Prevalence of viral pathogens in a sample of hospitalized Egyptian children with acute lower respiratory tract infections: a two-year prospective study

BACKGROUND

Viral pneumonias are a major cause of childhood mortality. Proper management needs early and accurate diagnosis. This study objective is to investigate the viral etiologies of pneumonia in children.

RESULTS

This prospective study enrolled 158 and 101 patients in the first and second year, respectively, and their mean age was 4.72 ± 2.89. Nasopharyngeal swabs were collected and subjected to virus diagnosis by reverse transcription polymerase chain reaction (RT-PCR). Viral etiologies of pneumonia were evidenced in 59.5% of the samples in the first year, all of them were affirmative for influenza A, 2 samples were affirmative for Human coronavirus NL63, and one for Human coronavirus HKU1. In the second year, 87% of patients had a viral illness. The most prevalent agents are human metapneumovirus which was detected in 44 patients (43.6%) followed by human rhinovirus in 35 patients (34.7%) and then parainfluenza-3 viruses in 33 patients (32.7%), while 14 patients had a confirmed diagnosis for both Pan coronavirus and Flu-B virus.

CONCLUSIONS

Viral infection is prevalent in the childhood period; however, the real magnitude of viral pneumonia in children is underestimated. The reverse transcriptase polymerase chain reaction has to be a vital tool for epidemiological research and is able to clear the gaps in-between clinical pictures and final diagnoses.

Sleep quality and anxiety symptoms in Egyptian children and adolescents during COVID-19 pandemic lockdown

BACKGROUND

Coronavirus Disease Pandemic 2019 has a pervasive effect on all health aspects include psychological and mental health. This study aimed to assess the hidden stressful impact of COVID-19 pandemic on Egyptian children and adolescents' lifestyles 2 months after lockdown in Egypt by detecting symptoms of anxiety and sleep disorders. Online questionnaire was used by snowball sampling approach 2 months after lockdown targeting children and adolescents.

RESULTS

The overall mean Sleep Disturbance Scale for Children score (SDSC) in participated groups was 44.6 ± 11.72. Of 765 participants 502 (65.6%) showed the symptoms suggestive of sleep disorder. Disorders of initiating and maintaining sleep were the most common among participants as 168 (33.4%) of them were suffering from it while 79 (15.7%) children were suffering from excessive somnolence. Linear stepwise regression revealed that anxiety score, understanding safety measures, and following strict quarantine measures significantly predicted SDSC (p = 0.001, 0.009, 0.046). Significant positive correlations were found between SDSC and extra screen usage, understanding safety and quarantine measures, anxiety signs, and change in child lifestyle with (p = 0.029, 0.010, 0.001 and 0.001) sequentially. Significant positive correlation was found between family income affection, SDSC, and anxiety with p value (00.001, 00.4).

CONCLUSION

Child deprived of his or her normal lifestyle is vulnerable to develop anxiety symptoms and sleep disturbances. Low income, extra screen time, and restricted quarantine measures are all contributing factors that influence children and adolescent's mental health.

Assessment of Quality of Life of Primary Caregivers of Egyptian Asthmatic Children and Adolescents

Background:

Asthma as a serious public health problem worldwide exerts a serious load on children's health-related quality of life (HRQOL) and their families.

Objective:

We assess the HRQOL of the primary caregivers of Egyptian asthmatic children and adolescents and its relation to HRQOL of their children and asthma severity.

Materials and Methods:

A cross-sectional study was conducted on 128 pairs of asthmatic children (7–16 years) and their primary caregivers. Pediatric asthma quality of life (QOL) questionnaire, pediatric asthma caregiver's QOL questionnaire, and asthma control questionnaire were used.

Results:

Uncontrolled asthmatic patients had statistically significantly lower mean caregiver score compared to controlled asthmatic (P < 0.005). There was a statistically significant positive correlation between caregiver's individual and overall QOL scores and their children (individual and overall QOL scores) (P < 0.05). A statistically significant negative correlation between asthma severity and QOL scores of the caregivers of asthmatic children and adolescents was found (P < 0.05).

Conclusion:

The QOL of the primary caregivers of asthmatic children is significantly adversely affected by their children's illness severity.

Impact of Coronavirus Disease-19 Lockdown on Egyptian Children and Adolescents: Dietary Pattern Changes Health Risk

BACKGROUND: Lockdown and school closure related to the coronavirus disease 2019 (COVID-19) have unfavorable effects on children and adolescents. AIM: This study was conducted to survey the changes in dietary pattern and related health factors in Egyptian children and adolescents during the COVID-19 outbreak closure. MATERIALS AND METHODS: Data were collected through a dietary pattern, eating behavior, and physical activity electronic questionnaire conducted through social media sites, targeting parents of children and adolescents after two whole months of lockdown and school closure in Egypt. RESULTS: This study included 765 participants, 31.8% noted increased appetite, 45.6% reported increased sweets and unhealthy food consumption, and 37.6% showed increased frequent snacking between meals. Alongside 53.1% showed increase in late snacks during night after COVID-19 closure. The majority of our participants 82.0% noted associative change in eating behavior with boring and 94.6% revealed increased usage of electronics and screen time. This study showed significant positive correlation between increased appetite and mobile screen time, laptop screen time, and video gaming. Increased sweets and unhealthy food consumption was positively correlated with TV watching and mobile screen time. A significant positive correlation was revealed between uncaring about eating fruits and vegetables and increase screen time for each of mobile, and laptop and remote learning. Furthermore, there was positive correlation between decreased protein serving intake and each of mobile screen time and remote learning. TV watching and laptop screen times showed positively significantly association with frequent snacking between meals. Mobile screen time, TV screen time, and video gaming were positively significantly correlated with late night snacking. CONCLUSIONS: The present study concluded prolonged lockdown leads to changes in eating patterns, related to contributing factors of physical inactivity and prolonged screen time.

Relation of Asthma Control with Quality of Life among a Sample of Egyptian Asthmatic School Children

BACKGROUND:

Asthma is considered a chronic health illness that not only resulted in physical symptoms but also emotional effects. It is; therefore, so important to assess the quality of life of asthmatic patients besides their level of disease control.

AIM:

To determine the correlation of asthma control with the health-related quality of life (HRQOL) of asthmatic children in Egypt.

METHODS:

One hundred and twenty-eight asthmatic Egyptian children were enrolled in the study. They were subjected to asthma severity grading, asthma control questionnaire (ACQ) and pediatric asthma quality of life questionnaire (PAQLQ). Studied cases were taken from 6 primary and preparatory schools, Giza governorate.

RESULTS:

The mean child control score was significantly higher in not well-controlled asthmatics compared to well-controlled asthmatics (p < 0.005). The not well controlled asthmatic children showed significantly lower activity limitation score, symptoms score, and overall asthmatic score compared to controlled asthmatic children (p < 0.05). The severity of asthma shows significant positive correlation with symptoms score, emotional function score and overall asthmatic score (p < 0.05).

CONCLUSION:

The quality of life for the asthmatic children is strongly correlated with the level of asthma control and severity.

Oxidative Stress and Anti-Oxidant Markers in Premature Infants with Respiratory Distress Syndrome

BACKGROUND

Neonatal respiratory distress syndrome (RDS) caused by decreased surfactant and structural lung immaturity. The imbalance between oxidative status and antioxidant defence system was suggested to be an important trigger for lung affection with RDS.

AIM

The goal of the current research was to elucidate the significance of the oxidant/ antioxidant status in the pathogenesis of RDS in preterm infants.

PATIENTS AND METHODS

This controlled study included 31 preterm neonates with RDS and 36 healthy preterm neonates. Quantification level of oxidative stress biomarkers; malondialdehyde (MDA) & hydrogen peroxide (H₂O₂) along with antioxidant enzymes activity; catalase (CAT) & superoxide dismutase (SOD) in plasma of healthy premature neonates compared with those with RDS.

RESULTS

status of oxidative stress markers (MDA & H₂O₂) showed a significant increase with decreased levels of antioxidant enzymes activity (CAT & SOD) in neonates with RDS when compared to healthy prematures.

CONCLUSION

The results obtained in this study indicate that the increased oxidative stress accompanied by reduced antioxidant defences may play a significant role in the pathogenesis of respiratory distress in preterm newborns.

Heavy Metals Can either Aid or Oppose the Protective Function of the Placental Barrier

BACKGROUND:

In developing countries, toxic heavy metals are a threatening catastrophe to human health, particularly in the vulnerable group of pregnant mothers and their fetuses. Fortunately, the placenta can be a protective barrier to the fetuses.

AIM:

To explore the relationship between serum lead, cadmium and arsenic levels in pregnant mothers and their newborns, to address the placental barrier in this situation.

METHODS:

A cross-sectional study was conducted on 100 pregnant mothers at the time of labour and their newborns. Serum cadmium, lead, and arsenic levels were measured using the Inductively Coupled Plasma Mass Spectrometry.

RESULTS:

All the studied heavy metals concentrations showed a significant elevation in the maternal blood relative to the cord blood. There was a significant association between the maternal lead and both fetal lead and arsenic. Meanwhile, a negative but insignificant correlation was recorded between the maternal cadmium and each of the fetal cadmium, lead, and arsenic.

CONCLUSION:

The study findings indicated a weak relation between maternal and fetal blood heavy metals, except for the influence of maternal lead, so it can be assumed that the placental barriers are partially protective against those toxic pollutants, putting into consideration the influence of their different natures.

Mercury Materno-fetal Burden and Its Nutritional Impact

BACKGROUND:

Mercury exists worldwide in food, water and air throwing its health hazards on all body systems.

AIM:

To show the influence of the presence of mercury in pregnant mothers’ blood on its level in the umbilical cord blood; and to display the relationship between the different foodstuff on the mercury levels in pregnant mothers’ and umbilical cord blood.

PATIENTS AND METHODS:

This cross-sectional study was conducted on randomly chosen 113 pregnant mothers at the time of labour and on their newborns. Full history, sociodemographic data and food frequency questionnaire for dietary assessment were recorded. The Maternal and neonatal anthropometric measurements together with the Apgar scoring were also measured. Serum mercury levels in both mothers’ and umbilical cord blood were measured using the Inductively Coupled Plasma Mass Spectrometry (ICP-MS).

RESULTS:

A high percentage of mothers (82.3%) were exposed to passive smoking. There was a statistically significant positive correlation between the maternal and fetal umbilical cord blood mercury levels (p = 0.002). There was an insignificant negative correlation between the maternal blood and fetal umbilical cord blood mercury levels on one side and each of the different foodstuff on the other side (fish, vegetables, fruits and proteins, for example, meat and legumes). An insignificant positive correlation was found between dairy products and of the maternal blood and umbilical cord blood mercury levels.

CONCLUSION:

The fetal umbilical cord blood mercury levels correlate positively with the maternal blood mercury. The different foodstuff can influence the maternal and umbilical cord blood mercury levels whether by increase or decrease. Strict measures should be taken to decrease environmental mercury contamination with attention to pregnant mothers.

Serum Zinc Level and Its Correlation with Vesikari System Scoring in Acute Pediatric Diarrhea

BACKGROUND

Diarrhea remains the most common infectious disease worldwide. Zinc has been studied extensively recently for its potential effect on prevention, control and treatment of acute diarrhoea.

AIM

This study was designed to correlate the level of zinc with the severity of pediatric diarrhoea estimated by Vesikari Scoring System.

PATIENTS AND METHODS

The present study included 80 children aged two months to 30 months from those suffering from the acute diarrheal episode and admitted to Pediatric Hospital "Abo El Rish" Cairo University. Serum Zinc level was assessed by a colorimetric method with a spectrophotometer.

RESULTS

Zinc deficiency was detected in 45 (56.2%) patient of the studied group Significant negative correlations were found between serum zinc level and severity of dehydration and duration of hospitalization (p < 0.05).

CONCLUSION

Zinc level has an essential role in acute pediatric diarrhoea. Zinc therapy should be considered beside Oral rehydration salts (ORS) to achieve maximum impact on diarrheal diseases; clinical trials are recommended to support the zinc supplementation in developing countries.

Glutathione Transferase as a Potential Marker for Gut Epithelial Injury versus the Protective Role of Breast Milk sIgA in Infants with Rota Virus Gastroenteritis

BACKGROUND:

Secretory immunoglobulin A (SIgA) plays an important protective role in the recognition and clearance of enteric pathogens.

AIM:

This study was designed to assess if mucosal integrity “measured by secretory IgA (SIgA)” is a protective factor from more epithelial alteration “measured by glutathione transferase” in infants with Rota gastroenteritis and its relation to infants’ feeding pattern.

PATIENTS AND METHODS:

This study was conducted on 79 infants aged 6 months and less from those diagnosed as having gastroenteritis and admitted to Gastroenteritis Department in Abo El Rish Pediatric Hospital, Cairo University. Plasma glutathione s-transferases and Stool SIgA were measured using ELISA technique. Rota virus detection was done by Reverse transcriptase PCR.

RESULTS:

SIgA was found to be significantly positive in exclusive breast fed infants, Glutathione transferase was significantly more frequently positive in Rota positive cases than Rota negative cases by Reverse transcriptase PCR. A significant negative correlation between Glutathione transferase and Secretory IgA was found, (p < 0.05).

CONCLUSION:

Breast feeding should be encouraged and highly recommended in the first two years of life as it provides Secretory IgA to breast fed infants who in turn protect them against epithelial damage caused by Rota viral gastroenteritis.

Prediction of Gut Wall Integrity Loss in Viral Gastroenteritis by Non-Invasive Marker

BACKGROUND:

Intestinal fatty acid binding proteins (I-FABPs) are mainly expressed in the intestinal villi, which are the initial site of destruction in viral gastroenteritis.

AIM:

This study was designed to assess serum I-FABPs as a predictor of gut wall integrity loss in viral gastroenteritis.

PATIENTS AND METHODS:

This case-control cross-sectional study was conducted on 93 cases of acute viral gastroenteritis. Twenty-eight healthy children matching in age were recruited as control group. Serum I-FABPs were measured using ELISA technique. Viral detection and typing were done by PCR for adenovirus, and by Reverse transcriptase PCR for rotavirus, astrovirus and norovirus.

RESULTS:

Serum I-FABPs level was significantly higher in the cases compared to the controls and was also higher in the 46 rotavirus gastroenteritis cases compared to other viral gastroenteritis cases. Serum I- FABPs level was significantly higher in severely dehydrated cases as compared to mildly dehydrated ones (P=0.037).

CONCLUSION:

Serum I-FABPs could be used as an early and sensitive predictor marker of gut wall integrity loss in children with viral gastroenteritis and its level can indicate case severity.

Clinical Relevance of Transforming Growth Factor-β1, Interleukin-6 and Haptoglobin for Prediction of Obesity Complications in Prepubertal Egyptian Children

BACKGROUND:

The rate of obesity is increasing throughout the world. Obesity in adults’ research is characterized by chronic inflammation, associated with type 2 Diabetes and cardiovascular risk. The degree to which these changes occur in childhood obesity is not fully defined.

AIM:

This study was designed to explore the relation between circulating levels of pro-inflammatory cytokines, and obesity.

PATIENTS AND METHODS:

This cross sectional case control study was carried out in 50 randomly selected pre-pubertal overweight and obese children compared with fifty apparently healthy children of matched age and sex. Serum levels of transforming growth factor-β1, interleukin-6, and haptoglobin were quantified by ELISA technique.

RESULTS:

ANOVA test followed by Post Hoc test showed highly significant increase in the serum levels of the transforming growth factor-β1, interleukin-6 and haptoglobin among obese children compared to overweight and healthy children respectively. The body weight, BMI and BMI z-score were significantly positively correlated with serum levels of the three pro-inflammatory cytokines. Serum levels of interleukin-6, and haptoglobin were found to be strong predictors of complications in severe obesity by linear regression analysis.

CONCLUSIONS:

Obesity is associated with chronic low-grade inflammation. High levels of interleukin-6 and haptoglobin are considered to be early biomarkers of inflammation associated with severe obesity with subsequent cardiovascular and type 2 diabetes risk.

Avian influenza A(H5N1) and A(H9N2) seroprevalence and risk factors for infection among Egyptians: a prospective, controlled seroepidemiological study

BACKGROUND

A(H5N1) and A(H9N2) avian influenza viruses are enzootic in Egyptian poultry, and most A(H5N1) human cases since 2009 have occurred in Egypt. Our understanding of the epidemiology of avian viruses in humans remains limited. Questions about the frequency of infection, the proportion of infections that are mild or subclinical, and the case-fatality rate remain largely unanswered.

METHODS

We conducted a 3-year, prospective, controlled, seroepidemiological study that enrolled 750 poultry-exposed and 250 unexposed individuals in Egypt.

RESULTS

At baseline, the seroprevalence of anti-A(H5N1) antibodies (titer, ≥80) among exposed individuals was 2% significantly higher than that among the controls (0%). Having chronic lung disease was a significant risk factor for infection. Antibodies against A(H9N2) were not detected at baseline when A(H9N2) was not circulating in poultry. At follow-up, A(H9N2) was detected in poultry, and consequently, the seroprevalence among exposed humans was between 5.6% and 7.5%. Vaccination of poultry, older age, and exposure to ducks were risk factors for A(H9N2) infection.

CONCLUSIONS

Results of this study indicate that the number of humans infected with avian influenza viruses is much larger than the number of reported confirmed cases. In an area where these viruses are enzootic in the poultry, human exposure to and infection with avian influenza becomes more common.

Serum Asymmetric Dimethylarginine, and Adiponectin as Predictors of Atherosclerotic Risk among Obese Egyptian Children

BACKGROUND: Obesity is associated with an increased risk of developing hyperinsulinemia, dyslipidemia, hypertension, premature atherosclerosis, and coronary artery disease in the future.AIM: This study is designed to assess the relationship between serum adiponectin, asymmetric dimethylarginine (ADMA), and lipid profile among Egyptian overweight and obese children.METHODS: This cross sectional case control study included 40 selected pre-pubertal overweight and obese children, 24 girls (60%) and 16 boys (40%) aged between 5 to 13 years (8.85 ± 2.7 years), from new cases attending the National nutrition institute clinic during 2013. Forty apparently healthy children of matched age and sex were recruited as a control group.RESULTS: Obese group showed highly significant higher levels of serum ADMA, triglycerides, and total cholesterol compared with healthy controls (P <0.000 in all). However, serum adiponectin levels were highly significant lower in obese children compared to healthy controls (P < 0.000). Serum ADMA showed significant positive correlations with height, serum total cholesterol and serum triglycerides levels and significant negative correlation with the body mass index and weight for age z score.  Serum adiponectin showed significant negative correlations with BMI, weight, and weight for age z score and significant positive correlation with serum triglycerides. By linear regression analysis; serum adiponectin, and serum triglycerides levels were significant predictors of high serum ADMA level (p =0.045 and 0.015 respectively). BMI, weight, height and serum triglycerides were significant predictors of low serum adiponectin levels (p = 0.005, 0.022, 0.026 and 0.015 respectively).CONCLUSIONS: Our results revealed that ADMA, Adiponectin and lipid profile can be considered as predictive biomarkers in prediction and prevention of atherosclerotic risk in the future among overweight and obese Egyptian children.

Prospective study of avian influenza transmission to humans in Egypt

BACKGROUND

The highly pathogenic avian influenza (HPAI) H5N1 virus remains a public health threat and continues to cause outbreaks among poultry as well as human infections. Since its appearance, the virus has spread to numerous geographic areas and is now considered endemic in Egypt and other countries. Most studies on human H5N1 cases were conducted to investigate outbreak situations and were not designed to address fundamental questions about the epidemiology of human infection with H5N1 viruses. Our objective for this study is to answer these questions by estimating the prevalence and incidence rates of human cases and determine associated risk and protective factors in areas where H5N1 viruses are endemic.

METHODS/DESIGN

We designed a 3-year prospective cohort study of 1000 individuals of various exposure levels to poultry in Egypt. At onset, we will collect sera to estimate baseline antibody titers against AI viruses H4-H16. Two follow-up visits are scheduled at 1-year intervals following initial enrollment. At follow-up, we will also collect sera to measure changes in antibody titers over time. Thus, annual prevalence rates as well as incidence rates of infection will be calculated. At each visit, exposure and other data will be collected using a specifically tailored questionnaire. This data will be used to measure risk and protective factors associated with infection. Subjects will be asked to contact the study team any time they have influenza-like illness (ILI). In this case, the study team will verify infection by rapid influenza A test and obtain swabs from the subject's contacts to isolate and characterize viruses causing acute infection.

DISCUSSION

Epidemiologic studies at the influenza human-animal interface are rare, hence many questions concerning transmission, severity, and extent of infection at the population level remain unanswered. We believe that our study will help tackle and clarify some of these issues.

Can a single serum CA125 assay predict the outcome of threatened abortion?

Earlier work suggested that high levels of CA125 could be detected in the sera of women with threatened abortion. In this study, we used CA125 as a method of anticipating outcome in cases of threatened abortion and compared the results with ultrasonic findings. Three groups of patients were studied.(1) 57 women who threatened to abort, but whose pregnancy continued.(2) 43 women with a threatened abortion, who subsequently aborted, and (3) 50 normal women who had no bleeding in early pregnancy. There was a highly significant increase in serum CA125 in women who aborted compared with the other two groups (P<0.001). The results compared well with conventional ultrasound and serum CA125 may be developed as a cheap, sensitive and specific predictor of outcome in cases of threatened abortion.

Low-molecular weight heparin in patients with recurrent early miscarriages of unknown aetiology

The aim of this randomised prospective study was to assess the efficacy of early thromboprophylaxis with low-molecular weight heparin (LMWH) in women with a history of recurrent first trimester spontaneous abortion or miscarriages without identifiable causes vs no treatment. The study comprised of 340 women with unexplained spontaneous recurrent miscarriages. Patients in group A were prescribed LMWH (Enoxaparin sodium 0.2 ml, 20 mg, once daily subcutaneously) from the time of confirmation of fetal viability by ultrasonography until 34 weeks' gestation, and folic acid tablets 0.5 mg daily until 13 weeks' gestation. Patients in group B were given folic acid tablets 0.5 mg daily until 13 weeks' gestation. Termination of pregnancy was the primary outcome. There was a significant difference in the incidence of both early (4.1% vs 8.8%) and late miscarriages (1.1% vs 2.3%) in group A than in group B, respectively. There were no differences between both groups as regards the occurrence of pre-eclampsia, placental abruption, caesarean delivery, intra-partum bleeding or ecchymosis at operative wounds. There were no differences in most of the neonatal values between both groups. However, the mean birth weight was significantly higher in group A. LMWH seems to be a safe drug and effective in significantly reducing the incidence of recurrent miscarriages of unknown aetiology when given in the first trimester and continued throughout pregnancy.

Transplacental transmission of hepatitis C virus in HIV-negative mothers

The aim of this work was to evaluate transplacental transmission of hepatitis C virus (HCV) in HIV-negative pregnant women who were HCV-PCR-positive, and also to determine the serotypes of the virus in these cases. Therefore, 767 pregnant women were screened for anti-HCV antibodies, hepatitis B surface antigen (HBsAg) and anti-HIV antibodies. HCV PCR was performed for HCV-positive women. Those who were PCR-positive were tested for anti-HCV IgM. Neonates of PCR-positive mothers were tested for virus transmission by the PCR test. Virus serotyping was done for mothers and neonates. Anti-HCV antibodies were detected in 105 out of 767 (13.7%) pregnant women. PCR was positive in 18 out of 67 HCV-positive women (26.9%). Transplacental transmission occurred in 11.1% of HIV-negative pregnant women. HCV type 4 predominates in Egypt (83.3%). Mothers who are PCR-positive and have high aspartate aminotransferase and positive anti-HCV IgM are most likely to transmit HCV to their babies.

Detection of pregnant women at risk of cervical incompetence by transvaginal sonography during straining

OBJECTIVE

To evaluate the ability of transvaginal sonography (TVS) undertaken, during straining to detect incompetent cervix in pregnant women at risk.

METHOD

Forty-seven pregnant women with risk factor(s) for cervical incompetence and 22 pregnant women (control) were evaluated for cervical changes detected by TVS during rest, transfundal pressure and during the stress induced by straining.

RESULTS

The control group demonstrated no cervical changes. The changes were more significant during straining than with transfundal pressure. In the group with risk factor(s), 48.9% showed negative response and 51.1% demonstrated positive response. The pregnancy outcome was more favourable in the group with negative response (full term pregnancy 82.6% vs 70.8%, preterm delivery 13% vs 16.7% and pregnancy loss 4.4% vs 12.5%).

CONCLUSION

TVS during straining can be applied as a stress test in women at risk for cervical incompetence.

Bladder stone: a complication of intravesical migration of Lippes loop

We report on a woman in whom an intrauterine contraceptive device (Lippes loop) migrated from the uterus to the bladder with formation of a calculus. Eight years elapsed between intrauterine insertion of the device and its retrieval with the calculus from the bladder.