Biomedical invasive pressure sensor coatings: calibration and waveform perspectives.

The biocompatibility of invasive biomedical sensors is a fundamental issue in the design of implanted sensors. Therefore, the unique packaging of the sensor is a crucial design procedure that must be performed and evaluated correctly. Under steady-state measurements, the sensor calibration can be done quickly, and the corresponding errors and loss in the sensor's sensitivity, because of the packaging material, can be compensated easily. This paper investigates the effect of the presence and absence of biocompatible silicone paste as packaging material on the catheter sensor's output waveform morphology, and the sensor's response time under dynamic measurements. The procedure to calibrate the sensor during the design is presented to compensate for the effect of packaging material in terms of state-space formulation. In conclusion, errors in peak pressure and waveform shape in the catheter sensor can be significantly reduced by the geometry and the packaging materials of the catheter sensor. At last, we believe that using biocompatible silicone paste as packaging material on the catheter sensor is scalable.

Risk factors, characteristics and outcomes of necrotizing enterocolitis in late preterm and term infants.

OBJECTIVE: To identify the risk factors, characteristics and outcomes of necrotizing enterocolitis (NEC) at our institution. STUDY DESIGN: A retrospective case-control analysis of the charts of all late preterm and term infants, who had NEC of Bell's stage ≥ II from 1995 to 2009, along with infants of the same gestational age. Thirty-two late preterm infants had NEC meeting criteria and 128 late preterm and term infants were chosen as matched controls. RESULTS: The 32 NEC infants were more likely to have the following characteristics: a culture-proven sepsis (p = 0.0001), be small for their gestational age (p = 0.003), have a congenital heart disease (p = 0.007), and suffer from hypoxic- ischemic encephalopathy (p = 0.04). The presence of hypotension, metabolic acidosis, thrombocytopenia, and pneumoperitoneum was associated with a poor prognosis. Twelve of the 13 (92%) NEC infants who died had a surgical intervention. CONCLUSION: In this study, late preterm and term infants who developed NEC had other underlying clinical diagnoses and had culture-proven sepsis. Mortality rate was high in infants who required surgical intervention, indicating that they were gravely ill from the onset. Thrombocytopenia, hypotension and metabolic acidosis in late preterm and term infant with NEC were associated with poor prognosis.

Infections with the 2009 H1N1 influenza virus among hematopoietic SCT recipients: a single center experience.

We retrospectively reviewed medical records of 39 hematopoietic SCT (HSCT) recipients who presented at our hospital between 1 October 2009 and 31 January 2010 with the 2009 H1N1 influenza infection. The median age at presentation was 13.8 years (range: 3.3-56.9), infections developed at a median of 585 days (range: 0-2316) post transplant, the majority (n=27, 69%) occurred in allogeneic HSCT recipients, 12 (31%) patients were on immunosuppressive therapy and 12 (31%) had GVHD. Lower airway disease was present in 8 patients (21%). In total, 15 patients (39%) were hospitalized with a median duration of 4.5 days (range: 3-27 days) and 3 (8%) required mechanical ventilation; 2 of whom died.

Spectral investigations of intraluminal impedance signals.

In this paper, an investigation of the spectral characteristics of intraluminal impedance signals using local Hilbert-Huang transform is presented. The impedance waveform may contain three main events: reflux event, swallow event and baseline region corresponding to no activity. The three events are analysed using local Hilbert-Huang transform to characterize the frequency contents of each event. In addition to the results of the Hilbert-Huang transform a time domain description of each event is presented.

Extraction of foetal ECG by combination of singular value decomposition and neuro-fuzzy inference system.

Extraction of foetal ECG that is embedded in the maternal ECG is a challenging problem. This paper presents a combined system to extract foetal ECG from maternal abdominal ECG. The system uses a combination of singular value decomposition (SVD) and a neuro-fuzzy inference system. The SVD is used to construct two reference signals, while the fuzzy system is used as an adaptive canceller. The algorithm is applied on synthetic as well as real data and the results are presented. In addition, the paper presents an example of using the same system as a noise removal tool.

A clinical and genetic study of 56 Saudi Wilson disease patients: identification of Saudi-specific mutations.

Wilson disease (WD) is a hereditary disorder, with recessive transmission and genetic heterogeneity. Several mutations of ATP7B, the gene underlying WD, were reported in many ethnic groups. In this study, mutation screening in ATP7B of 56 Saudi Arabian WD patients was undertaken. The clinical data of all patients were recorded. The entire ATP7B coding sequence, including intron-exon boundaries were screened for mutation by the polymerase chain reaction (PCR)-based mutation detection technique and DNA sequencing. Thirty-nine patients were symptomatic at presentation and 17 subjects were pre-symptomatic siblings of affected patients. Fourteen patients had neurological, 11 patients had mixed (hepatic and neurological), and 14 patients had hepatic presentations. Family history suggestive of WD was present in 72% of cases and 68% had consanguineous parents. Genetic analysis showed disease-causing mutations in three exons (exons 8, 19 and 21) of the ATP7B gene in 28 patients (50%). Mutations in exons 21 (18 cases) and 19 (one case) were unique for Saudis. This large series of Saudi patients with WD has shown wide variability in the genomic substrate of WD. There is no correlation between genotype and clinical presentation.

Simulation of intraluminal impedance.

Intraluminal impedance describes the electrical impedance inside the Gastrointestinal tract (GIT). These observations provide information about the state of the GIT that assists in the diagnosis. This paper presents numerical modeling of impedance measurements inside the GIT in order to evaluate the data generated under different conditions, such as various catheter configurations, different esophagus wall widths, different positions of the catheter inside the GIT and the presence of materials with different conductivities between the electrodes. The model used in the simulation assumes realistic esophagus and the values of the conductivities are obtained from literature. The results of this paper will be useful in the design and interpretation of the GIT impedance measurements.

Thresholding reflux episodes in impedance measurements using a neuro-fuzzy system.

Multiple intraluminal impedance measurements (MII) provides impedance signals which reflect the changes in the electrical conductivity inside the gastrointestinal tract (GIT). To determine a reflux episode from MII signals, wavelet transform is used to detect the edges of the impedance, then thresholding impedance at certain level. A predictor for the value of the threshold is constructed by training a fuzzy system using a number of features. During training process the predictor clusters the features into classes of similar feature values. The trained system is used to predict the threshold applied on the distal channel. Subsequently, a combination of wavelet transform and fuzzy logic is used to classify the episodes. In this paper we present the results of one stage of the system that predicts the threshold applied on the impedance value.

Extrahepatic biliary atresia in Saudi Arabia: the importance of early diagnosis and referral.

OBJECTIVE: A retrospective analysis of the medical records of children who were managed for extrahepatic biliary atresia (EHBA) over a 6-year period. MATERIALS AND METHODS: Twelve children were managed at King Fahad National Guard Hospital with a diagnosis of extrahepatic biliary atresia from January 1993 through December 1998. The data obtained included age, sex, clinical presentation, age at referral, investigations, management, complications and follow-up. RESULTS: There were 7 males and 5 females with age of onset of jaundice ranging from 3 days to 42 days (mean 10 days). The mean age at referral was 17 weeks (range 6-49 weeks). Kasai Portoenterostomy (PE) was performed in 7 infants and the mean age at surgery was 8 weeks (range 7 to 10.5 weeks). Four children could not undergo Kasai PE because they were more than 20 weeks old and 1 child although 10 weeks old had extensive liver cirrhosis and was considered not suitable for the procedure. One child who had primary liver transplant outside the Kingdom and 4 children who had Kasai PE are still alive. Seven children are lost to follow-up and are probably dead. CONCLUSION: The incidence of EHBA in Saudi Arabia is unknown and the disease is probably rare based on our review. Although jaundice, pale stools and dark urine were observed in early infancy, referral was always late. Public and health professional's awareness of the clinical features of EHBA is important in early identification of infants and early referral. Starting paediatric hepatobiliary centers in Saudi Arabia will improve the management of these cases.

Detection of gastrointestinal tract events from multichannel intraluminal impedance measurements.

Investigation of Gastrointestinal tract (GIT) using multichannel intraluminal impedance technique (MII) is presented. The MII traces have large variations which correspond to the occurrence of certain activity that causes the impedance to change. A technique to detect the tract events from MII data is developed using wavelet transform. The resulting transformed signals are used to detect the occurrence of GIT events and to classify the events as swallow, reflux, or gas reflux. The technique is also used in estimating reflux event duration and the bolus velocity.

Physician's perceptions of fever in children. Facts and myths.

OBJECTIVE: To ascertain the knowledge and attitude of physicians, regarding fever in children. METHODS: A self-administered questionnaire was mailed to 600 randomly selected pediatricians, family practice physicians, emergency medicine physicians and general practitioners, who practice in Saudi Arabia. Appropriateness of responses to questions was determined on the basis of current medical literature. A rectal temperature of 38.0 degrees C is generally accepted as indicative of fever in children. RESULTS: Of the 600 physicians surveyed, 419 (70%) completed and returned the questionnaire; 17% of the physicians were consultants, 28% specialists and 55% general practitioners. Fifty-eight percent of the physicians had 10 years or more of experience. A rectal temperature of less than 38.0 degrees C was considered to indicate fever by 38% of physicians. Nearly 84% of physicians would initiate antipyretic therapy at a temperature of 38.5 degrees C or less and 56% cited a temperature of 40.0 degrees C or less to be dangerous. Only 5% believed that fever was not dangerous, while the remaining cited the principal danger of fever to be convulsions (69%), brain damage (35%), or death (8%). The responses to the main purpose of antipyretic treatment were to prevent convulsions (70%), to make the child comfortable (55%) and to prevent brain damage (29%). Approximately 53% of physicians reported that the most serious consequences of febrile convulsions were brain damage, learning disability, epilepsy, or death. Only 26% of physicians agreed that a sleeping child with fever should be left undisturbed. Approximately 25% advised inappropriate dosage or administration intervals of paracetamol. Almost all physicians recommended sponging or bathing to reduce fever. All respondents try to educate parents regarding fever and its management. CONCLUSION: A significant number of the surveyed physicians have demonstrated a serious lack of knowledge of the nature, dangers and management of an extremely common health problem. Physicians differ substantially in their knowledge of, and attitude toward fever in children, which is perhaps attributed to their different background in medical education and clinical training.

A novel deletion mutation within the carboxyl terminus of the copper-transporting ATPase gene causes Wilson disease.

In patients with Wilson disease (WD), an autosomal recessive disorder, toxic accumulation of copper results in fatal liver disease and irreversible neuronal degeneration. ATP7B, the gene mutated in WD, contains 21 exons and encodes a copper-transporting ATPase. In this study, all exons of the ATP7B gene of nine WD patients were screened for alterations by conventional mutation detection enhancement (MDE) heteroduplex analysis, followed by direct sequencing of the regions that showed heteroduplex formation. For the first time, a novel deletion mutation (4193delC) in exon 21, causing a frameshift leading to premature truncation of the protein was detected in four of nine patients. The 4193delC removes several signals within the carboxyl terminal domain that may disrupt trafficking of ATP7B protein through trans-Golgi network at the cellular level.

Turcot's syndrome in an Arab child.

A 12 year old female child of Arab origin presented with chronic bloody diarrhoea and growth failure. Physical examination confirmed a growth failure and cafe-au-lait patches. Colonoscopy and colon biopsies showed adenocarcinoma of the colon and laparotomy confirmed metastases to the liver. A diagnosis of Turcot's Syndrome was entertained in this child.

Benign recurrent intrahepatic cholestasis in a Saudi child.

We report a case of benign recurrent intrahepatic cholestasis (BRIC) in an 11-year-old Saudi girl who developed three episodes of pruritus and jaundice at the ages of 4, 8, and 9 years. These episodes were almost stereotypic and lasted 5-8 weeks. Although she had elevated liver enzymes and serum bile acids in her blood during the attacks, they returned to normal between attacks. Thorough investigation excluded other causes of liver disease and her recurrent attacks were shortened by cholestyramine therapy. A diagnosis of BRIC should be kept in mind in patients with cholestasis.

Liver glycogenosis due to phosphorylase kinase deficiency: PHKG2 gene structure and mutations associated with cirrhosis.

Mutations in three different genes of phosphorylase kinase (Phk) subunits, PHKA2, PHKB and PHKG2, can give rise to glycogen storage disease of the liver. The autosomal-recessive, liver-specific variant of Phk deficiency is caused by mutations in the gene encoding the testis/liver isoform of the catalytic gamma subunit, PHKG2. To facilitate mutation detection and to improve our understanding of the molecular evolution of Phk subunit isoforms, we have determined the structure of the human PHKG2 gene. The gene extends over 9.5 kilonucleotides and is divided into 10 exons; positions of introns are highly conserved between PHKG2 and the gene of the muscle isoform of the gamma subunit, PHKG1. The beginning of intron 2 harbors a highly informative GGT/GT microsatellite repeat, the first polymorphic marker in the PHKG2 gene at human chromosome 16p11.2-p12.1. Employing the gene sequence, we have identified homozygous translation-terminating mutations, 277delC and Arg44ter, in the two published cases of liver Phk deficiency who developed cirrhosis in childhood. As liver Phk deficiency is generally a benign condition and progression to cirrhosis is very rare, this finding suggests that PHKG2 mutations are associated with an increased cirrhosis risk.

Diagnostic value of Doppler ultrasound in the assessment of liver cirrhosis in children: histopathological correlation.

We have correlated flow abnormalities in the hepatic vasculature with histological findings in the liver to determine the accuracy of Doppler ultrasound in the diagnosis of liver cirrhosis in children. Eighteen children admitted for evaluation of unknown liver disease were examined prospectively and blindly with Doppler ultrasound prior to liver biopsy. Biopsy specimens showed established cirrhosis in 9 of 18, early cirrhosis in 5 of 18, and no cirrhosis in 4 of 18 children. Doppler studies were also performed on 20 control subjects. The portal vein velocity was decreased (p < 0.0005) and the arterio-portal velocity ratio was increased (p < 0.0005) in the established cirrhosis cohort relative to the controls. For the criteria of the established cirrhosis cohort, the sensitivities of the loss of the reverse flow component in the hepatic veins, the arterio-portal velocity ratio being greater than 3.0, the portal vein velocity being less than 20 cm/s, and the existence of focal flow acceleration in the hepatic veins were 100%, 78%, 67%, and 44%, respectively. The specificity of all these criteria was 100%. The indicators were not useful in the diagnosis of early cirrhosis.

Vesicoureteral reflux in children. Experience in riyadh, saudi arabia.

There are a few reports about the size of the problem of vesicoureteral reflux (VUR) in developing countries. We attempted in our study to assess the experience of this problem in children in a tertiary care medical center in the period between June 1983 till June 1993. VUR was diagnosed in 24 patients, of whom 71% were boys. The mean age of the patients was 36.5 months; seven (29%) of them were below one year of age. The commonest presentation was urinary tract infection. E. coli was the most common organism and was resistant to the first chpice chemoprophylaxis in 50% of cases. Urine culture was also positive in 37.5% of children who were grossly asymptomatic. Ultrasound study failed to detect VUR in 25% of cases. There were eleven patients with mild to moderate reflux (grades I, II, III) of whom 9% required ureter reimplantation by open surgery. Eleven patients had severe reflux (grades IV,V) of whom 72% required the same procedure. Post-operatively, of the nine patients who had reimplantation, seven (77.5%) had successful surgery and maintained normal renal function after a mean duration of follow up of 30 months (range from 6 to 84 months), one patient developed end-stage renal disease, and one patient was lost to follow-up. We conclude that VUR is not uncommon in early childhood. Early referral of severe cases for surgical reimplantation is recommended.