The Experts below are selected from a list of 417 Experts worldwide ranked by ideXlab platform
Yoshio Okada - One of the best experts on this subject based on the ideXlab platform.
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influence of unfused cranial bones on magnetoencephalography signals in human infants
Clinical Neurophysiology, 2021Co-Authors: Seok Lew, Matti Hamalainen, Seppo P Ahlfors, Yoshio OkadaAbstract:Abstract Objective To clarify the effects of unfused cranial bones on magnetoencephalography (MEG) signals during early development. Methods In a simulation study, we compared the MEG signals over a spherical head model with a circular hole mimicking the Anterior Fontanel to those over the same head model without the Fontanel for different head and Fontanel sizes with varying skull thickness and conductivity. Results The Fontanel had small effects according to three indices. The sum of differences in signal over a sensor array due to a Fontanel, for example, was Conclusion MEG signal is weakly affected by a Fontanel. However, the effects can be extensive and significant for radial sources, thicker skull and large Fontanels. The Fontanel effects can be intuitively explained by the concept of secondary sources at the Fontanel wall. Significance The minor influence of unfused cranial bones simplifies MEG analysis, but it should be considered for quantitative analysis.
Richard E. Kirschner - One of the best experts on this subject based on the ideXlab platform.
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Extensive aplasia cutis congenita and the risk of sagittal sinus thrombosis.
Archives of dermatology, 2005Co-Authors: Jonathan Kantor, Albert C. Yan, Chad M. Hivnor, Paul J. Honig, Richard E. KirschnerAbstract:A full-term 1-day-old boy weighing 3140 g was transferred to our tertiary care children’s hospital with large areas of skin defects on his scalp, trunk, and extremities. His parents were nonconsanguineous, and the results of prenatal maternal laboratory screening for human immunodeficiency virus, hepatitis B, group B streptococci, and rapid plasma reagin were negative. Intrauterine fetal death of a twin had been reported at 16 to 18 weeks of gestation. No other complications were noted during the pregnancy. On physical examination, a full-thickness ulcer of the scalp vertex was observed extending from the Anterior Fontanel to the posterior Fontanel in an area overlying the sagittal sinus. The defect measured 5 7 cm and revealed exposed dura and subcutaneous vessels (Figure 1). Two symmetric, vertically oriented, full-thickness defects, each measuring 3.2 cm, with minimal surrounding erythema, were noted on the lateral aspect of the abdomen (Figure 2). Examination of the knees revealed symmetric full-thickness defects that appeared as yellow-red, indurated ulcers. Symmetric, linear scars were observed bilaterally in the axillary and inguinal creases. Magnetic resonance imaging of the head and a magnetic resonance venogram revealed patent major intracranial venous sinuses and slight hypoplasia of the left transverse sinus (considered a normal congenital variation). A relative lack of subcutaneous fat over the superior aspect of the skull was also observed, consistent with the clinical presentation. Concern that the extensive open defect posed a high risk for sagittal sinus thrombosis, hemorrhage, or meningitis prompted plastic surgery and neurosurgery consultations. The scalp defect was repaired by plastic surgery with a skin graft, while the remaining areas of aplasia cutis congenita were allowed to heal by secondary intention. Over the next 3 weeks, the scalp healed well, without complications, as did the other areas of aplasia on the abdomen and knees. DIAGNOSTIC CHALLENGE
Pracha Nuntnarumit - One of the best experts on this subject based on the ideXlab platform.
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cerebral blood flow velocity changes after bovine natural surfactant instillation
Journal of Perinatology, 2000Co-Authors: Pracha Nuntnarumit, Henrietta S Bada, Wenjian Yang, Sheldon B KoronesAbstract:OBJECTIVE: To determine the effects of bovine natural surfactant (beractant) instillation on cerebral hemodynamics in preterm infants with respiratory distress syndrome (RDS). STUDY DESIGN: Preterm infants who required surfactant for RDS were enrolled. Cerebral blood flow velocity (CBFV) waveforms from the pericallosal artery were analyzed by pulsed Doppler ultrasonography with the Anterior Fontanel serving as an acoustic window. CBFV was measured before and at 5, 10, 20, and 30 minutes after the first dose of a bolus instillation of surfactant in four aliquots. Simultaneously with CBFV measurements, mean blood pressure (MBP), heart rate, and ventilator settings were recorded. pH, PACO2, and PAO2 before and at 30 minutes after surfactant administration were also determined. RESULTS: The 30 enrolled preterm infants had a mean birth weight of 973 gm (513 to 1996 gm) and a mean gestational age of 27 weeks (23 to 33 weeks). Mean postnatal age at surfactant administration was 4.7 ± 2.7 hours. There were no significant changes in pH and PACO2 before and at 30 minutes after surfactant (before surfactant: mean pH of 7.29 ± 0.07 and mean PACO2 of 44.4 ± 7.1 torr; after surfactant: mean pH of 7.31 ± 0.07 and mean PACO2 of 42.7 ± 8.3 torr). PAO2 increased significantly from a pre-surfactant mean of 83 torr to 130 torr at 30 minutes after surfactant (p < 0.05), with no significant changes in mean airway pressure. There were no significant changes in MBP, heart rate, mean CBFV, peak systolic flow velocity, and diastolic flow velocity before and after surfactant instillation regardless of gestational age. Individual changes in mean CBFV were related to MBP changes (p < 0.001, linear mixed models with random effects). CONCLUSION: In low birth weight infants with RDS, bovine surfactant instillation is not associated with a significant alteration in cerebral hemodynamics. However, the direct relationship between CBFV and MBP is consistent with the reported pressure-passive cerebral circulation in sick preterm infants.
Jonathan Kantor - One of the best experts on this subject based on the ideXlab platform.
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Extensive aplasia cutis congenita and the risk of sagittal sinus thrombosis.
Archives of dermatology, 2005Co-Authors: Jonathan Kantor, Albert C. Yan, Chad M. Hivnor, Paul J. Honig, Richard E. KirschnerAbstract:A full-term 1-day-old boy weighing 3140 g was transferred to our tertiary care children’s hospital with large areas of skin defects on his scalp, trunk, and extremities. His parents were nonconsanguineous, and the results of prenatal maternal laboratory screening for human immunodeficiency virus, hepatitis B, group B streptococci, and rapid plasma reagin were negative. Intrauterine fetal death of a twin had been reported at 16 to 18 weeks of gestation. No other complications were noted during the pregnancy. On physical examination, a full-thickness ulcer of the scalp vertex was observed extending from the Anterior Fontanel to the posterior Fontanel in an area overlying the sagittal sinus. The defect measured 5 7 cm and revealed exposed dura and subcutaneous vessels (Figure 1). Two symmetric, vertically oriented, full-thickness defects, each measuring 3.2 cm, with minimal surrounding erythema, were noted on the lateral aspect of the abdomen (Figure 2). Examination of the knees revealed symmetric full-thickness defects that appeared as yellow-red, indurated ulcers. Symmetric, linear scars were observed bilaterally in the axillary and inguinal creases. Magnetic resonance imaging of the head and a magnetic resonance venogram revealed patent major intracranial venous sinuses and slight hypoplasia of the left transverse sinus (considered a normal congenital variation). A relative lack of subcutaneous fat over the superior aspect of the skull was also observed, consistent with the clinical presentation. Concern that the extensive open defect posed a high risk for sagittal sinus thrombosis, hemorrhage, or meningitis prompted plastic surgery and neurosurgery consultations. The scalp defect was repaired by plastic surgery with a skin graft, while the remaining areas of aplasia cutis congenita were allowed to heal by secondary intention. Over the next 3 weeks, the scalp healed well, without complications, as did the other areas of aplasia on the abdomen and knees. DIAGNOSTIC CHALLENGE
Sheldon B Korones - One of the best experts on this subject based on the ideXlab platform.
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cerebral blood flow velocity changes after bovine natural surfactant instillation
Journal of Perinatology, 2000Co-Authors: Pracha Nuntnarumit, Henrietta S Bada, Wenjian Yang, Sheldon B KoronesAbstract:OBJECTIVE: To determine the effects of bovine natural surfactant (beractant) instillation on cerebral hemodynamics in preterm infants with respiratory distress syndrome (RDS). STUDY DESIGN: Preterm infants who required surfactant for RDS were enrolled. Cerebral blood flow velocity (CBFV) waveforms from the pericallosal artery were analyzed by pulsed Doppler ultrasonography with the Anterior Fontanel serving as an acoustic window. CBFV was measured before and at 5, 10, 20, and 30 minutes after the first dose of a bolus instillation of surfactant in four aliquots. Simultaneously with CBFV measurements, mean blood pressure (MBP), heart rate, and ventilator settings were recorded. pH, PACO2, and PAO2 before and at 30 minutes after surfactant administration were also determined. RESULTS: The 30 enrolled preterm infants had a mean birth weight of 973 gm (513 to 1996 gm) and a mean gestational age of 27 weeks (23 to 33 weeks). Mean postnatal age at surfactant administration was 4.7 ± 2.7 hours. There were no significant changes in pH and PACO2 before and at 30 minutes after surfactant (before surfactant: mean pH of 7.29 ± 0.07 and mean PACO2 of 44.4 ± 7.1 torr; after surfactant: mean pH of 7.31 ± 0.07 and mean PACO2 of 42.7 ± 8.3 torr). PAO2 increased significantly from a pre-surfactant mean of 83 torr to 130 torr at 30 minutes after surfactant (p < 0.05), with no significant changes in mean airway pressure. There were no significant changes in MBP, heart rate, mean CBFV, peak systolic flow velocity, and diastolic flow velocity before and after surfactant instillation regardless of gestational age. Individual changes in mean CBFV were related to MBP changes (p < 0.001, linear mixed models with random effects). CONCLUSION: In low birth weight infants with RDS, bovine surfactant instillation is not associated with a significant alteration in cerebral hemodynamics. However, the direct relationship between CBFV and MBP is consistent with the reported pressure-passive cerebral circulation in sick preterm infants.