Biomedical subjects

P Hofmann

Publications and source records attributed to P Hofmann.

At least 19 recordsLinked to original sources

PubMed2000

Phenotype, intestinal morphology, and survival of homozygous and heterozygous endothelin B receptor--deficient (spotting lethal) rats.

BACKGROUND/PURPOSE: Spotting lethal (sl) rats, a model for Hirschsprung's disease, recently have been found to carry a deletion in the endothelin B (ET(B)) gene, causing functional lack of ET(B) receptors. The ET(B) receptor mediates, together with and in counterbalance to the ET(A) receptor, endothelin actions on vessels, cell proliferation, and migration. The authors investigated the effect of homozygosity (sI/sI) or heterozygosity (+/sl) on phenotype, intestinal morphology, and survival. METHODS: Weight, circumference, and serum albumin were measured. Histological tests of major organs and immunoperoxidase reaction for Peripherin, glial fibrillary acid protein (GFAP), and S-100 in small and large intestine were performed. Peripherin-immunostained sections of colon and jejunum were analyzed morphometrically. Screening for sepsis included search for enterocolitis, bacterial infection, endotoxin, and iNOS mRNA. RESULTS: Sl/sl rats died within 4 weeks of life, showing an early and a later death group. Serum albumin levels were decreased in sl/sl rats, whereas signs of sepsis were rare. Immunostaining uncovered alterations in nerve and glial cells in the whole gut of sl/sl rats, and to a subtle degree also in +/sl rats, which appear clinically normal. Morphometric quantification yielded statistically significant alterations in sl/sl rats only. No obvious abnormalities were found in other organs. CONCLUSIONS: Sl/sl rats die from malnutrition rather than sepsis, too early for ischemic complications to occur. Rats of the later death group are a suitable model for studying the ET8 receptor in vivo. Subtle abnormalities in the enteric nervous system of heterozygous rats underline the critical role of the "gene dose" for functional compensation.

Animals↗

PubMed2000

Prolactin and beta-endorphin serum elevations after ECT in manic patients.

OBJECTIVE: Alterations in prolactin and beta-endorphin serum levels after ECT are well-established findings in depression. The present study focuses on electroconvulsive therapy (ECT) response patterns of the mentioned parameters in patients suffering from acute mania. METHOD: Following the first three ECTs of a treatment series in 19 patients diagnosed according to DSM-III-R criteria as suffering from mania, blood samples were drawn before, and 20, 30 and 40 minutes after ECT. Serum prolactin and beta-endorphin levels were established in order to gain information about the effects of ECT on different neurotransmitter systems. RESULTS: A significant transient increase in serum prolactin after ECT was found. Furthermore, in females but not males, delta(max)prolactin diminished over the course of treatment as prolactin baseline levels increased. beta-endorphin levels showed a stable transient increase after ECT stimulus regardless from sex or treatment. CONCLUSION: The reported findings reflect those established in depression. This suggests that they are epiphenomenal to ECT.

Acute Disease↗

PubMed2000

Total numbers of lymphocyte subsets in different lymph node regions of uninfected and SIV-infected macaques.

Human immunodeficiency virus (HIV) infection leads to a decline of CD4+ T-cells in blood. Because blood represents only a small proportion of the total lymphocyte pool, it is important to investigate other lymphoid organs. So far, only relative proportions of lymphocyte subsets in single peripheral lymph node (LN) regions of HIV-infected patients and simian immunodeficiency virus (SIV)-infected macaques have been documented. We have therefore quantified the absolute numbers of lymphocyte subsets in blood and six different LN regions of 10 uninfected and 26 SIV-infected macaques. In addition, we have determined the expression of markers of activation and differentiation. Already, in uninfected monkeys, there were significant differences in the cellular composition of different LN regions. Infection with SIV resulted in drastic changes in the proportion as well as absolute numbers of different lymphocyte subsets. Moreover, the relative contribution of the single LN regions to the total lymphocyte pool was also altered.

Animals↗

PubMed2000

Selective induction of the monocyte-attracting chemokines MCP-1 and IP-10 in vesicular stomatitis virus-infected human monocytes.

It is characteristic of viral infections that monocytes/macrophages and lymphocytes infiltrate infected tissue, and neutrophils are absent. CC and non-ELR CXC chemokines predominantly attract mononuclear leukocytes, whereas the ELR motif-expressing CXC chemokines primarily act on neutrophils. To investigate the general role of chemokines in viral diseases, we determined their release and expression patterns after infection of human monocytes with vesicular stomatitis virus (VSV). Human monocytes were productively infected by VSV. Surprisingly, VSV did not induce the release of the proinflammatory cytokines tumor necrosis factor-alpha (TNF-alpha), interleukin-1beta (IL-1beta), and IL-6. In contrast, we found a strong induction of the CC chemokine monocyte chemotactic protein-1 (MCP-1) and the non-ELR CXC chemokine interferon-gamma (IFN-gamma) inducible protein-10 (IP-10) by VSV on the gene and protein level. The expression and release of the neutrophil chemoattractants IL-8 and growth-related oncogene-alpha (GRO-alpha) remained unaffected after VSV infection. Our results indicate that the typical monocyte and lymphocyte-dominated leukocyte infiltration of virus-infected tissue is based on a selective induction of mononuclear leukocyte-attracting chemokines.

Cells, Cultured↗

PubMed2000

Change in left atrial and ventricular dimensions during and immediately after exercise.

PURPOSE: The aim of this study was to evaluate differences in the left atrial (LAD), total ventricular end-diastolic (TEDD), end-systolic diameters (TESD), and left ventricular shortening fraction (SF) compared with heart rate (HR) and systolic blood pressure (SBP) during exercise and recovery. METHODS: Healthy young male (N = 15) and female (N = 16) subjects performed an incremental cycle ergometer test in upright position, and three phases of energy supply were defined by means of blood lactate concentration (LA) and respiratory gas exchange variables (I: aerobic; II: aerobic-anaerobic transition; III: anaerobic). Subjects were required to rest their arms on a steering bar and to lean their upper body forward; two dimensional (2-D) echocardiograms were obtained over the left parasternal area at rest (R), at the end of each phase, immediately within 15 s post, and 6 min after exercise (6 min). By using VINGMED's "Anatomical M-Mode," it was possible to extract M-Mode Sweeps from stored 2-D-Loops and perform the M-Mode measurement. RESULTS: In contrast to the significant decrease in TEDD and TESD from III to 15 s up to resting values and the significant increase in SF from III to 15 s, the moderate decrease in HR immediately post exercise (15 s) was not significant. The SBP showed a significantly decrease from III to 15 s; in contrast to TEDD, TESD, and SF, the values at 15 s were comparable with the values at II. For LAD, significant increase during exercise and a decrease during recovery were observed. Sex-specific differences of changes in measured variables could not be found. CONCLUSION: We concluded that post exercise measurement of left ventricular and atrial dimensions or SF were not valid to describe heart function at maximal exercise although immediately post exercise HR was near maximal level.

Adult↗

PubMed2000

Cytokine profiles in heart, spleen, and thymus during the acute stage of experimental coxsackievirus B3-induced chronic myocarditis.

Since cytokines play an important role in the pathogenesis of virus-induced chronic heart diseases, cytokine mRNA expression was studied in coxsackievirus B3-infected NMRI mice during the acute phase of myocarditis until the onset of chronic cardiac disease. Virus replication, cytokine induction, inflammatory cell infiltration and myocardial damage were studied by titer determination, reverse transcription-polymerase chain reaction (RT-PCR), and histopathology. To investigate whether the coxsackievirus B3-induced cytokine mRNA accumulation was only limited to the heart or generalized, spleen and thymus specimens were also included. Surprisingly, interleukin (IL)-10 as a deactivator of T cell and macrophage functions was transcribed in the myocardium nearly in parallel with virus replication from Day 1 through Day 14. At Day 3 p.i., the mRNA of IL-1alpha, tumor necrosis factor (TNF)-alpha, IL-6, and interferon (IFN)-beta accumulated. At Days 4, 7, and 14, IL-12-specific mRNA was produced. Furthermore, increasing amounts of IFN-gamma mRNA were found, whereas IL-2 and IL-4 mRNA remained undetectable. TNF-alpha, IL-1alpha, IL-10, IL-12, and IFN-gamma mRNA persisted into the late stage of myocarditis. In the spleen a closely correlated expression of virus and IL-10-specific mRNAs was also found, and in addition, IFN-beta, TNF-alpha, and IL-6 were detected. In striking contrast to heart and spleen tissue, the distinct expression of viral RNA in the thymus was not accompanied by an increased cytokine mRNA production. These data provide evidence for a unique coxsackievirus B3-induced cytokine pattern in the myocardium and spleen and suggest that persistently expressed IL-10 may play a leading role in acute and chronic myocarditis by subverting the immune response.

Acute Disease↗

PubMed2000

[Performance enhancement through training at medium altitude-- from the perspective of sports medicine].

In the last 20 years, maximal oxygen uptake (VO2max) of athletes in different sport disciplines has increased, and the world records in endurance sports have improved markedly. One of the factors that has influenced the increase in endurance performance has been perceived to be altitude training. In this paper we describe the advantages and disadvantages of a "regular" altitude training (live high/train high) aiming to improve sea level performance and compare it with a new method, the so called "live high/train low" method. This method uses the advantages and avoids the side effects of altitude exposure. Several papers have shown that altitude training is able to improve VO2max but the individual response may be substantially different. In most cases it is not possible to prove statistical significance and therefore we have no data about differences between both altitude training methods. However, it is suspected that the risk of overtraining is reduced in the high/low method. Although not statistically significant it is suggested that the "high/low" method can more efficiently improve endurance performance at sea level. A monitoring of submaximal variables of exercise performance is recommended to avoid overtraining and to control the development of performance. From the current knowledge the "live high/train low" method is suggested to be the more effective altitude training method for athletes.

Acclimatization↗

PubMed1999

The heart rate turn point reliability and methodological aspects.

PURPOSE: The aim of the study was to test protocol variations on the heart rate performance curve (HRPC) and the heart rate turn point (HRTP) according to Conconi et al. (1996). Respiratory gas exchange variables were used to define three phases of energy supply (I, II, III). METHODS: Eighteen healthy young male subjects performed 4 tests (T1-T4). T1: initial speed of 6 km x h(-1) followed by increments of 0.6 km x h(-1) every 60 s. Subjects were than randomized for the next three tests. T2: initial speed 5.6 km x h(-1) followed by increments of 0.2 km x h(-1) every 20 s; T3: similar to T2, in the second half of phase III acceleration (S) was increased. T4: like T2, at the beginning of phase III, S was increased. No differences were found in the degree of the deflection of the HRPC expressed as factor kHR between T1 (0.228 +/- 0.225) and T2 (0.248 +/- 0.231) but a significant increase was found in T3 (0.533 +/- 0.248) and T4 (0.770 +/- 0.258). RESULTS: The modifications of the protocol (T3 and T4) systematically influenced the deflection of the HRPC, but kHR was highly reproducible in all tests. Eleven subjects showed degrees of deflection in the HRPC in all tests. There were no significant differences for S, HR, and VO2 at the HRTP. An HRTP was not found in seven subjects in neither T1 or T2; however, in T3 and T4, these seven subjects showed a deflection of HRPC resulting from the protocol. The HRTP was found to be dependent on the start of the acceleration in phase III. In cases with a linear time course in the HRPC in T1 and T2, in T3 an HRTP was found at 15.6 km x h(-1) and in T4 at 13.6 km x h(-1) , respectively. CONCLUSION: The Conconi test protocol with an accelerated increase in S in the final phase of the test has a major influence on the occurrence of the HRTP in cases of near linear HRPC.

Adolescent↗

PubMed1999

CD2-mediated CD59 stimulation in keratinocytes results in secretion of IL-1alpha, IL-6, and GM-CSF: implications for the interaction of keratinocytes with intraepidermal T lymphocytes.

Normal epidermal keratinocytes are here shown to express membrane-associated complement inhibitory protein CD59 in vitro that protects keratinocytes from damage by complement because preincubation with blocking antibodies to CD59 renders the cells susceptible to complement mediated lysis. CD59 expression in keratinocytes is constitutive and not modulated by inflammatory cytokines, phorbol myristate acetate (PMA), and a number of other agents tested. Antibody mediated cross-linking of CD59, however, revealed an additional function of CD59: keratinocytes in vitro are activated to secrete the cytokines IL-1alpha, IL-6, and GM-CSF. CD59 mediated induction of these cytokines is regulated at the transcriptional level. Binding of keratinocytes to HL60 cells that express CD59 ligand CD2 induced the same pattern of secreted cytokines whereas binding to CD2-negative HL60 cells did not. Induction of cytokine secretion was completely blocked by preincubation of keratinocytes with both anti-CD58 and anti-CD59 antibodies together. The results demonstrate that CD2-mediated CD59 stimulation in human keratinocytes leads to synthesis of a particular set of cytokines implying a potential activation pathway in the interaction of keratinocytes with intraepithelial CD2+ T cells.

Antibodies, Blocking↗

PubMed1999

[Hypophyseal-hypothalamo-thyroid axis in affective disorders].

For centuries there has been convincing evidence that diseases of the thyroid gland may produce psychiatric symptoms. Nowadays systematic data are available concerning a higher incidence of thyroid diseases in psychiatric patients and vice versa a higher incidence of psychiatric disorders in thyroid patients. A more subtle approach concerns challenge tests like the TRH test. It could be shown that depressive patients show a blunted TSH response to TRH in 30-40% of the cases. This might lead to a definition of a subgroup of depressives from a psychoneuroendocrinological point of view. But it also might have an impact on the prediction of treatment outcome in psychopharmacological treatment approaches.

Anxiety Disorders↗

PubMed1998

Protective effects of fruits and vegetables against in vivo clastogenicity of cyclosphosphamide or benzo[a]pyrene in mice.

Seven fruits and 10 vegetables commonly consumed in Germany were investigated for their anticlastogenic potencies against cyclophosphamide (CP) and benzo[a]pyrene (BaP) in the in vivo mouse bone marrow micronucleus assay. We detected protective effects in 76.5% and 70.6% of the samples, respectively, and more or less distinct quantitative differences between the various plant materials and the two clastogens investigated. With respect to CP, moderate activities were exerted by sweet cherries, strawberries, cucumber, radish and tomatoes, average activities by bananas, oranges, peaches, asparagus and red beets and strong activities by yellow red peppers and especially spinach. Apples (cultivar Jona Gold), brussels sprouts, cauliflower and onions were inactive. With respect to BaP, we found moderate activities in strawberries, brussels sprouts and radish, average activities in sweet cherries, oranges, peaches, asparagus, red beets, cucumber and spinach and strong activities in bananas and kiwi. Apples, cauliflower, onions, tomatoes and yellow-red peppers were inactive. When oranges were fractionated according to previously described schemes (Edenharder et al., 1995), anticlastogenic activities against CP were exerted by materials extracted with n-hexane, acetone and 2-propanol and in the terminal residue, but not in the dichloromethane and water phases. With respect to BaP, materials extracted with acetone showed strong anticlastogenicity while the 2-propanol fraction, the aqueous phase and the terminal residue were less potent. The n-hexane and the dichloromethane fractions were inactive. In red beets, all fractions showed anticlastogenicity against CP and BaP as well. However, the n-hexane and dichloromethane fractions were most potent with respect to CP, while for BaP the aqueous phase and the terminal residue were most effective. These result suggest the presence of various (groups of) anticlastogenic compounds with different chemical structure.

Animals↗

PubMed1998

Parasympathetic receptor blockade and the heart rate performance curve.

Parasympathetic receptor blockade and the heart rate performance curve. Med. Sci Sports Sci., Vol. 30. No. 2, pp. 229-233, 1998. The aim of the present study was to investigate the influence of parasympathetic receptor blockade on the heart rate performance curve (HRPC). Twenty healthy male subjects performed a first cycle ergometer test (F), showing a HRPC deflection of varying degree and direction. Subjects then in random order performed two additional cycle ergometer tests, one with atropine (A) and the other with placebo (P). Two lactate turn points (LTP1, and LTP2) were determined by means of linear regression turn point analysis. The degree and direction of the deflection of the HRPC was calculated mathematically as factor kHR (kHR>0 = downsloping of HPRC; kHR<0 = upsloping of HRPC). In comparison with that in F and P, HR in A was significantly higher at rest, LTP1, LTP2, and during recovery, but not at Power(max). An upsloping deflection of the HRPC was seen in only five cases in F and P, whereas in A 10 cases were observed (P < 0.05). In A, kHR was significantly lower than in F and P. A significant correlation for kHR was found among F, P, and A. Independent from parasympathetic receptor blockade and the HR at Power(max), the HR at LTP2 was lower in cases with negative kHR (upsloping). In A as well as in P a significant correlation was observed between kHR and HR at LTP2. The individual time course of HRPC is reproducible and may be independent of parasympathetic activity.

Adult↗

PubMed1998

The heart rate performance curve and left ventricular function during exercise in patients after myocardial infarction.

PURPOSE: The aim of the study was to investigate the heart rate turn point (HRTP) in the time course of the heart rate performance curve (HRPC) in patients after myocardial infarction, and the relationship between the HRTP, the left ventricular function, and the second lactate turn point (LTP2). METHODS: We studied the degree and the direction of the HRPC and the left ventricular ejection fraction (LVEF) in 49 male patients 57 +/- 8 d after their first posterior wall infarction (MI). An incremental cycle ergometer test was performed and three phases of energy supply were defined (I: aerobic; II: aerobic-anaerobic transition; III: anaerobic) via blood lactate LA concentration. HRTP and LVEF-turn points (LVEFTP) were assessed by linear turn point analysis. The degree and direction of the deflection of HRPC were described as factor k (k > 0.1: downward deflection; -0.1 < k < 0.1: linear time curse; k < -0.1: upward deflection). The LVEF was determined by RNA. The difference between Pmax and LTP2 was calculated for LVEF (delta LVEF). RESULTS: An HRTP could be found in 44 and a LVEFTP in 47 cases. The HRTP occurred at 85 +/- 17 Watt (W), which correlated (r = 0.95; P < 0.001) with the LTP2 (84 +/- 17 W) and the LVEFTP (84 +/- 17 W, r = 0.93; P < 0.001). From LTP2 to Pmax a significant decrease in LVEF was found. There was a correlation between the percentage of HRmax at the HRTP and k (r = 0.70), as well as delta LVEF (r = 0.56). CONCLUSIONS: To prevent myocardial overloading, it seems to be useful to determine the HRTP, which indicate the workload where LVEF decreases.

Anaerobic Threshold↗

PubMed1998

[Total hysteroscopic endometrium resection: a critical analysis of indications, technique and results].

130 total hysteroscopic resections of the endometrium (RE) were performed at the Department of Gynecology and Obstetrics of the Deutschlandsberg Hospital from August 1, 1992 to May 31, 1997. 115 patients (88.5%) suffered from distinctive therapy-resistant uterine bleeding in terms of hypermenorrhea and menorrhagia, frequently combined with poly- and dysmenorrhea. 15 (11.5%) women who had previously been operated for breast cancer developed--during continuous treatment with tamoxifen--endometrial hyperplasia or polyps on which RE was performed after a hysteroscopic biopsy or resection had been carried out in a second setting. The operation showed that 98 out of 115 patients (85.2%) had pathologic anomalous uteri which were the organic cause of the uterine bleeding. Only 17 women (14.8%) suffered from dysfunctional uterine bleeding (12 cases) or from iatrogenically reduced coagulability (5 cases). The majority of the women (106 cases = 81.5%) were older than 40 (average 46.9 +/- 6.21 years). All RE were performed under inhalation anesthesia whereby the complete uterine cavity up to the inner orifice of the uterus was resected with the resectoscope loop. 92 out of 130 patients (70.8%) underwent a hysteroscopy or a dilatation and curettage before the RE. 77 patients (66.9%) received pretreatment with drugs to reduce the endometrium. 15 women (13.0%) underwent a laparoscopic tubal sterilization in the same setting. Finally, the results of 107 patients were analyzed excluding dropouts and patients who had undergone continuous treatment with tamoxifen and those who had an observation time of less than 6 months. After an observation period of 6-58 months, the success rate was 84.1%. For treatment of relapses 7 second resections were performed, whereby in 1 patient with a further uterine bleeding the uterus had to be extirpated. Nine of the 10 remaining patients had a hysterectomy, 1 patient refused any further treatment. The total hysterectomy rate was 12.2%. Basically, RE is absolutely practicable as far as the treatment of abnormal uterine bleeding is concerned, since hysterectomy can be avoided in a number of cases. Satisfactory long-term results, however, can only be achieved if indication and operation technique are of high quality. A problem which has not yet been solved is the indication and treatment of proliferating adenomyosis uteri interna.

Adult↗

PubMed1997

Synthesis of ganglioside GM1 containing a thioglycosidic bond to its labeled ceramide(s). A facile synthesis starting from natural gangliosides.

Capitalizing on the readily available ganglioside, GM1, we have devised a simple synthesis of labeled GM1 analogues with sulfur in place of oxygen in their linkage to the ceramide residue (SGM1). The sugar moiety of ganglioside GM1 was released by ozonolysis and subsequent alkaline fragmentation in good yield. During acetylation of the ganglioside sugar, the carboxyl group of the sialic acid residue lactonized with the 2-hydroxyl group of the inner galactose moiety (galactose II). The resulting sialoyl-II2-lactone of pentadeca-O-acetyl-monosialogangliotetraose could be readily transformed into the alpha-glycosyl bromide. Subsequent treatment of this glycosyl bromide with potassium thioacetate afforded the sialoyl-II2-lactone of tetradeca-O-acetyl-1-S-acetyl-1-thio-beta-monosialogangliotetra ose. The latter could be condensed with (2R, 3R, 4E)-3-O-benzoyl-2-dichloroacetamido-1-iodo-4-octadecen -3-ol in methanolic sodium acetate to afford a protected lyso-SGM1 derivative. One-step removal of the protecting groups under alkaline conditions gave beta-monosialogangliotetraosyl thiosphingosine. This lyso-SGM1 was converted into labeled analogues of SGM1 using the N-succinimidoyl derivative of radiocarbon-labeled octanoic and octadecanoic acid, respectively. Subsequent actions of GM1-beta-galactosidase, beta-hexosaminidase A, sialidase and again GM1-beta-galactosidase on these labeled analogues of SGM1 in the presence of taurodeoxycholate produced the respective analogues of GM2, GM3, lactosylceramide and glucosylceramide, respectively.

Carbohydrate Conformation↗

PubMed1997

Susceptibility of mononuclear phagocytes to influenza A virus infection and possible role in the antiviral response.

Among leukocytes, only monocytes and macrophages were found to be highly susceptible to an infection by influenza A virus. After infection, de novo viral protein synthesis was initiated but then interrupted after 4-6 h. Most macrophages died by apoptosis within 25-30 h. Before cell death, however, macrophages responded to influenza A virus with a high cytokine gene transcription and subsequent release of tumor necrosis factor alpha (TNF-alpha), interleukin-1 (IL-1), IL-6, interferon (IFN)-alpha/beta, and CC-chemokines. The basic mechanisms of virus-induced cytokine expression are still unknown and appear to involve transcription factors such as nuclear factor-kappaB and AP-1 which, however, were only activated for 2 h and declined below control values thereafter. After influenza A virus infection, only the mononuclear cell attracting CC-chemokines macrophage inflammatory protein 1alpha (MIP-1alpha), MIP-1beta, and RANTES were produced while the prototype neutrophil CXC-chemoattractants IL-8 and GRO-alpha were entirely suppressed. This selective induction of CC-chemokines may explain the preferential influx of mononuclear leukocytes into virus-infected tissue. Our data show that monocytes and macrophages represent a primary target for an influenza A virus infection. Thus, the mononuclear phagocyte response leads to a rapid proinflammatory reaction and an enhanced immigration of mononuclear leukocytes, which may condition the infected host for the subsequent virus antigen-specific defense.

Apoptosis↗

PubMed1997

Respiratory comfort of automatic tube compensation and inspiratory pressure support in conscious humans.

OBJECTIVE: To compare the new mode of ventilatory support, which we call automatic tube compensation (ATC), with inspiratory pressure support (IPS) with respect to perception of respiratory comfort. ATC unloads the resistance of the endotracheal tube (ETT) in inspiration by increasing the airway pressure, and in expiration by decreasing the airway pressure according to the non-linear pressure-flow relationship of the ETT. DESIGN: Prospective randomized single blind cross-over study. SETTING: Laboratory of the Section of Experimental Anaesthesiology (Clinic of Anaesthesiology; University of Freiburg). SUBJECTS: Ten healthy volunteers. INTERVENTIONS: The subjects breathed spontaneously through an ETT of 7.5 mm i.d. Three different ventilatory modes, each with a PEEP of 5 cmH2O, were presented in random order using the Dräger Evita 2 ventilator with prototype software: (1) IPS (10 cmH2O, 1 s ramp), (2) inspiratory ATC (ATC-in), (3) inspiratory and expiratory ATC (ATC-in-ex). MEASUREMENTS AND MAIN RESULTS: Immediately following a mode transition, the volunteers answered with a hand sign to show how they perceived the new mode compared with the preceding mode in terms of gain or loss in subjective respiratory comfort: "better", "unchanged" or "worse". Inspiration and expiration were investigated separately analyzing 60 mode transitions each. Flow rates were continuously measured. The transition from IPS to either type of ATC was perceived positively, i.e. as increased comfort, whereas the opposite transition from ATC to IPS was perceived negatively, i.e. as decreased comfort. The transition from ATC-in to ATC-in-ex was perceived positively whereas the opposite mode transition was perceived negatively in expiration only. Tidal volume was 1220 +/- 404 ml during IPS and 1017 +/- 362 ml during ATC. The inspiratory peak flow rate was 959 +/- 78 ml/s during IPS and 1048 +/- 197 ml/s during ATC. CONCLUSIONS: ATC provides an increase in respiratory comfort compared with IPS. The predominant cause for respiratory discomfort in the IPS mode seems to be lung over-inflation.

Adult↗

PubMed1997

The Conconi test.

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Anaerobic Threshold↗