ahmed elmasry - Academia.edu (original) (raw)

Papers by ahmed elmasry

Research paper thumbnail of Dynamic Standby Prediction for Leakage Tolerant Microprocessor Functional Units

Leakage power is projected to comprise approximately 50% of the processor's power for sub 65... more Leakage power is projected to comprise approximately 50% of the processor's power for sub 65nm technologies. Much of this power is consumed in the processor's func-tional units. Accordingly, leakage control techniques are employed to reduce leakage in these ...

Research paper thumbnail of Semantics of Time-Varying Attributes and their Use for Temporal Database Design

Based on a systematic study of the semantics of temporal attributes of entities, this paper provi... more Based on a systematic study of the semantics of temporal attributes of entities, this paper provides new guidelines for the design of temporal relational databases. The notions of observation and update patterns of an attribute capture when the attribute changes value and when the changes are recorded in the database. A lifespan describes when an attribute has a value. And derivation functions describe how the values of an attribute for all times within its lifespan are computed from stored values. The implications for temporal database design of the semantics that may be captured using these concepts are formulated as schema decomposition rules.

Research paper thumbnail of Distribution-Sensitive Construction of Minimum-Redundancy Prefix Codes

Computing Research Repository, 2005

A new method for constructing minimum-redundancy prefix codes is described. This method does not ... more A new method for constructing minimum-redundancy prefix codes is described. This method does not build a Huffman tree; instead it uses a property of optimal codes to find the codeword length of each weight. The running time of the algorithm is shown to be O(nk), where n is the number of weights and k is the number of different codeword lengths. When the given sequence of weights is already sorted, it is shown that the codes can be constructed using O(log 2k−1 n) comparisons, which is sub-linear if the value of k is small.

Research paper thumbnail of A Low-Power Multi-Pin Maze Routing Methodology

As VLSI technologies scale into the deep submicron (DSM) realm, the minimum feature size continue... more As VLSI technologies scale into the deep submicron (DSM) realm, the minimum feature size continues to shrink. In contrast, the average die size is expected to remain constant or to slightly increase with each tech-nology generation. This results in an average increase in the ...

Research paper thumbnail of A Comparative Study Between Static and Dynamic Sleep Signal Generation Techniques for Leakage Tolerant Designs

IEEE Transactions on Very Large Scale Integration Systems, 2008

Power gating techniques are rapidly gaining popularity assisting the management of leakage power ... more Power gating techniques are rapidly gaining popularity assisting the management of leakage power consumption for deep submicrometer microprocessors' functional units. Power gating is based on an input sleep signal to set the functional unit into a low leakage mode. However, power gating techniques in general inherently lack information about the utilization profile of the functional units they manage. This limitation is usually handled either statically by using a fixed length counter that generates the sleep signal when the functional unit is idle for a specified number of cycles or dynamically by changing the number of cycles before the sleep signal is generated depending on the previous history of operation. In this paper, a comparative study between the static and dynamic approaches regarding the power-performance tradeoff will be presented. It will be shown that the dynamic sleep signal generator is capable of tracking the operation of the functional units while achieving accuracies up to 90% compared to an average of 40%-60% for the static sleep signal generator (SSSG). Additionally it saves up to 80% more leakage versus the SSSG. This study is very important in assisting circuit designers choose between both techniques depending on the power gated circuit.

Research paper thumbnail of A low-power direct digital frequency synthesizer architecture for wireless communications

A novel low-power direct digital frequency synthesizer (DDFS) architecture is presented. The sine... more A novel low-power direct digital frequency synthesizer (DDFS) architecture is presented. The sine and cosine functions are generated by linearly interpolating between the sample points, reducing the size of the ROM look-up table to 416 bits for 9-bit output resolution. The DDFS is implemented in 0.8 μm CMOS technology and features 60 dBc spectral purity, 48 Hz frequency resolution, with

Research paper thumbnail of Modelling a 1.25 Gb/s optical transmitter in IEEE 1076.1 standard VHDL-AMS

The need for simulation models that are reliable and able to predict the conceptual as well as th... more The need for simulation models that are reliable and able to predict the conceptual as well as the implementation errors early in the design process is a must in the current tight time to market constrains. In this paper, a model for a 7.25 Gb/s fiber channel transmitter is presented. The model is implemented using the IEEE 1076.1 standard VHDL-AMS. The modelled system is composed of two sections; an analog section, comprising the laser diode and the laser driver, and a digital section, consisting of an 8B/10B encoder and a 10:1 multiplexer.

Research paper thumbnail of Temporally Enhanced Database Design

Research paper thumbnail of Optimal Prefix Codes with Fewer Distinct Codeword Lengths are Easier to Construct

A new method for constructing minimum-redundancy binary prefix codes is described. Our method doe... more A new method for constructing minimum-redundancy binary prefix codes is described. Our method does not explicitly build a Huffman tree; instead it uses a property of optimal prefix codes to compute the codeword lengths corresponding to the input weights. Let nnn be the number of weights and kkk be the number of distinct codeword lengths. The running time of our algorithm is O(16kcdotn)O(16^k \cdot n)O(16kcdotn), which is asymptotically faster than Huffman's algorithm for sufficiently small kkk. If the given weights were presorted, our algorithm requires O(9kcdotlog2k−1n)O(9^k \cdot \log^{2k-1}{n})O(9kcdotlog2k−1n) comparisons, which is sub-linear for sufficiently small kkk.

Research paper thumbnail of Distribution-Sensitive Construction of Minimum-Redundancy Prefix Codes

A new method for constructing minimum-redundancy prefix codes is described. This method does not ... more A new method for constructing minimum-redundancy prefix codes is described. This method does not build a Huffman tree; instead it uses a property of optimal codes to find the codeword length of each weight. The running time of the algorithm is shown to be O(nk), where n is the number of weights and k is the number of different codeword lengths. When the given sequence of weights is already sorted, it is shown that the codes can be constructed using O(log2k− 1n) comparisons, which is sub-linear if the value of k is small.

Research paper thumbnail of Sleep Disordered Breathing

Upsala Journal of Medical Sciences, 2001

Lithocholic acid (LCA) is a potent hepatotoxic compound. Fetal LCA may have a role in the pathoge... more Lithocholic acid (LCA) is a potent hepatotoxic compound. Fetal LCA may have a role in the pathogenesis of neonatal cholestasis/extrahepatic biliary atresia (EHBA). Fetal liver efficiently hydroxylates LCA in several positions. This may represent a detox-ification ...

Research paper thumbnail of CPAP treatment of a population-based sample—what are the benefits and the treatment compliance

Sleep Medicine, 2006

Background & purpose: Continuous positive airway pressure (CPAP) treatment has positive effects, ... more Background & purpose: Continuous positive airway pressure (CPAP) treatment has positive effects, including improved insulin sensitivity in sleep-laboratory cohorts with obstructive sleep apnea syndrome. There is still a lack of data on benefits obtained and possibilities to treat less symptomatic individuals. The aim of this study was to evaluate the effect of CPAP treatment on metabolic profile and quality of life (QoL) in a population-based sample of men with sleep apnea. Another purpose was to investigate the compliance to CPAP in this population. Patients and methods: A population-based sample of 38 men with an AHI R10 were treated with CPAP regardless of symptom profile. The controls included men with AHI !10 matched for age and hypertension. The effects were evaluated after 3 weeks and 6 months. Insulin resistance was quantified using the homeostasis model assessment (HOMA). Daytime sleepiness, QoL and subjective symptom load was assessed using the Epworth Sleepiness Scale (ESS), the Medical Outcomes Study Short Form Health Survey (SF-36) and the Minor Symptoms Evaluation-Profile (MSE-P) questionnaires, respectively. Results: Complete three-week data were obtained from 28 treated men and 28 controls. Compared with controls, the CPAP group displayed a greater reduction of fasting serum insulin (PZ0.02), decrease in insulin resistance (PZ0.01) and an increase in IGF-1 (PZ0.005). The CPAP group further showed an improvement in the SF-36 domains of mental health (PZ0.03) and vitality (PZ0.06) and a reduction in symptom load in the sleep dimension of the MSE-P. Only 11 (29%) of subjects starting CPAP were still on treatment after 6 months. Those who still used CPAP had a higher score on ESS at baseline (11.3 (4.4) vs. 5.9 (3.4), P!0.0001). Conclusions: Benefits of short-term treatment included signs of reduced insulin resistance and improved QoL. However, in this populationbased sample compliance with CPAP was very low. More severe sleepiness was a positive predictive factor for treatment compliance. q Sleep Medicine 7 (2006) 553-560 www.elsevier.com/locate/sleep 1389-9457/$ -see front matter q

Research paper thumbnail of Reported snoring - does validity differ by age

Journal of Sleep Research, 2000

Snoring is a major sign of obstructive sleep apnoea syndrome. Despite the frequent number of stud... more Snoring is a major sign of obstructive sleep apnoea syndrome. Despite the frequent number of studies based on subjective reports of snoring, self-reported snoring has hardly been validated at all. In some previous epidemiological studies, a significant association between snoring and cardiovascular morbidity and mortality was found only below the age of 50–60 y. This study was performed to investigate whether this is due to a decrease in the validity of reported snoring with increasing age. In a population-based study, 2668 men aged 40–79 y answered a questionnaire including questions on snoring. Those who reported loud and disturbing snoring often or very often were regarded as habitual snorers. Without taking account of reported snoring, an age-stratified sample of these men was selected and their snoring was measured using a microphone for 1 night. Significant snoring was defined as recorded snoring sounds for ≥ 10% of the night. The participants were divided into younger (age 40–59, mean ± SD: 51.8 ± 4.6 y, n=132) and older (age 60–79, 67.7 ± 5.4 y, n=99) age groups. When analysing the validity of reported snoring, no significant differences were found between the younger and older age groups in terms of specificity [younger: 82% (95% CI 74–90%), older: 88% (81–95%)] or sensitivity [younger: 40% (26–54%), older: 35% (17–53%)]. These data indicate that, in men aged 40–79 y, the validity of reported snoring is similar in different age groups. The lack of an association between reported snoring and cardiovascular disease at higher ages can, therefore, not be explained by a decrease in the validity of reported snoring.

Research paper thumbnail of Obstructive sleep apnoea and urine catecholamines in hypertensive males: a population-based study

European Respiratory Journal, 2002

Studies addressing the relationship between obstructive sleep apnoea (OSA) and sympathoadrenal ac... more Studies addressing the relationship between obstructive sleep apnoea (OSA) and sympathoadrenal activity have been criticized for poor control of factors known to confound sympathetic function, including hypertension. The aim of this study was to investigate the relationship between OSA and urinary catecholamines in a population-based sample of hypertensive males.

Research paper thumbnail of The role of habitual snoring and obesity in the development of diabetes: a 10-year follow-up study in a male population

Journal of Internal Medicine, 2000

Abstract. Elmasry A, Janson C, Lindberg E, Gislason T, Tageldin MA, Boman G (Uppsala University, ... more Abstract. Elmasry A, Janson C, Lindberg E, Gislason T, Tageldin MA, Boman G (Uppsala University, Akademiska Sjukhuset, Uppsala, Sweden; Ain Shams University, Cairo, Egypt; and Viffilsstadir Hospital, Gardabær, Iceland). The role of habitual snoring and obesity in the development of diabetes: a 10-year follow-up study in a male population. J Intern Med 2000; 248: 13–20.Objectives. There are many similarities between diabetes (mainly type 2) and sleep breathing disturbances regarding risk factors, anthropometric criteria and consequences of morbidity and mortality. The aim of this study was to investigate whether the association between habitual snoring and diabetes is entirely dependent on obesity.Design. A population-based prospective study.Setting. The municipality of Uppsala, Sweden.Subjects and methods. In 1984 and in 1994, 2668 men aged 30–69 years at baseline answered questionnaires concerning sleep breathing disturbances and somatic diseases.Results. Of those with habitual snoring in 1984, 5.4% reported that they had developed diabetes during the 10-year period compared with 2.4% of those without habitual snoring (P < 0.001). Amongst obese snorers, 13.5% developed diabetes compared with 8.6% of obese non-snorers (P = 0.17). In a multiple logistic regression model, the odds ratio (95% confidence interval) for development of diabetes was higher in obese snorers [7.0 (2.9–16.9)] than in obese non-snorers [5.1 (2.7–9.5)] after adjustment for age, weight gain, smoking, alcohol dependence and physical inactivity.Conclusions. We conclude that, in males aged 30–69 years, habitual snoring is associated with an increased incidence of diabetes within 10 years. Although obesity is the main risk factor for developing diabetes, coexistent habitual snoring may add to this hazard.

Research paper thumbnail of Sleep-disordered breathing and glucose metabolism in hypertensive men: a population-based study

Journal of Internal Medicine, 2001

Abstract. Elmasry A, Lindberg E, Berne C, Janson C, Gislason T, Awad Tageldin M, Boman G (Uppsala... more Abstract. Elmasry A, Lindberg E, Berne C, Janson C, Gislason T, Awad Tageldin M, Boman G (Uppsala University, Akademiska Sjukhuset, Uppsala, Sweden; Ain Shams University, Cairo, Egypt; and Vifilsstadir Hospital, Gardabaer, Iceland). Sleep-disordered breathing and glucose metabolism in hypertensive men: a population-based study. J Intern Med 2001; 249: 153–161.Objectives. Diabetes mellitus and obstructive sleep apnoea (OSA) are two prevalent medical problems. Both are strongly associated with obesity and hypertension. The aim of this study was to investigate whether the association between OSA and diabetes is entirely dependent on obesity in hypertensive men.Design. A population-based study.Setting. The municipality of Uppsala, Sweden.Subjects and methods. In 1994, 2668 men aged 40–79 years answered a questionnaire regarding snoring, sleep disturbances and somatic diseases. An age-stratified sample of 116 hypertensive men was selected for a whole-night sleep study. Twenty-five of them had diabetes, defined as reporting regular medical controls for diabetes or having a fasting blood glucose ≥6.1 mmol L−1.Results. The prevalence of severe OSA, defined as apnoea-hypopnoea index (AHI) ≥20 h−1 was significantly higher in diabetic patients than in normoglycaemic subjects (36 vs. 14.5%, P < 0.05). The sample was divided into four groups based on the presence or absence of severe OSA and the presence or absence of central obesity, defined as waist-to-hip ratio (WHR) ≥1.0. In a logistic regression model with the non-OSA, WHR <1.0 as the reference group, the adjusted odds ratio (95% confidence interval) for diabetes was 11.8 (2.0–69.8) in the OSA, WHR ≥1.0 group, whilst it was 3.6 (0.9–14.8) in the non-OSA, WHR ≥1.0 group and 5.7 (0.3–112) in the OSA, WHR <1.0 group. In a linear regression model, after adjustment for WHR, there was a significant relationship between variables of sleep-disordered breathing and fasting insulin, glucose and haemoglobin A1c.Conclusions. We conclude that, in hypertensive men, although obesity is the main risk factor for diabetes, coexistent severe OSA may add to this risk. Sleep breathing disorders, independent of central obesity, may influence plasma insulin and glycaemia.

Research paper thumbnail of Evolution of Sleep Apnea Syndrome in Sleepy Snorers A Population-based Prospective Study

This study followed a small number of men previously studied polysomnographically 10 yr earlier t... more This study followed a small number of men previously studied polysomnographically 10 yr earlier to investigate the relationship between the development of sleep-disordered breathing and age, weight gain, and smoking. In 1984, 3,201 men answered a questionnaire including questions about snoring and excessive daytime sleepiness (EDS). Of those reporting symptoms related to obstructive sleep apnea syndrome (OSAS), a random sample of 61 men was investigated using whole-night polysomnography in 1985. Ten years later, 38 men participated in the present follow-up, which included a structured interview and polysomnography. During the 10-yr period, nine men had been treated for OSAS. Of the 29 untreated subjects, the number of men with OSAS, defined as an apnea-hypopnea index (AHI) of &gt;/= 5/h, increased from four in 1985 to 13 in 1995 (p &lt; 0.01). In this small sample, no significant associations were found between DeltaAHI (i.e., AHI 1995 - AHI 1985) and age, weight gain, or smoking. We conclude that, among this small group of individuals who were selected for original polysomnographic study and follow-up because they were thought to have symptoms of sleep apnea, sleep-disordered breathing became significantly worse over time.

Research paper thumbnail of qawsedrf

Research paper thumbnail of Dynamic Standby Prediction for Leakage Tolerant Microprocessor Functional Units

Leakage power is projected to comprise approximately 50% of the processor's power for sub 65... more Leakage power is projected to comprise approximately 50% of the processor's power for sub 65nm technologies. Much of this power is consumed in the processor's func-tional units. Accordingly, leakage control techniques are employed to reduce leakage in these ...

Research paper thumbnail of Semantics of Time-Varying Attributes and their Use for Temporal Database Design

Based on a systematic study of the semantics of temporal attributes of entities, this paper provi... more Based on a systematic study of the semantics of temporal attributes of entities, this paper provides new guidelines for the design of temporal relational databases. The notions of observation and update patterns of an attribute capture when the attribute changes value and when the changes are recorded in the database. A lifespan describes when an attribute has a value. And derivation functions describe how the values of an attribute for all times within its lifespan are computed from stored values. The implications for temporal database design of the semantics that may be captured using these concepts are formulated as schema decomposition rules.

Research paper thumbnail of Distribution-Sensitive Construction of Minimum-Redundancy Prefix Codes

Computing Research Repository, 2005

A new method for constructing minimum-redundancy prefix codes is described. This method does not ... more A new method for constructing minimum-redundancy prefix codes is described. This method does not build a Huffman tree; instead it uses a property of optimal codes to find the codeword length of each weight. The running time of the algorithm is shown to be O(nk), where n is the number of weights and k is the number of different codeword lengths. When the given sequence of weights is already sorted, it is shown that the codes can be constructed using O(log 2k−1 n) comparisons, which is sub-linear if the value of k is small.

Research paper thumbnail of A Low-Power Multi-Pin Maze Routing Methodology

As VLSI technologies scale into the deep submicron (DSM) realm, the minimum feature size continue... more As VLSI technologies scale into the deep submicron (DSM) realm, the minimum feature size continues to shrink. In contrast, the average die size is expected to remain constant or to slightly increase with each tech-nology generation. This results in an average increase in the ...

Research paper thumbnail of A Comparative Study Between Static and Dynamic Sleep Signal Generation Techniques for Leakage Tolerant Designs

IEEE Transactions on Very Large Scale Integration Systems, 2008

Power gating techniques are rapidly gaining popularity assisting the management of leakage power ... more Power gating techniques are rapidly gaining popularity assisting the management of leakage power consumption for deep submicrometer microprocessors' functional units. Power gating is based on an input sleep signal to set the functional unit into a low leakage mode. However, power gating techniques in general inherently lack information about the utilization profile of the functional units they manage. This limitation is usually handled either statically by using a fixed length counter that generates the sleep signal when the functional unit is idle for a specified number of cycles or dynamically by changing the number of cycles before the sleep signal is generated depending on the previous history of operation. In this paper, a comparative study between the static and dynamic approaches regarding the power-performance tradeoff will be presented. It will be shown that the dynamic sleep signal generator is capable of tracking the operation of the functional units while achieving accuracies up to 90% compared to an average of 40%-60% for the static sleep signal generator (SSSG). Additionally it saves up to 80% more leakage versus the SSSG. This study is very important in assisting circuit designers choose between both techniques depending on the power gated circuit.

Research paper thumbnail of A low-power direct digital frequency synthesizer architecture for wireless communications

A novel low-power direct digital frequency synthesizer (DDFS) architecture is presented. The sine... more A novel low-power direct digital frequency synthesizer (DDFS) architecture is presented. The sine and cosine functions are generated by linearly interpolating between the sample points, reducing the size of the ROM look-up table to 416 bits for 9-bit output resolution. The DDFS is implemented in 0.8 μm CMOS technology and features 60 dBc spectral purity, 48 Hz frequency resolution, with

Research paper thumbnail of Modelling a 1.25 Gb/s optical transmitter in IEEE 1076.1 standard VHDL-AMS

The need for simulation models that are reliable and able to predict the conceptual as well as th... more The need for simulation models that are reliable and able to predict the conceptual as well as the implementation errors early in the design process is a must in the current tight time to market constrains. In this paper, a model for a 7.25 Gb/s fiber channel transmitter is presented. The model is implemented using the IEEE 1076.1 standard VHDL-AMS. The modelled system is composed of two sections; an analog section, comprising the laser diode and the laser driver, and a digital section, consisting of an 8B/10B encoder and a 10:1 multiplexer.

Research paper thumbnail of Temporally Enhanced Database Design

Research paper thumbnail of Optimal Prefix Codes with Fewer Distinct Codeword Lengths are Easier to Construct

A new method for constructing minimum-redundancy binary prefix codes is described. Our method doe... more A new method for constructing minimum-redundancy binary prefix codes is described. Our method does not explicitly build a Huffman tree; instead it uses a property of optimal prefix codes to compute the codeword lengths corresponding to the input weights. Let nnn be the number of weights and kkk be the number of distinct codeword lengths. The running time of our algorithm is O(16kcdotn)O(16^k \cdot n)O(16kcdotn), which is asymptotically faster than Huffman's algorithm for sufficiently small kkk. If the given weights were presorted, our algorithm requires O(9kcdotlog2k−1n)O(9^k \cdot \log^{2k-1}{n})O(9kcdotlog2k−1n) comparisons, which is sub-linear for sufficiently small kkk.

Research paper thumbnail of Distribution-Sensitive Construction of Minimum-Redundancy Prefix Codes

A new method for constructing minimum-redundancy prefix codes is described. This method does not ... more A new method for constructing minimum-redundancy prefix codes is described. This method does not build a Huffman tree; instead it uses a property of optimal codes to find the codeword length of each weight. The running time of the algorithm is shown to be O(nk), where n is the number of weights and k is the number of different codeword lengths. When the given sequence of weights is already sorted, it is shown that the codes can be constructed using O(log2k− 1n) comparisons, which is sub-linear if the value of k is small.

Research paper thumbnail of Sleep Disordered Breathing

Upsala Journal of Medical Sciences, 2001

Lithocholic acid (LCA) is a potent hepatotoxic compound. Fetal LCA may have a role in the pathoge... more Lithocholic acid (LCA) is a potent hepatotoxic compound. Fetal LCA may have a role in the pathogenesis of neonatal cholestasis/extrahepatic biliary atresia (EHBA). Fetal liver efficiently hydroxylates LCA in several positions. This may represent a detox-ification ...

Research paper thumbnail of CPAP treatment of a population-based sample—what are the benefits and the treatment compliance

Sleep Medicine, 2006

Background & purpose: Continuous positive airway pressure (CPAP) treatment has positive effects, ... more Background & purpose: Continuous positive airway pressure (CPAP) treatment has positive effects, including improved insulin sensitivity in sleep-laboratory cohorts with obstructive sleep apnea syndrome. There is still a lack of data on benefits obtained and possibilities to treat less symptomatic individuals. The aim of this study was to evaluate the effect of CPAP treatment on metabolic profile and quality of life (QoL) in a population-based sample of men with sleep apnea. Another purpose was to investigate the compliance to CPAP in this population. Patients and methods: A population-based sample of 38 men with an AHI R10 were treated with CPAP regardless of symptom profile. The controls included men with AHI !10 matched for age and hypertension. The effects were evaluated after 3 weeks and 6 months. Insulin resistance was quantified using the homeostasis model assessment (HOMA). Daytime sleepiness, QoL and subjective symptom load was assessed using the Epworth Sleepiness Scale (ESS), the Medical Outcomes Study Short Form Health Survey (SF-36) and the Minor Symptoms Evaluation-Profile (MSE-P) questionnaires, respectively. Results: Complete three-week data were obtained from 28 treated men and 28 controls. Compared with controls, the CPAP group displayed a greater reduction of fasting serum insulin (PZ0.02), decrease in insulin resistance (PZ0.01) and an increase in IGF-1 (PZ0.005). The CPAP group further showed an improvement in the SF-36 domains of mental health (PZ0.03) and vitality (PZ0.06) and a reduction in symptom load in the sleep dimension of the MSE-P. Only 11 (29%) of subjects starting CPAP were still on treatment after 6 months. Those who still used CPAP had a higher score on ESS at baseline (11.3 (4.4) vs. 5.9 (3.4), P!0.0001). Conclusions: Benefits of short-term treatment included signs of reduced insulin resistance and improved QoL. However, in this populationbased sample compliance with CPAP was very low. More severe sleepiness was a positive predictive factor for treatment compliance. q Sleep Medicine 7 (2006) 553-560 www.elsevier.com/locate/sleep 1389-9457/$ -see front matter q

Research paper thumbnail of Reported snoring - does validity differ by age

Journal of Sleep Research, 2000

Snoring is a major sign of obstructive sleep apnoea syndrome. Despite the frequent number of stud... more Snoring is a major sign of obstructive sleep apnoea syndrome. Despite the frequent number of studies based on subjective reports of snoring, self-reported snoring has hardly been validated at all. In some previous epidemiological studies, a significant association between snoring and cardiovascular morbidity and mortality was found only below the age of 50–60 y. This study was performed to investigate whether this is due to a decrease in the validity of reported snoring with increasing age. In a population-based study, 2668 men aged 40–79 y answered a questionnaire including questions on snoring. Those who reported loud and disturbing snoring often or very often were regarded as habitual snorers. Without taking account of reported snoring, an age-stratified sample of these men was selected and their snoring was measured using a microphone for 1 night. Significant snoring was defined as recorded snoring sounds for ≥ 10% of the night. The participants were divided into younger (age 40–59, mean ± SD: 51.8 ± 4.6 y, n=132) and older (age 60–79, 67.7 ± 5.4 y, n=99) age groups. When analysing the validity of reported snoring, no significant differences were found between the younger and older age groups in terms of specificity [younger: 82% (95% CI 74–90%), older: 88% (81–95%)] or sensitivity [younger: 40% (26–54%), older: 35% (17–53%)]. These data indicate that, in men aged 40–79 y, the validity of reported snoring is similar in different age groups. The lack of an association between reported snoring and cardiovascular disease at higher ages can, therefore, not be explained by a decrease in the validity of reported snoring.

Research paper thumbnail of Obstructive sleep apnoea and urine catecholamines in hypertensive males: a population-based study

European Respiratory Journal, 2002

Studies addressing the relationship between obstructive sleep apnoea (OSA) and sympathoadrenal ac... more Studies addressing the relationship between obstructive sleep apnoea (OSA) and sympathoadrenal activity have been criticized for poor control of factors known to confound sympathetic function, including hypertension. The aim of this study was to investigate the relationship between OSA and urinary catecholamines in a population-based sample of hypertensive males.

Research paper thumbnail of The role of habitual snoring and obesity in the development of diabetes: a 10-year follow-up study in a male population

Journal of Internal Medicine, 2000

Abstract. Elmasry A, Janson C, Lindberg E, Gislason T, Tageldin MA, Boman G (Uppsala University, ... more Abstract. Elmasry A, Janson C, Lindberg E, Gislason T, Tageldin MA, Boman G (Uppsala University, Akademiska Sjukhuset, Uppsala, Sweden; Ain Shams University, Cairo, Egypt; and Viffilsstadir Hospital, Gardabær, Iceland). The role of habitual snoring and obesity in the development of diabetes: a 10-year follow-up study in a male population. J Intern Med 2000; 248: 13–20.Objectives. There are many similarities between diabetes (mainly type 2) and sleep breathing disturbances regarding risk factors, anthropometric criteria and consequences of morbidity and mortality. The aim of this study was to investigate whether the association between habitual snoring and diabetes is entirely dependent on obesity.Design. A population-based prospective study.Setting. The municipality of Uppsala, Sweden.Subjects and methods. In 1984 and in 1994, 2668 men aged 30–69 years at baseline answered questionnaires concerning sleep breathing disturbances and somatic diseases.Results. Of those with habitual snoring in 1984, 5.4% reported that they had developed diabetes during the 10-year period compared with 2.4% of those without habitual snoring (P < 0.001). Amongst obese snorers, 13.5% developed diabetes compared with 8.6% of obese non-snorers (P = 0.17). In a multiple logistic regression model, the odds ratio (95% confidence interval) for development of diabetes was higher in obese snorers [7.0 (2.9–16.9)] than in obese non-snorers [5.1 (2.7–9.5)] after adjustment for age, weight gain, smoking, alcohol dependence and physical inactivity.Conclusions. We conclude that, in males aged 30–69 years, habitual snoring is associated with an increased incidence of diabetes within 10 years. Although obesity is the main risk factor for developing diabetes, coexistent habitual snoring may add to this hazard.

Research paper thumbnail of Sleep-disordered breathing and glucose metabolism in hypertensive men: a population-based study

Journal of Internal Medicine, 2001

Abstract. Elmasry A, Lindberg E, Berne C, Janson C, Gislason T, Awad Tageldin M, Boman G (Uppsala... more Abstract. Elmasry A, Lindberg E, Berne C, Janson C, Gislason T, Awad Tageldin M, Boman G (Uppsala University, Akademiska Sjukhuset, Uppsala, Sweden; Ain Shams University, Cairo, Egypt; and Vifilsstadir Hospital, Gardabaer, Iceland). Sleep-disordered breathing and glucose metabolism in hypertensive men: a population-based study. J Intern Med 2001; 249: 153–161.Objectives. Diabetes mellitus and obstructive sleep apnoea (OSA) are two prevalent medical problems. Both are strongly associated with obesity and hypertension. The aim of this study was to investigate whether the association between OSA and diabetes is entirely dependent on obesity in hypertensive men.Design. A population-based study.Setting. The municipality of Uppsala, Sweden.Subjects and methods. In 1994, 2668 men aged 40–79 years answered a questionnaire regarding snoring, sleep disturbances and somatic diseases. An age-stratified sample of 116 hypertensive men was selected for a whole-night sleep study. Twenty-five of them had diabetes, defined as reporting regular medical controls for diabetes or having a fasting blood glucose ≥6.1 mmol L−1.Results. The prevalence of severe OSA, defined as apnoea-hypopnoea index (AHI) ≥20 h−1 was significantly higher in diabetic patients than in normoglycaemic subjects (36 vs. 14.5%, P < 0.05). The sample was divided into four groups based on the presence or absence of severe OSA and the presence or absence of central obesity, defined as waist-to-hip ratio (WHR) ≥1.0. In a logistic regression model with the non-OSA, WHR <1.0 as the reference group, the adjusted odds ratio (95% confidence interval) for diabetes was 11.8 (2.0–69.8) in the OSA, WHR ≥1.0 group, whilst it was 3.6 (0.9–14.8) in the non-OSA, WHR ≥1.0 group and 5.7 (0.3–112) in the OSA, WHR <1.0 group. In a linear regression model, after adjustment for WHR, there was a significant relationship between variables of sleep-disordered breathing and fasting insulin, glucose and haemoglobin A1c.Conclusions. We conclude that, in hypertensive men, although obesity is the main risk factor for diabetes, coexistent severe OSA may add to this risk. Sleep breathing disorders, independent of central obesity, may influence plasma insulin and glycaemia.

Research paper thumbnail of Evolution of Sleep Apnea Syndrome in Sleepy Snorers A Population-based Prospective Study

This study followed a small number of men previously studied polysomnographically 10 yr earlier t... more This study followed a small number of men previously studied polysomnographically 10 yr earlier to investigate the relationship between the development of sleep-disordered breathing and age, weight gain, and smoking. In 1984, 3,201 men answered a questionnaire including questions about snoring and excessive daytime sleepiness (EDS). Of those reporting symptoms related to obstructive sleep apnea syndrome (OSAS), a random sample of 61 men was investigated using whole-night polysomnography in 1985. Ten years later, 38 men participated in the present follow-up, which included a structured interview and polysomnography. During the 10-yr period, nine men had been treated for OSAS. Of the 29 untreated subjects, the number of men with OSAS, defined as an apnea-hypopnea index (AHI) of &gt;/= 5/h, increased from four in 1985 to 13 in 1995 (p &lt; 0.01). In this small sample, no significant associations were found between DeltaAHI (i.e., AHI 1995 - AHI 1985) and age, weight gain, or smoking. We conclude that, among this small group of individuals who were selected for original polysomnographic study and follow-up because they were thought to have symptoms of sleep apnea, sleep-disordered breathing became significantly worse over time.

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