflex.

Evolution of antigen binding receptors

This review addresses issues related to the evolution of the complex multigene families of antigen binding receptors that function in adaptive immunity. Advances in molecular genetic technology now permit the study of immunoglobulin (Ig) and T cell receptor (TCR) genes in many species that are not commonly studied yet represent critical branch points in vertebrate phylogeny. Both Ig and TCR genes have been defined in most of the major lineages of jawed vertebrates, including the cartilaginous fishes, which represent the most phylogenetically divergent jawed vertebrate group relative to the mammals. Ig genes in cartilaginous fish are encoded by multiple individual loci that each contain rearranging segmental elements and constant regions. In some loci, segmental elements are joined in the germline, i.e. they do not undergo genetic rearrangement. Other major differences in Ig gene organization and the mechanisms of somatic diversification have occurred throughout vertebrate evolution. However, relating these changes to adaptive immune function in lower vertebrates is challenging. TCR genes exhibit greater sequence diversity in individual segmental elements than is found in Ig genes but have undergone fewer changes in gene organization, isotype diversity, and mechanisms of diversification. As of yet, homologous forms of antigen binding receptors have not been identified in jawless vertebrates; however, acquisition of large amounts of structural data for the antigen binding receptors that are found in a variety of jawed vertebrates has defined shared characteristics that provide unique insight into the distant origins of the rearranging gene systems and their relationships to both adaptive and innate recognition processes.

Precise developmental regulation of Ets family transcription factors during specification and commitment to the T cell lineage

Ets family transcription factors control the expression of a large number of genes in hematopoietic cells. Here we show strikingly precise differential expression of a subset of these genes marking critical, early stages of mouse lymphocyte cell-type specification. Initially, the Ets family member factor Erg was identified during an arrayed cDNA library screen for genes encoding transcription factors expressed specifically during T cell lineage commitment. Multiparameter fluorescence-activated cell sorting for over a dozen cell surface markers was used to isolate 18 distinct primary-cell populations representing discrete T cell and B cell developmental stages, pluripotent lymphoid precursors, immature NK-like cells and myeloid hematopoietic cells. These populations were monitored for mRNA expression of the Erg, Ets-1, Ets-2, Fli-1, Tel, Elf-1, GABPalpha, PU.1 and Spi-B genes. The earliest stages in T cell differentiation show particularly dynamic Ets family gene regulation, with sharp transitions in expression correlating with specification and commitment events. Ets, Spi-B and PU.1 are expressed in these stages but not by later T-lineage cells. Erg is induced during T-lineage specification and then silenced permanently, after commitment, at the beta-selection checkpoint. Spi-B is transiently upregulated during commitment and then silenced at the same stage as Erg. T-lineage commitment itself is marked by repression of PU.1, a factor that regulates B-cell and myeloid genes. These results show that the set of Ets factors mobilized during T-lineage specification and commitment is different from the set that maintains T cell gene expression during thymocyte repertoire selection and in all classes of mature T cells.

Differential effects of excitatory amino acid receptor antagonism in the ventral respiratory group

This study tested the hypothesis that selective antagonism of excitatory amino acid (EAA) receptors within the ventral respiratory group (VRG) would induce changes in both respiratory rhythm and pattern. In the paralyzed, decerebrate, vagotomized and ventilated cat, baseline values for respiratory (Ttot), inspiratory (Ti), and expiratory (Te) durations and peak integrated phrenic nerve (integralPN) amplitude were established. Microinjection of the non-NMDA (N-methyl-d-aspartate) receptor antagonist NBQX (2, 3-dihydroxy-6-nitro-7-sulfamoyl-benzo(F)quinoxaline) into rostral/inspiratory-modulated (iVRG) or caudal/expiratory-modulated VRG elicited an immediate apnea. When PN activity resumed, Ttot was significantly decreased, and integralPN amplitude was attenuated. NMDA receptor antagonism with microinjections of AP5 (2-amino-5-phosphonopentanoic acid) into iVRG decreased Te for more than 30 min. NMDA receptor antagonism in inspiratory/expiratory-modulated VRG (level of obex, transitional VRG) yielded either apnea or a significant reduction in Ttot, Ti and integralPN amplitude. Our data suggest that endogenous EAA receptor-mediated neurotransmission throughout the VRG is active in the determination of both respiratory timing and pattern. Our data further suggest that tVRG serves a unique function within the respiratory network.

The pressure toward enactment and the hatred of reality

The pressure toward enactment is investigated in terms of the threats that primitive, pre-thinking states of mind exert on attempts to know and understand. Clinical material and a review of the literature suggest that when the analyst confronts (by thinking) rather than complies (by action) with the hidden demands of omnipotence, he or she triggers and is then subject to the pre-thinking mental realm of concrete sensory bombardment, which can penetrate and obliterate his or her separately thinking mind. One important pressure driving the analyst toward enactment derives from a defensive response aimed at avoiding the threat of such concrete projections.

A long form of the skate IgX gene exhibits a striking resemblance to the new shark IgW and IgNARC genes

Differential screening has been used to identify cDNAs encoding a long form of IgX in Raja eglanteria (clearnose skate). Comparisons of the IgX long form with the previously described short-form IgX cDNAs and the genomic IgX locus indicate that the V and two 5' C regions of the short and long forms of IgX are >90% identical at the nucleotide level. Differences between the V sequences of the long- and short-form IgX genes are concentrated in complementarity determining regions, suggesting that these forms are derived through alternative splicing of the same genomic loci or transcription of highly related loci. The extreme conservation of nucleotide sequence, including third position codons, among different cDNAs as well as the near identity of nucleotide sequence in the intervening sequences of germline IgX, IgX short-form sterile transcripts and IgX long-form sterile transcripts indicate that the multiple IgX loci are recently diverged from one another and/or are under intense gene correction. Phylogenetic analyses of the known cartilaginous fish immunoglobulin loci demonstrate that the long form of IgX is orthologous to IgW/IgNARC (NARC) and is most consistent with: 1) the divergence of the IgX/IgW/NARC and IgM-like loci from a common ancestral locus prior to the divergence of the cartilaginous/bony fish lineages and 2) the divergence of the NAR locus from the IgX/IgW/NARC gene(s) after the cartilaginous/bony fish split but prior to the shark/skate split, approximately 220 million years ago.

Rapid separation and quantitation of combined neutral and polar lipid classes by high-performance liquid chromatography and evaporative light-scattering mass detection

Modifications are described for an innovative and widely used high-performance liquid chromatography technique that resolves a very broad spectrum of lipids for quantitation by evaporative light-scattering detection. Substitution of acetone for 2-propanol in a portion of the solvent gradient program yields consistent resolution of diacylglycerol and cholesterol without sacrificing baseline resolution of the remaining major lipid classes. Moreover, previously noted instabilities in triacylglycerol retention time are eliminated. The introduction of acetone also enables a 20% reduction in flow-rate without an increase in total run time. As a further modification of the mobile phase composition, acetic acid and ethanolamine are substituted for the serine-ethylamine combination that was originally shown to improve column performance. The combination of acetic acid and ethanolamine yields the same result but the increased volatility of these solutes over serine results in decreased baseline noise. Finally, 1,2-hexadecanediol is introduced as an internal standard that is well suited for this method. The chromatographic performance obtained with these modifications is demonstrated in compositional analyses of lipid extracts from rat liver, heart, kidney and brain.

alpha, beta, gamma, and delta T cell antigen receptor genes arose early in vertebrate phylogeny

A series of products were amplified using a PCR strategy based on short minimally degenerate primers and R. eglanteria (clearnose skate) spleen cDNA as template. These products were used as probes to select corresponding cDNAs from a spleen cDNA library. The cDNA sequences exhibit significant identity with prototypic (alpha, beta, gamma, and delta T cell antigen receptor (TCR) genes. Characterization of cDNAs reveals extensive variable region diversity, putative diversity segments, and varying degrees of junctional diversification. This demonstrates expression of both alpha/beta and gamma/delta TCR genes at an early level of vertebrate phylogeny and indicates that the three major known classes of rearranging antigen receptors were present in the common ancestor of the present-day jawed vertebrates.

Heterocyclic amides: inhibitors of acyl-CoA:cholesterol O-acyl transferase with hypocholesterolemic activity in several species and antiatherosclerotic activity in the rabbit

A series of heterocyclic amides were synthesized and evaluated as inhibitors of acyl-CoA: cholesterol O-acyltransferase (ACAT) in vitro and for cholesterol lowering in cholesterol-fed rats. Compounds were evaluated for cell-based macrophage ACAT inhibition, bioactivity, and adrenal toxicity. Candidates were selected for evaluation in cholesterol-fed dogs and, ultimately, the injured cholesterol-fed rabbit model of atherosclerosis. The heterocyclic amides potently inhibited rabbit liver ACAT (IC50's = 0.014-0.11 microM), and the majority of compounds significantly lowered plasma cholesterol (42-68%) in an acute cholesterol-fed rat model at 3 mg/kg. The most efficacious compounds in the rat were evaluated for bioactivity in vivo and arterial ACAT inhibition in a cell-based macrophage ACAT assay. Two highly bioactive analogs, (+/-)-2-(3-dodecylisoxazol-5-yl)-2-phenyl-N-(2,4,6-trimethoxypheny l) acetamide (13a) and (+/-)-2-(5-dodecylisoxazol-3-yl)-2-phenyl-N-(2,4,6-trimethoxypheny l) acetamide (16a), were selected for further study and were found to be nontoxic in a guinea pig model of adrenal toxicity. Compounds 13a and 16a lowered total cholesterol in the cholesterol-fed rat, rabbit, and dog models of pre-established hypercholesterolemia. Compound 13a in the injured cholesterol-fed rabbit model of atherosclerosis was effective in slowing the development of cholesteryl ester-rich thoracic aortic lesions, reducing lesion coverage by 53% at a dose of 1 mg/kg.

Inhibitors of acyl-CoA:cholesterol O-acyltransferase. 17. Structure-activity relationships of several series of compounds derived from N-chlorosulfonyl isocyanate

Several series of acyl-CoA:cholesterol O-acyltransferase inhibitors were prepared by the stepwise addition of nitrogen, oxygen, and sulfur nucleophiles to N-chlorosulfonyl isocyanate. The (aminosulfonyl)ureas 3-44 were the most potent inhibitors in vitro, with several compounds having IC50 values < 1 microM. Although the other series of compounds were not as potent in vitro, many compounds did display good in vivo activity in cholesterol-fed rats. Several of the oxysulfonyl carbamates (including CI-999, 115) showed excellent lipid-lowering activity in the chronic in vivo screen, demonstrating significant cholesterol lowering in a pre-established hypercholesterolemic state.

Sources of coming out self-efficacy for lesbians

The empirical literature on disclosing a lesbian sexual orientation has explored the circumstantial and demographic variables related to this act. This exploratory study utilized self-efficacy theory (Bandura, 1986) to investigate the extent to which each of the four sources of efficacy information (e.g., performance accomplishments, vicarious experience, verbal persuasion, or emotional arousal) contributed to the coming out self-efficacy of lesbians, that is, the sense of confidence possessed by a lesbian to disclose her sexual orientation to others. Anonymous survey packets were completed by 134 lesbians. Results of regression analyses indicated that emotional arousal was the most potent predictor of coming out self-efficacy. Verbal persuasion and vicarious experience also were significant. The most theoretically salient source of self-efficacy information, performance accomplishments (Bandura, 1986), was not a significant predictor of coming out self-efficacy. Further, significant correlations were found between coming out self-efficacy and outness and life-style satisfaction, which were also significantly correlated to measures of psychological adjustment.

From research to practice: the effects of the jointly sponsored dissemination of an arthritis self-care nursing intervention

Various educational programs have been developed and found to be effective in the self-management of arthritis. This study reexamined the effectiveness of one such program, "Bone Up On Arthritis" (BUOA), when the program was delivered by a community-based service organization to a sample of persons (N = 154) who differed widely in disease type and demographic characteristics. Arthritis Foundation staff implemented BUOA at four national sites; data were collected and analyzed by University of Michigan nurse researchers. Investigators found improved scores on all outcome measures (self-care behavior, helplessness, pain, dysfunction, and depression). These findings suggest that "Bone Up" is an effective nursing intervention in multiple organizational and community environments and for diverse patient populations.

Generation of immunoglobulin light chain gene diversity in Raja erinacea is not associated with somatic rearrangement, an exception to a central paradigm of B cell immunity

In all vertebrate species examined to date, rearrangement and somatic modification of gene segmental elements that encode portions of the antigen-combining sites of immunoglobulins are integral components of the generation of antibody diversity. In the phylogenetically primitive cartilaginous fishes, gene segments encoding immunoglobulin heavy and light chain loci are arranged in multiple clusters, in which segmental elements are separated by only 300-400 bp. In some cases, segmental elements are joined in the germline of nonlymphoid cells (joined genes). Both genomic library screening and direct amplification of genomic DNA have been used to characterize at least 89 different type I light chain gene clusters in the skate, Raja. Analyses of predicted nucleotide sequences and predicted peptide structures are consistent with the distribution of genes into different sequence groups. Predicted amino acid sequence differences are preferentially distributed in complementarity-determining versus framework regions, and replacement-type substitutions exceed neutral substitutions. When specific germline sequences are related to the sequences of individual cDNAs, it is apparent that the joined genes are expressed and are potentially somatically mutated. No evidence was found for the presence of any type I light chain gene in Raja that is not germline joined. The type I light chain gene clusters in Raja appear to represent a novel gene system in which combinatorial and junctional diversity are absent.

Immunoglobulin light chain class multiplicity and alternative organizational forms in early vertebrate phylogeny

The prototypic chondrichthyan immunoglobulin (Ig) light chain type (type I) isolated from Heterodontus francisci (horned shark) has a clustered organization in which variable (V), joining (J), and constant (C) elements are in relatively close linkage (V-J-C). Using a polymerase chain reaction-based approach on a light chain peptide sequence from the holocephalan, Hydrolagus colliei (spotted ratfish), it was possible to isolate members of a second light chain gene family. A probe to this light chain (type II) detects homologs in two orders of elasmobranchs, Heterodontus, a galeomorph and Raja erinacea (little skate), a batoid, suggesting that this light chain type may be present throughout the cartilaginous fishes. In all cases, V, J, and C regions of the type II gene are arranged in closely linked clusters typical of all known Ig genes in cartilaginous fishes. All representatives of this type II gene family are joined in the germline. A third (kappa-like) light chain type from Heterodontus is described. These findings establish that a degree of light chain class complexity comparable to that of the mammals is present in the most phylogenetically distant extant jawed vertebrates and that the phenomenon of germline-joined (pre-rearranged) genes, described originally in the heavy chain genes of cartilaginous fishes, extends to light chain genes.

The Albrecht Nursing Model for Home Healthcare. Predictors of satisfaction with a self-care intervention program

Satisfaction with a self-care intervention program was evaluated through this quantitative study of arthritis clients at home. The results indicate that the clients were highly satisfied with the intervention. In this era of consumer satisfaction with their care, nurse administrator's knowledge of which interventions are satisfying is important for staff development and case management in the community.

Effect of a high-fat diet on the performance response to porcine somatotropin (PST) in finishing pigs

One hundred sixty pigs were used in a 2 x 2 factorial design to compare the performance response to daily injection of porcine somatotropin (PST); (0 or 2 mg/d) in animals fed a 14% CP corn-soy diet (control, C) to those fed a diet with 10% added fat (F) and calorie:protein and lysine:protein ratios similar to that of the C diet. Treatments, assigned randomly to 20 pens (n = 5/treatment) of eight pigs each, were initiated at 90 kg body weight and continued for 28 d. Responses to PST and dietary fat were typical. These include improved gain and feed efficiency and decreased feed intake. The effects of dietary fat on intake and efficiency were accounted for largely by the difference in energy density of these diets. Across diets, PST treatment resulted in a 13% improvement in ADG (P less than .001), a 13% decrease in feed intake (P less than .0001) and a 22% improvement in efficiency (P less than .0001). Of particular interest were the additive (PST x diet interaction, P less than .2) effects of PST and dietary fat on gain in these animals. Pigs treated with PST that were fed the F diet had greater rates of gain than did PST-treated pigs fed the C diet (P less than .05). Treatment with PST increased ADG by 9% in pigs consuming the C diet vs 16% in pigs fed the F diet. Similarly, dietary fat resulted in 4 and 11% increases in ADG in pigs treated with 0 or 2 mg of PST/d.(ABSTRACT TRUNCATED AT 250 WORDS)

Temperature-sensitive vaccinia virus mutants identify a gene with an essential role in viral replication

Vaccinia virus mutants ts2 and ts25, members of the same complementation group, exhibit a temperature-dependent arrest at the stage of viral DNA replication. The lesions responsible for the mutant phenotypes have been localized to the far left region of the HindIII B genomic fragment by marker rescue studies. Hybrid selection analyses established that the DNA fragments positive for rescue represented the first open reading frame of the HindIII B fragment and encoded a 30-kilodalton protein. The gene is expressed early after infection as a rightwardly transcribed 1-kilobase-pair mRNA whose coordinates were determined by S1 nuclease mapping. To further the phenotypic analysis of the mutants, the accumulation of viral DNA sequences during permissive and nonpermissive infections was quantitated. The extent of the DNA- phenotype was shown to vary in different cell types. In mouse L cells at either high or low multiplicity of infection, nonpermissive DNA synthesis was less than 5% of that seen in permissive infections. This severe defect was mirrored by correspondingly low viral yields. In infections of BSC40 monkey cells, however, the deficiencies in both DNA synthesis and virus production were far less severe. For one mutant (ts2), the temperature sensitivity in BSC40 cells varied inversely with the multiplicity of infection.

Vaccinia virus encodes an essential gene with strong homology to protein kinases

The B1 gene of vaccinia virus encodes a 34-kDa protein which is essential for viral replication. Temperature-sensitive mutants bearing lesions in this gene arrest at the stage of DNA replication during nonpermissive infections. In this report, the sequence of the 34-kDa open reading frame is presented, and the mutations in two ts alleles are identified. Analysis of the deduced protein sequence reveals strong homology with catalytic domains of numerous protein kinases. The lesion in one of the mutants alters an invariant glycine residue within one such domain.

Effect of temperature on intra- and interspecific crosses of diploid and tetraploid red clover, Trifolium pratense L

Reciprocal intraspecific crosses of diploid and tetraploid Trifolium pratense L. and reciprocal interspecific crosses of 4N T. pratense and T. medium were attempted in conjunction with a 40 °C temperature treatment on the female parent. The temperature treatment was found to be of little benefit in interspecific and intraspecific hybridization attempts. No cytologically verified interspecific hybrids were found from either heat-treated or non-heat-treated crosses. Intraspecific crosses produced no viable triploid offspring. One seedling was found to possess 17 chromosomes but died before positive verifications could be made. However, several seedlings from male-sterile diploid × tetraploid crosses were found to possess 28 chromosomes. These resulting tetraploids were cross compatible with other tetraploids.

CYTOPHOTOMETRIC DETERMINATION OF DNA CONTENT IN NICOTIANA MEGACHROMOSOMES

DNA content in normal Nicotiana chromosomes and in unusually long chromosomes called megachromosomes was determined by Feulgen cytophotometric techniques. DNA content estimates expressed as per cent transmittance were made at specific points on a megachromosome and the mean value for these measurements was compared to the mean transmittance values for normal chromosomes in the same pretreated metaphase cell. DNA measurements for interphase cells, unpretreated metaphase cells and the metaphase chromosome which forms the megachromosome were also obtained. Our observations support the conclusion that comparable unit areas of normal chromosomes and megachromosomes contain equivalent amounts of DNA. The finding of DNA amounts in megachromosomes comparable to DNA levels in normal chromosomes is interpreted as evidence for a replicative mechanism of megachromosome origin instead of a simple extension of the DNA in a chromosome of normal length throughout the length of a megachromosome.