Assessment of cysteine synthesis in very low-birth weight neonates using a [13C6]glucose tracer

Background/Purpose

Cysteine is an amino acid necessary for the synthesis of all proteins, the antioxidant glutathione, and the neuromodulator taurine. Whether cysteine is an essential amino acid for premature neonates remains controversial. Using a [¹³C₆]glucose precursor in very-low-birth weight (VLBW) premature neonates, we measured the ¹³C content of cysteine in hepatically derived apolipoprotein (apo) B-100 and in the plasma to determine whether cysteine synthesis occurs and to relate minimum synthetic capacity to neonatal maturity.

Methods

Twelve VLBW premature neonates (birth weight, 907 ± 274 [SD] g; gestational age, 26.8 ± 2.4 weeks) were studied on day of life 7.8 ± 4.2 while on total parenteral nutrition (TPN) for 5.6 ± 4.5 days. A 4-hour intravenous infusion of [¹³C₆]glucose was administered. Blood samples were obtained immediately before and at the end of the infusion. Isotopic enrichment of cysteine was determined by gas chromatography/mass spectrometry. Analysis of variance, Student's t test, and linear regression were used for comparisons.

Results

The ¹³C isotope ratio of apo B-100-derived cysteine after the [¹³C₆]glucose infusion was significantly higher than baseline (18.57 ± 0.38 [SEM] vs 17.54 ± 0.25 mol%, P < .05). The ¹³C isotope ratio of plasma cysteine was also significantly higher than baseline (17.36 ± 0.25 vs 16.91 ± 0.16 mol%, P < .05). When expressed as a product/precursor ratio, the mole percent above baseline of [¹³C]apo B-100 cysteine/[¹³C₆]glucose correlated with birth weight (r = 0.74, P < .01).

Conclusions

Very low-birth weight neonates are capable of cysteine synthesis as evidenced by incorporation of ¹³C label into hepatically derived apo B-100 cysteine and plasma cysteine from a glucose precursor. The minimum capacity for intrahepatic cysteine synthesis appears to be directly proportional to the maturity of the neonate and may impact the capabilities of VLBW neonates to counteract oxidative stresses such as bronchopulmonary dysplasia and necrotizing enterocolitis.     

Unsafe at any speed--kids riding all-terrain vehicles

Background

All-terrain vehicle (ATV) sales have climbed 89% in the last 5 years. We sought to determine if pediatric ATV accidents have increased in frequency and morbidity.

Methods

Medical records of children treated in our emergency unit for ATV accidents from 1993 to 2003 were reviewed. The 11 years were divided into 2 periods, January 1993 to June 1998 and July 1998 to December 2003, to allow comparisons and analysis of trends over time.

Results

We treated 184 children, with 90% requiring admission. Comparing the first and second halves of the study, patients treated increased from 8.7 ± 4.8 (mean ± SD) to 24.5 ± 11.1 per year (P < .01), patients requiring immediate operation increased from 4 (9%) of 44 to 24 (17%) of 140, and patients with serious injuries (resulting in direct intensive care unit admission, immediate operation, or death) rose from 12 (27%) of 44 to 51 (36%) of 140. Patient age was 11.5 ± 3.9 years. Sixty-eight percent of the children sustained multiple injuries and 50% required surgery. Only 35% of the children wore helmets.

Conclusion

Over the 2 periods, there was a significant increase in number of patients treated, and considerable increases in serious injuries, and need for immediate operation. Despite inherent risks with riding ATVs, helmet use and patient age were remarkably low.     

Role of the central amygdala in modulating the pituitary-adrenocortical and clinical responses in experimental herpes simplex virus-1 encephalitis

The amygdala is known to regulate neuroendocrine and behavioral responses to a variety of stimuli. Herpes simplex virus-1 (HSV-1) is the common cause of viral encephalitis, manifested by hypothalamic-pituitary-adrenal (HPA) axis activation, fever, hypermotor activity and aggression. We examined here the role of the central amygdala (cAMG) in regulating the HPA axis function, febrile and behavioral responses to HSV-1 infection in rats. Bilateral electrolytic lesions were performed in the cAMG. HSV-1 encephalitis was induced by intracerebroventricular (ICV) inoculation of purified virions. Motor activity and body temperature were examined by a biotelemetric system. ICV inoculation of HSV-1 caused a marked time-dependent increase in serum corticotropin (ACTH) and corticosterone at 4 and 24 h post-infection. These responses were attenuated in rats with bilateral lesions of the cAMG. HSV-1 infection induced fever, motor hyperactivity and aggressive behavior. These responses were also attenuated in rats with cAMG lesions. The cAMG plays an important role in mediating the neuroendocrine, febrile and behavioral responses to HSV-1 infection.     

Category specific dysnomia after thalamic infarction: a case-control study

Category specific naming impairment was described mainly after cortical lesions. It is thought to result from a lesion in a specific network, reflecting the organization of our semantic knowledge. The deficit usually involves multiple semantic categories whose profile of naming deficit generally obeys the animate/inanimate dichotomy. Thalamic lesions cause general semantic naming deficit, and only rarely a category specific semantic deficit for very limited and highly specific categories. We performed a case-control study on a 56-year-old right-handed man who presented with language impairment following a left anterior thalamic infarction. His naming ability and semantic knowledge were evaluated in the visual, tactile and auditory modalities for stimuli from 11 different categories, and compared to that of five controls. In naming to visual stimuli the patient performed poorly (error rate>50%) in four categories: vegetables, toys, animals and body parts (average 70.31+/-15%). In each category there was a different dominating error type. He performed better in the other seven categories (tools, clothes, transportation, fruits, electric, furniture, kitchen utensils), averaging 14.28+/-9% errors. Further analysis revealed a dichotomy between naming in animate and inanimate categories in the visual and tactile modalities but not in response to auditory stimuli. Thus, a unique category specific profile of response and naming errors to visual and tactile, but not auditory stimuli was found after a left anterior thalamic infarction. This might reflect the role of the thalamus not only as a relay station but further as a central integrator of different stages of perceptual and semantic processing.     

Eosinophilic Pericarditis—A Rare Complication of Idiopathic Hypereosinophilic Syndrome in a Child

We describe an 18-month-old child with idiopathic hypereosinophilic syndrome (IHES) who presented with fever, and cervical lymphadenoathy. Chest X-ray showed marked cardiomegaly, and echocardiogram revealed large pericardial effusion. Other causes of pericarditis were excluded. Despite the initiation of steroid therapy, signs of impending cardiac tamponade developed. Pericardiocentesis yielded bloody fluid with a white blood count of 14,800/mm³, of which 23% were eosinophils. The child recovered after pericardial drainage and prolonged systemic steroid therapy. Eosinophilic pericarditis is a rare but potentially dangerous complication of IHES.     

Sonographic biometry of the frontal lobe in normal and growth-restricted neonates

Assessing the impact of restricted intrauterine growth on neonatal frontal lobe (FL) dimensions is important. We aimed to create a sonographic nomogram of FL dimensions in neonates at different gestational ages (GA) and evaluate the impact of small head circumference (HC) on FL dimensions. We conducted sonographic biometry of the FL at birth. We included 218 newborn infants born at GA of 24-43 wk: appropriate for GA and normal HC (n = 178), and small for GA and small HC (n = 23). Infants with a 5-min Apgar score <7, severe congenital malformations, or chromosomal abnormalities were excluded. Through a coronal ultrasound scan via the anterior fontanelle at the level where the most lateral point of the left Sylvian fissure was best demonstrated, we drew a triangle connecting the most lateral point of the Sylvian fissure, the corpus callosum, and the subcalvarian point of the interhemispheric fissure. We measured the three sides of the triangle, Sylvian-fontanellar distance, Sylvian-callosal distance, and fontanellar-callosal distance, and calculated the frontal triangular area. All four FL dimensions increased significantly between 24 and 43 wk of gestation in both appropriate for GA-normal HC and small for GA-small HC neonates, and were strongly correlated with HC and birth weight. Regression lines of GA against Sylvian-fontanellar distance, Sylvian-callosal distance, fontanellar-callosal distance, and frontal triangular area in the appropriate for GA-normal HC group differed significantly from those of the small for GA-small HC group (p < 0.05). Male neonates had significantly larger Sylvian-fontanellar and Sylvian-callosal distances than females (p < 0.01 and p < 0.015, respectively). In conclusion, FL measures increased significantly between 24 and 43 wk of gestation, and were strongly correlated with HC. We speculate that a sonographically small fetal HC implies growth restriction of the fetal FL.