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Biomedical subjects

F Gigliotti

Publications and source records attributed to F Gigliotti.

At least 19 recordsLinked to original sources
PubMed1999

Chest wall kinematics and respiratory muscle action in walking healthy humans.

We studied chest wall kinematics and respiratory muscle action in five untrained healthy men walking on a motor-driven treadmill at 2 and 4 miles/h with constant grade (0%). The chest wall volume (Vcw), assessed by using the ELITE system, was modeled as the sum of the volumes of the lung-apposed rib cage (Vrc,p), diaphragm-apposed rib cage (Vrc,a), and abdomen (Vab). Esophageal and gastric pressures were measured simultaneously. Velocity of shortening (V(di)) and power [Wdi = diaphragm pressure (Pdi) x V(di)] of the diaphragm were also calculated. During walking, the progressive increase in end-inspiratory Vcw (P < 0.05) resulted from an increase in end-inspiratory Vrc,p and Vrc,a (P < 0.01). The progressive decrease (P < 0.05) in end-expiratory Vcw was entirely due to the decrease in end-expiratory Vab (P < 0.01). The increase in Vrc,a was proportionally slightly greater than the increase in Vrc,p, consistent with minimal rib cage distortion (2.5 +/- 0.2% at 4 miles/h). The Vcw end-inspiratory increase and end-expiratory decrease were accounted for by inspiratory rib cage (RCM,i) and abdominal (ABM) muscle action, respectively. The pressure developed by RCM,i and ABM and Pdi progressively increased (P < 0.05) from rest to the highest workload. The increase in V(di), more than the increase in the change in Pdi, accounted for the increase in Wdi. In conclusion, we found that, in walking healthy humans, the increase in ventilatory demand was met by the recruitment of the inspiratory and expiratory reserve volume. ABM action accounted for the expiratory reserve volume recruitment. We have also shown that the diaphragm acts mainly as a flow generator. The rib cage distortion, although measurable, is minimized by the coordinated action of respiratory muscles.

Abdominal Muscles↗
PubMed1999

Chest wall hyperinflation during acute bronchoconstriction in asthma.

The mechanics of the chest wall was studied in seven asthmatic patients before and during histamine-induced bronchoconstriction (B). The volume of the chest wall (VCW) was calculated by three-dimensional tracking of 89 chest wall markers. Pleural (Ppl) and gastric (Pga) pressures were simultaneously recorded. VCW was modeled as the sum of the volumes of the pulmonary-apposed rib cage (VRC,p), diaphragm-apposed rib cage (VRC,a), and abdomen (VAB). During B, hyperinflation was due to the increase in end-expiratory volume of the rib cage (0.63 +/- 0.09 L, p < 0.01), whereas change in VAB was inconsistent (0.09 +/- 0.07 L, NS) because of phasic recruitment of abdominal muscles during expiration. Changes in end-expiratory VRC,p and VRC,a were along the rib cage relaxation configuration, indicating that both compartments shared proportionally the hyperinflation. VRC,p-Ppl plot during B was displaced leftward of the relaxation curve, suggesting persistent activity of rib cage inspiratory muscles throughout expiration. Changes in end-expiratory VCW during B did not relate to changes in FEV(1) or time and volume components of the breathing cycle. We concluded that during B in asthmatic patients: (1) rib cage accounts largely for the volume of hyperinflation, whereas abdominal muscle recruitment during expiration limits the increase in VAB; (2) hyperinflation is influenced by sustained postinspiratory activity of the inspiratory muscles; (3) this pattern of respiratory muscle recruitment seems to minimize volume distortion of the rib cage at end-expiration and to preserve diaphragm length despite hyperinflation.

Abdominal Muscles↗
PubMed1999

Immune-mediated inflammation directly impairs pulmonary function, contributing to the pathogenesis of Pneumocystis carinii pneumonia.

The clinical severity of Pneumocystis carinii pneumonia (PCP) correlates closely with the appearance of pulmonary markers of inflammation. Therefore, a model system was developed whereby physiological studies could be performed on live mice to determine the extent to which pulmonary inflammation contributes to respiratory impairment during PCP. P. carinii-infected severe combined immunodeficient mice displayed little evidence of pulmonary inflammation and exhibited normal oxygenation and dynamic lung compliance. When comparably infected littermates were immunologically reconstituted, however, an intense immune-mediated inflammatory response was observed that resulted in significant decreases in both lung compliance and oxygenation. As the pneumonia resolved pulmonary function returned toward normal. To begin to define the cell populations contributing to inflammation-associated respiratory impairment during PCP, similar studies were performed in CD4(+) T cell-depleted mice. Mice depleted of both CD4(+) and CD8(+) cells developed infection, but they demonstrated neither abnormal lung compliance nor increased respiratory rate and displayed no markers of lung injury. In contrast, mice depleted of only CD4(+) T cells exhibited severe pulmonary inflammation and injury, decreased oxygenation and lung compliance, and increased respirations. Respiratory compromise was associated with the presence of activated CD8(+) cells and neutrophils in broncho-alveolar lavage fluid. These observations provide direct experimental evidence that the host's response to P. carinii directly impairs pulmonary function and contributes to the pathogenesis of PCP. Furthermore, CD8(+) T cells likely contribute to the respiratory compromise observed during PCP.

Animals↗
PubMed1998

Molecular characterization of mouse Pneumocystis carinii surface glycoprotein A.

Since the mouse offers an easily manipulated experimental animal model for the study of the immunopathogenesis of pneumonia caused by the opportunist Pneumocystis carinii, we cloned and characterized cDNAs encoding an abundant, immunogenic surface antigen termed glycoprotein A (gpA) from mouse P. carinii. A cDNA library was constructed in bacteriophage lambda gt11 from P. carinii-infected mouse lung poly(A+) RNA. Using a nucleic acid probe derived from a conserved region of the mouse P. carinii gpA structural gene, cDNAs encoding gpA were identified. A composite full-length gpA coding sequence was assembled from two overlapping cDNA clones. A DNA element homologous to the rat P. carinii upstream conserved sequence (UCS) was identified at the 5' end of several of the mouse P. carinii gpA cDNA clones, just upstream of the sequences encoding gpA structural gene isoforms. Using primer extension analysis, two neighboring putative transcriptional start sites were located on UCS-gpA mRNAs approximately 25 and 30 nt, respectively, upstream of the most 5' gpA cDNA clone isolated, suggesting a 5' UCS of 489 or 494 nucleotides in mouse P. carinii gpA. A comparative alignment of the composite mouse P. carinii gpA deduced amino acid sequence with gpA homologs from rat, human and ferret P. carinii demonstrated 156 identical residues, including 46 cysteines, further supporting the hypothesis for conserved secondary structure, as well as function, for gpA from all P. carinii.

Amino Acid Sequence↗
PubMed1998

Antigenic properties of recombinant glycosylated and nonglycosylated Pneumocystis carinii glycoprotein A polypeptides expressed in baculovirus-infected insect cells.

Since a continuous culture system is not yet available for the opportunistic fungal pathogen Pneumocystis carinii, obtaining suitable amounts of purified P. carinii antigens free of mammalian-host lung contaminants is difficult. Hence, production of recombinant antigen possessing epitopes found in native P. carinii antigens is critical for immunological studies. We utilized the baculovirus expression vector system (BEVS) in insect cells to determine whether B-cell epitopes present in the protein core of a native P. carinii surface glycoprotein were conserved in the recombinant polypeptide, and to investigate its glycosylation by insect cells. B-cell epitopes were retained, but the insect cells appeared to hyperglycosylate the recombinant protein.

Animals↗
PubMed1998

Recognition of Pneumocystis carinii antigens by local antibody-secreting cells following resolution of P. carinii pneumonia in mice.

To examine the repertoire of Pneumocystis carinii antigens recognized by antibody-secreting B cells from tracheobronchial lymph nodes isolated immediately following recovery from P. carinii pneumonia, monoclonal antibodies (MAbs) were produced from these cells. In contrast to previous studies of systemic immunity, P. carinii gpA was not the immunodominant antigen recognized by these B cells. Forty-nine (91%) of 54 P. carinii-specific hybridoma culture supernatants reacted with P. carinii antigens other than gpA. Many of the resulting MAbs recognized a previously uncharacterized antigen expressed on the surface of both cysts and trophozoites. Western blotting using one of the cloned MAbs revealed reactivity with a broad range of antigenic material, with the most intense reactivity in the 50- to 65-kDa region of the blot. The antigens identified by these MAbs merit further investigation regarding protective immunity to P. carinii because they were recognized by B cells in the context of recovery from P. carinii pneumonia.

Animals↗
PubMed1998

Immunization with Pneumocystis carinii gpA is immunogenic but not protective in a mouse model of P. carinii pneumonia.

Immunization with whole Pneumocystis carinii has been shown to protect mice from the development of P. carinii pneumonia (PCP) when they are subsequently immunosuppressed and challenged with viable organisms. To determine whether these results could be duplicated by using a subunit vaccine, we examined the immunogenicity and efficacy of an immunization strategy based on P. carinii gpA. This antigen was chosen for study because passive immunoprophylaxis, based on gpA, has been shown to be partially protective in various animal models of infection. Immunization with gpA produced an anti-gpA specific antibody response comparable to that resulting from immunization with whole organisms. However, in contrast to immunization with whole P. carinii, which was protective, immunization with gpA did not protect T-cell-depleted mice from the development of PCP. These studies suggest that other antigens in addition to gpA need to be evaluated for their role in protective immunity against P. carinii.

Animals↗
PubMed1998

Induction of fibrinogen expression in the lung epithelium during Pneumocystis carinii pneumonia.

Pneumocystis carinii is an important pulmonary pathogen responsible for morbidity and mortality in patients with AIDS. The acute-phase response (APR), the primary mechanism used by the body to restore homeostasis following infection, is characterized by increased levels of circulating fibrinogen (FBG). Although the liver is the primary site of increased FBG synthesis during the APR, we unexpectedly discovered that FBG is synthesized and secreted by lung alveolar epithelial cells in vitro during an inflammatory stimulus. Therefore, we sought to determine whether lung epithelial cells produce FBG in vivo using animal models of P. carinii pneumonia (PCP). Inflammation was noted by an influx of macrophages to P. carinii-infected alveoli. Northern hybridization revealed that gamma-FBG mRNA increased two- to fivefold in P. carinii-infected lung tissue, while RNA in situ hybridization demonstrated increased levels of gamma-FBG mRNA in the lung epithelium. Immunoelectron microscopy detected lung epithelial cell-specific production of FBG, suggesting induction of a localized inflammatory response resembling the APR. A systemic APR was confirmed by a two- to fivefold upregulation of the levels of hepatic gamma-FBG mRNA in animals with PCP, resulting in a corresponding increase in levels of FBG in plasma. Furthermore, immunoelectron microscopy revealed the presence of FBG at the junction of cell membranes of trophic forms of P. carinii organisms aggregated along the alveolar epithelium. These results implicate FBG in the pathogenesis of PCP in a manner similar to that of the adhesive glycoproteins fibronectin and vitronectin, which are known to participate in intra-alveolar aggregation of organisms and adherence of P. carinii to the lung epithelium.

Acute-Phase Reaction↗
PubMed1998

Antigenic characterization of Pneumocystis carinii.

Studies of Pneumocystis carinii have been limited by our inability to propagate it in continuous culture. In this context, studies of P. carinii antigens have provided significant insight into the biology of this organism. The mannose-rich surface major surface glycoprotein of P. carinii termed glycoprotein A (gpA) is the best studied of these P. carinii antigens. Significant genetic and immunologic diversity exists between the gpA molecules expressed by P. carinii derived from different mammalian sources. The molecular and biochemical nature of gpA and other P. carinii antigens including p55 are reviewed. In addition, available information concerning the role of P. carinii gpA and other antigens in host-organism interactions are also discussed.

Animals↗
PubMed1998

Selected animal models: vaginal candidosis, Pneumocystis pneumonia, dermatophytosis and trichosporosis.

A clear understanding of the pathogenesis of fungal disease remains elusive. While technological advances in molecular biology and microbial genetics have provided scientists with major new insights into both microbial virulence factors as well as host susceptibility to infection, there is currently no substitute for animal models in elucidating microbe-host interactions. Animal models are also essential for the evaluation of new antimicrobial agents, including studies of efficacy, adverse reactions and pharmacokinetics. The single most important advance in animal models in the last decade, has been the availability of genetically unique strains of animals as alternative to animals treated with immunosuppressive drugs for use in studies on microbial virulence and host defence mechanisms. These unique strains of test animals also enhance our understanding of the modes of action of antifungal drugs and their metabolism. Some of these advances will be discussed in this symposium.

Animals↗
PubMed1997

A Pneumocystis carinii group I intron ribozyme that does not require 2' OH groups on its 5' exon mimic for binding to the catalytic core.

The recent increase in the population of immunocompromised patients has led to an insurgence of opportunistic human fungal infections. The lack of effective treatments against some of these pathogens makes it important to develop new therapeutic strategies. One such strategy is to target key RNAs with antisense compounds. We report the development of a model system for studying the potential for antisense targeting of group I self-splicing introns in fungal pathogens. The group I intron from the large ribosomal subunit RNA of mouse-derived Pneumocystis carinii has been isolated and characterized. This intron self-splices in vitro. A catalytically active ribozyme, P-8/4x, has been constructed from this intron to allow measurement of dissociation constants for potential antisense agents. At 37 degrees C, in 50 mM Hepes (25 mM Na+), 15 mM MgCl2, and 135 mM KCl at pH 7.5, the exogenous 5' exon mimic r(AUGACU) binds about 60 000 times more tightly to this ribozyme than to r(GGUCAU), a mimic of its complementary binding site on the ribozyme. This enhanced binding is due to tertiary interactions. This tertiary stabilization is increased by single deoxynucleotide substitutions in the exon mimic at every position except for the internal A, which is essentially unchanged. Thus 2' OH groups of the 5' exon mimic do not form stabilizing tertiary interactions with the P-8/4x ribozyme, in contrast to the Tetrahymena L-21 ScaI ribozyme. Furthermore, at 37 degrees C, the exogenous 5' exon mimic d(ATGACT) binds nearly 32 000 times more tightly to the P-8/4x ribozyme than to r(GGUCAU). Therefore, oligonucleotides without 2' OH groups can exploit tertiary stabilization to bind dramatically more tightly and with more specificity than possible from base pairing. These results suggest a new paradigm for antisense targeting: targeting the tertiary interactions of structural RNAs with short antisense oligonucleotides.

Animals↗
PubMed1997

Neutralization of interferon-gamma exacerbates pneumocystis-driven interstitial pneumonitis after bone marrow transplantation in mice.

The role of IFNgamma in the development of infection-driven interstitial pneumonitis in a model of murine graft-versus-host disease was investigated. Mice were given either syngeneic or allogeneic bone marrow transplants along with lung Pneumocystis carinii infections and were treated with either control mAb or anti-IFNgamma mAb. At day 21 after transplant, lung weights were elevated nearly twofold in all groups. By day 41, mice in all groups had cleared the P. carinii but only the mice given allogeneic transplants and anti-IFNgamma had increased lung weights. Increased lung weights in the anti-IFNgamma-treated mice corresponded to alveolar infiltration of eosinophils, neutrophils, and multinucleated giant cells and exacerbated interstitial pneumonitis compared with mice treated with control antibody. Intracellular staining indicated that there were 3- to 10-fold more CD4+ cells producing IFNgamma than those producing IL-4 in the lung lavages of mice given either syngeneic or allogeneic transplant. Treatment of transplanted mice with anti-IFNgamma resulted in a significant decrease in IFN-gamma-producing CD4+ and CD8+ cells in the lung lavages but no change in the number of IL-4-producing CD4+ cells. These data indicate that IFNgamma is critical for controlling the development of P. carinii-driven interstitial pneumonia after either syngeneic or allogeneic bone marrow transplant in mice.

Animals↗
PubMed1997

Short-term effects of bracing on exercise performance in mild idiopathic thoracic scoliosis.

In adolescent idiopathic thoracic scoliosis (ITS) working capacity may be reduced during exercise. Despite concern about its usefulness, bracing is still being used in ITS. Thus the effects of bracing on exercise performance need to be examined. We studied six females, ages 12-15 years who had mild ITS (Cobb angle range 20-35 degrees). Pulmonary volumes, maximal voluntary ventilation (MVV), breathing pattern, the lowest (most negative in sign) pleural pressure during sniff maneuver (Pplsn), and pleural pressure swings (Pplsw) were measured first. Then, Pplsw, O2 uptake (VO2), CO2 output (VCO2), heart rate (HR) at rest and during progressive incremental exercise on a cycling ergometer (10 watts/min) were recorded. The exercise test was performed under control conditions without bracing (C) and after 7 days of bracing with the braced on (B). Dyspnea was measured by a modified Borg scale. At rest, bracing mildly affected total lung capacity and forced vital capacity (p < 0.03 for both) but not breathing pattern, Pplsn, or Pplsw (%Pplsn), a measure of respiratory effort. Furthermore, bracing did not consistently affect maximum work rate (WRmax). In both B and C VO2 was below (< 70%) the predicted value, VE was below (< 45%) MVV, and HR reserve was < 15 beats/min, indicating some cardiovascular deconditioning. On the other hand, respiratory frequency (Rf) increased more in B than in C (p < 0.03). In addition, Pplsw, Pplsw (%Pplsn), and Pplsw (%Pplsn)/VT, an index of neuroventilatory dissociation (NVD) of the respiratory pump, were greater in B (p < 0.03 for all). At a similar work rate, the Borg rating score was greater with bracing on than off, and the difference (delta Borg) tended to relate to concurrent changes in Pplsw (%Pplsn)/VT (r2 = 0.71; p < 0.07). We conclude that bracing affects respiratory effort, NVD, and dyspnea score during progressive exercise. These effects are consistent with increased lung elastance. Diminished exercise tolerance in patients with mild ITS probably reflects impaired physical fitness but is not affected by bracing. Training programs proposed for this subset of patients to increase peripheral muscle performance might also consider NVD of the respiratory pump.

Adolescent↗
PubMed1997

Pneumocystis carinii host origin defines the antibody specificity and protective response induced by immunization.

To determine how the known host species-specific antigenic variation of Pneumocystis carinii would affect immune recognition, mice were immunized with either mouse- or ferret-derived P. carinii, with subsequent analysis of the immune response and the ability of the mice to resist infection after immunosuppression and challenge. Immunization with mouse-derived P. carinii produced a strong immune response to mouse but not ferret P. carinii. These mice were completely protected from P. carinii pneumonia when challenged by intratracheal inoculation with mouse P. carinii. In contrast, immunization with ferret P. carinii produced a limited antibody response to mouse P. carinii and had no protective effect. These results show that P. carinii from different host species are immunologically distinct, and any possible use of immunotherapy for P. carinii pneumonia in humans must take into consideration these biologically significant antigenic differences in P. carinii of animal origin.

Animals↗
PubMed1997

Lack of relation of granulocyte antibodies (antineutrophil antibodies) to neutropenia in children with human immunodeficiency virus infection.

BACKGROUND: Neutropenia in children and adults with HIV infection is frequently observed, perhaps as a result of impaired myelopoiesis, drug myelotoxicity, immune destruction or opportunistic infection. The presence of antineutrophil antibodies (granulocyte antibodies) has been associated with severe neutropenia in some reports but not in others, and such antibody assays can be confounded by the presence of immune complexes and HLA antibodies. METHODS: To determine both the prevalence of granulocyte antibodies in children with HIV infection and whether such antibodies were related to neutropenia, we screened the sera of 30 HIV-infected children by performing granulocyte immunofluorescence, granulocyte agglutination and lymphocytotoxic anti-HLA antibody assays. Reactivity was graded by a standard numeric score calculated per number of reactive cells. RESULTS: Of 26 evaluable sera, 16 (62%) had granulocyte antibodies, 6 (23%) had HLA antibodies and 4 (15%) had neither. There was no correlation between presence of granulocyte antibodies and degree of neutropenia. CONCLUSIONS: We conclude that granulocyte antibodies are highly prevalent in children with HIV infection but do not correlate with the degree of neutropenia. Antineutrophil antibody determination as currently performed does not appear to be useful in the evaluation of the HIV-infected neutropenic child.

Adolescent↗
PubMed1997

Protection against Pneumocystis carinii pneumonia by antibodies generated from either T helper 1 or T helper 2 responses.

To determine whether different antibody isotypes associated with T helper 1 (Th1) or Th2 responses are protective against Pneumocystis carinii, mice with disrupted interleukin 4 genes (IL-4(-/-) mice) or gamma interferon genes (IFN-gamma(-/-) mice) along with wild-type C57BL/6 mice were immunized intratracheally against P. carinii, depleted of T cells in vivo by use of monoclonal antibodies, and rechallenged intratracheally with 10(7) viable P. carinii organisms. Nearly all immunized mice resolved their lung P. carinii infections (limit of detection, log10 4.06) within 21 days of challenge even though they were depleted of T cells. Unimmunized mice depleted of T cells had significant lung infections (>log10 5.5) at day 21 post-P. carinii challenge. IFN-gamma(-/-) and wild-type mice developed P. carinii-specific immunoglobulin primarily of the immunoglobulin G1 (IgG1) subclass with relatively little P. carinii-specific IgG2a, IgG2b, or IgG3 in their sera, characteristic of a Th2-type response. In contrast, IL-4(-/-) mice had primarily an IgG2b P. carinii-specific antibody response in their sera with very little IgG1. Although IgG2b was the predominant isotype in IL-4(-/-) mice, optical density values of IgG2a and IgG3 were significantly higher in these mice (two and three times, respectively) than in IFN-gamma(-/-) mice, characteristic of a Th1-type response. Together, these data indicate that resolution of P. carinii infection can be mediated by specific antibody responses and that the antibody response can be either a predominantly Th1 or Th2 type. Furthermore, although wild-type mice mounted a Th2-like antibody response, IL-4(-/-) mice could resolve P. carinii pneumonia, indicating that resistance to P. carinii can occur in the absence of IL-4.

Animals↗
PubMed1996

Glycoprotein A is the immunodominant antigen of Pneumocystis carinii in mice following immunization.

A rapid and simple dual enzyme-linked immunosorbent assay was developed to quantitate the relative frequency of monoclonal antibodies produced against Pneumocystis carinii glycoprotein A (gpA) or other antigens of P. carinii after immunization with whole organisms. In BALB/cj mice, P. carinii gpA was clearly the immunodominant antigen, with a quarter of all hybridomas secreting antibody directed against this molecule.

Animals↗