Brown fat necrosis with calcifications in the newborn: Risk factors, radiographic findings, and clinical course

Objective:

To describe the radiographic appearance of subclinical calcified brown fat necrosis and the associated clinical and laboratory findings.

Materials and Methods:

Picture Archiving and Communications Sytem (PACS) was searched using keywords “soft tissue calcification” and “chest.” The clinical record was searched for prior cardiac surgery, bypass, Extracorporeal Membrane Oxygentation (ECMO) and prostaglandin use. Age when calcifications were first detected, location, resolution, and associated laboratory abnormalities were recorded.

Results:

Nine patients were identified. None had skin lesions. All patients had congenital heart disease and had experienced cardiac/respiratory arrest and/or severe hypotension 1–6 weeks before soft tissue calcifications occurred. Calcifications resolved by 9 weeks to 5 months in 3 patients. The remaining were either deceased or lacked follow-up imaging. Renal ultrasound was performed in all but 1 patient. Nephrocalcinosis was only seen in 1 patient.

Conclusion:

Brown fat necrosis is subclinical, diagnosed on plain film, and likely self-limited. It occurs in term and preterm infants who have undergone significant systemic stress and carries a poor prognosis.

Impaired hypercarbic and hypoxic responses from developmental loss of cerebellar Purkinje neurons: implications for sudden infant death syndrome

Impaired responsivity to hypercapnia or hypoxia is commonly considered a mechanism of failure in sudden infant death syndrome (SIDS). The search for deficient brain structures mediating flawed chemosensitivity typically focuses on medullary regions; however, a network that includes Purkinje cells of the cerebellar cortex and its associated cerebellar nuclei also helps mediate responses to carbon dioxide (CO2) and oxygen (O2) challenges and assists integration of cardiovascular and respiratory interactions. Although cerebellar nuclei contributions to chemoreceptor challenges in adult models are well described, Purkinje cell roles in developing models are unclear. We used a model of developmental cerebellar Purkinje cell loss to determine if such loss influenced compensatory ventilatory responses to hypercapnic and hypoxic challenges. Twenty-four Lurcher mutant mice and wild-type controls were sequentially exposed to 2% increases in CO2 (0-8%) or 2% reductions in O2 (21-13%) over 4 min, with return to room air (21% O2/79% N2/0% CO2) between each exposure. Whole body plethysmography was used to continuously monitor tidal volume (TV) and breath frequency (f). Increased f to hypercapnia was significantly lower in mutants, slower to initiate, and markedly lower in compensatory periods, except for very high (8%) CO2 levels. The magnitude of TV changes to increasing CO2 appeared smaller in mutants but only approached significance. Smaller but significant differences emerged in response to hypoxia, with mutants showing smaller TV when initially exposed to reduced O2 and lower f following exposure to 17% O2. Since cerebellar neuropathology appears in SIDS victims, developmental cerebellar neuropathology may contribute to SIDS vulnerability.

Retropleural teratoma presenting as an abdominal mass in a 9-month-old boy

BACKGROUND

Teratomas are rare tumors that present most commonly in the anterior mediastinum and retroperitoneum. To date, the retropleural primary site has not been reported.

CASE PRESENTATION

A 9-month-old boy presented with a large, painless, right-sided abdominal mass. Laboratory values, including tumor markers α-fetoprotein and β-human chorionic gonadotropin, were within normal limits. Diagnostic imaging, including abdominal ultrasound, computed tomographic scan, and magnetic resonance imaging, suggested a large retroperitoneal mass consistent with a teratoma. Because the mass was thought to be arising from the retroperitoneum, an abdominal approach was chosen. After adequate exposure, it became clear that the tumor was arising from above the diaphragm. The diaphragm was incised, and the pleural cavity was entered. The tumor was found in the retropleural space where it was dissected away from the inferior vena cava, aorta, and chest wall. The patient recovered without complications.

RESULTS

Histologic examination revealed a mature cystic teratoma with no malignant features. The patient has been disease-free at 7-year follow-up, based upon both clinical examination and diagnostic imaging.

CONCLUSION

This is the first case report of a teratoma arising from the retropleural space. Preoperative imaging may be inaccurate for guiding surgical planning because the diaphragm may not be clearly visualized with current diagnostic techniques. Surgeons should be cautious regarding the location of tumors that arise near the diaphragm and should plan surgical resection carefully.

Transient receptor potential melastatin 8 channel involvement in the regulation of vascular tone

The transient receptor potential melastatin 8 (TRPM8) channel has been characterized as a cold and menthol receptor expressed in a subpopulation of sensory neurons but was recently identified in other tissues, including the respiratory tract, urinary system, and vasculature. Thus TRPM8 may play multiple functional roles, likely to be in a tissue- and activation state-dependent manner. We examined the TRPM8 channel presence in large arteries from rats and the functional consequences of their activation. We also aimed to examine whether these channels contribute to control of conscious human skin blood flow. TRPM8 mRNA and protein were detected in rat tail, femoral and mesenteric arteries, and thoracic aorta. This was confirmed in single isolated vascular myocytes by immunocytochemistry. Isometric contraction studies on endothelium-denuded relaxed rat vessels found small contractions on application of the TRPM8-specific agonist menthol (300 microM). However, both menthol and another agonist icilin (50 microM) caused relaxation of vessels precontracted with KCl (60 mM) or the alpha-adrenoceptor agonist phenylephrine (2 microM) and a reduction in sympathetic nerve-mediated contraction. These effects were antagonized by bromoenol lactone treatment, suggesting the involvement of Ca(2+)-independent phospholipase A(2) activation in TRPM8-mediated vasodilatation. In thoracic aorta with intact endothelium, menthol-induced inhibition of KCl-induced contraction was enhanced. This was unaltered by preincubation with either N(omega)-nitro-l-arginine methyl ester (l-NAME; 100 nM), a nitric oxide synthase inhibitor, or the ACh receptor antagonist atropine (1 microM). Application of menthol (3% solution, topical application) to skin caused increased blood flow in conscious humans, as measured by laser Doppler fluximetry. Vasodilatation was markedly reduced or abolished by prior application of l-NAME (passive application, 10 mM) or atropine (iontophoretic application, 100 nM, 30 s at 70 microA). We conclude that TRPM8 channels are present in rat artery vascular smooth muscle and on activation cause vasoconstriction or vasodilatation, dependent on previous vasomotor tone. TRPM8 channels may also contribute to human cutaneous vasculature control, likely with the involvement of additional neuronal mechanisms.

Modulation of contractile function through neuropeptide Y receptors during development of cardiomyocyte hypertrophy

Severity of left ventricular hypertrophy (LVH) correlates with elevated plasma levels of neuropeptide Y (NPY) in hypertension. NPY elicits positive and negative contractile effects in cardiomyocytes through Y(1) and Y(2) receptors, respectively. This study tested the hypothesis that NPY receptor-mediated contraction is altered during progression of LVH. Ventricular cardiomyocytes were isolated from spontaneously hypertensive rats (SHRs) pre-LVH (12 weeks), during development (16 weeks), and at established LVH (20 weeks) and age-matched normotensive Wistar Kyoto (WKY) rats. Electrically stimulated (60 V, 0.5 Hz) cell shortening was measured using edge detection and receptor expression determined at mRNA and protein level. The NPY and Y(1) receptor-selective agonist, Leu(31)Pro(34)NPY, stimulated increases in contractile amplitude, which were abolished by the Y(1) receptor-selective antagonist, BIBP3226 [R-N(2)-(diphenyl-acetyl)-N-(4-hydroxyphenyl)methyl-argininamide)], confirming Y(1) receptor involvement. Potencies of both agonists were enhanced in SHR cardiomyocytes at 20 weeks (2300- and 380-fold versus controls). Maximal responses were not attenuated. BIBP3226 unmasked a negative contraction effect of NPY, elicited over the concentration range (10(-12) to 3 x 10(-9) M) in which NPY and PYY(3-36) attenuated the positive contraction effects of isoproterenol, the potencies of which were increased in cardiomyocytes from SHRs at 20 weeks (175- and 145-fold versus controls); maximal responses were not altered. Expression of NPY-Y(1) and NPY-Y(2) receptor mRNAs was decreased (55 and 69%) in left ventricular cardiomyocytes from 20-week-old SHRs versus age-matched WKY rats; parallel decreases (32 and 80%) were observed at protein level. Enhancement of NPY potency, producing (opposing) contractile effects on cardiomyocytes together with unchanged maximal response despite reduced receptor number, enables NPY to contribute to regulating cardiac performance during compensatory LVH.

ETHE1 mutations are specific to ethylmalonic encephalopathy

Mutations in ETHE1, a gene located at chromosome 19q13, have recently been identified in patients affected by ethylmalonic encephalopathy (EE). EE is a devastating infantile metabolic disorder, characterised by widespread lesions in the brain, hyperlactic acidaemia, petechiae, orthostatic acrocyanosis, and high levels of ethylmalonic acid in body fluids. To investigate to what extent ETHE1 is responsible for EE, we analysed this gene in 29 patients with typical EE and in 11 patients presenting with early onset progressive encephalopathy with ethylmalonic aciduria (non-EE EMA). Frameshift, stop, splice site, and missense mutations of ETHE1 were detected in all the typical EE patients analysed. Western blot analysis of the ETHE1 protein indicated that some of the missense mutations are associated with the presence of the protein, suggesting that the corresponding wild type amino acid residues have a catalytic function. No ETHE1 mutations were identified in non-EE EMA patients. Experiments based on two dimensional blue native electrophoresis indicated that ETHE1 protein works as a supramolecular, presumably homodimeric, complex, and a three dimensional model of the protein suggests that it is likely to be a mitochondrial matrix thioesterase acting on a still unknown substrate. Finally, the 625G-->A single nucleotide polymorphism in the gene encoding the short chain acyl-coenzyme A dehydrogenase (SCAD) was previously proposed as a co-factor in the aetiology of EE and other EMA syndromes. SNP analysis in our patients ruled out a pathogenic role of SCAD variants in EE, but did show a highly significant prevalence of the 625A alleles in non-EE EMA patients.

Intrathecal enzyme replacement therapy reduces lysosomal storage in the brain and meninges of the canine model of MPS I

Enzyme replacement therapy (ERT) has been developed for several lysosomal storage disorders, including mucopolysaccharidosis I (MPS I), and is effective at reducing lysosomal storage in many tissues and in ameliorating clinical disease. However, intravenous ERT does not adequately treat storage disease in the central nervous system (CNS), presumably due to effects of the blood-brain barrier on enzyme distribution. To circumvent this barrier, we studied whether intrathecal (IT) recombinant human alpha-L-iduronidase (rhIDU) could penetrate and treat the brain and meninges. An initial dose-response study showed that doses of 0.46-4.14 mg of IT rhIDU successfully penetrated the brain of normal dogs and reached tissue levels 5.6 to 18.9-fold normal overall and 2.7 to 5.9-fold normal in deep brain sections lacking CSF contact. To assess the efficacy and safety in treating lysosomal storage disease, four weekly doses of approximately 1 mg of IT rhIDU were administered to MPS I-affected dogs resulting in a mean 23- and 300-fold normal levels of iduronidase in total brain and meninges, respectively. Quantitative glycosaminoglycan (GAG) analysis showed that the IT treatment reduced mean total brain GAG to normal levels and achieved a 57% reduction in meningeal GAG levels accompanied by histologic improvement in lysosomal storage in all cell types. The dogs did develop a dose-dependent immune response against the recombinant human protein and a meningeal lymphocytic/plasmacytic infiltrate. The IT route of ERT administration may be an effective way to treat the CNS disease in MPS I and could be applicable to other lysosomal storage disorders.

Absence of genetic linkage of chromosome 5q31 with asthma and atopy in the general population

BACKGROUND

Clinical asthma is associated with increased serum total immunoglobulin E (IgE), atopy (skin prick test positivity to common aeroallergens), and bronchial hyperreactivity (BHR) to non-specific stimuli (positive methacholine challenge test). A region on chromosome 5q31-33 has been linked with increased total serum IgE and BHR. A study of the genetic linkage of this region with clinical asthma and atopy was therefore undertaken.

METHODS

A polymorphic microsatellite marker in chromosome 5q31 (D5S399) was studied in 119 sibling pairs recruited from the general population who shared asthma, atopy, and/or BHR. Based on our population distribution of 13 different alleles, it was expected that by chance alone sibling pairs would share on average 1.24 alleles and that a significant excess would indicate genetic linkage.

RESULTS

No evidence of linkage was found in 45 siblings concordant for asthma (shared alleles = 1.09, p = 0.95), in 103 sibling pairs with atopy (shared alleles = 1.18, p = 0.82), in 51 sibling pairs with BHR (shared alleles = 1.22, p = 0.62), or in 68 sibling pairs who shared atopy in the absence of BHR (shared alleles = 1.22, p = 0.61). A slight non-significant excess of shared alleles (1.44, p = 0.11) was observed in siblings who shared BHR without atopy.

CONCLUSIONS

No evidence of genetic linkage of chromosome 5q31 with either clinical asthma or atopy was therefore detected in the population studied. Linkage between chromosome 5q and BHR needs further investigation.

CCK antagonist pre-treatment inhibits meal-enhanced drug absorption in dogs

Duodenal administration of casein and oleate increased plasma levels from oral administration of a poorly water-soluble antiepileptic drug as compared to duodenal glucose and saline in a canine model. Pre-treatment with intravenous MK-329, benzodiazepine CCK A-receptor antagonist, blocked the duodenal oleate effect on drug plasma levels in a single dog preliminary study. In a follow-up study, oral drug co-administration with Intralipid increased drug plasma levels as compared to drug co-administration with a noncaloric equivalent-volume load in seven dogs. Pre-treatment with MK-329 reduced drug plasma levels from co-administration with Intralipid toward fasted-state values. While increased drug solubility in the lipid vehicle might have been projected to account for the fed-state effect in the oral studies, the gut peptide inhibitor studies suggest that biliary secretion plays a major role in promoting the dissolution and subsequent absorption of this lipophilic drug. The data also support the hypothesis that meal-enhanced pancreatic secretion provides a greater fluid volume for drug dissolution in the small intestine. An increase in the extent of drug dissolution in the stomach, as a result of meal prolongation of gastric residence time, does not appear to contribute substantially to fed-state increases in drug plasma levels from oral drug co-administration with a lipid meal.

Lesions dorsal to the suprachiasmatic nuclei abolish split activity rhythms of hamsters

Constant light exposure (LL) can result in "splitting" of circadian rhythms into two components coupled about 12 hr apart. Splitting has been interpreted as evidence for the presence of two main oscillators or groups of oscillators underlying circadian rhythms. Abolition of splitting after unilateral suprachiasmatic nucleus ablation suggested that each suprachiasmatic nucleus could correspond to one of these component oscillators. We examined whether lesions outside the suprachiasmatic nuclei (SCN) would abolish split activity rhythms of hamsters in LL. Wheel-running activity was recorded for 3 months after surgery. Tissue damage was assessed by Klüver-Barrera staining. Damage to areas dorso-caudal to the SCN was able to abolish the split condition. Bilateral damage to the anterior SCN, partial unilateral SCN ablation or unilateral periventricular damage also abolished the split pattern. These results indicate that destruction of one SCN is not essential for the elimination of split rhythms since lesions dorsal to the SCN or partial bilateral SCN damage are also effective. Indirect lesion effects on SCN function or damage to extra-SCN oscillators may account for the loss of the split condition.

Phenobarbital induction and acetaminophen hepatotoxicity: resistance in the obese Zucker rodent

The obese Zucker rodent appears to lack a significant induction response after phenobarbital pretreatment. Induction of the hepatic cytochrome P-450 system with phenobarbital is known to enhance acetaminophen hepatotoxicity. The purpose of this study was to evaluate the influence of phenobarbital enzyme induction on acetaminophen hepatotoxicity in the obese and lean Zucker rodent. A preliminary study was performed evaluating the pharmacokinetics of acetaminophen in both the obese and lean Zucker rats. Data were utilized to calculate appropriate loading doses of acetaminophen during the subsequent hepatotoxicity study. Phenobarbital enzyme-inducing regimens were administered p.o. to achieve similar steady-state phenobarbital plasma concentrations. Control rats received appropriate placebo solutions. Serum hepatic transaminase enzymes and histologic evidence of hepatocellular necrosis were utilized to evaluate hepatic damage after p.o. administration of 1300 mg of acetaminophen to both obese and lean Zucker rats. Obese Zucker control animals had approximately 2.5 times the total hepatic glutathione content compared to their lean control (164.9 +/- 43.2 vs. 65.3 +/- 18.4 mumol/whole liver). Obese Zucker animals receiving only acetaminophen showed a trend toward a reduced incidence of hepatocellular necrosis compared to similarly treated lean littermates. Obese Zucker rodents pretreated with phenobarbital had an even more pronounced resistance to acetaminophen-induced hepatocellular necrosis (P less than .01) when compared to similarly treated lean littermates. Thus, acetaminophen hepatotoxicity is reduced in the obese Zucker rat and pretreatment with phenobarbital offers further protection against hepatocellular damage. We suggest that the previously unrecognized increase in hepatic glutathione plays a major role in the resistance of the obese Zucker rat to acetaminophen hepatotoxicity.

Su Clinica Familiar, Harlingen, Texas

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