Biomedical subjects

J Krieger

Publications and source records attributed to J Krieger.

At least 91 records · Page 5Linked to original sources

PubMed1997

An evaluation of bioactive ceramic in the treatment of periodontal osseous defects.

Bioglass particulates were surgically placed in the periodontal osseous defects of 12 patients. The clinical parameters studied were probing depth, attachment level as measured with the Florida Probe, and standardized bitewing radiograph comparisons. Data was collected initially, and at 3-, 6-, and 24-month posttreatment intervals. Statistically significant improvements were demonstrated in all clinical parameters studied. There was a mean probing depth reduction of 3.33 mm, a mean attachment gain of 1.92 mm, and a mean radiographic bone fill of 3.47 mm. Results were stable over the 24-month period. Ease of handling and excellent tissue response were characteristic of the material.

Adult↗

PubMed1996

Expression of an olfactory receptor in Escherichia coli: purification, reconstitution, and ligand binding.

An olfactory receptor has been expressed in bacterial cells as a fusion protein with glutathione S-transferase (GST). Overexpression of receptor protein yielding about 10% of the cell protein was achieved with mutants lacking the N-terminus and the first transmembrane region or with mutants carrying three positively charged residues in the first intracellular loop. The overexpressed fusion protein accumulated in inclusion bodies and could be solubilized in detergent. It was purified by metal chelation chromatography based on a C-terminal 6-histidine tag, and the GST portion was removed after proteolytic cleavage. The purified receptor was reconstituted into lipid vesicles and specific binding of odor ligands was shown by photoaffinity labeling and tryptophan fluorescence measurements. Thus, for the first time, an odorant receptor/ligand pair becomes available in large amounts for biophysical and screening studies.

Amino Acid Sequence↗

PubMed1996

[Sleep-related respiratory disorders].

Sleep-related respiratory disorders are mainly represented by the consequences of partial or total upper airway obstruction during sleep, which lead to clinical pictures ranging from "pure" snoring to full-blown obstructive sleep apnea syndrome, including obstructive sleep hypopnea syndrome and upper airway resistance syndrome. These pictures share symptoms like snoring and excessive daytime sleepiness. Beyond the social and professional impairment and the increased risk of traffic and work accidents, these patients are exposed to the complications of systemic hypertension, which is often associated, and of less frequent cardiorespiratory failure. The diagnosis is based upon polysomnography which demonstrates the ventilation abnormalities. Since stable weight loss is most often impossible to obtain, the treatment of choice is based on nasal continuous positive airway pressure during sleep. In some selected cases, facial bone surgery may be helpful.

Adolescent↗

PubMed1996

[Medical treatment of snoring and obstructive sleep apnea syndrome].

Although snoring may have deleterious effects by itself, its only clearly identified hazard is that of a social nuisance; therefore, treatment of snoring should before all make no harm. Conversely, the potential hazards of obstructive sleep apnea are well established, and it is clearly important to eliminiate sleep apneas. The medical treatments which may improve snoring and obstructive sleep apneas are basically the same. They include avoidance of risk factors such as obesity, alcohol and hypnotics as well as active treatments such as positional treatment, dental appliances and by nasal continuous positive airway pressure. Nasal continuous positive airway pressure has become the treatment of choice for obstructive sleep apnoea, since it is both efficient and safe. Its only limitation is related to variable acceptance by patients.

Dental Prosthesis↗

PubMed1996

Binding proteins from the antennae of Bombyx mori.

From an antennal library of Bombyx mori cDNA clones encoding different binding proteins have been isolated. The deduced amino acid sequences showed only moderate homology to each other but shared several common structural features. Based on a sequence comparison with the antennal binding proteins from different moth species, one of the clones appears to encode a pheromone binding protein, whereas two others represent new members of the two general odorant binding protein families. A fourth clone encodes a protein which is related to antennal binding proteins so far found only in Drosophila melanogaster.

Amino Acid Sequence↗

PubMed1996

[Propensity for sleep and diurnal somnolence in the course of sleep apnea syndrome].

Daytime sleepiness is one of the major symptoms of obstructive sleep apnea. However, its definition raises problems, since it may be based on either subjective feeling (evaluated by means of questionnaires or analog visual scales), physiological drive or need (inferred by a sleep latency) or on the concept of sleep propensity defined as the probability of falling asleep (measured by the occurrence of sleep in various circumstances of daily life). Data from the literature suggest that sleep fragmentation and hypoxemia, both related to sleep apneas, cause daytime sleepiness. Our own data show that sleep propensity in a group of 44 patients with obstructive sleep apnea was correlated with the increase in esophageal pressure swings during obstructive apneas. This result suggests that the increased respiratory effort against occluded upper airways also contributes to daytime sleepiness in patients with obstructive sleep apnea.

Circadian Rhythm↗

PubMed1996

Long-term compliance with CPAP therapy in obstructive sleep apnea patients and in snorers.

A prospective study aimed at objectively evaluating compliance with nasal continuous positive airway pressure (CPAP) treatment was conducted in 728 obstructive sleep apnea [OSA; apnea/hypopnea index (AHI) > 15 events/hour] patients and 98 nonapneic snorers (AHI < or = 15 events/hour). Five-hundred seventy-five OSA patients and 33 nonapneic snorers underwent CPAP therapy and were followed-up for an average of 1,176 +/- 38 days (27 to 4,203 days). Compliance to treatment was measured by the mean rate of use of the CPAP device obtained from a built-in time counter. Acceptance of treatment was measured using Kaplan-Meier's model. The acceptance of CPAP was greater than 90% at 3 years and greater than 85% at 7 years in OSA patients. It was greater than 60% at 3 years in nonapneic snorers. The mean rate of CPAP use was 5.7 +/- 1.8 hours/day in OSA patients and 5.6 +/- 1.4 hours/day in snorers who were still on CPAP on October 1, 1995. It was correlated positively with age, body mass index, and AHI, and it was correlated negatively with daytime partial pressure of oxygen (PaO2), forced expiratory volume in 1 second (FEV1), and vital capacity in the group of OSA patients. This study shows that CPAP therapy is reasonably accepted by OSA patients as well as by nonapneic snorers. Both within and between groups, objective disease severity (as measured by the respiratory event index and daytime and nighttime hypoxemia), rather than patients' symptoms or complaints, seemed to play a role in the quality of compliance to treatment.

Body Mass Index↗

PubMed1996

Role of chemosensitivity in intrathoracic pressure changes during obstructive sleep apnea.

We tested the hypothesis that the awake ventilatory response to hypoxia and hypercapnia may contribute to the variability of respiratory effort developed in response to upper airway obstruction in obstructive sleep apnea syndrome. The polygraphic recordings of 38 patients diagnosed as having obstructive sleep apnea on the basis of an apnea+hypopnea index greater than 10 were examined. All subjects received hypoxic and hypercapnic ventilatory tests the day before the nocturnal polysomnography. Thirty apneas during non-rapid eye movement (NREM) sleep and at least 10 apneas during rapid eye movement sleep were analyzed. For each considered apnea, we measured esophageal pressure (Pes) swings during the first three breaths preceding apnea and during the first three and last three occluded efforts occurring during the apnea. We considered as indices of respiratory effort the overall increase from the minimum to the maximum Pes (delta Pes), the rate of increase of Pes during apnea (RPes), and the maximal respiratory effort at the end of apnea (Pes max fin). In NREM sleep, all three indices of respiratory effort were correlated positively with the awake ventilatory response to hypoxia or hypercapnia and with the apnea index. No correlation was found between the indices of respiratory effort and body mass index, age, pulmonary function tests, awake blood gases, apnea duration, and apnea desaturation. In rapid eye movement sleep, none of the considered variables predicted the degree of respiratory effort. In conclusion, our results suggest that the degree of ventilatory response to upper airway occlusion in obstructive sleep apnea may be influenced by the sensitivity of central neural drive to chemical stimuli.

Adult↗

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↗

PubMed1996

Respiratory effort. A factor contributing to sleep propensity in patients with obstructive sleep apnea.

To test the hypothesis that respiratory effort during obstructive apneas contributes, together with hypoxemia and sleep fragmentation, to excessive daytime sleepiness, we investigated the relationship between daytime sleepiness and polysomnographic variables in 44 patients with obstructive sleep apnea (OSA). In all patients, daytime sleep propensity was assessed by an 11-item standardized self-questionnaire yielding a sleepiness score and by a modified sleep latency test yielding a mean sleep latency. Respiratory effort during apneas was evaluated by measuring esophageal pressure swings using an esophageal balloon. Within each apneic cycle, we measured the esophageal pressure swings during the first three and the last three occluded efforts during the apnea to define the overall increase, its ratio to apnea duration, and the maximal effort developed during obstruction. In the group of patients as a whole, the sleepiness score was negatively correlated with the mean sleep latency (r=-0.38, p=0.01). The sleepiness score was correlated with the indexes of respiratory effort during apneas (ie, the overall increase, its ratio to apnea duration, and the maximal end-apneic swing in esophageal pressure) and with the apnea+hypopnea index. The mean sleep latency was correlated with all indexes of nocturnal hypoxemia (ie, the mean lowest oxyhemoglobin saturation [SaO2] and the index of apnea associated with a fall in SaO2 below 90% and 80%). We conclude that the degree of respiratory effort during obstructive apneas contributes to self-rated sleep propensity in patients with OSA.

Adult↗

PubMed1996

Respiratory effort during sleep apneas after interruption of long-term CPAP treatment in patients with obstructive sleep apnea.

Apneas generally reappear in patients with obstructive sleep apnea (OSA) when treatment with continuous positive airway pressure (CPAP) is interrupted. However, a single-night treatment interruption may be associated with a lesser severity of sleep apneas than before treatment. We hypothesized that this decrease in severity of sleep apneas reflects changes in the respiratory response to upper airway obstruction. Therefore, we compared indexes of respiratory effort during sleep in 25 patients with OSA before and after 1 year of CPAP treatment. Respiratory effort was assessed by means of an esophageal balloon. After 1 year of CPAP treatment, there was a decrease in the maximal end-apneic esophageal pressure swings (Pes) (from 56.7 +/- 5.4 to 30.3 +/- 2.6 cm H2O; p = 0.000; mean +/- SEM), in the overall increase in Pes during an apnea (35.2 +/- 3.6 vs 16.5 +/- 1.5 cm H2O; p = 0.000), as well as the rate of increase in Pes (1.1 +/- 0.1 vs 0.6 +/- 0.1 cm H2O/s; p = 0.000). Although body mass index (BMI) did not change significantly, the individual changes in BMI significantly correlated with the changes in respiratory effort after 1 year of CPAP treatment. Apnea duration and apnea-related oxygen desaturation also decreased significantly. We conclude that long-term CPAP treatment induces changes in respiratory control that persist at least on the first night of treatment interruption.

Esophagus↗

PubMed1995

[Sleep and COPD].

In COPD patients hypoxaemia does worsen during sleep and particularly during REM sleep. However, severe sleep-related O2 desaturation is only observed in patients who exhibit a marked daytime hypoxaemia. Nocturnal desaturation is due to the combination of alveolar hypoventilation and ventilation-perfusion mismatch; alveolar hypoventilation is the predominant mechanism, at least during REM sleep. Sleep-related hypoxaemia leads to peaks of pulmonary hypertension but also to cardiac arrhythmias. Hypoxaemia can be particularly severe when COPD is associated with a sleep apnoea syndrome (this association is rather frequent). A severe nocturnal desaturation needs a treatment with prolonged oxygen therapy, especially if daytime hypoxaemia (PaO2 < 55-60 mmHg) is present. The real benefit from oxygen therapy limited to sleep time in nocturnal desaturators who have not a significant daytime hypoxaemia, has not been yet demonstrated.

Humans↗

PubMed1995

Two classes of olfactory receptors in Xenopus laevis.

Xenopus laevis possess a gene repertoire encoding two distinct classes of olfactory receptors: one class related to receptors of fish and one class similar to receptors of mammals. Sequence comparison indicates that the fish-like receptors represent closely related members of only two subfamilies, whereas mammalian-like receptors are more distantly related, most of them representing a different subfamily. The fish-like receptor genes are exclusively expressed in the lateral diverticulum of the frog's nose, specialized for detecting water-soluble odorants, whereas mammalian-like receptors are expressed in sensory neurons of the main diverticulum, responsible for the reception of volatile odors.

Amino Acid Sequence↗

PubMed1995

Prolactin secretion during sleep in obstructive sleep apnoea patients.

Plasma prolactin (PRL) concentration exhibits a sleep-dependent pattern, with highest levels during sleep and lowest levels during the waking period. The syndrome of obstructive sleep apnoea (OSA) is associated with severe hypoxaemia and chronic sleep fragmentation, both of which could affect the sleep-entrained PRL rhythm. Treatment with nasal continuous positive airway pressure (CPAP) immediately restores a normal sleep structure by successful abolition of the apnoeas. In the present study, seven OSA patients underwent two night studies, once when no treatment was given and once during the first night of CPAP treatment. Sleep was recorded polygraphically in all experiments. Plasma PRL was measured at 10 min intervals and secretory rates were calculated by a deconvolution procedure. CPAP treatment greatly reduced hypoxaemia and improved sleep quality. The secretory pulse amplitude and the total amount of PRL secreted during the night remained constant regardless of whether patients were treated or not. The only difference found was a lower pulse frequency in untreated OSA patients as compared to treated patients, which may be attributed either to hypoxaemia or to sleep disturbance or to the combined action of both. Treatment may be considered to normalize PRL release by restoring pulse frequency to values similar to those observed for normal subjects.

Journal Article↗

PubMed1995

Regulation of plasma volume during obstructive sleep apnoea.

The evidence that plasma volume is altered in obstructive sleep apnoea is an indirect one, based on the observation of a paradoxical elimination of peripheral oedema along with a decrease in water and sodium excretion and of a decrease in haematocrit when apnoeas are eliminated with continuous positive airway pressure (CPAP) treatment. A suggested interpretation of these observations is that in the untreated condition, increased renal sodium excretion and increased vascular membrane permeability lead to increased urine and salt excretion and to a fluid shift from the plasma to the extracellular space, causing nocturnal polyuria, peripheral oedema and haemoconcentration. Treatment with continuous positive airway pressure reverses the increased membrane permeability and urine excretion, allowing the peripheral oedema to resolve and the haematocrit to decrease. Increased atrial natriuretic peptide release and decreased renin-angiotensin-aldosterone activity, along with an increased release of thromboxane and of endothelin (which have been reported in untreated obstructive sleep apnoea), could be the mechanisms of the observed alterations in fluid distribution in obstructive sleep apnoea.

Journal Article↗

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

Determinants of effective continuous positive airway pressure in obstructive sleep apnea. Role of respiratory effort.

We investigated whether cephalometric measurements, nocturnal indices of negative intrathoracic pressure, or the frequency of sleep-related breathing disorders were related to the level of effective continuous positive airway pressure (CPAP) in patients with obstructive sleep apnea (OSA). We examined 22 OSA patients who underwent two consecutive polysomnographic recordings, the first for diagnosis and the second for CPAP titration. Cephalometric measurements, spirometric data, and blood-gas analysis results were available for all subjects. In the diagnostic polysomnography, at least 30 apneas were analyzed during non-rapid-eye-movement (NREM) sleep and 10 apneas during rapid eye movement (REM) sleep for each patient. Swings in esophageal pressure (Pes) during the preapneic period and during the beginning and the end of obstructive apneas were calculated as the average of three consecutive breaths (or ineffective efforts). The difference in Pes from the minimal initial to the maximal final apneic respiratory effort (DPes) and the rate of increase in Pes (RPes = DPes/apnea duration) during apnea were computed. Within an apnea, the lowest Pes always occurred during the first three occluded breaths and the highest during the last three, with a more marked difference in NREM sleep. The level of effective CPAP was correlated with the length of the soft palate (r = 0.69, p = 0.000), RPes (r = 0.55, p = 0.008), and DPes (r = 0.49, p = 0.02). The correlations of effective CPAP level with body mass index and apnea + hypopnea index were not significant. A model including length of the uvula, DPes, and RPes accounted for 56 to 59% of the variability in effective CPAP.(ABSTRACT TRUNCATED AT 250 WORDS)

Airway Resistance↗