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Biomedical subjects

M Oswald

Publications and source records attributed to M Oswald.

At least 37 records · Page 2Linked to original sources
PubMed1996

Pulmonary hypertension in the obstructive sleep apnoea syndrome: prevalence, causes and therapeutic consequences.

"Cor pulmonale" is a classic feature of the "Pickwickian syndrome". Earlier studies have reported a high prevalence of pulmonary hypertension (PH) in obstructive sleep apnoea (OSA) patients, but this has not been confirmed by recent studies with a more adequate methodology, including larger groups of patients. The first part of this review is devoted to the prevalence of PH in OSA; most recent studies agree on prevalence of 15-20%. The second (and major) part of the study deals with the causes and mechanisms of PH in OSA. Pulmonary hypertension is rarely observed in the absence of day-time hypoxaemia, and the severity of nocturnal events (apnoea index (AI), apnoea+ hypopnoea index (AHI) does not appear to be the determining factor of PH. Diurnal arterial blood gas disturbances and PH are most often explained by the presence of severe obesity (obesity-hypoventilation syndrome) and, principally, by association of OSA with chronic obstructive pulmonary disease (the so called "overlap syndrome"). Bronchial obstruction is generally of mild-to-moderate degree and may be asymptomatic. The final part of the review analyses the therapeutic consequences of the presence of PH in OSA patients. Pulmonary hypertension, which is generally mild-to-moderate, does not need a specific treatment. When nasal continuous positive airway pressure (CPAP) fails to correct sleep-related hypoxaemia, supplementary oxygen must be administered. In patients with marked daytime hypoxaemia (arterial oxygen tension (Pa,O2), < or = 7.3 kPa (55 mmHg) conventional O2 therapy (nocturnal + diurnal) is required.

Adult↗
PubMed1996

Pulmonary hemodynamics in the obstructive sleep apnea syndrome. Results in 220 consecutive patients.

We have investigated pulmonary hemodynamics in a large series of consecutive, unselected patients with obstructive sleep apnea syndrome (OSAS). The aims of this study were to evaluate the frequency of pulmonary artery hypertension (PH) in OSAS and to analyze, as far as possible, its mechanisms. Two hundred twenty patients were included on the basis of a polysomnographic diagnosis of OSAS (apnea+hypopnea index > 20). PH, defined by a resting mean pulmonary artery mean pressure (PAP) of at least 20 mm Hg, was observed in 37 of 220 patients (17%). Patients with PH differed from the others with regard to pulmonary volumes (vital capacity [VC], FEV1) and the FEV1/VC ratio that were significantly lower (p < 0.001); PaO2 (64.4 +/- 9.3 vs 74.7 +/- 10.1 mm Hg; p < 0.001); PaCO2 (43.8 +/- 5.4 vs 37.6 +/- 3.9 mm Hg; p < 0.001), apnea+hypopnea index (100 +/- 33 vs 74 +/- 32; p < 0.001), and mean nocturnal arterial oxygen saturation (SaO2) (88 +/- 6% vs 94 +/- 2%; p < 0.001). Patients with PH were also more overweight (p < 0.001). Multiple regression analysis showed that 50% of the variance of PAP could be predicted by an equation including PaCO2 (accounting for 32% of the variance), FEV1 (12%), airway resistance (4%), and mean nocturnal SaO2 (2%). In conclusion, PH is observed, in agreement with previous studies, in less than 20% of OSAS patients. PH is strongly linked to the presence of an obstructive (rather than restrictive) ventilatory pattern, hypoxemia, and hypercapnia, and is generally accounted for by an associated obstructive airways disease. In this regard, the severity of OSAS plays only a minor role.

Adult↗
PubMed1995

Association of HLA class I antigen deficiency related to a TAP2 gene mutation with familial bronchiectasis.

Two siblings with pansinusitis, nasal polyps, and bronchiectasis were found to have histocompatibility lymphocyte antigen (HLA) class I antigen deficiency ("bare lymphocyte syndrome") and dysfunction of natural killer cells. Reduced class I cell surface expression resulted from a single mutation in the TAP2 gene, which is located in the class II region of the major histocompatibility complex and encodes subunit 2 of the class I peptide transporter. The defect was transmitted in an autosomal recessive manner. This deficiency did not lead to severe viral infections but was apparently associated with susceptibility to bacterial infections of the respiratory mucosae. We suggest that class I HLA typing should be systematically performed in children with unexplained bronchiectasis.

Adolescent↗
PubMed1995

Association of chronic obstructive pulmonary disease and sleep apnea syndrome.

The association of chronic obstructive pulmonary disease (COPD) and sleep apnea syndrome (SAS), which are both frequent diseases, is likely to occur in a number of patients. We have prospectively investigated a large series (n = 265) of patients who were selected solely on the basis of a confirmed diagnosis of SAS (apnea + hypopnea index > 20/hr). An obstructive spirographic pattern, defined by an FEV1/VC ratio < or = 60%, was observed in 30 of 265 patients (11%). These patients (subgroup "overlap") were older (58 +/- 9) versus 53 +/- 10 yr, p = 0.01) than the remainder of the study population, and all were male patients. Body mass index (BMI) was identical in overlap patients to that in the remainder. Vital capacity and FEV1 were lower, by definition, in the overlap group. PaO2 was lower (66 +/- 10 versus 74 +/- 10 mm Hg, p < 0.001) and PaCO2 higher (42 +/- 6 versus 38 +/- 4 mm Hg, p < 0.001) in the overlap group. Hypoxemia (Pao2, < or = 65 mm Hg) was observed in 17 of 30 overlap patients and in 54 of 235 of the remainder. Hypercapnia (Paco2 > or = 45 mm Hg) was observed in 8 of 30 overlap patients and in 19 of 235 of the remainder. The pulmonary artery mean pressure (PAP) was higher in overlap patients both at rest (20 +/- 6 versus 15 +/- 5 mm Hg, p < 0.01) and during steady-state exercise (37 +/- 12 versus 29 +/- 10 mm Hg, p = 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiac Catheterization↗
PubMed1995

[Possibilities of surgical therapy in prostatic carcinoma].

Radical surgical treatment of localized prostate cancer is performed to heal the patient of his malignant disease. Surgery for advanced prostate cancer, e.g. transurethral resection for obstruction or hemorrhage, is always a palliative modality and has to be seen in the context of systemic treatment. Radical prostatectomy is a major intervention which allows complete removal of the prostate gland and the seminal vesicles at the same time. Due to resection at the distal end of the prostatic urethra, the bladder sphincter system is partially destroyed. In general, to guarantee radicality, the erectile nerves and vessels are sectioned, resulting in erectile impotency. Preservation of these structures to maintain potency is indicated only exceptionally. Radical prostatectomy is today a routine operation with minimal mortality (0.5-1%) and minor complication rate. Average hospitalization is about 10 days. Long-term postoperative morbidity is characterized by urinary incontinence and erectile impotency. Incontinence takes a long time to heal. A certain number of patients will keep a generally not very bothersome stress dribbling; however, some may show complete leakage, necessitating an anti-incontinence operation. For an indication of radical prostatectomy, two essential factors have to be considered: the usually extremely slow growth of prostate cancer and the high prevalence of clinically insignificant latent carcinomas. It is for these reasons and for the consequences on live quality that radical prostatectomy should not be performed on patients with a life expectancy of less than 10 years.

Aged↗
PubMed1994

Medical treatment of pulmonary hypertension in chronic lung disease.

In chronic respiratory diseases, especially chronic obstructive pulmonary disease (COPD) pulmonary arterial hypertension is generally mild to moderate and the necessity for treating it can, therefore, be questioned. In fact, pulmonary hypertension, even when modest, may worsen markedly during acute episodes, exercise and sleep. These acute increases in mean pulmonary artery pressure (PAP) could contribute to the development of right heart failure. Therefore, the medical treatment of pulmonary hypertension is justified. There are, at the present time, no selective pulmonary vasodilators, with the exception of inhaled nitric oxide. Indeed, vasodilators appear less effective in COPD compared to primary pulmonary hypertension. Thus, there is, at present, no justification for the long-term use of vasodilators in COPD patients. Long-term oxygen therapy (LTOT) attenuates and sometimes reverses the progression of pulmonary hypertension, although the condition rarely returns to normal. We do not know whether the structural changes of the pulmonary vasculature in COPD patients are potentially reversible with LTOT. The longer the daily duration of LTOT the better are the haemodynamic results. At present, LTOT remains the best treatment for pulmonary hypertension in COPD patient. In the future, treatment of this condition in COPD patients could combine LTOT and specific vasodilators.

Humans↗
PubMed1994

Pulmonary hemodynamics in patients with chronic obstructive pulmonary disease before and during an episode of peripheral edema.

We have investigated pulmonary hemodynamics in 16 patients with COPD with respiratory insufficiency, exhibiting marked peripheral edema. All the patients had previously undergone, within the last 6 months (T1), a right heart catheterization, in a stable state of their disease, when they were free of edema. Patients were subdivided into two groups according to the level of right ventricular end-diastolic pressure (RVEDP) during the episode of edema (T2): patients with a markedly elevated RVEDP (> 12 mm Hg) indicating the presence of right ventricular failure (RVF) = group 1, n = 9; patients with a normal or slightly elevated RVEDP (< 12 mm Hg) = group 2 (no RVF), n = 7. In group 1 pulmonary artery mean pressure (PAP) increased very significantly from T1 (27 +/- 5) to T2 (40 +/- 6 mm Hg, p < 0.001) as did RVEDP, from 7.5 +/- 3.9 to 13.4 +/- 1.2 mm Hg (p < 0.001). These hemodynamic changes paralleled a marked worsening of arterial blood gases, PaO2 falling from 63 +/- 4 to 49 +/- 7 mm Hg (p < 0.01) and PaCO2 increasing from 46 +/- 7 to 59 +/- 14 mm Hg (p < 0.01). On the other hand, in group 2, PAP was stable during the episode of edema (from 20 +/- 6 to 21 +/- 5 mm Hg), as was RVEDP (from 5.5 +/- 2.4 to 5.1 +/- 1.5 mm Hg), and changes in arterial blood gases from T1 to T2 were small and nonsignificant. It is concluded that RVF is effectively present in at least some patients with COPD with peripheral edema and is associated with a significant increase of PAP from baseline, probably accounted for by hypoxic vasoconstriction. Thus, pressure overload may contribute to the development of RVF. In other patients there are no hemodynamic signs of RVF, PAP is stable, and the origin of edema is not well understood.

Aged↗
PubMed1992

Nature and rate of vascular refilling during hemodialysis and ultrafiltration.

The change of blood volume, of blood and plasma density (rho b, rho p) following a short ultrafiltration pulse (duration: 20 min; mean rate -35 ml/min) within the first hour of hemodialysis was analyzed in 13 hemodynamically stable patients (30 single measurements). Protein concentration of refilling volume (7 g/liter) was calculated from its density (1009.25 +/- 3.7 kg/m3, at 20 degrees C) and from the linear relationship between plasma density and protein concentration (cp) of uremic plasma samples (rho p = 1007.46 + 0.2422 x cp). The filtration coefficient (Lp,calc) determined from a relation derived from Starling's hypothesis was 5.6 +/- 1.4 ml/(min.mm Hg.50 kg lean body mass); N = 13, mean +/- SD, minimum 3.2, maximum 8.0. A model describing the dynamics of blood and plasma volume was developed. It was fit to on-line measurements of relative blood volume changes by variation of the filtration coefficient and of initial blood volume (Lp,fit, Vb,fit). The linear regression between Vb,fit and blood volume determined from anthropometry (Vb,calc) was highly significant (r = 0.79, N = 30, P < 0.001). Compared to Vb,calc, Vb,fit was typically increased by 21 +/- 11%, reflecting a fluid overload at the beginning of the treatment. Lp,fit was not different from Lp,calc. Lp,fit significantly increased with blood volume excess. Due to the small but definite protein content of refilling volume, the model accounts for increased blood volume recovery and occasional overshoot of blood and plasma volumes following ultrafiltration.

Adult↗
PubMed1992

Benefit from long-term O2 therapy in chronic obstructive pulmonary disease patients.

The Nocturnal Oxygen Therapy Trial (NOTT) and Medical Research Council (MRC) trial have clearly indicated that long-term oxygen therapy (LTO) improved survival in patients with hypoxemic chronic obstructive pulmonary disease (COPD), but the mechanisms accounting for this improved survival could not be established. In particular, there was no link between survival and changes in pulmonary hemodynamics. More recent studies have shown even better results of survival in patients under LTO after at least 5 years. LTO improves the quality of life in these patients by improving their neuropsychological condition, by increasing their walking distance, and by reducing the time spent in hospital. Whether LTO improves pulmonary hemodynamics and right ventricular function is still debated. No significant changes in mean pulmonary artery pressure (PAP) were observed in the MRC study in patients receiving O2 during greater than 15 h/day, whereas a modest but significant fall in PAP was noticed after 6 months in the NOTT patients receiving O2 during greater than 18 h/day. In our own study, confirmed by more recent data from our laboratory, a reversal in the progression of pulmonary hypertension was observed in patients receiving O2 during greater than 16 h/day, but it is not possible to say whether a rather small decrease in PAP and pulmonary vascular resistance will have favorable effects on life expectancy. Presently, we do not know whether LTO can reverse, at least partially, the structural changes in the pulmonary vessels possibly induced by chronic alveolar hypoxia, and we need to perform further studies in this field.

Clinical Trials as Topic↗
PubMed1992

Chronic obstructive pulmonary disease and sleep apnea syndrome.

The term "overlap syndrome" was introduced by Flenley to describe the association of sleep apnea syndrome (SAS) with chronic obstructive pulmonary disease (COPD). Epidemiologic data on the prevalence of the overlap syndrome are not available, but the frequency of an associated COPD in SAS patients has been emphasized in almost all the studies analyzing the development of respiratory insufficiency in SAS patients. In a large series (n = 264) of unselected SAS patients who had undergone detailed pulmonary function tests, we observed an obstructive ventilatory defect (FEV1/VC < 60%) in 30 of 264 patients (11%). These patients had lower daytime PaO2 and higher PaCO2 than the other patients and they had higher resting and exercising pulmonary artery mean pressure (right heart catheterization was performed in 215 of 264 patients). We conclude that the risk of developing respiratory insufficiency and cor pulmonale is higher in overlap patients.

Adult↗
PubMed1991

Fibronectin is a non-viral substrate for the HIV proteinase.

The retrovirus encoded proteinase (PR) is required for the proper maturation of viral particles into infectious virus. The PR had been considered highly substrate specific, cleaving exclusively the viral gag and gag-pol protein precursor. It has recently been reported, however, that cytoskeleton and other cellular filament proteins can be cleaved by the HIV-1 PR. Here we have evidence that a cell-associated protein, the fibronectin (A-chain), is also cleaved in vitro specifically by this PR. The possibility of a cytotoxic role of the PR is conceivable.

Amino Acid Sequence↗
PubMed1991

[Pulmonary artery hypertension in chronic respiratory diseases].

Pulmonary hypertension (PH) is one of the evolutive complications in respiratory diseases leading to chronic respiratory insufficiency (CRI). In most cases PH is mild, but acute worsening can happen and especially during exercise, during sleep (particularly during rapid-eye-movement sleep) and during acute respiratory failure. Usually, pulmonary artery pressure finds again the level observed prior to the worsening. Although PH is usually mild, it is of prognostic value in CRI and particularly in patients with chronic obstructive pulmonary disease (CODP): the survival rate is significantly lower in patients with PH compared with those without PH and the higher PAP is the lower the survival rate. In general, long-term changes in PAP in COPD patients are mild. Long-term oxygen therapy can reverse the progression of PH and increase the survival rate. PH can lead with more or less delay to cor pulmonale and right heart failure (RHF). Oedema can be due to RHF but in some cases they can also be explained by the stimulation of the renin-angiotensin system with increasing of the aldosterone level, due to the fall in renal blood flow. These renal hemodynamic changes are related to arterial blood gas changes (hypercapnic acidosis, hypoxemia).

Chronic Disease↗
PubMed1991

Evolution of physiological variables in patients with chronic obstructive pulmonary disease before and during long-term oxygen therapy.

In 24 patients with severe chronic obstructive pulmonary disease (COPD), we investigated the evolution of pulmonary volumes, arterial blood gases (ABG) and mean pulmonary artery pressure (PAP), before (T0-T1) and during (T1-T2) long-term oxygen therapy (LTO). LTO was initiated at T1 on usual criteria (PaO2 persistently less than or equal to 55 mm Hg) and was given during greater than or equal to 16 h/day. The T0-T1 period ranged from 12 to 186 months (mean 53 +/- 41 months) and the T1-T2 period from 12 to 120 months (mean 44 +/- 30 months). There was a significant worsening of the obstructive pattern (FEV1 decreasing from 1,084 +/- 326 to 879 +/- 318 ml, p less than 0.005) and of ABG (PaO2 decreasing from 58.2 +/- 9.2 to 51.6 +/- 6.5 mm Hg, p less than 0.01) before the onset of LTO, whereas there was a rather good stability of ABG during LTO and the changes in pulmonary volumes were modest and statistically nonsignificant (FEV1 decreased from 879 +/- 318 to 809 +/- 247 ml). PAP tended to increase from T0 to T1 and to decrease from T1 to T2, but these changes only reached the level of statistical significance when they were expressed as changes per year (+1.0 +/- 2.7 vs. -1.3 +/- 4.5 mm Hg, p less than 0.05). The evolution of physiological variables was nearly identical in subgroups of patients who had died (n = 13) or were still alive (n = 11) at the time of data collection (T3) and this held particularly true for PAP.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Pressure↗
PubMed1991

Inhibition of the retroviral HIV-proteinase impairs maturation to infectious human immunodeficiency virus (HIV).

Newly developed inhibitors block the aspartic-type retroviral proteinase of the human immunodeficiency virus (HIV) at nanomolar concentration. The viral proteinase is responsible for the processing of viral encoded proteins. Applied to HIV infected cell culture, these inhibitors exhibit antiviral effects. The detailed analysis of these antiviral effects demonstrated that the synthesis of viral particles is only minimally decreased while the rate of infectious HIV particles is substantially reduced. The lack of infectivity is due to a failure in particle maturation which again is caused by the inhibition of the viral proteinase.

Antiviral Agents↗
PubMed1991

Frequency and mechanism of daytime pulmonary hypertension in patients with obstructive sleep apnoea syndrome.

In order to study the frequency and the mechanisms of daytime pulmonary hypertension (PH) in obstructive sleep apnoea syndrome (OSAS) lung function tests, blood gas analysis and right-heart catheterization were performed in 46 consecutive patients. OSAS was assessed by polysomnography. 9 patients only (20%) had PH (mean pulmonary artery pressure (Ppa) greater than or equal to 20 mmHg). Patients with PH had lower daytime PaO2 (60.8 +/- 7.6 vs. 76.2 +/- 9.4 mmHg; p less than 0.001), higher daytime PaCO2 (44.8 +/- 4.2 vs. 38.0 +/- 4.0 mmHg; p less than 0.001), lower forced vital capacity (FVC) and forced expiratory volume (FEV1) (p less than 0.001), but the severity of OSAS was not different whether PH was present or not (apnoea index: 62 +/- 34 hour in the PH group vs. 65 +/- 40 hour, apnoea + hypopnoea index 102 +/- 33 hour in the PH group vs. 86 +/- 36 hour, lowest sleep SaO2: 59 +/- 21% in the PH group vs. 66 +/- 18%). There were significant correlations between Ppa and: daytime PaO2 (r = -0.61; p less than 0.001), PaCO2 (r = 0.55; p less than 0.001), FEV1 (r = -0.52; p less than 0.001) but not between Ppa and apnoea index, apnoea + hypopnoea index, lowest sleep SaO2. PH and daytime hypoxaemia were associated either with chronic airway obstruction or with severe obesity.

Adult↗