Immune checkpoint modulation enhances HIV-1 antibody induction

Eliciting protective titers of HIV-1 broadly neutralizing antibodies (bnAbs) is a goal of HIV-1 vaccine development, but current vaccine strategies have yet to induce bnAbs in humans. Many bnAbs isolated from HIV-1-infected individuals are encoded by immunoglobulin gene rearrangments with infrequent naive B cell precursors and with unusual genetic features that may be subject to host regulatory control. Here, we administer antibodies targeting immune cell regulatory receptors CTLA-4, PD-1 or OX40 along with HIV envelope (Env) vaccines to rhesus macaques and bnAb immunoglobulin knock-in (KI) mice expressing diverse precursors of CD4 binding site HIV-1 bnAbs. CTLA-4 blockade augments HIV-1 Env antibody responses in macaques, and in a bnAb-precursor mouse model, CTLA-4 blocking or OX40 agonist antibodies increase germinal center B and T follicular helper cells and plasma neutralizing antibodies. Thus, modulation of CTLA-4 or OX40 immune checkpoints during vaccination can promote germinal center activity and enhance HIV-1 Env antibody responses.

Elucidation of broadly neutralizing antibodies (bnAb) is a goal in HIV vaccine development. Here, Bradley et al. show that administration of CTLA-4 blocking antibody with vaccine antigens increases HIV-1 envelope antibody responses in macaques and a bnAb precursor mouse model.

An examination of protein binding and protein-facilitated uptake relating to in vitro-in vivo extrapolation

As explained by the free drug theory, the unbound fraction of drug has long been thought to drive the efficacy of a molecule. Thus, the fraction unbound term, or f_u, appears in equations for fundamental pharmacokinetic parameters such as clearance, and is used when attempting in vitro to in vivo extrapolation (IVIVE). In recent years though, it has been noted that IVIVE does not always yield accurate predictions, and that some highly protein bound ligands have more efficient uptake than can be explained by their unbound fractions. This review explores the evolution of f_u terms included when implementing IVIVE, the concept of protein-facilitated uptake, and the mechanisms that have been proposed to account for facilitated uptake.

Immunodominance of Antibody Recognition of the HIV Envelope V2 Region in Ig-Humanized Mice

In the RV144 gp120 HIV vaccine trial, decreased transmission risk was correlated with Abs that reacted with a linear epitope at a lysine residue at position 169 (K169) in the HIV-1 envelope (Env) V2 region. The K169 V2 response was restricted to Abs bearing Vλ rearrangements that expressed aspartic acid/glutamic acid in CDR L2. The AE.A244 gp120 in AIDSVAX B/E also bound to the unmutated ancestor of a V2-glycan broadly neutralizing Ab, but this Ab type was not induced in the RV144 trial. In this study, we sought to determine whether immunodominance of the V2 linear epitope could be overcome in the absence of human Vλ rearrangements. We immunized IgH- and Igκ-humanized mice with the AE.A244 gp120 Env. In these mice, the V2 Ab response was focused on a linear epitope that did not include K169. V2 Abs were isolated that used the same human VH gene segment as an RV144 V2 Ab but paired with a mouse λ L chain. Structural characterization of one of these V2 Abs revealed how the linear V2 epitope could be engaged, despite the lack of aspartic acid/glutamic acid encoded in the mouse repertoire. Thus, despite the absence of the human Vλ locus in these humanized mice, the dominance of Vλ pairing with human VH for HIV-1 Env V2 recognition resulted in human VH pairing with mouse λ L chains instead of allowing otherwise subdominant V2-glycan broadly neutralizing Abs to develop.

Tissue memory B cell repertoire analysis after ALVAC/AIDSVAX B/E gp120 immunization of rhesus macaques

The ALVAC prime/ALVAC + AIDSVAX B/E boost RV144 vaccine trial induced an estimated 31% efficacy in a low-risk cohort where HIV‑1 exposures were likely at mucosal surfaces. An immune correlates study demonstrated that antibodies targeting the V2 region and in a secondary analysis antibody-dependent cellular cytotoxicity (ADCC), in the presence of low envelope-specific (Env-specific) IgA, correlated with decreased risk of infection. Thus, understanding the B cell repertoires induced by this vaccine in systemic and mucosal compartments are key to understanding the potential protective mechanisms of this vaccine regimen. We immunized rhesus macaques with the ALVAC/AIDSVAX B/E gp120 vaccine regimen given in RV144, and then gave a boost 6 months later, after which the animals were necropsied. We isolated systemic and intestinal vaccine Env-specific memory B cells. Whereas Env-specific B cell clonal lineages were shared between spleen, draining inguinal, anterior pelvic, posterior pelvic, and periaortic lymph nodes, members of Env‑specific B cell clonal lineages were absent in the terminal ileum. Env‑specific antibodies were detectable in rectal fluids, suggesting that IgG antibodies present at mucosal sites were likely systemically produced and transported to intestinal mucosal sites.

HIV-1 Envelope Mimicry of Host Enzyme Kynureninase Does Not Disrupt Tryptophan Metabolism

The HIV-1 envelope protein (Env) has evolved to subvert the host immune system, hindering viral control by the host. The tryptophan metabolic enzyme kynureninase (KYNU) is mimicked by a portion of the HIV Env gp41 membrane proximal region (MPER) and is cross-reactive with the HIV broadly neutralizing Ab (bnAb) 2F5. Molecular mimicry of host proteins by pathogens can lead to autoimmune disease. In this article, we demonstrate that neither the 2F5 bnAb nor HIV MPER-KYNU cross-reactive Abs elicited by immunization with an MPER peptide-liposome vaccine in 2F5 bnAb V_HDJ_H and V_LJ_L knock-in mice and rhesus macaques modified KYNU activity or disrupted tissue tryptophan metabolism. Thus, molecular mimicry by HIV-1 Env that promotes the evasion of host anti-HIV-1 Ab responses can be directed toward nonfunctional host protein epitopes that do not impair host protein function. Therefore, the 2F5 HIV Env gp41 region is a key and safe target for HIV-1 vaccine development.

Amino Acid Changes in the HIV-1 gp41 Membrane Proximal Region Control Virus Neutralization Sensitivity

Most HIV-1 vaccines elicit neutralizing antibodies that are active against highly sensitive (tier-1) viruses or rare cases of vaccine-matched neutralization-resistant (tier-2) viruses, but no vaccine has induced antibodies that can broadly neutralize heterologous tier-2 viruses. In this study, we isolated antibodies from an HIV-1-infected individual that targeted the gp41 membrane-proximal external region (MPER) that may have selected single-residue changes in viral variants in the MPER that resulted in neutralization sensitivity to antibodies targeting distal epitopes on the HIV-1 Env. Similarly, a single change in the MPER in a second virus from another infected-individual also conferred enhanced neutralization sensitivity. These gp41 single-residue changes thus transformed tier-2 viruses into tier-1 viruses that were sensitive to vaccine-elicited tier-1 neutralizing antibodies. These data demonstrate that Env amino acid changes within the MPER bnAb epitope of naturally-selected escape viruses can increase neutralization sensitivity to multiple types of neutralizing antibodies, and underscore the critical importance of the MPER for maintaining the integrity of the tier-2 HIV-1 trimer.

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Amino acid changes in the HIV gp41 MPER can regulate neutralization sensitivity of distal epitopes.

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MPER antibodies isolated early are resistant to MPER changes that enhance neutralization sensitivity.

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HIV gp41 MPER is critical for determining overall HIV envelope conformations.

The HIV-1 envelope protein (Env) is the primary target for neutralizing antibodies. Most HIV-1 vaccines elicit neutralizing antibodies that are active against highly neutralization-sensitive (tier-1) or rare vaccine-matched more neutralization-resistant (tier-2) viruses, but no vaccine has induced antibodies that can broadly neutralize heterologous tier-2 viruses. In this study, we identified changes that occurred in two HIV-1-infected individuals in the membrane proximal region of the HIV-1 Env that resulted in neutralization sensitivity to antibodies targeting distal epitopes on the HIV Env. These single-residue changes thus transformed tier-2 viruses into tier-1 viruses, highlighting the importance of MPER residues in maintaining neutralization-resistant virus.

Structural Constraints of Vaccine-Induced Tier-2 Autologous HIV Neutralizing Antibodies Targeting the Receptor-Binding Site

Antibodies that neutralize autologous transmitted/founder (TF) HIV occur in most HIV-infected individuals and can evolve to neutralization breadth. Autologous neutralizing antibodies (nAbs) against neutralization-resistant (Tier-2) viruses are rarely induced by vaccination. Whereas broadly neutralizing antibody (bnAb)-HIV-Envelope structures have been defined, the structures of autologous nAbs have not. Here, we show that immunization with TF mutant Envs gp140 oligomers induced high-titer, V5-dependent plasma neutralization for a Tier-2 autologous TF evolved mutant virus. Structural analysis of autologous nAb DH427 revealed binding to V5, demonstrating the source of narrow nAb specificity and explaining the failure to acquire breadth. Thus, oligomeric TF Envs can elicit autologous nAbs to Tier-2 HIVs, but induction of bnAbs will require targeting of precursors of B cell lineages that can mature to heterologous neutralization.

Location and nucleotide sequence of the gene for the proton-translocating subunit of wheat chloroplast ATP synthase

The proton-translocating subunit of wheat chloroplast ATP synthase is encoded by a chloroplast gene that has been accurately mapped and whose nucleotide sequence has been determined. The predicted sequence of 81 amino acids has been confirmed in part by determination of the sequence of the first 40 amino acids from the NH(2) terminus of the protein, and it shows 100% homology with the known amino acid sequence of the spinach protein but no more than 35% homology with the amino acid sequences of bacterial and mitochondrial proteins. The gene shows no deviation from the "universal" genetic code and is not split. A potential ribosome binding site is located 12 nucleotides upstream from the initiation codon, but sequences homologous to prokaryotic promotors and transcription terminators are not apparent.

The long-term use of inhaled tobramycin in patients with cystic fibrosis

Tobramycin nebuliser solution (TNS) has been investigated in several clinical trials, including a large, placebo-controlled study that demonstrated efficacy over a 24-week period. The open-label extension phase of this trial enabled observations to be conducted for an additional period of almost 18 months. Patients from both treatment arms (n=396) entered the open-label phase and received up to nine 28-day on, 28-day off cycles of TNS 300 mg by aerosol twice daily (b.i.d.). Mean lung function in patients who had received placebo during the double-blind phase improved during the first three cycles of the open-label treatment. However, lung function in these patients did not recover to the levels seen in those patients who had received TNS throughout the double-blind and open-label phases. In both groups of patients, improvement was maintained during the study. Greater improvements were seen in adolescents compared with older patients. Adverse events were generally uncommon, with a notably lower incidence of fever, anorexia, abdominal pain and vomiting than was observed in the double-blind phase among patients who received placebo, and a generally low incidence of tinnitus. We conclude that long-term TNS administration is safe and effective.

Improved detection of CFTR mutations in Southern California Hispanic CF patients

Mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene cause cystic fibrosis (CF), a common autosomal recessive disease in Caucasians. The broad mutation spectrum varies among different patient groups. Current molecular diagnoses are designed to detect 80-97% of CF chromosomes in Caucasians and Ashkenazi Jews but have a much lower detection rate in Hispanic CF patients. Grebe et al. [1994] reported a 58% detection rate in Hispanic patients. Since then, there has been no large-scale, complete mutational analysis of Hispanic CF patients. In this study, the mutations in 62 Hispanic patients from southern California were investigated. The entire coding and flanking intronic regions of the CFTR gene were analyzed by temporal temperature gradient gel electrophoresis (TTGE) followed by sequencing to identify the mutations. Eleven novel mutations were discovered in this patient group: 3876delA, 406-1G>A, 935delA, 663delT, 3271delGG, 2105-2117del13insAGAAA, 3199del6, Q179K, 2108delA, 3171delC, and 3500-2A>T. Among the mutations, seven were out-of-frame insertions and deletions that result in truncated proteins, two were splice-site mutations, one was an in-frame 6 bp deletion, and one was a missense mutation that involved the non-conservative change of glutamine-179 to lysine. All patients presented severe classical clinical course with pancreatic insufficiency and poor growth, consistent with the nature of truncation mutation. The results indicate that TTGE screening following the analysis of recurrent mutations will substantially improve the mutation detection rate for Hispanic CF patients from southern California.

Psychosocial responses of adolescent cystic fibrosis patients to lung transplantation

What psychosocial issues do adolescent cystic fibrosis (CF) patients experience after undergoing lung transplantation (Tx)? The aim of this study was to determine, using an ethnographic study design, the common themes and emotional responses in post-lung transplant adolescent CF patients of the Cardiothoracic Transplant Clinic at the Childrens Hospital Los Angeles. Nineteen CF lung transplant recipients were studied (eight males, 11 females: mean age at time of transplant, 15.7 +/- 2.7 yr). The mean time interval from Tx to interview was 25.4 months (range 1-58 months). Sixteen patients had living donor lobar lung Tx while three patients received cadaveric lungs. A series of 25 questions was used to assess the psychosocial impact of Tx, and a semi-structured interview focused on the following five domains: lifestyle, family functioning, social functioning, body image, and psychological functioning. The major themes identified by patients included: a strong desire to set and attain meaningful long-range goals, the need to control as many aspects of their lives as possible while dealing with parental over-protectiveness, and the adjustment to a new lifestyle. Common emotional responses included manageable fear/anxiety of lung rejection and uncertainty of the future, impatience with disruptions of daily routines caused by post-transplant medical management and its effect on the attainment of set goals, and frustration with parental over-protectiveness. In general, patients reported a positive outlook on life, with greater emphasis on sought-after goals as well as inter-personal relationships. This study demonstrates that adolescent CF transplant recipients develop long-term goals and plans for independence. By identifying and anticipating the emotional needs of this population, health care providers can assist patients in improving the quality of their lives from a physiological, as well as a psychological, viewpoint.

A novel mutation detected by temporal temperature gradient gel electrophoresis led to the confirmative prenatal diagnosis of a Hispanic CF family

Mutational analysis of 30 recurrent known mutations detects only about 58% of Hispanic cystic fibrosis (CF) chromosomes. The low mutation detection rate has greatly hindered prenatal diagnosis and carrier testing of Hispanic families who have multiple affected children with unidentified cystic fibrosis transmembrane conductance regulator (CFTR) mutations. We recently employed a temporal temperature gradient gel electrophoresis (TTGE) method to effectively scan unknown mutations in the entire CFTR gene. A novel mutation, 2105-2117 del13insAGAAA was identified in a Hispanic family heterozygous for delta F508. The discovery of the devastating mutation facilitated the prenatal diagnosis for this family who already had two severely affected children. The fetus was found to be a compound heterozygote of delta F508/2105-2117 del13insAGAAA. This case emphasizes the importance of whole gene mutational analysis in patients with a clinical diagnosis of CF, but without the identifiable DNA mutations by routine mutation analysis. Finding of CF mutations in the patient would allow proper genetic counselling and prenatal and carrier detection of at-risk family members.

Amphidiploid Brassica juncea contains conserved progenitor genomes

To perform a detailed study of genome evolution in the natural Brassica amphidiploid B. juncea, we have constructed two linkage maps based on RFLP (restriction fragment length polymorphism) markers; one generated from a cross between a resynthesized B. juncea (a chromosome doubled interspecific B. rapa x B. nigra hybrid) and a natural B. juncea cultivar, the other from a cross between two B. juncea cultivars. By using a common cultivar in both crosses, the two maps could be unambiguously integrated. All loci exhibited disomic inheritance of parental alleles in the natural x resynthesized cross, showing that B. rapa chromosomes paired exclusively with their A-genome homologues in B. juncea and that B. nigra chromosomes likewise paired with their B-genome homologues. The maps derived from the two crosses were also perfectly collinear. Furthermore, these maps were collinear with maps of the diploid progenitor species (B. nigra and B. rapa) produced using the same set of RFLP probes. These data indicate that the genome of B. juncea has remained essentially unchanged since polyploid formation. Our observations appear to refute the suggestion that the formation of polyploid genomes is accompanied by rapid change in genome structure.

A novel CFTR frame-shift mutation, 935delA, in two Hispanic cystic fibrosis patients

The currently available mutation analysis panel detects about 50-60% of CFTR mutations in Hispanic patients. In order to search for Hispanic CF mutations, we developed a temporal temperature gradient gel electrophoresis (TTGE) method to screen for unknown mutations. Using TTGE to study the CFTR gene has lead to the discovery of many novel mutations in Hispanic patients. A novel frame-shift mutation, 935delA, was found in two unrelated patients. One was heterozygous for two novel frame-shift mutations, 663delT and 935delA, and the other was heterozygous for DeltaF508 and 935delA. Both patients showed severe phenotype with meconium ileus, pancreatic insufficiency, and early pulmonary microbial colonization with Pseudomonas aeruginosa. Patient 1 died at 4 years of age. Patient 2 had an upper lobectomy. The 935delA mutation produces a truncated polypeptide with only 21% of the full-length protein. The severe course of clinical manifestation is consistent with two oppressively truncated mutant polypeptides encoded by both mutant alleles in patient 1 and the compound heterozygosity truncation and DeltaF508 mutations in patient 2.

Amphidiploid Brassica juncea contains conserved progenitor genomes

To perform a detailed study of genome evolution in the natural Brassica amphidiploid B. juncea, we have constructed two linkage maps based on RFLP (restriction fragment length polymorphism) markers; one generated from a cross between a resynthesized B. juncea (a chromosome doubled interspecific B. rapa × B. nigra hybrid) and a natural B. juncea cultivar, the other from a cross between two B. juncea cultivars. By using a common cultivar in both crosses, the two maps could be unambiguously integrated. All loci exhibited disomic inheritance of parental alleles in the natural × resynthesized cross, showing that B. rapa chromosomes paired exclusively with their A-genome homologues in B. juncea and that B. nigra chromosomes likewise paired with their B-genome homologues. The maps derived from the two crosses were also perfectly collinear. Furthermore, these maps were collinear with maps of the diploid progenitor species (B. nigra and B. rapa) produced using the same set of RFLP probes. These data indicate that the genome of B. juncea has remained essentially unchanged since polyploid formation. Our observations appear to refute the suggestion that the formation of polyploid genomes is accompanied by rapid change in genome structure.Key words: RFLP, comparative mapping, Brassica rapa, Brassica nigra, genome evolution.

Superantigens and cystic fibrosis: resistance of presenting cells to dexamethasone

Staphylococcus aureus, a common pulmonary pathogen in cystic fibrosis (CF), produces exotoxins that are extremely potent superantigens. A number of animal studies have shown that superantigens cause pulmonary inflammation, but the possible role of superantigens in CF has not been investigated. The present study assessed possible differences between control and CF B cells in presenting superantigens to T cells. Immortalized B-cell lines were used as superantigen-presenting cells to avoid environmental influences (e.g., infection or antibiotics) common to freshly isolated cells. The results show that CF B-cell lines presented a staphylococcal superantigen to the immortalized T-cell line (Jurkat) as effectively as did control B-cell lines as measured by interleukin-2 production. However, in contrast to the case for control B-cell lines, dexamethasone did not inhibit CF B-cell lines from presenting superantigen. The resistance of superantigen-presenting CF B cells to corticosteroids suggests that the pulmonary response to superantigens may be poorly regulated in CF, leading to an exaggerated inflammatory response to S. aureus.

Intermittent administration of inhaled tobramycin in patients with cystic fibrosis. Cystic Fibrosis Inhaled Tobramycin Study Group

BACKGROUND AND METHODS

We conducted two multicenter, double-blind, placebo-controlled trials of intermittent administration of inhaled tobramycin in patients with cystic fibrosis and Pseudomonas aeruginosa infection. A total of 520 patients (mean age, 21 years) were randomly assigned to receive either 300 mg of inhaled tobramycin or placebo twice daily for four weeks, followed by four weeks with no study drug. Patients received treatment or placebo in three on-off cycles for a total of 24 weeks. The end points included pulmonary function, the density of P. aeruginosa in sputum, and hospitalization.

RESULTS

The patients treated with inhaled tobramycin had an average increase in forced expiratory volume in one second (FEV1) of 10 percent at week 20 as compared with week 0, whereas the patients receiving placebo had a 2 percent decline in FEV1 (P<0.001). In the tobramycin group, the density of P. aeruginosa decreased by an average of 0.8 log10 colony-forming units (CFU) per gram of expectorated sputum from week 0 to week 20, as compared with an increase of 0.3 log10 CFU per gram in the placebo group (P<0.001). The patients in the tobramycin group were 26 percent (95 percent confidence interval, 2 to 43 percent) less likely to be hospitalized than those in the placebo group. Inhaled tobramycin was not associated with detectable ototoxic or nephrotoxic effects or with accumulation of the drug in serum. The proportion of patients with P. aeruginosa isolates for which the minimal inhibitory concentration of tobramycin was 8 microg per milliliter or higher increased from 25 percent at week 0 to 32 percent at week 24 in the tobramycin group, as compared with a decrease from 20 percent at week 0 to 17 percent at week 24 in the placebo group.

CONCLUSIONS

In a 24-week study of patients with cystic fibrosis, intermittent administration of inhaled tobramycin was well tolerated and improved pulmonary function, decreased the density of P. aeruginosa in sputum, and decreased the risk of hospitalization.

3849 + 10 kb C --> T splicing mutation in Hispanic CF patients

Seven patients compound heterozygous for the 3849 + 10kb C --> T mutation in the CFTR gene were found among the 152 patients attending the CHLA CF Clinic. The frequency of this mutation accounts for 2.3 and 3.9% of thetotal and Hispanic CF alleles of CHLA patients. These are significantly higher than the 0.6% of the general CF population. The average age of diagnosis of this group of Hispanics is 3.1 years, which is much younger than that reported for CF patients of other ethnicities with the same mutation. Both pancreatic sufficient and pancreatic insufficient patients were observed. It is concluded that the 3849 + 10kb C --> T mutation is associated with a variable but potentially mild type of CF.

Genetic analysis of Hispanic individuals with cystic fibrosis

We have performed molecular genetic analyses of Hispanic individuals with cystic fibrosis (CF) in the southwestern United States. Of 129 CF chromosomes analyzed, only 46% (59/129) carry delta F508. The G542X mutation was found on 5% (7/129) of CF chromosomes. The 3849 + 10kbC-->T mutation, detected primarily in Ashkenazi Jews, was present on 2% (3/129). R1162X and R334W, mutations identified in Spain and Italy, each occurred on 1.6% (2/129) of CF chromosomes. W1282X and R553X were each detected once. G551D and N1303K were not found. Overall, screening for 22 or more mutations resulted in detection of only 58% of CF transmembrane conductance regulator gene mutations among Hispanic individuals. Analysis of KM19/XV2c haplotypes revealed an unusual distribution. Although the majority of delta F508 mutations are on chromosomes of B haplotypes, the other CF mutations are on A and C haplotypes at higher-than-expected frequencies. These genetic analyses demonstrate significant differences between Hispanic individuals with CF and those of the general North American population. Assessment of carrier/affected risk in Hispanic CF individuals cannot, therefore, be based on the mutation frequencies found through studies of the general population but must be adjusted to better reflect the genetic makeup of this ethnic group. Further studies are necessary to identify the causative mutation(s) in this population and to better delineate genotype/phenotype correlations. These will enable counselors to provide more accurate genetic counseling.

Conditioned medium from irradiated bovine pulmonary artery endothelial cells stimulates increased protein synthesis by irradiated bovine lung fibroblasts in vitro

Pulmonary fibrosis, a potentially fatal consequence of radiation exposure, occurs by unknown mechanisms. The hypothesis that endothelial cells, injured by radiation, could alter the biochemical function of lung fibroblasts, was tested by exposing cultures of bovine pulmonary artery endothelial cells to 0 or 5 Gy radiation and then incubating them in fresh medium for 48 h. This endothelial cell conditioned medium (ECCM) was then applied to irradiated or nonirradiated cultures of bovine lung fibroblasts. Forty-eight hours later the fibroblasts were analyzed for their ability to synthesize DNA and protein. The ECCM from injured cells stimulated fibroblast protein synthesis twofold to threefold in irradiated fibroblasts without increasing DNA synthesis. It also stimulated a significant but less marked increase in protein synthesis in nonirradiated fibroblasts. Two-dimensional gel electrophoresis revealed this increased synthesis to be expressed in less than 10% of the 1100 separable fibroblast proteins. This study shows that endothelial cells injured by radiation produce factors that stimulate injured fibroblasts to markedly increase their synthesis of certain intracellular proteins, while not stimulating fibroblast replication.

Autopolyploidy in Dactylis glomerata L.: further evidence from studies of chloroplast DNA variation

Chloroplast DNA variation has been used to examine some of the maternal lineages involved in the evolution of the intraspecific polyploid complex, Dactylis glomerata L. Diploid (2x) and tetraploid (4x) individuals were collected from natural populations of the subspecies glomerata (4x), marina (4x) and lusitanica (2x), as well as from sympatric 2x/4x populations of the Galician type. Digestion of their ctDNA with 11 restriction endonucleases revealed enough variation to characterise three ctDNA variants, designated MBMK, MBmK and mBMK. The distribution of these ctDNA variants reflects different stages in their spread among the populations. The MBMK ctDNA variant predominated at both ploidy levels in subspecies glomerata, lusitanica and marina, and in recent tetraploid Galician/glomerata hybrids. The MBmK variant was detected in a single tetraploid individual and probably results from a relatively recent mutation. Fixation of the mBMK minority variant in the diploid and tetraploid Galician populations adds to the evidence concerning the possible origin of the Galician tetraploids. It means that the Galician diploids were maternal ancestors of the tetraploids. This result complements evidence from earlier studies based on morphology or biochemical markers, and reduces the likelihood that the tetraploids arose by hybridisation between an ancient Galician diploid and an alien tetraploid. It is, however, consistent with a true autopolyploid origin of the tetraploids.

A simplified method for autoregulation of blood flow in the extracorporeal membrane oxygenation circuit

The ability of autoregulate blood flow in the extracorporeal membrane oxygenation (ECMO) circuit is critical to prevent cavitation and air embolism. Conventional circuits have used a spring-loaded mechanical switching device that interrupts the flow of power to the roller head when falling venous return collapses the venous bladder. This device has been less than desirable due to being poorly adjustable, subject to sporadic flow in periods of hypovolemia, and not commercially available. An improved alternative is reported using a commercially available pressure monitor and computerized switching device, which, when attached to the venous reservoir or bladder, has the ability to autoregulate blood flow in the ECMO circuit by smoothly regulating the roller head velocity. Experience with this system in the laboratory employing a swine model, and in 35 infants, is reported without device-related complications.

In wheat ctDNA, segments of ribosomal protein genes are dispersed repeats, probably conserved by nonreciprocal recombination

Some dispersed repeated sequences and their flanking regions from wheat and maize ctDNAs have been characterized. Two sets of wheat ctDNA repeats were found to be the chloroplast ribosomal protein genes rpl2 and rpl23, plus nonfunctional segments of them, designated rpl2' and rpl23'. Pairwise comparisons were made between the wheat rpl23 and rpl23', and the maize rpl23' sequences. The precise patterns of homology suggest that the divergence of the wheat and maize nonfunctional (rpl23') sequences is being retarded by nonreciprocal recombination, biased by selection for individuals with functional (rpl23) sequences). The implied involvement of these sequences in mechanisms of homologous recombination, and therefore in the creation and spread of new ctDNA variants, is discussed.

Common features of three inversions in wheat chloroplast DNA

We have determined the DNA sequences of regions involved in two of the three inversions known to have occurred during the evolution of wheat chloroplast DNA. This establishes the extent of the second largest of the three inversions. Examination of these sequences suggests that although short repeated sequences are present, the endpoints of the second and third inversions are not associated with repeated sequences as long as those associated with the first inversion. However the endpoints of all three inversions are all adjacent to at least one tRNA gene, and there is evidence that three of the tRNA genes have been subjected to partial duplication, possibly at the time of inversion. This suggests that tRNA genes might be involved with rearrangements of chloroplast DNA, as has also been postulated for mitochondrial DNA.

Growth failure in bronchopulmonary dysplasia: elevated metabolic rates and pulmonary mechanics

Growth failure is a major problem in infants with bronchopulmonary dysplasia (BPD), but the cause is unknown. We studied 13 infants with BPD but without other medical problems that could contribute to growth failure at 6 months' corrected age. We measured resting oxygen consumption (Vo2), Pao2, airway resistance, specific airway conductance, and dynamic pulmonary compliance (Cdyn) by body plethysmography and growth. Growth failure was defined as height and weight less than the tenth percentile of the Babson growth curves. Vo2 in infants with growth failure and BPD was markedly elevated compared with that in control infants and infants with BPD and normal growth. Vo2 showed an inverse correlation with body weight in infants with BPD but not in control infants. Although Vo2 was inversely related to Cdyn, the total work of breathing only partially explained the increased metabolic demands of the growth failure group. We speculate that growth failure in infants with BPD is partially the result of increased metabolic demands from increased work of breathing but that other mechanisms may act to elevate the metabolic expenditure of these infants.

The pattern of amyloplast DNA accumulation during wheat endosperm development

The accumulation of amyloplast DNA during endosperm development was studied in two cultivars of spring wheat, Triticum aestivum L. 'Chinese Spring' (CS) and 'Spica', small and relatively larger-grained cultivars, respectively. Endosperms were isolated between 9 and 45 days post anthesis (dpa) and the amyloplast DNA content of endosperm nucleic-acid extracts was measured by quantitative hybridisation with a homologous chloroplast-DNA probe. The endosperm cells of CS and Spica accumulated amyloplast DNA during development in a similar way. In both cultivars there was a large increase in the amount of plastid DNA (ptDNA) per endosperm between 9 and about 15 dpa, after which there was no further increase. Because nuclear DNA continued to accumulate until 24 dpa, the percentage contribution of amyloplast DNA to total DNA fluctuated in both cultivars during development, reaching maxima at 12 dpa of about 1.00% and 0.85%, and dropping to apparently constant levels of 0.60% and 0.52% in CS and Spica, respectively, by 24 dpa. In both cultivars, the average number of ptDNA copies per amyloplast was calculated to increase from about 10 copies at 9 dpa to about 50 copies in the mature amyloplasts at 31 dpa. However, the heavier endosperms of Spica contain more cells than those of CS and the varieties therefore differed in the amount of ptDNA that accumulated per endosperm: Spica endosperms accumulated 110 ng of ptDNA by 15 dpa, compared with only 85 ng in CS. The apparent accumulation of ptDNA copies in wheat amyloplasts during endosperm development contrasts with the decline in chloroplast-DNA copies in wheat chloroplasts during leaf development.

Persistent morbidity and mortality of protein calorie malnutrition in young infants with CF

Young infants with cystic fibrosis (CF) are at risk for developing symptomatic protein-calorie malnutrition (PCM) characterized by hypoalbuminemia, edema, and anemia. We reviewed the hospital charts of all infants less than 12 months of age referred to our CF clinic between 1979 and 1982 and found nine patients with PCM (13%). Their courses were characterized by age less than 7 months (nine patients), frequent use of soy formula (eight patients), presence of gastrointestinal or respiratory symptoms before being diagnosed with CF (eight patients), severe respiratory distress often requiring mechanical ventilation (five patients), significant infections (three patients), and high mortality (five patients). We further noted that eight infants were not on pancreatic enzyme therapy at the onset of PCM. This clinical study extends the findings of earlier reports of PCM in patients with CF by showing that this syndrome persists as a major source of morbidity and mortality in young infants with CF, especially those fed soy formula and not receiving pancreatic enzyme supplements. Because PCM can develop rapidly and may be the presenting sign of CF in young infants, we speculate that early diagnosis of CF with institution of pancreatic supplements may decrease incidence and severity of PCM in young patients with CF.

Copy numbers of chloroplast and nuclear genomes are proportional in mature mesophyll cells of Triticum and Aegilops species

The possibility of estimating the proportion of chloroplast DNA (ctDNA) and nuclear DNA (nDNA) in nucleic-acid extracts by selective digestion with the methylation-sensitive restriction enzyme PstI, was tested using leaf extracts from Spinacia oleracea and Triticum aestivum. Values of ctDNA as percentage nDNA were estimated to be 14.58%±0.56 (SE) in S. oleracea leaves and 4.97%±0.36 (SE) in T. aestivum leaves. These estimates agree well with those already reported for the same type of leaf material. Selective digestion and quantitative dot-blot hybridisation were used to determine ctDNA as percentage nDNA in expanded leaf tissue from species of Triticum and Aegilops representing three levels of nuclear ploidy and six types of cytoplasm. No significant differences in leaf ctDNA content were detected: in the diploids the leaf ctDNA percentage ranged between 3.8% and 5.1%, and in the polyploids between 3.5% and 4.9%. Consequently, nuclear ploidy and nDNA amount were proportional to ctDNA amount (r(19)=0.935, P>0.01) and hence to ctDNA copy number in the mature mesophyll cells of these species. There was a slight increase in ctDNA copy numbers per chloroplast at higher ploidy levels. The balance between numbers of nuclear and chloroplast genomes is discussed in relation to polyploidisation and to the nuclear control of ctDNA replication.

Chloroplast transfer RNAs and tRNA genes of wheat

Fractionation (by two-dimensional polyacrylamide gel electrophoresis) of total tRNA from wheat chloroplasts yields about 33 RNA spots. Of these, 30 have been identified by aminoacylation as containing tRNAs specific for 17 amino acids.Hybridization of labeled individual tRNAs to cloned chloroplast DNA fragments has revealed the location of at least nine pairs of tRNA genes in the segments of the inverted repeat, at least twelve tRNA genes in the large single copy region and one tRNA gene in the small single copy region.A comparison of this wheat chloroplast tRNA gene map to that of maize and of other higher plants suggests that gene rearrangements have occurred during evolution, even within cereal chloroplast DNA. These rearrangements have taken place within the inverted repeat, within the large single copy region and between the inverted repeat and the large single copy region.

HEPES may stimulate cultured endothelial cells to make growth-retarding oxygen metabolites

Zwitterion buffers are often used to modulate the pH of cell culture medium but their effect on cultured cells is controversial. We found that addition of 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES) caused superoxide dismutase (SOD) inhibitable increases in nitroblue tetrazolium dye reduction and SOD and catalase inhibitable decreases in the growth of cultured bovine pulmonary artery endothelial cells. The findings suggest that HEPES stimulates endothelial cells to make toxic oxygen metabolites that contribute to decreased cell growth.

Pulmonary vascular response to oxygen in infants with severe bronchopulmonary dysplasia

The cardiac catheterization data of six infants with bronchopulmonary dysplasia (BPD) were reviewed to examine the responsiveness of their pulmonary vascular beds to changes in oxygen tension. The infants were studied because of slow recovery from their oxygen requirements and clinical evidence of persistent pulmonary hypertension. All were receiving home oxygen therapy and had abnormal chest radiographs and right ventricular hypertrophy by ECG at the time of catheterization (mean age, 25 months). All infants had mean pulmonary artery pressure greater than 25 mm Hg in room air, with a mean of 48 mm Hg. All decreased mean pulmonary artery pressure by at least 10 mm Hg when placed in high levels of inspired oxygen (FiO2 greater than 80), with a mean pulmonary artery pressure of 25 mm Hg. This represented a significant decrease in mean pulmonary artery pressure from room air pressures (P less than .005). Mean pulmonary artery pressure was also measured in three infants who were breathing supplemental oxygen by nasal cannula at flow rates similar to levels used for outpatient therapy. Most of the reduction in mean pulmonary artery pressure that occurred at high FiO2 occurred at these lower flow rates of supplemental oxygen. It is concluded that infants with bronchopulmonary dysplasia who have pulmonary hypertension generally have reactive pulmonary vascular beds, responsive to supplemental oxygen. Continuous oxygen therapy by nasal cannula may be useful in the treatment of pulmonary hypertension associated with bronchopulmonary dysplasia.

Maternal smoking increases xenobiotic metabolism in placenta but not umbilical vein endothelium

It is unclear whether placental xenobiotic metabolism can protect the human conceptus. In particular, the role of placental metabolism of toxic components of cigarette smoke such as polycyclic aromatic hydrocarbons (PAHs) is poorly understood. We hypothesized that increased aryl hydrocarbon hydroxylase (AHH) activity observed in placentas from smokers might help clear PAHs from maternal circulation and thereby prevent transplacental induction of AHH by PAHs. Our studies of AHH activity in human placentas and umbilical vein endothelium support this premise. While AHH activity was significantly increased in placentas from smokers compared with activity in placentas from nonsmokers, AHH activity in umbilical vein endothelium from these same pregnancies was unaffected by maternal smoking and remained low. In order to confirm that AHH present in endothelium was inducible, we also demonstrated dose-dependent increases in AHH activity in primary cultures of human umbilical vein endothelial cells exposed to PAHs. These findings may indicate first pass protection of the fetus by placental xenobiotic metabolism, or that endogenous factors suppress AHH induction in the fetus but not placenta.

Unsuspected cardiopulmonary abnormalities complicating bronchopulmonary dysplasia

Bronchopulmonary dysplasia is a serious chronic lung disease of infancy but despite numerous problems such as poor growth, recurrent lower respiratory tract infections, and cor pulmonale, steady improvement and recovery may generally be expected. We report four infants with bronchopulmonary dysplasia in whom the cardiopulmonary course did not show the usual steady improvement. Each infant was found to have an unsuspected cardiopulmonary lesion in addition to lung disease: two had congenital heart disease and two upper airway obstruction. Three improved after surgical intervention but one patient died immediately after this. Persistent right ventricular hypertrophy in patients with bronchopulmonary dysplasia maintained on supplemental oxygen, and a particularly slow rate of recovery from the need for supplemental oxygen are markers that should lead to evaluation for coexisting cardiopulmonary abnormalities.

Cyclical abnormalities in the bactericidal function, superoxide production, and lysozyme activity of neutrophils obtained from a healthy woman during menstruation: reversal by pretreatment with aspirin

Neutrophils obtained from most of 13 healthy young women during menstruation and those obtained from the same women on nonmenstrual days killed comparable numbers of Staphylococcus aureus strain 502A, produced comparable amounts of superoxide anion, and had comparable lysozyme levels. In contrast, neutrophils obtained from a few women during menstruation exhibited decreased function. In particular, neutrophils from one healthy woman developed transient menstrual period-related abnormalities in bactericidal function, superoxide anion production, and lysozyme activity and release; these abnormalities occurred during each of three menstrual periods tested but not during three menstrual periods following the ingestion of aspirin for 14 days. The results suggest that menstrual period-related dysfunction of neutrophils may occur in some healthy women, sometimes rendering them more susceptible to menstrual period-related infections.

Hyperoxia stimulates alveolar macrophages to produce and release a factor which increases neutrophil adherence

Hyperoxia stimulates alveolar macrophages (AM) to make and release a factor which increases neutrophil adherence to nylon fiber. Production of the neutrophil adherence-stimulating factory by AM exposed to hyperoxia is maximal after AM have been exposed to hyperoxia for 72 h and requires protein synthesis by intact AM. The adherence factor is heat-labile and by column chromatography elutes in a molecular-weight range of approximately 8000-18,000 daltons. The lungs of animals exposed to hyperoxia and contribute to neutrophil-mediated lung injury from hyperoxia.

Hyperoxia damages cultured endothelial cells causing increased neutrophil adherence

Exposure of cultured bovine pulmonary artery endothelial cells to hyperoxia (95% O2) caused cellular injury manifested by decreased growth rates and release of cytoplasmic lactic dehydrogenase (LDH). In addition, a greater number of polymorphonuclear leukocytes (PMN) adhered to endothelial cells that had been exposed to hyperoxia for 24 or 48 h than to control endothelial cells that had been exposed to normoxia (15% O2). Direct endothelial cell injury from hyperoxia may contribute to vascular damage and the increased PMN accumulation seen in lungs of animals exposed to hyperoxia.

Chloroplast DNA variation between species of Triticum and Aegilops. Location of the variation on the chloroplast genome and its relevance to the inheritance and classification of the cytoplasm

Restriction endonuclease analysis revealed interspecific and intraspecific variation between the chloroplast DNAs and therefore between the cytoplasms of 14 selected species of Triticum and Aegilops. Eleven distinct chloroplast DNA types were detected, the differences between them residing in the varied combination of a relatively few DNA alterations.The variation was simple enough for chloroplast DNA analysis to be used as a basis for the identification and classification of the Triticum and Aegilops cytoplasms. There was good agreement with the classification based on analysis of the phenotypic effects of the cytoplasm when combined with the T. aestivum nucleus in nuclear-cytoplasmic hybrids (Tsunewaki et al. 1976). There was however no correlation between specific chloroplast DNA alterations and any of the phenotypic effects known to be associated with specific cytoplasms.Although the diploid species examined included all those which have been suggested as possible donors of the cytoplasm and the B genome to T. aestivum, none of the chosen accessions belonged to the same cytoplasmic class as T. aestivum itself, except that of the tetraploid T. dicoccoides. Therefore, none of the diploid accessions analysed was the B genome donor. The analyses did however support several other suggestions which have been made concerning wheat ancestry. Scoring the different chloroplast DNA types according to the rarity of their banding patterns indicated that four of the eleven cytoplasms are of relatively recent origin.The DNA alterations most easily detectable by the limited comparison of the eleven Triticum/Aegilops chloroplast DNA types using only 4 endonucleases were insertions and deletions. These ranged between approximately 50 bp and 1,200 bp in size and most of them were clustered in 2 segments of the large single-copy region of the genome. Only two examples of the loss of restriction endonuclease sites through possible point mutations were observed. No variation was detected in the inverted repeat regions. Several of the deletions and insertions map close to known chloroplast protein genes, and there is also an indication that the more variable regions of the chloroplast genome may contain sequences which have allowed DNA recombination and rearrangement to occur.

Angiotensin converting enzyme concentrations in the lung lavage of normal rabbits and rabbits treated with nitrogen mustard exposed to hyperoxia

Increased concentrations of angiotensin converting enzyme (ACE) were found in lung lavages from rabbits exposed to hyperoxia for 72 h and the concentrations of ACE were correlated with ratios of extravascular lung water to body weight (r = 0.69, p less than 0.05) and albumin concentrations in lung lavages (r = 0.89, p less than 0.01). In parallel studies, rabbits treated with nitrogen mustard in which granulocytopenia was maintained throughout the 72-h hyperoxic exposure period had less evidence of edematous lung injury and lower concentrations of ACE in their lung lavages than similarly treated rabbits in which granulocytopenia was not maintained. The results suggested that granulocytes contribute to acute edematous lung injury from hyperoxia and that ACE concentrations in lung lavages reflect this process.

The pharmacokinetics and efficacy of an aminoglycoside administered into the cerebral ventricles in neonates: implications for further evaluation of this route of therapy in meningitis

The optimal dose, frequency, and duration of intraventricular therapy for gram-negative meningitis (GNM) have never been determined. A prospective evaluation of the pharmacokinetics of intraventricular amikacin was undertaken in neonates with GNM. After the initial intraventricular instillation of 5 mg of amikacin via a Rickham reservoir, a 10-fold variation in the cerebrospinal fluid (CSF) concentration and a fivefold variation in half-life of the drug were noted. These variations were related to differences in the CSF volume secondary to hydrocephalus, myelomeningocele, and/or brain abscess. Successful therapy required maintaining the concentration of amikacin in CSF well above the minimal inhibitory concentration for the infecting organism at all times. A retrospective review of GNM demonstrated that the mortality was lower after intraventricular than after systemic therapy. These data suggest that if careful attention is given to the pharmacokinetics of intraventricular therapy, this route may be a valuable adjunct to therapy for GNM in neonates.

4.5S ribonucleic acid, a novel ribosome component in the chloroplasts of flowering plants

A species of low-molecular-weight ribosomal RNA, referred to as '4.5S rRNA', was found in addition to 5S rRNA in the large subunit of chloroplast ribosomes of a wide range of flowering plants. It was shown by sequence analysis that several variants of this RNA may occur in a plant. Furthermore, although in most flowering plants the predominant variant contains about 100 nucleotides, in the broad bean it has less than 80. It seems, therefore, to be much more diverse in size and sequence than the other ribosomal RNA species. Like 5S rRNA , it does not contain modified nucleotides and it is also unusual in having an unphosphorylated 5'-end. It is apparently neither a homologue of cytosol 5.8S rRNA nor a fragment of 23S rRNA.

Nucleotide sequences of chloroplast 5S ribosomal ribonucleic acid in flowering plants

Evidence for the sequence of duckweed (Lemna minor) chloroplast 5S rRNA was derived from the analysis of partial and complete enzymic digests of the 32P-labelled molecule. The possible sequence of the chloroplast 5S rRNA from three other flowering plants was deduced by complete digestion with T1 ribonuclease and comparison of the sequences of the oligonucleotide products with homologous sequences in the duckweed 5S rRNA. This analysis indicates that the chloroplast 5S rNA species differ appreciably from their cytosol counterparts but bear a strong resemblance to one another and to the 5S rRNA species of prokaryotes. Structural features apparently common to all 5S rRNA molecules are also discussed.

On-line storage and retrieval of chemical information. I. Structure entry

An interactive program has been developed for entering, verifying, and storing chemical structures encoded in the Wiswesser Line Notation. The program calculates a molecular formula from the WLN for checking and then generates a bit string fragment code and connection table of the atoms in the structure. The encoding and entry of the WLN using a CRT has significantly improved the speed of the total compound registration process.