Zdena Pavlova

Human BAT Possesses Molecular Signatures That Resemble Beige/Brite Cells

Brown adipose tissue (BAT) dissipates chemical energy and generates heat to protect animals from cold and obesity. Rodents possess two types of UCP-1 positive brown adipocytes arising from distinct developmental lineages: “classical” brown adipocytes develop during the prenatal stage whereas “beige” or “brite” cells that reside in white adipose tissue (WAT) develop during the postnatal stage in response to chronic cold or PPARγ agonists. Beige cells’ inducible characteristics make them a promising therapeutic target for obesity treatment, however, the relevance of this cell type in humans remains unknown. In the present study, we determined the gene signatures that were unique to classical brown adipocytes and to beige cells induced by a specific PPARγ agonist rosiglitazone in mice. Subsequently we applied the transcriptional data to humans and examined the molecular signatures of human BAT isolated from multiple adipose depots. To our surprise, nearly all the human BAT abundantly expressed beige cell-selective genes, but the expression of classical brown fat-selective genes were nearly undetectable. Interestingly, expression of known brown fat-selective genes such as PRDM16 was strongly correlated with that of the newly identified beige cell-selective genes, but not with that of classical brown fat-selective genes. Furthermore, histological analyses showed that a new beige cell marker, CITED1, was selectively expressed in the UCP1-positive beige cells as well as in human BAT. These data indicate that human BAT may be primary composed of beige/brite cells.

Unequivocal Identification of Brown Adipose Tissue in a Human Infant

We report the unique depiction of brown adipose tissue (BAT) by magnetic resonance imaging (MRI) and computed tomography (CT) in a human 3‐month‐old infant. Based on cellular differences between BAT and more lipid‐rich white adipose tissue (WAT), chemical‐shift MRI and CT were both capable of generating distinct signal contrasts between the two tissues and against surrounding anatomy, utilizing fat‐signal fraction metrics in the former and x‐ray attenuation values in the latter. While numerous BAT imaging experiments have been performed previously in rodents, the identification of BAT in humans has only recently been described with fusion positron emission and computed tomography in adults. The imaging of BAT in children has not been widely reported and, furthermore, MRI of human BAT in general has not been demonstrated. In the present work, large bilateral supraclavicular BAT depots were clearly visualized with MRI and CT. Tissue identity was subsequently confirmed by histology. BAT has important implications in regulating energy metabolism and nonshivering thermogenesis and has the potential to combat the onset of weight gain and the development of obesity. Current findings suggest that BAT is present in significant amounts in children and that MRI and CT can differentiate BAT from WAT based on intrinsic tissue properties. J. Magn. Reson. Imaging 2012;35:938–942.

Two-year outcome of infants weighing 600 grams or less at birth and born 1994 through 1998

OBJECTIVE: To assess the neurologic and developmental outcome at 2 years of age in preterm infants with birth weights 600 g or lower. METHODS: We conducted a retrospective review from January 1994 through December 1998 for placental histopathology, maternal factors, neonatal intensive care unit course, growth, neurologic/special sense status, and development at 2 years of age corrected for prematurity. RESULTS: Of the 104 neonates weighing 600 g or less, 24 survived to nursery discharge (23%). Two infants died of chronic lung disease after discharge, and 21 of the remaining 22 infants (95%) returned for follow‐up. Placental pathology was available for 21 (95%); acute inflammation was present in 67%, and other abnormalities occurred in 76%. Mean birth weight was 537 (430‐600) g, and mean gestational age was 24 (22‐27) weeks. At birth, 55% were below the tenth percentile for birth weight. At nursery discharge and 2 years of age, 94% were below the tenth percentile for weight, length, and head circumference. Nineteen of 21 (90%) infants were abnormal on neurodevelopmental follow‐up. Major problems were cerebral palsy, blindness, gastrostomies, and ventriculoperitoneal shunts. CONCLUSION: Abnormal placental histology was present in all but one infant, suggesting fetal injury before birth. Only eight of 20 infants with chorioamnionitis were diagnosed clinically, and all infants had a complicated course. We found a high incidence of intrauterine growth restriction and an almost universal pattern of impaired postnatal growth with extremely poor neurodevelopmental outcome at 2 years of age. (Obstet Gynecol 2003;101:18‐23.

Human developing enamel proteins exhibit a sex-linked dimorphism.

SummaryThe amelogenin protein of developing dental enamel is generally accepted to mediate the regulation of the form and size of the hydroxyapatite crystallites during enamel biomineralization (1). A genetic disorder of enamel development (amelogenesis imperfecta) has been linked to theamelogenin geneAMEL (2–3), and loci regulating enamel thickness and tooth size have been mapped to the human sex chromosomes (4). In the human genome there are twoAMEL loci with one copy of the gene on each of the sex chromosomes (AMELX andAMELY), whereas in the mouse only anAMELX locus is present (5). It is presently unknown if humanAMELY is transcriptionally active. These observations prompted us to examine specimens of human developing enamel for sexual dimorphism at the protein level. We report here, for the first time, a diagnosis of differences in human enamel proteins which permits the distinction of specimens according to the sex of the individual.

Small noncleaved follicular center cell (FCC) lymphoma: Burkitt and non‐Burkitt variants in the United States. I. Clinical features

With the understanding that Burkitts lymphoma was of follicular center cell (FCC) derivation, Lukes and Collins classified the tumor, descriptively, as small noncleaved FCC lymphoma. Two subtypes were described: Burkitt and non‐Burkitt. Attempting to define the clinicopathologic features of the subtypes, we studied 42 patients: 25 Burkitt and 17 non‐Burkitt. Histologically, the Burkitt tumor demonstrated remarkable uniformity of nuclear size and contour, whereas the non‐Burkitt variant had greater variability. Immunoglobulin monoclonality was demonstrated in 83% of Burkitt and 81% of non‐Burkitt cases. Burkitt patients tended to be younger. Gastrointestinal disease was seen in 15 Burkitt and only four non‐Burkitt patients (P < 0.05). Disseminated disease was found in the majority of both variants. Marrow involvement was demonstrated in 4.5% of Burkitt and 37.5% of non‐Burkitt patients (P < 0.05). Median survival of Burkitt patients was 10.5 months versus 7.7 months in the non‐Burkitt group. The authors believe that significant biologic differences between the variants have been demonstrated, which may be of potential value to the clinician.

Small noncleaved follicular center cell lymphoma: Burkitt's and non-Burkitt's variants in the US II. Pathologic and immunologic features

The morphologic criteria for the two variants of small noncleaved follicular center cell (SNC FCC) lymphoma in the Lukes‐Collins classification, Burkitts (BL) and non‐Burkitts variants (NBL), were evaluated and related to the results of multiparameter laboratory and clinical studies. Forty‐two patients were studied: 25 cases were classified as BL according to World Health Organization (WHO) criteria. Seventeen cases were classified as NBL on the basis of greater variability in nuclear size and shape, more prominent nucleoli, and greater variation in the amount of cytoplasm. Neoplastic follicles were present in three cases of BL and two of NBL, indicating an FCC origin for this lymphoma. Electron microscopic examination confirmed the light microscopic features. Immunoglobulin (Ig) monoclonality, as demonstrated by immunofluorescence (surface Ig) and/or immunoperoxidase staining for cytoplasmic immunoglobulin (CIg), was demonstrated in 21 of 24 (87.5%) of BL and 13 of 16 (71%) of NBL. Clinically, BL presented more frequently in extranodal sites and with gastrointestinal involvement than NBL. Bone marrow involvement was more common in NBL patients. Both groups had advanced stage disease at diagnosis. The median survival was 10.5 months in BL and 7.7 months in NBL. The results of this study indicate that BL and NBL are biologically related variants of SNC FCC lymphoma but have different presentations, which may be clinically significant.

Meconium-stained amniotic fluid and neonatal morbidity in near-term and term deliveries with acute histologic chorioamnionitis and/or funisitis.

OBJECTIVE:To determine the incidence of meconium-stained amniotic fluid (MSAF) and neonatal morbidity in near-term and term deliveries with histologic acute chorioamnionitis and/or funisitis compared to those with normal placental histology.STUDY DESIGN:In a retrospective case–control design, we compared the incidence of MSAF and neonatal outcome in 45 cases of acute histologic chorioamnionitis and/or funisitis with 89 cases of normal placental histology. We reviewed the obstetric and neonatal records for perinatal complications and neonatal morbidity.RESULTS:Mean birthweights (3372±473 vs 3287±518 g) were similar in infants born to mothers with histologic chorioamnionitis and/or funisitis compared to infants born to mothers with normal placental histology. The incidence of MSAF was significantly higher in the group with acute chorioamnionitis/funisitis (p<0.05). Similarly, the incidence of admissions to newborn intensive care unit, respiratory distress, meconium aspiration syndrome, and presumed sepsis was also significantly higher (p<0.05) in this group.CONCLUSION:The incidence of MSAF and neonatal morbidity is higher in the presence of acute inflammation of placental membranes. The presence of meconium in the amniotic fluid should alert the physician to the potential for infection and increased neonatal morbidity.

Human amelogenins: Sequences of “TRAP” molecules

SummaryThe extracellular protein matrix of devoloping enamel includes a major class of proteins, the amelogenins, which are believed to be concerned in regulating enamel biomineralization. Previous studies have shown the amelogenins of the extracellular matrix to be a complex of proline-rich hydrophobic proteins which, it is suggested, arise through posttranslational and postsecretory processing of a primary ameloblast gene product. More recently, it has been shown that the human amelogenin gene is located on both the X and Y chromosomes raising the possibility that polymorphism at the level of the gene may also contribute to the observed complexity of these enamel matrix proteins. To investigate such possible amelogenin polymorphism in developing human dental enamel, individual samples of human enamel proteins were fractionated by size-exclusion and reversed-phase high pressure liquid chromatography (HPLC). Two tyrosine-rich amelogenin polypeptides (TRAPs) of approximately 5 kDa in size were isolated from an individual human dentition and characterized by automated gas-phase sequencing. These polypeptides were found to be of 42 (TRAP-2) and 44 (TRAP-1) amino acid residues in length; TRAP-2 lacked a carboxy-terminal-Gly-Trp sequence as has previously been described for analogous bovine TRAP molecules. However, residue#25 of the human TRAP-2 sequence was refractory to sequencing, apparently differing from the Trp-25 identified in TRAP-1. These findings suggest (1) two forms of TRAP molecules, differing only by cleavage of a carboxy-terminal dipeptide, are a general feature of human and other mammalian enamel proteins, probably being derived by postsecretory cleavage from the primary extracellular amelogenin; and (2) in human developing enamel four forms of TRAPs may arise either from polymorphism at the level of the gene, or by posttranscriptional alternative splicing of amelogenin mRNAs, coupled with specific postsecretory proteolytic processing.

A rare presentation of Pompe disease with massive hypertrophic cardiomyopathy at birth.

Abstract We report a term infant with Pompe disease presenting in the immediate newborn period. The infant was born at 40 weeks gestation, weighing 3600 g to a 32 year-old black female. Infant presented at delivery with massive hypertrophic cardiomyopathy and pulmonary hypertension. Diagnosis was confirmed by low α-glucosidase activity. The histopathology and electron microscopic findings were consistent with Pompe disease. This is the second reported case of Pompe disease presenting at delivery.

Isolation and partial characterization of a human amelogenin from a single fetal dentition using HPLC techniques

SummaryA strategy based on high pressure liquid chromatography (HPLC) techniques for the isolation or a principal amelogenin molecule from a single human dentition is described. A partial sequence (33 residues) for this 24 kDa amelogenin is presented and related to earlier studies of human 5 kDa tyrosine-rich amelogenin polypeptides (TRAPs). A failure to identify amino acid residue #25 (tryptophan in other amelogenins) suggests that this 24 kDa amelogenin is the progenitor of the human TRAP-2 molecule and provides further support for the possibility of several human amelogenin gene products, generated by splice-junction selection, from the single amelogenin gene in the same individual. Alternatively, multiple amelogenins may arise by expression of both the AMELX and AMELY loci.