Increased prevalence of obstructive lung disease in patients with obstructive sleep apnea.

STUDY PURPOSES: This study aims to determine whether there is an increased prevalence of obstructive lung diseases (OLDs) in patients with obstructive sleep apnea (OSA). We also determined whether among the OLD patients there is a difference in the prevalences of specific chronic disease co-morbidities between patients with and without OSA. METHODS: The prevalences of COPD, asthma, and COPD combined with asthma (ICD-9 coding) were compared between 1,497 adult OSA patients and 1,489 control patients, who were matched for age, gender, geographic location, and primary care physician. The prevalences of specific co-morbidities were measured in the OLD groups between patients with OSA and the matched control group. RESULTS: COPD, asthma, and COPD combined with asthma were found to be more prevalent among OSA patients compared to the matched controls. Prevalences among patients with and without OSA, respectively, were COPD-7.6 and 3.7 % (P<0.0001), asthma-10.4 and 5.1 % (P<0.0001), COPD plus asthma-3.3 and 0.9 % (P<0.0001). The Charlson Comorbidity Index was greater for OSA patients (2.3 ± 0.2) than for controls (1.9 ± 1.8; P<0.0001). These trends held for all severity ranges of OSA. Patients with OSA and COPD were characterized by more severe hypoxia at night compared with the OSA patients without OLD. CONCLUSION: OSA was associated with an increased prevalence of OLDs.

The economic impact of obstructive sleep apnea.

PURPOSE OF REVIEW: Obstructive sleep apnea (OSA) has a substantial economic impact on healthcare systems. We reviewed parameters affecting healthcare costs (race, low education, and socioeconomic status) on OSA comorbidity, and costs and the effect of OSA treatment on medical costs. RECENT FINDINGS: OSA is associated with increased cardiovascular disease (CVD) morbidity and substantially increased medical costs. Risk for OSA and resulting CVD are associated with obesity, tobacco smoking, black race, and low socioeconomic status; all these are associated with poor continuous positive airway pressure (CPAP) adherence. Healthcare costs are not normally distributed, that is, the costliest and the sickest upper third of patients consume 65-82% of all medical costs. Only a limited number of studies have explored the effect of CPAP on medical costs. SUMMARY: Costs of untreated OSA may double the medical expenses mainly because of CVD. Identifying the costliest, sickest upper third of OSA patients will reduce expenses to healthcare systems. Studies exploring the effect of CPAP on medical costs are essential. In addition, tailoring intervention programs to reduce barriers to adherence have the potential to improve CPAP treatment, specially in at-risk populations that are sicker and consume more healthcare costs.

Bone mineral density alteration in obstructive sleep apnea by derived computed tomography screening.

The association between obstructive sleep apnea (OSA) and bone mineral density (BMD) is poorly elucidated and has contradictory findings. Abdominal computed tomography (CT) for other indications can provide a valuable opportunity for osteoporosis screening. Thus, we retrospectively explored the association between OSA and BMD by examining abdominal CT vertebrae images for a multitude of conditions and indications. We included 315 subjects (174 with OSA and 141 without OSA) who performed at least two CT scans (under similar settings). Both groups had a similar duration between the first and second CT scans of 3.6 years. BMD decreased in those with OSA and increased age. A multivariate linear regression indicated that OSA is associated with BMD alterations after controlling for age, gender, and cardiovascular diseases. Here, we report that OSA is associated with BMD alterations. Further studies are required to untangle the complex affect of OSA on BMD and the possible clinical implications of vertebra-depressed or femoral neck fractures.

Determinants of elevated healthcare utilization in patients with COPD.

BACKGROUND: Chronic obstructive pulmonary disease (COPD) imparts a substantial economic burden on western health systems. Our objective was to analyze the determinants of elevated healthcare utilization among patients with COPD in a single-payer health system. METHODS: Three-hundred eighty-nine adults with COPD were matched 1:3 to controls by age, gender and area of residency. Total healthcare cost 5 years prior recruitment and presence of comorbidities were obtained from a computerized database. Health related quality of life (HRQoL) indices were obtained using validated questionnaires among a subsample of 177 patients. RESULTS: Healthcare utilization was 3.4-fold higher among COPD patients compared with controls (p < 0.001). The "most-costly" upper 25% of COPD patients (n = 98) consumed 63% of all costs. Multivariate analysis revealed that independent determinants of being in the "most costly" group were (OR; 95% CI): age-adjusted Charlson Comorbidity Index (1.09; 1.01-1.2), history of: myocardial infarct (2.87; 1.5-5.5), congestive heart failure (3.52; 1.9-6.4), mild liver disease (3.83; 1.3-11.2) and diabetes (2.02; 1.1-3.6). Bivariate analysis revealed that cost increased as HRQoL declined and severity of airflow obstruction increased but these were not independent determinants in a multivariate analysis. CONCLUSION: Comorbidity burden determines elevated utilization for COPD patients. Decision makers should prioritize scarce health care resources to a better care management of the "most costly" patients.

Changes in energy metabolism and respiration in different tracheal narrowing in rats.

Why obstructive sleep apnea (OSA) treatment does not completely restore healthy metabolic physiology is unclear. In rats, the need for respiratory homeostasis maintenance following airway obstruction (AO) is associated with a loss of thermoregulation and abnormal metabolic physiology that persists following successful obstruction removal. Here, we explored the effect of two different types of tracheal narrowing, i.e., AO and mild airway obstruction (mAO), and its removal on respiratory homeostasis and metabolic physiology. We show that after ten weeks, mAO vs. AO consumes sufficient energy that is required to maintain respiratory homeostasis and thermoregulation. Obstruction removal was associated with largely irreversible increased feeding associated with elevated serum ghrelin, hypothalamic growth hormone secretagogue receptor 1a, and a phosphorylated Akt/Akt ratio, despite normalization of breathing and energy requirements. Our study supports the need for lifestyle eating behavior management, in addition to endocrine support, in order to attain healthy metabolic physiology in OSA patients.

Obstructive sleep apnea and metabolic disorders in morbidly obese adolescents.

BACKGROUND: Little known about the prevalence of obstructive sleep apnea (OSA) in morbid obese adolescents and the association between OSA and comorbid factors. AIM: To examine the association between apnea-hypopnea index (AHI, a measure for OSA severity) and metabolic morbidity among morbidly obese adolescents. METHODS: We performed a population-based retrospective cohort study by reviewing sleep study, metabolic indices, and comorbidity-related data of a cohort (n = 106) of adolescents referred to a bariatric surgery clinic. We compared subjects with moderate/severe OSA (AHI ≥ 5) versus no/mild OSA (AHI < 5) OSA and three groups of subjects with increasing body mass index (BMI) concerning sleep-study and metabolic indices using univariate analyses. To assess the link between AHI and ferritin levels a multivariate linear regression (adjusted for BMI and mean cell volume) was preformed. RESULTS: A total of 71 patients met the inclusion criteria. Subjects with moderate/severe OSA (n = 32, 45%) had higher BMI, cholesterol, cholesterol/high-density lipoprotein (HDL) ratio, hemoglobin A1c, and serum ferritin levels (p < .05). AHI significantly increased across BMI strata (p = .02). Multivariate linear regression indicated that moderate/severe OSA was associated with higher levels of ferritin, unstandardized ß = 49.1 (nIU/ml) (p = .025). CONCLUSIONS: Morbidly obese adolescents with moderate/severe OSA versus no/mild OSA have a higher risk for metabolic complications. Therefore, OSA management should be considered in adolescents with morbid obesity, in addition to weight loss.

Upper Airway Obstruction Elicited Energy Imbalance Leads to Growth Retardation that Persists after the Obstruction Removal.

Upper airway obstruction can lead to growth retardation by unclear mechanisms. We explored the effect of upper airway obstruction in juvenile rats on whole-body energy balance, growth plate metabolism, and growth. We show that after seven weeks, obstructed animals' ventilation during room air breathing increased, and animals grew less due to abnormal growth plate metabolism. Increased caloric intake in upper airway-obstructed animals did not meet increased energy expenditure associated with increased work of breathing. Decreased whole-body energy balance induced hindrance of bone elongation following obstruction removal, and array pathways regulating growth plate development and marrow adiposity. This is the first study to show that rapidly growing animals cannot consume enough calories to maintain their energy homeostasis, leading to an impediment in growth in the effort to save energy.

Altered slow-wave sleep activity in children with rapid-onset obesity with hypothalamic dysregulation, hypoventilation, and autonomic dysregulation syndrome.

STUDY OBJECTIVES: Rapid-onset obesity with hypothalamic dysregulation, hypoventilation, and autonomic dysregulation (ROHHAD) is a rare condition. Little is known about sleep/wake and slow-wave activity in this condition, although the central hypothalamic dysfunction associated with autonomic dysregulation would make the occurrence of SWA deregulation most likely. METHODS: Two children with clinical presentation of ROHHAD syndrome were evaluated, diagnosed, and treated. Their polysomnographic studies were compared with 4 matched children with obstructive sleep apnea and 6 controls. RESULTS: Children that were clinically diagnosed with ROHHAD exhibited significantly weaker slow-wave activity power and shallower slow-wave activity slopes during the first 2 sleep cycles compared with children with obstructive sleep apnea or controls. CONCLUSIONS: This study shows that children with ROHHAD have suppressed slow-wave activity, possibly because of hypothalamic dysregulation that may contribute to their rapid-onset obesity and excessive daytime sleepiness.

Reduced sleep pressure in young children with autism.

STUDY OBJECTIVES: Sleep disturbances and insomnia are highly prevalent in children with Autism Spectrum Disorder (ASD). Sleep homeostasis, a fundamental mechanism of sleep regulation that generates pressure to sleep as a function of wakefulness, has not been studied in children with ASD so far, and its potential contribution to their sleep disturbances remains unknown. Here, we examined whether slow-wave activity (SWA), a measure that is indicative of sleep pressure, differs in children with ASD. METHODS: In this case-control study, we compared overnight electroencephalogram (EEG) recordings that were performed during Polysomnography (PSG) evaluations of 29 children with ASD and 23 typically developing children. RESULTS: Children with ASD exhibited significantly weaker SWA power, shallower SWA slopes, and a decreased proportion of slow-wave sleep in comparison to controls. This difference was largest during the first 2 hours following sleep onset and decreased gradually thereafter. Furthermore, SWA power of children with ASD was significantly negatively correlated with the time of their sleep onset in the lab and at home, as reported by parents. CONCLUSIONS: These results suggest that children with ASD may have a dysregulation of sleep homeostasis that is manifested in reduced sleep pressure. The extent of this dysregulation in individual children was apparent in the amplitude of their SWA power, which was indicative of the severity of their individual sleep disturbances. We, therefore, suggest that disrupted homeostatic sleep regulation may contribute to sleep disturbances in children with ASD.

Low socioeconomic status is a risk factor for CPAP acceptance among adult OSAS patients requiring treatment.

STUDY OBJECTIVE: To evaluate whether socioeconomic status (SES) has a role in obstructive sleep apnea syndrome (OSAS) patients' decision to accept continuous positive airway pressure (CPAP) treatment. DESIGN: Cross-sectional study; patients were recruited between March 2007 and December 2007. SETTING: University-affiliated sleep laboratory. PATIENTS: 162 consecutive newly diagnosed (polysomnographically) adult OSAS patients who required CPAP underwent attendant titration and a 2-week adaptation period. RESULTS: 40% (n = 65) of patients who required CPAP therapy accepted this treatment. Patients accepting CPAP were older, had higher apnea-hypopnea index (AHI) and higher income level, and were more likely to sleep in a separate room than patients declining CPAP treatment. More patients who accepted treatment also reported receiving positive information about CPAP treatment from family or friends. Multiple logistic regression (after adjusting for age, body mass index, Epworth Sleepiness Scale, and AHI) revealed that CPAP purchase is determined by: each increased income level category (OR, 95% CI) (2.4; 1.2-4.6), age + 1 year (1.07; 1.01-1.1), AHI ( > or = 35 vs. < 35 events/hr) (4.2, 1.4-12.0), family and/or friends with positive experience of CPAP (2.9, 1.1-7.5), and partner sleeps separately (4.3, 1.4-13.3). CONCLUSIONS: In addition to the already known determinants of CPAP acceptance, patients with low SES are less receptive to CPAP treatment than groups with higher SES. CPAP support and patient education programs should be better tailored for low SES people in order to increase patient treatment initiation and adherence.

[Obstructive sleep apnea syndrome in young infants].

UNLABELLED: Obstructive sleep apnea syndrome (OSAS) has been reported among children aged 3-6 years. Adenotonsillar hypertrophy is the most common cause of OSAS. The upper airway obstruction results in repeated obstructive apneas and hypopneas, associated with oxygen desaturations and sleep fragmentation. OSAS in children is associated with higher respiratory morbidity as well as significant clinical consequences, mainly neurocognitive and behavioral problems, impaired growth and cardiac dysfunction. The objectives of the present study were to determine the clinical and sleep characteristics of OSAS in children younger than 2 years, and to evaluate morbidity and health care utilization of infants with OSAS. This retrospective study included 35 children younger than 2 years of age, referred for polysomnography because of suspected OSAS. The controL group included healthy children, matched by age, gender and pediatrician. RESULTS: A total of 33 infants were diagnosed with OSAS. Mean apnea/hypopnea index [AHI) was 18.7 +/- 18.1 events/ hour [range 1.3-90.2]. In 10 infants a pattern of intermittent hypoxemia was observed. Infants with OSAS demonstrated a higher number of primary care clinic visits (20.8 +/- 14 vs. 12.1 +/- 6.6, P < 0.02). A higher percentage of children with OSAS visited the emergency room (60.6% vs. 32.2%, P < 0.03), and was hospitalized (36.3% vs. 12.9%, P < 0.03). Duration of hospitalization was also higher in the OSAS group [23.2 +/- 14.1% vs. 3 +/- 2.1%, P < 0.05). The number of drug prescriptions was higher among the study group [25.9 +/- 21.8% vs. 13.6 +/- 10.1, P < 0.03). Thirteen patients underwent adenoidectomy with or without tonsillectomy, resulting in improvement of AHI, decreasing from 26.4 +/- 24 before to 3.6 +/- 4.5 events per hour after surgery (p < 0.01). CONCLUSIONS: OSAS can be found in infants younger than 2 years of age. OSAS at this young age is characterized by a higher morbidity in comparison to healthy children. Early diagnosis and treatment may prevent morbidity in young children with OSAS.

Irreversible metabolic abnormalities following chronic upper airway loading.

STUDY OBJECTIVES: Treatment of obstructive sleep apnea increases obesity risk by an unclear mechanism. Here, we explored the effects of upper airway obstruction and its removal on respiratory homeostasis, energy expenditure, and feeding hormones during the sleep/wake cycle from weaning to adulthood. METHODS: The tracheas of 22-day-old rats were narrowed, and obstruction removal was performed on post-surgery day 14. Energy expenditure, ventilation, and hormone-regulated feeding were analyzed during 49 days before and after obstruction. RESULTS: Energy expenditure increased and body temperature decreased in upper airway obstruction and was only partially recovered in obstruction removal despite normalization of airway resistance. Increased energy expenditure was associated with upregulation of ventilation. Decreased body temperature was associated with decreased brown adipose tissue uncoupling protein 1 level, suppressed energy expenditure response to norepinephrine, and decreased leptin level. Upper airway obstructed animals added less body weight, in spite of an increase in food intake, due to elevated hypothalamic orexin and neuropeptide Y and plasma ghrelin. Animals who underwent obstruction removal fed more due to an increase in hypothalamic neuropeptide Y and plasma ghrelin. CONCLUSIONS: The need to maintain respiratory homeostasis is associated with persistent abnormal energy metabolism and hormonal regulation of feeding. Surgical treatment per se may not be sufficient to correct energy homeostasis, and endocrine regulation of feeding may have a larger effect on weight change.

Oxygen and Carbon Dioxide Rhythms Are Circadian Clock Controlled and Differentially Directed by Behavioral Signals.

Daily rhythms in animal physiology are driven by endogenous circadian clocks in part through rest-activity and feeding-fasting cycles. Here, we examined principles that govern daily respiration. We monitored oxygen consumption and carbon dioxide release, as well as tissue oxygenation in freely moving animals to specifically dissect the role of circadian clocks and feeding time on daily respiration. We found that daily rhythms in oxygen and carbon dioxide are clock controlled and that time-restricted feeding restores their rhythmicity in clock-deficient mice. Remarkably, day-time feeding dissociated oxygen rhythms from carbon dioxide oscillations, whereby oxygen followed activity, and carbon dioxide was shifted and aligned with food intake. In addition, changes in carbon dioxide levels altered clock gene expression and phase shifted the clock. Collectively, our findings indicate that oxygen and carbon dioxide rhythms are clock controlled and feeding regulated and support a potential role for carbon dioxide in phase resetting peripheral clocks upon feeding.

Upper airway loading induces growth retardation and change in local chondrocyte IGF-I expression is reversed by stimulation of GH release in juvenile rats.

Chronic resistive airway loading (CAL) impairs growth in juvenile rats. The effects of CAL on epiphyseal growth plate (EGP) structure and insulin-like growth factor (IGF)-I gene expression have not been explored. Little is known about whether stimulants of endogenous growth hormone (GH) secretion can normalize this growth impairment. This study explored the effect of CAL on circulating and EGP GH/IGF-I pathway GH and the effect of ritanserin (endogenous GH stimulant) on somatic growth and the GH/IGF-I axis. We hypothesized that CAL would lead to a decrease in body temperature (Tb) and alterations of GH/IGF-I pathways, consequently leading to growth retardation. The tracheae of 22-day-old male rats were obstructed by tracheal banding (38 sham-operated control, 42 CAL). Tibial EGP morphometry, liver and EGP IGF mRNA, and serum GH and IGF-I levels were analyzed with quantitative real-time PCR and ELISA. Tb and locomotion activity (MA) were measured with telemetric transmitters inserted into the abdominal cavity. CAL animals had lower Tb and MA despite preserved food consumption. CAL impaired both tibial and tail length gains. Tail and tibial length gains inversely correlated with tracheal resistance. Circulating GH and IGF-I, liver and EGP IGF-I mRNA, and EGP width were decreased in the CAL group. Ritanserin administration to CAL animals normalized circulating and local EGP GH and IGF-I levels and minimized the longitudinal growth impairment. We conclude that CAL causes growth delay associated with alterations in the GH/IGF-I axis. Stimulation of GH release by ritanserin restored both global and local GH/IGF-I pathways, yet growth parameters were only partially restored.

Abnormal Growth and Feeding Behavior in Upper Airway Obstruction in Rats.

Pediatric obstructive sleep apnea (OSA) is a syndrome manifesting with snoring and increased respiratory effort due to increased upper airway resistance. In addition to cause the abnormal sleep, this syndrome has been shown to elicit either growth retardation or metabolic syndrome and obesity. Treating OSA by adenotonsillectomy is usually associated with increased risk for obesity, despite near complete restoration of breathing and sleep. However, the underlying mechanism linking upper airways obstruction (AO) to persistent change in food intake, metabolism, and growth remains unclear. Rodent models have examined the impact of intermittent hypoxia on metabolism. However, an additional defining feature of OSA that is not related to intermittent hypoxia is enhanced respiratory loading leading to increased respiratory effort and abnormal sleep. The focus of this mini review is on recent evidence indicating the persistent abnormalities in endocrine regulation of feeding and growth that are not fully restored by the chronic upper AO removal in rats. Here, we highlight important aspects related to abnormal regulation of metabolism that are not related to intermittent hypoxia per se, in an animal model that mimics many of the clinical features of pediatric OSA. Our evidence from the AO model indicates that obstruction removal may not be sufficient to prevent the post-removal tendency for abnormal growth.

Sleep staging using nocturnal sound analysis.

Sleep staging is essential for evaluating sleep and its disorders. Most sleep studies today incorporate contact sensors that may interfere with natural sleep and may bias results. Moreover, the availability of sleep studies is limited, and many people with sleep disorders remain undiagnosed. Here, we present a pioneering approach for rapid eye movement (REM), non-REM, and wake staging (macro-sleep stages, MSS) estimation based on sleep sounds analysis. Our working hypothesis is that the properties of sleep sounds, such as breathing and movement, within each MSS are different. We recorded audio signals, using non-contact microphones, of 250 patients referred to a polysomnography (PSG) study in a sleep laboratory. We trained an ensemble of one-layer, feedforward neural network classifiers fed by time-series of sleep sounds to produce real-time and offline analyses. The audio-based system was validated and produced an epoch-by-epoch (standard 30-sec segments) agreement with PSG of 87% with Cohen's kappa of 0.7. This study shows the potential of audio signal analysis as a simple, convenient, and reliable MSS estimation without contact sensors.

Gender differences in morbidity and health care utilization among adult obstructive sleep apnea patients.

STUDY OBJECTIVE: To explore gender differences in morbidity and total health care utilization 5 years prior to diagnosis of obstructive sleep apnea (OSA). DESIGN: Case-control study; patients were recruited between January 2001 and April 2003. SETTING: Two university-affiliated sleep laboratories. PATIENTS: 289 women (22-81 years) with OSA were matched with 289 men with OSA for age, body mass index (BMI), and apnea-hypopnea index (AHI). All OSA patients were matched 1:1 with healthy controls by age, geographic area, and primary physician. MEASUREMENTS AND RESULTS: Women with OSA compared to men with OSA have lower perceived health status and Functional Outcomes of Sleep Questionnaire score (54.5% vs. 28.4%, P <0.05 and 67.5+/-21.4 vs. 76+/-20.1, P <0.05, respectively). Compared to men with OSA, women with OSA have higher risk of hypothyroidism (OR 4.7; 95% CI, 2.3-10) and arthropathy (OR 1.6, 95% CI, 1.1-2.2) and lower risk for CVD (OR 0.7; 95% CI, 0.5-0.91). Compared to controls, both women and men with OSA had 1.8 times higher 5-year total costs (P <0.0001). Compared to men with OSA, expenditures for women with OSA are 1.3 times higher (P <0.0001). The multiple logistic regression (adjusting for BMI, AHI) revealed that age (OR 1.04; 95% CI, 1.01-1.07), antipsychotic and anxiolytic drugs (OR 2.3; 95% CI, 1.2-4.4), and asthma (OR 2.4; 95% CI, 1.1-5.6) are independent determinants for "most costly" OSA women. CONCLUSION: Compared to men with similar OSA severity, women are heavier users of health care resources. Low FOSQ score and poor perceived health status in addition to overuse of psychoactive drugs are associated with high health care utilization among women with OSA.

Chronic upper airway resistive loading induces growth retardation via the GH/IGF-I axis in prepubescent rats.

The effect of upper airway loading on longitudinal bone growth and various components of the growth hormone (GH)/insulin-like growth factor I (IGF-I) axis has not been fully elucidated. In the present study, the effect of chronic resistive airway loading (CAL) in a prepubescent rat model on linear bone growth and weight gain was investigated. We hypothesize that CAL induced in prepubescent rats will lead to impaired longitudinal growth due to impairment in circulating and liver GH/IGF-I parameters. The tracheae of 22-day-old rats were obstructed by tracheal banding to increase inspiratory esophageal pressure. The GH/IGF-I markers were analyzed using ELISA, RT-PCR, and Western immunoblot analysis 14 days after surgery. Animals exhibited impaired longitudinal growth as demonstrated by reduction of tibia and tail length gains by 40% (P < 0.0001) and body weight gain by 24% (P < 0.0001). No differences were seen in total body energy balance, i.e., oxygen consumption, daily food intake, or arterial blood gases. Circulating GH, IGF-I, and IGF binding protein-3 (IGFBP-3) levels were reduced by 40% (P = 0.037), 30% (P < 0.006), and 27% (P = 0.02), respectively, in the CAL group. Liver IGF-I mRNA level decreased by 20% (P < 0.0002), whereas GH receptor mRNA and protein expression were unchanged. We conclude that impaired longitudinal growth in prepubescent CAL rats is related to a decrease in GH, IGF-I, and IGFBP-3 levels.

Abnormal Growth and Feeding Behavior Persist After Removal of Upper Airway Obstruction in Juvenile Rats.

Pediatric obstructive sleep-disordered breathing is associated with growth retardation, but also with obesity that has a tendency to persist following treatment. We investigated the effect of upper airways obstruction (AO) and of obstruction removal (OR) in juvenile rats on gut-derived ghrelin and related hypothalamic factors, feeding, and growth hormone (GH) homeostasis. Here, we show that after seven weeks of AO, animals gained less weight compared to controls, despite an increase in food intake due to elevated ghrelin and hypothalamic feeding factors. OR rats who had complete restoration of tracheal diameter, consumed more food due to increased ghrelin and exhibited growth retardation due to deregulation of GH homeostasis. This study is the first to show dysregulation of the hormonal axes controlling feeding behavior and growth that are not fully restored following OR. Thus, surgical treatment by itself may not be sufficient to prevent post-surgical increased food intake and growth retardation.