Search PubMed⌕ Search

Biomedical subjects

F Gigliotti

Publications and source records attributed to F Gigliotti.

At least 55 records · Page 3Linked to original sources
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↗
PubMed1996

Antibody-mediated shift in the profile of glycoprotein A phenotypes observed in a mouse model of Pneumocystis carinii pneumonia.

It is well established that Pneumocystis carinii has the molecular capability for variation of a major surface antigen, glycoprotein A (gpA). However, the extent of expression of gpA variation among P. carinii organisms infecting a single host and whether this variation has any impact on host-parasite immunological interactions is unknown. Using a mouse model of P. carinii pneumonia, we were able to demonstrate the expression of more than one gpA phenotype in a closed population of infected mice. Administration of monoclonal antibody (MAb) 2B5, which is specific for one of the gpA phenotypes, resulted in a marked diminution in the frequency of this particular gpA phenotype in the population of organisms. This effect was due to a loss of trophozoites bearing the specific epitope recognized by MAb 2B5; cysts bearing the same epitope appeared unaffected. Interestingly, P. carinii was unable to introduce a new phenotype into the population to compensate for the loss of trophozoites bearing the epitope recognized by MAb 2B5. Discontinuing administration of MAb 2B5 allowed the MAb 2B5-binding phenotype to reemerge. This finding suggests that the phenotype recognized by MAb 2B5 was continually produced even when MAb 2B5 was present. Thus, although P. carinii exhibited a form of antigenic variation, it did not appear able to rapidly introduce new phenotypes into the population in response to destruction by antibodies.

Animals↗
PubMed1995

Cloning and characterization of a conserved region of human and rhesus macaque Pneumocystis carinii gpA.

Although the genes encoding Pneumocystis carinii (Pc) glycoprotein A (gpA) display a high degree of host species-specific genotypic diversity, the Pc gpA derived from different host species share defined regions of significant homology in their primary amino acid (aa) structure. Using two degenerate oligodeoxyribonucleotide (oligo) primers corresponding to a conserved Cys region (Cys-primers) of the ferret (F), rat (R) and mouse (M) PcgpA, a 306-bp portion of the human (H) PcgpA was amplified from only one of three known HPc-infected lung samples using PCR. The deduced aa sequence of the HPc PCR product was 72% similar to the corresponding region of a published HPc gpA aa sequence. Because the conserved Cys-primers amplified only one of three samples of HPcgpA, a primer-pair was designed from sequences internal to the Cys-primer sequences of the HPcgpA PCR product (hPc). The hPc primers amplified the expected 254-bp product from each of the three HPc-infected lung DNA samples, suggesting that the Cys-primers may have either amplified a HPcgpA present in fewer copies in the genome of HPc or, alternatively, amplified a gene from an uncommon strain of Pc encoding an isoform variant of gpA not present in the other human isolates analyzed in this report. Restriction analysis of the amplified products demonstrated heterogeneity in the internal sequence, confirming that more than one gpA exists in HPc as well. To determine the relationship of HPcgpA to the gpA of Pc from another primate, the hPc primers were used successfully to amplify a 261-bp product from Pc-infected Rhesus macaque (Rm) lung genomic DNA. These results are consistent with our earlier findings that closely related host species are infected with Pc organisms encoding similar gpA, suggesting that the evolutionary divergence of Pc followed that of the mammalian host species.

Animals↗
PubMed1995

Isoform diversity and tandem duplication of the glycoprotein A gene in ferret Pneumocystis carinii.

Two ferret P. carinii gpA cDNA clones were identified that reacted identically with a panel of anti-gpA monoclonal antibodies, although their nucleotide sequences were 22% divergent. Each clone hybridized to a single mRNA species of 3,600 nucleotides only in P. carinii-infected lung mRNA, but RT-PCR analysis demonstrated that these cDNA clones were derived from two distinct gpA mRNA transcripts. Further PCR analysis demonstrated that the ferret P. carinii genome contains at least two gpA genes lying in tandem on a single chromosome separated by a 329-bp intergenic region. Based on the terminal gene sequences of this tandem repeat and the cDNA clones, a composite full-length ferret P. carinii gpA coding sequence was constructed. The intergenic region immediately downstream of the stop codon of the first gpA gene contains three putative polyadenylation signals, and constitutes the 3' untranslated region (UTR) of the gpA mRNA. Primer extension of the gpA mRNA resulted in products extending 74 and 244 nucleotides into the 5' UTR. However, the intergenic region lying greater than 25 nucleotides upstream of the first methionine of the second gpA gene was found to be absent from the 5' UTR.

Amino Acid Sequence↗
PubMed1995

Active immunity to Pneumocystis carinii reinfection in T-cell-depleted mice.

Immunocompetent C.B-17 mice were immunized against Pneumocystis carinii by several intratracheal inoculations with infective P. carinii. These mice and another group of C.B-17 mice naive to P. carinii were then depleted of CD4+ cells by treatment with both anti-CD4 and anti-Thy1 monoclonal antibodies. Both groups of mice were then challenged with an infective inoculum containing 10(7) P. carinii organisms by intratracheal instillation. The mean log10 counts of P. carinii nuclei in the lungs of the nonimmune mice were 4.98, 5.89, and 6.77 when they were killed at 4, 10, and 19 days, respectively, after challenge. The P. carinii counts in the lungs of the immune mice were significantly lower at each time point and below detectable levels at 10 and 19 days. Analysis of P. carinii DNA by PCR revealed no detectable P. carinii in the lungs of the immunized mice at either 10 or 19 days, whereas all of the nonimmunized mice contained P. carinii DNA at all time points. The sera of immune but not nonimmune mice contained P. carinii-specific immunoglobulin G. These results indicate that immunization of an immunocompetent host against P. carinii can protect against P. carinii pneumonia even after the host is depleted of CD4+ cells. In addition, the results are consistent with the possibility that antibodies were responsible for the observed protection against P. carinii.

Animals↗
PubMed1995

Comparative effects of plasma exchange and pyridostigmine on respiratory muscle strength and breathing pattern in patients with myasthenia gravis.

BACKGROUND: Pyridostigmine, an acetylcholinesterase antagonist, is useful in improving respiratory function in patients with myasthenia gravis. More recently, plasma exchange has been employed in myasthenia gravis because it acts presumably by removal of circulating antibodies against acetylcholine receptors. Surprisingly, comparative data on the effects of pyridostigmine and plasma exchange on lung volumes, respiratory muscle strength, and ventilatory control system in patients with myasthenia gravis are lacking. METHODS: Nine consecutive patients with grade IIb myasthenia gravis were studied under control conditions and after a therapeutic dose of pyridostigmine. In a second study the patients were re-evaluated a few days after a cycle of plasma exchange, before taking pyridostigmine. In each subject pulmonary volumes, inspiratory (MIP) and expiratory (MEP) muscle force, and respiratory muscle strength, calculated as average MIP and MEP as percentages of their predicted values, were measured. The ventilatory control system was evaluated in terms of volume (tidal volume, VT) and time (inspiratory time, TI, and total time, TTOT) components of the respiratory cycle. Mean inspiratory flow (VT/TI)--that is, the "driving"--and TI/TTOT: that is, the "timing"--components of ventilation were also measured. RESULTS: In each patient treatment relieved weakness and tiredness, and dyspnoea grade was reduced with plasma exchange. Following treatment, vital capacity (VC) increased on average by 9.7% with pyridostigmine and by 14% with plasma exchange, and MIP increased by 18% and 26%, respectively. In addition, with plasma exchange but not with pyridostigmine forced expiratory volume in one second (FEV1) increased by 16% and MEP increased by 24.5%, while functional residual capacity (FRC) decreased a little (6.8%). The change in respiratory muscle strength was related to change in VC (r2 = 0.48). With plasma exchange, VT increased by 18.6% and VT/TI increased by 13.5%, while neither TI nor TI/TTOT changed. CONCLUSIONS: Plasma exchange can be used in patients with myasthenia gravis when symptoms are not adequately controlled by anticholinesterase agents. Plasma exchange increases respiratory muscle force and tidal volume due to changes in "driving" but not "timing" of the respiratory cycle.

Adult↗
PubMed1995

Mechanical loading and control of breathing in patients with severe chronic obstructive pulmonary disease.

BACKGROUND: High neural drive to the respiratory muscles and rapid and shallow breathing are frequently observed in patients with chronic obstructive pulmonary disease (COPD), and both mechanical and chemical factors are thought to play a part. However, the interrelation between these factors and the modifications in the control of breathing are not clearly defined. The effects of an acute decrease in mechanical load by the administration of a high dose of a beta 2 agonist were studied. METHODS: Nine spontaneously breathing patients with severe COPD took part in the study. Criteria for entry were FEV1 of < 40% of predicted and an improvement in FEV1 of < 200 ml after inhalation of 400 micrograms fenoterol. The following parameters were measured: lung volumes, tidal volume (VT), respiratory frequency (Rf), maximal pleural pressure during a sniff manoeuvre (PPLmax), pleural pressure swings (PPLsw), lung resistance (RL), RL/PPLmax ratio, and surface electromyographic activity (EMG) of diaphragm (EDI) and parasternal (EPS) muscles. Arterial oxygen saturation (SaO2), end tidal carbon dioxide pressure (PETCO2), and the electrocardiogram were also monitored. Each variable was measured under control conditions and 20 and 40 minutes after the inhalation of 800 micrograms fenoterol. In five patients the effects of placebo were also studied. RESULTS: Fenoterol resulted in an increase in FEV1 and decrease in FRC. SaO2 did not change, while PETCO2 fell and heart rate increased. The VT increased, and Rf decreased, PPLsw fell and PPLmax increased, thus the PPLsw/PPLmax ratio fell. Both RL and RL/PPLmax also fell, and a substantial decrease in EDI and EPS was observed. Changes in PPLsw were related to changes in FEV1 and RL. Changes in VT and Rf, and EDI/TI and EPS/TI were also related to changes in PPLsw and RL/PPLmax ratio, but not to changes in FEV1. No variation was observed with placebo. CONCLUSIONS: In patients with severe COPD a decrease in inspiratory muscle loading relative to the maximal available strength, as expressed by the RL/PPLmax and PPLsw/PPLmax ratios, appears to be the major determinant of changes in breathing pattern and inspiratory muscle activity (decrease in EMG).

Aged↗
PubMed1995

Control of breathing in patients with limb girdle dystrophy: a controlled study.

BACKGROUND: In patients with limb girdle dystrophy the relative contribution of peripheral factors (respiratory muscle weakness, and lung and/or airway involvement) and central factors (blunted and/or inadequate chemoresponsiveness) in respiratory insufficiency has not yet been established. To resolve this, lung volumes, arterial blood gas tensions, respiratory muscle strength, breathing pattern and neural respiratory drive were investigated in a group of 15 patients with limb girdle dystrophy. An age-matched normal group was studied as a control. METHODS: Respiratory muscle strength was assessed as an arithmetic mean of maximal inspiratory (MIP) and expiratory (MEP) pressures. Breathing pattern was evaluated in terms of volume (ventilation VE, tidal volume VT) and time (respiratory frequency Rf, inspiratory time TI, expiratory time TE) components of the respiratory cycle. Neural respiratory drive was assessed as the mean inspiratory flow (VT/TI), mouth occlusion pressure (P0.1) and electromyographic activity (EMG) of the diaphragm (EMGd) and the intercostal parasternal (EMGp) muscles. In 10 of the 15 patients the responses to carbon dioxide (PCO2) stimulation were also evaluated. RESULTS: Most patients exhibited a moderate decrease in vital capacity (VC) (range 37-87% of predicted), MIP (range 23-84% of predicted), and/or MEP (range 13-41% of predicted). The arterial carbon dioxide tension (PaCO2) was increased in three patients breathing room air, while PaO2 was normal in all. Compared with the control group Rf was higher, and VT, TI and TE were lower in the patients. EMGd and EMGp were higher whilst VT/TI and P0.1 were normal in the patients. Respiratory muscle strength was inversely related to EMGd and EMGp. PaCO2 was found to relate primarily to VC and duration of illness, but not to respiratory muscle strength. During hypercapnic rebreathing delta VE/delta PCO2, delta VT/delta PCO2, and delta P0.1/delta PCO2 were lower than normal, whilst delta EMGd/delta PCO2 and delta EMGp/delta PCO2 were normal in most patients. A direct relation between respiratory muscle strength and delta VT/delta PCO2 was found. CONCLUSIONS: The respiratory muscles, especially expiratory ones, are weak in patients with limb girdle dystrophy. Reductions in respiratory muscle strength are associated with increased neural drive and decreased ventilatory output (delta VT/delta PCO2). The decrease in VC, together with the duration of disease, influence PaCO2. VC is a more useful test than respiratory muscle strength for following the course of limb girdle dystrophy.

Adult↗
PubMed1995

Carbon dioxide responsiveness in COPD patients with and without chronic hypercapnia.

To ascertain whether and to what extent the reduced ventilatory response to a hypercapnic stimulus in chronic obstructive pulmonary disease (COPD) patients depends on a blunted chemoresponsiveness of central origin or to mechanical impairment, we studied two groups of COPD patients without (group A) and with (group B) chronic hypercapnia, but with similar degrees of airway obstruction and hyperinflation. The study was performed on 17 patients (9 normocapnic and 8 hypercapnic). Six age-matched normal subjects (group C) were also studied as a control. During a CO2 rebreathing test, ventilation (VE), mouth occlusion pressure (P0.1), and the electromyographic activity of diaphragm (Edi) were recorded and then plotted against end-tidal carbon dioxide tension (PCO2). Inspiratory muscle strength was significantly lower in the hypercapnic group (group B) compared to normocapnic group (A), and in these groups compared to the control group (C). Both patient groups exhibited significantly lower delta VE/delta PCO2 than the control group. In hypercapnics, delta P0.1/delta PCO2 was significantly lower than in normocapnics and control group, whilst mouth occlusion pressure as % of maximal inspiratory pressure delta P0.1 (% MIP)/delta PCO2 did not differ significantly among the three groups. delta Edi/delta PCO2 increased from C to A. At a PCO2 of 8.65 kPa, VE was similar in the normocapnic and control group, but lower in hypercapnics; Edi was similar in hypercapnic and control group; but greater in normocapnics. P0.1(% MIP) did not differ significantly among groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1995

Effects of the iron lung on respiratory function in chronic hypercapnic COPD patients.

Whether or not short-term negative pressure ventilation (NPV) improves respiratory function by decreasing the drive to the respiratory muscles in hypercapnic chronic obstructive pulmonary disease (COPD) patients remains to be defined. In six severely obstructed hypercapnic COPD patients (Group A) with grade IV dyspnoea (modified Medical Research Council (MRC) dyspnoea scale), we evaluated pulmonary volumes, arterial blood gases, the pattern of breathing (tidal volume (VT) and respiratory frequency (Rf)) and the neuromuscular respiratory drive (NMRD), before and immediately after a 7 day period with the iron lung (IL). NMRD was assessed by expressing mouth occlusion pressure (P0.1) recorded during quiet breathing as a percentage of maximal P0.1 recorded during exogenous CO2 stimulation (P0.1 max,CO2). A group of six hypercapnic, less dyspnoeic (grade II to III) COPD patients (Group B), with similar mechanical characteristics, and another less obstructed historically normocapnic control group (Group C) were also considered. Before IL, in Group A VT was lower than in C, and P0.1 (%P0.1 max,CO2) was greater than in Group B and C. After a 7 day period with IL, VT increased, Rf decreased, and arterial blood gases and dyspnoea grade improved; P0.1 (%P0.1 max,CO2) significantly decreased remaining, however, greater than in Group C. In Group A the time course of arterial carbon dioxide tension (Pa,CO2) and P0.1 (%P0.1 max,CO2) were significantly related to each other. These data seem to indicate that IL is effective in improving respiratory function and symptoms in chronic hypercapnic severely dyspnoeic COPD patients. The observation that these effects were associated with a decrease in NMRD reflects an improved efficiency of the respiratory system. After IL, respiratory function in Group A was similar or even better than that in Group B. This study also considers the possibility of putting severely dyspnoeic hypercapnic COPD patients into an IL trial before starting a traditional rehabilitation programme.

Aged↗
PubMed1994

Electrodermal differentiation of deception: the effect of choice versus no choice of deceptive items.

In the differentiation-of-deception paradigm (DDP), the experimental and control conditions, respectively, consist of questions answered deceptively (D) and honestly (H). Previous DDP studies with the electrodermal SCR as the dependent variable have yielded the basic increase in responding to D relative to H questions (D > H), and have indicated that this effect is probably not due to cognitive factors such as differential retrieval difficulty, and is also relatively unaffected by motivational factors. To test the notion that the D > H effect does not represent genuine deception because of the elimination of the element of choice in the DDP, the present study varied, between two groups of 16 subjects, the degree to which subjects could choose which questions they would answer deceptively. If choice were necessary, or even important, for the differentiation-of-deception phenomenon, the D > H effect should have been greater in the free-choice condition, but the (nonsignificant) trend was in a direction opposite to this prediction. Another orthogonally-varied, between-subject manipulation, was the relative frequency of D and H items. The basic electrodermal D > H phenomenon, including the curious lack of response habituation during the session, has now been duplicated over a variety of conditions, but the mechanisms underlying the phenomenon are far from being well understood.

Adolescent↗
PubMed1994

Conserved sequence homology of cysteine-rich regions in genes encoding glycoprotein A in Pneumocystis carinii derived from different host species.

Pneumocystis carinii surface glycoprotein A (gpA) exhibits host species-specific phenotypic and genotypic variation. Despite this heterogeneity, the gpAs of P. carinii isolated from different host species appear to be homologous molecules sharing certain biochemical and antigenic characteristics. Using two degenerate oligodeoxyribonucleotide primers corresponding to conserved cysteine regions from ferret and rat P. carinii gpAs, a PCR product of approximately 300 bp was amplified from ferret, rat, and SCID mouse P. carinii-infected lung genomic DNA. Northern (RNA) hybridization revealed a transcript of 3,450 nucleotides in P. carinii-infected SCID mouse lung mRNA, which is similar in size to the transcripts for ferret and rat P. carinii gpAs. Nucleotide sequence analysis of SCID mouse P. carinii gpA subclones derived from the PCR products identified two isoforms, which were 89% identical to each other in the amplified region and 73 and 54% identical to the rat- and ferret-derived P. carinii gpA genes, respectively. Comparison of the deduced amino acid sequences of mouse, ferret, and rat P. carinii gpAs revealed striking similarity in residues adjacent to and including the conserved cysteines. Furthermore, the spacing of two proline residues is invariant, and a potential N-linked glycosylation site is found at a similar position in all of the gpAs. Despite the heterogeneity observed in P. carinii gpAs, the conservation of cysteine residues and adjacent sequences implies similar secondary structure and, most likely, similar function for the gpAs of P. carinii isolated from different host species.

Amino Acid Sequence↗
PubMed1994

Histamine induced changes in breathing pattern may precede bronchoconstriction in selected patients with bronchial asthma.

BACKGROUND: In asthmatic patients methacholine or histamine challenge may result in more rapid and shallow breathing. Bronchoconstriction can also be associated with changes in the pattern of breathing. However, few studies, particularly in patients with asthma, have investigated the possibility that changes in the pattern of breathing may precede the onset of bronchoconstriction. METHODS: Eight subjects were selected from 34 consecutive asthmatic patients who had previously exhibited a significant increase in respiratory frequency (Rf) and decrease in tidal volume (VT) accompanying a 20% or greater fall in FEV1 during a histamine bronchial provocation test. These patients also had bronchial hyperresponsiveness (histamine PC20FEV1 0.1-0.25 mg/ml). VT, Rf, and the ratio of VT to Rf were evaluated breath by breath under control conditions and two minutes after inhalation of either saline or each of a series of progressively increasing concentrations of histamine. In each subject the coefficient of variation (CV) for each breathing pattern variable was calculated under control conditions and at each histamine concentration over at least 30-40 breaths. For FEV1, VT and Rf step by step coefficients of variation were averaged and the mean (2SD) CV was considered to represent a threshold value in each patient. RESULTS: Histamine challenge resulted in increased Rf and Rf/VT, and decreased VT and FEV1. In all but one subject change in Rf and Rf/VT beyond the threshold value preceded change in FEV1 beyond the threshold value. The threshold concentrations of histamine for Rf and Rf/VT did not correlate with the threshold value for FEV1. CONCLUSIONS: In selected asthmatic patients a change in breathing pattern occurs prior to a change in FEV1. These results suggest that narrowing of the airways, in terms of decrease in FEV1, does not play a major part in the initial change in the pattern of breathing. This may be caused by direct stimulation of vagal airway receptors.

Adult↗
PubMed1994

Aminophylline and respiratory muscle interaction in normal humans.

The effects of intravenous infusion of aminophylline on respiratory muscle interaction were examined in seven normal subjects breathing at rest. Rib cage (RC-Ap) and abdominal (AB-Ap) volume displacements, pleural (Ppl), gastric (Pg), and transdiaphragmatic (Pdi) pressure swings, and electromyographic activity of the diaphragm (Edi) and the parasternal (Eps) muscles were measured under control and during infusion of either aminophylline or placebo in a double-blind randomized manner. Compared with placebo, aminophylline induced an increase in ventilation (p < 0.01) that was mainly accounted for by an increase in tidal volume (p = 0.01). Aminophylline induced a significant and similar increase in RC-Ap and AB-Ap as associated with increased Ppl and Pg swings (p = 0.002, and p < 0.01, respectively). On the contrary, no changes in end-expiratory RC and AB volume and in Ppl and Pg at end-expiration were observed, indicating that expiratory muscles did not contribute to the increase in tidal volume. Edi and Eps increased significantly with aminophylline, whereas Pdi/Edi ratio remained unchanged. We conclude that in normal humans breathing at rest: (1) aminophylline increases ventilation, promoting larger tidal volume; (2) this effect is due to increased neural drive to inspiratory muscles; (3) aminophylline does not promote any appreciable expiratory muscle recruitment and distortion in the pattern of chest wall motion.

Adult↗