Parasagittal vertex clots on head CT in infants with subdural hemorrhage as a predictor for abusive head trauma

BACKGROUND

Abusive head trauma (AHT) is the most common cause of subdural hemorrhage (SDH) in infants younger than 12 months old. Clot formation in the parasagittal vertex seen on imaging has been associated with SDH due to AHT. There have been very few studies regarding these findings; to our knowledge, no studies including controls have been performed.

OBJECTIVE

To describe parasagittal vertex clots on head computed tomography (CT) in infants with SDH and AHT compared to patients with SDH and accidental trauma, and to evaluate for parasagittal vertex clots in the absence of SDH in the setting of known accidental head trauma.

MATERIALS AND METHODS

All infants younger than 12 months old with SDH present on CT scan were retrospectively identified from 2004 to 2014. Blinded, independent review of all CT scans for clot formation at the parasagittal vertex was performed by a pediatric neuroradiologist.

RESULTS

Ninety-nine patients were eligible for analysis. Mean age was 4 months. Fifty-seven (57.6%) were male. Fifty-five (55.6%) patients were identified as having AHT and 22 (22.2%) had accidental trauma. Forty-five (81.2%) patients with AHT had parasagittal vertex clots present on CT scan compared to 8 (36.4%) patients with accidental trauma. Compared to patients without parasagittal vertex clots, those with parasagittal vertex clots were more likely to have AHT (66.2% vs. 32.3%, P=0.001), no known mechanism of injury (69.1% vs. 32.3%, P=0.015), retinal hemorrhage (75% vs. 35.5%, P=0.002) and hypoxic-ischemic changes (25% vs. 0%, P=0.002). Patients with parasagittal vertex clots have eight times the odds of AHT compared to patients without parasagittal vertex clots. Age-matched control patients who underwent head CT scan due to a history of accidental head injury without SDH were identified (n=87); no patient in the control group had parasagittal vertex clots.

CONCLUSION

The finding of parasagittal vertex clots on CT scans should raise suspicion for abuse and prompt further investigation, especially in the setting of no known, uncertain or inconsistent mechanism of injury.

Cranial Rhabdomyosarcoma Masquerading as Infectious Mastoiditis: Case Report and Literature Review

BACKGROUND

Rhabdomyosarcoma originating in the mastoid is rare and may be misdiagnosed as an infectious mastoiditis due to overlapping clinical and imaging features. We aimed to identify distinguishing characteristics to facilitate earlier diagnosis and treatment.

METHOD

Here we describe a case report and a systematic review of 23 reports describing previous cases of mastoid rhabdomyosarcoma. We compare these patients to a systematic review of patients with infectious mastoiditis and identify distinguishing clinical features.

RESULTS

A total of 43 patients with rhabdomyosarcoma of the mastoid were identified and compared with patients with mastoiditis. Rhabdomyosarcoma patients were more likely to present with a mass (86%) or cranial nerve dysfunction (83.7%), while mastoiditis patients were more likely to have fever (72.4%), pain (48.2%), and present at a younger age (4.4 vs. 6.1 years). The average lifespan with rhabdomyosarcoma of the mastoid was 7.1 months after diagnosis, with 41.7% of patients alive at the time of report.

CONCLUSIONS

Based on abstracted and aggregated information, we identified unique features observed more frequently in each of rhabdomyosarcoma and mastoiditis. These predictive features allow for the differentiation of each diagnosis and avoid the delay of proper treatment.

Neuroradiographic findings in 22q11.2 deletion syndrome

22q11.2 deletion syndrome (22q11.2DS) is a common genetic disorder with enormous phenotypic heterogeneity. Despite the established prevalence of developmental and neuropsychiatric issues in this syndrome, its neuroanatomical correlates are not as well understood. A retrospective chart review was performed on 111 patients diagnosed with 22q11.2DS. Of the 111 patients, 24 with genetically confirmed 22q11.2 deletion and brain MRI or MRA were included in this study. The most common indications for imaging were unexplained developmental delay (6/24), seizures of unknown etiology (5/24), and unilateral weakness (3/24). More than half (13/24) of the patients had significant radiographic findings, including persistent cavum septi pellucidi and/or cavum vergae (8/24), aberrant cortical veins (6/24), polymicrogyria or cortical dysplasia (4/24), inner ear deformities (3/24), hypoplastic internal carotid artery (2/24), and hypoplastic cerebellum (1/24). These findings reveal the types and frequencies of brain malformations in this case series, and suggest that the prevalence of neuroanatomical abnormalities in 22q11.2DS may be underestimated. Understanding indications for imaging and frequently encountered brain malformations will result in early diagnosis and intervention in an effort to optimize patient outcomes.

Ovarian Torsion in Pediatric Patients: A Review of Eleven Years' Experience

Objectives. To examine associated clinical features and evaluate published criteria regarding volumetric diagnosis of ovarian torsion (OT). Methods. Retrospective case-control study of patients presenting to an emergency department who underwent pelvic imaging for acute abdominal or pelvic pain. Cases were found to have OT at surgery. Controls received clinical diagnosis of either acute pelvic pain or ovarian cyst. Results. The sensitivity for OT using a cutoff AV of <20 mL was 50% (95% confidence interval [CI] = 35% to 65%); specificity was 29% (95% CI = 15% to 43%). The sensitivity for OT using a cutoff AV of >75 mL was 18% (95% CI = 7% to 30%); specificity was 93% (95% CI = 85% to 100%). The ratio of affected-side to unaffected-side AV of >15 had a sensitivity of 16% (95% CI = 5% to 27%); specificity was 98% (95% CI = 93% to 100%). Conclusions. The published criteria regarding the volumetric diagnosis of OT were inadequately sensitive for detecting OT. However, an affected-side AV >75 mL and an AV ratio >15 were reasonably specific.

Multiplication of Mycobacterium tuberculosis Within Normal and "Immune" Mouse Macrophages Cultivated With and Without Streptomycin

Acquired cellular immunity to infection with Mycobacterium tuberculosis is believed to reside in the capacity of mononuclear phagocytes of immunized animals to inhibit intracellular multiplication of the parasite. However, in macrophage tissue culture systems, it has been customary to employ streptomycin in the medium for the purpose of restricting extracellular, but not intracellular, growth of M. tuberculosis. In contrast, our data show that small amounts of streptomycin markedly inhibit intracellular as well as extracellular growth of M. tuberculosis in normal mouse peritoneal macrophages, and that the degree of this inhibition is directly proportional to the concentration of streptomycin used. In the absence of streptomycin, virulent tubercle bacilli grew as rapidly in "immune" macrophages as in normal macrophages. "Immune" macrophages, however, were slightly more resistant to destruction by the intracellularly multiplying mycobacteria. In the presence of streptomycin, however, intracellular mycobacterial growth was inhibited more in "immune" macrophages than in normal macrophages, and this effect also was directly proportional to the concentration of streptomycin used. Virulent mycobacteria grew somewhat more slowly within mouse peritoneal macrophages obtained after induction of a peritoneal exudate with glycogen than in noninduced cells. The rate of multiplication, though, was the same within normal and "immune" induced peritoneal cells except in the presence of streptomycin. As with noninduced macrophages, this drug inhibited the intracellular multiplication of virulent tubercle bacilli more effectively within "immune" induced than within normal induced cells. It would appear, therefore, that the greater inhibition of intracellular multiplication of virulent tubercle bacilli in "immune" macrophages in tissue culture noted by a number of investigators in the past may have been an artifact created by the use of streptomycin in the tissue culture medium.

Demonstration in tissue culture of lymphocyte-mediated immunity to tuberculosis

We have shown that splenic lymphocytes from mice immunized with viable attenuated mycobacterial cells (H37Ra) or ribonucleic acid prepared from these cells will bring about inhibition of multiplication of virulent tubercle bacilli (H37Rv) within normal mouse peritoneal macrophages in tissue culture. Apparently these lymphocytes, when stimulated with viable virulent tubercle bacilli, elaborate a filterable substance(s) which is responsible for this intracellular growth inhibitory effect.

Convalescence disguising disease progression in neonatal herpes encephalitis

Herpes encephalitis in neonates or young infants entails significant risk of mortality or morbidity. Prompt and aggressive treatment may lessen the chronic toll of herpes encephalitis. Unfortunately, an apparent uneventful recovery from herpes encephalitis may disguise evolving cerebral devastation. The discordance between evolving cerebral injury revealed by imaging and a patient's clinical improvement is illustrated by two patients, treated a decade apart.

Removal of FKBP12 enhances mTOR-Raptor interactions, LTP, memory, and perseverative/repetitive behavior

FK506-binding protein 12 (FKBP12) binds the immunosuppressant drugs FK506 and rapamycin and regulates several signaling pathways, including mammalian target of rapamycin (mTOR) signaling. We determined whether the brain-specific disruption of the FKBP12 gene in mice altered mTOR signaling, synaptic plasticity, and memory. Biochemically, the FKBP12-deficient mice displayed increases in basal mTOR phosphorylation, mTOR-Raptor interactions, and p70 S6 kinase (S6K) phosphorylation. Electrophysiological experiments revealed that FKBP12 deficiency was associated with an enhancement in long-lasting hippocampal long-term potentiation (LTP). The LTP enhancement was resistant to rapamycin, but not anisomycin, suggesting that altered translation control is involved in the enhanced synaptic plasticity. Behaviorally, FKBP12 conditional knockout (cKO) mice displayed enhanced contextual fear memory and autistic/obsessive-compulsive-like perseveration in several assays including the water maze, Y-maze reversal task, and the novel object recognition test. Our results indicate that FKBP12 plays a critical role in the regulation of mTOR-Raptor interactions, LTP, memory, and perseverative behaviors.

Siblings with leukoencephalopathy

Two consanguineous siblings presented with developmental regression and emerging spasticity. Cranial magnetic resonance imaging in both showed diffuse leukoencephalopathy. Further investigation established the siblings as having complex 1 deficiency consequent to a novel homozygous mutation in NDUFV1, a nuclear-encoded subunit of complex 1. Diffuse leukoencephalopathy may be a presentation of complex 1 deficiency.

Acquired obstructive hydrocephalus in globoid-cell leukodystrophy

Acquired obstructive hydrocephalus has developed rarely in patients with globoid cell leukodystrophy. This report describes a 21-month-old female with this concurrence.

Association of galectin-1 and galectin-3 with Gemin4 in complexes containing the SMN protein

In previous studies we showed that galectin-1 and galectin-3 are factors required for the splicing of pre-mRNA, as assayed in a cell-free system. Using a yeast two-hybrid screen with galectin-1 as bait, Gemin4 was identified as a putative interacting protein. Gemin4 is one component of a macromolecular complex containing approximately 15 polypeptides, including SMN (survival of motor neuron) protein. Rabbit anti-galectin-1 co-immunoprecipitated from HeLa cell nuclear extracts, along with galectin-1, polypeptides identified to be in this complex: SMN, Gemin2 and the Sm polypeptides of snRNPs. Direct interaction between Gemin4 and galectin-1 was demonstrated in glutathione S-transferase (GST) pull-down assays. We also found that galectin-3 interacted with Gemin4 and that it constituted one component of the complex co-immunoprecipitated with galectin-1. Indeed, fragments of either Gemin4 or galectin-3 exhibited a dominant negative effect when added to a cell-free splicing assay. For example, a dose-dependent inhibition of splicing was observed in the presence of exogenously added N-terminal domain of galectin-3 polypeptide. In contrast, parallel addition of either the intact galectin-3 polypeptide or the C-terminal domain failed to yield the same effect. Using native gel electrophoresis to detect complexes formed by the splicing extract, we found that with addition of the N-terminal domain the predominant portion of the radiolabeled pre-mRNA was arrested at a position corresponding to the H-complex. Inasmuch as SMN-containing complexes have been implicated in the delivery of snRNPs to the H-complex, these results provide strong evidence that galectin-1 and galectin-3, by interacting with Gemin4, play a role in spliceosome assembly in vivo.

Intrauterine subdural hematoma

A patient with neonatal macrocephaly due to bilateral chronic subdural hematoma is presented. There was no history of intrauterine trauma or coagulopathy. Such patients are apparently rare. The pathogenesis of intrauterine chronic subdural hematoma in such patients is unclear.

Galectin-3 expression and subcellular localization in senescent human fibroblasts

Galectin-3 is a galactose/lactose-binding protein (M(r) approximately 30,000), identified as a required factor in the splicing of pre-mRNA. In the LG1 strain of human diploid fibroblasts, galectin-3 could be found in both the nucleus and the cytoplasm of young, proliferating cells. In contrast, the protein was predominantly cytoplasmic in senescent LG1 cells that have lost replicative competence through in vitro culture. Incubation of young cells with leptomycin B, a drug that disrupts the interaction between the leucine-rich nuclear export signal and its receptor, resulted in the accumulation of galectin-3 inside the nucleus. In senescent cells, galectin-3 staining remained cytoplasmic even in the presence of the drug, thus suggesting that the observed localization in the cytoplasm was due to a lack of nuclear import. In heterodikaryons derived from fusion of young and senescent LG1 cells, the predominant phenotype was galectin-3 in both nuclei. These results suggest that senescent LG1 cells might lack a factor(s) specifically required for galectin-3 nuclear import.

Export of galectin-3 from nuclei of digitonin-permeabilized mouse 3T3 fibroblasts

Galectin-3 is a galactose-/lactose-binding protein (M(r) approximately 30,000), identified as a required factor in the splicing of pre-mRNA. Immunofluorescence staining revealed that galectin-3 distributes differentially between the nucleus and the cytoplasm, depending on the proliferative state of the cells under analysis. Using digitonin-permeabilized mouse 3T3 fibroblasts, we provide evidence that galectin-3 is rapidly and selectively exported from the nucleus. Although both phosphorylated and nonphosphorylated isoforms of galectin-3 are found in the nuclear fraction, only phosphorylated galectin-3 is identified in the exported fraction, implying that phosphorylation is important for the nuclear export of the protein. The rate of galectin-3 export is temperature dependent and is decreased by the addition of wheat germ agglutinin. More strikingly, galectin-3 export can be inhibited by the addition of leptomycin B, a drug that disrupts the interaction between the leucine-rich nuclear export signal and its receptor, CRM1 (chromosome maintenance region 1). Indeed, a putative leucine-rich nuclear export signal can be found in residues 241-249 of the murine galectin-3 sequence. Finally, gel filtration of the exported material showed that galectin-3 can be found in at least two high molecular weight complexes (approximately 650 and approximately 60 kDa), both of which can be disrupted by lactose.

A comparative nuclear localization study of galectin-1 with other splicing components

Using both conventional and laser confocal fluorescence microscopy, the intracellular distribution of galectin-1 in HeLa cells was analyzed and compared with the localization of previously documented markers of the nucleus and cytoplasm. The Sm epitopes of the small nuclear ribonucleoprotein complexes (snRNPs) and the non-snRNP splicing factor SC35 yielded only nuclear staining. On the other hand, the enzyme lactate dehydrogenase was cytoplasmic. In contrast to these patterns in which nuclear versus cytoplasmic localizations appeared to be mutually exclusive, galectin-1, as well as galectin-3, yielded simultaneous nuclear and cytoplasmic staining. Confocal microscopy showed galectin-1 fluorescence throughout most of the sections from the top of the cell to the bottom. Through the middle sections, as the plane of focus cuts through the nucleus, there was definite fluorescence staining in the nuclear compartment. This nuclear localization was critically dependent on the type of detergent used to permeabilize the cell: cells treated with saponin or digitonin yielded exclusively cytoplasmic staining while Triton X-100-treated cells showed nuclear as well as cytoplasmic labeling. Finally, double-immunofluorescence analysis showed that, within the nucleoplasm, the following pairs of nuclear antigens could be colocalized in certain speckled structures: (a) SC35 versus Sm; (b) galectin-1 versus Sm; (c) galectin-3 versus Sm; and (d) galectin-1 versus galectin-3. These results establish the presence of galectin-1 in the nuclei of HeLa cells, a conclusion consistent with the identification of the protein in nuclear extracts of the same cells and with its documentation as a factor in pre-mRNA splicing.

Atretic parietal cephaloceles revisited: an enlarging clinical and imaging spectrum?

PURPOSE

We describe imaging features that are clues to the diagnosis of atretic cephaloceles and discuss clinical findings and a possible mechanism by which these lesions develop.

METHODS

Eight children (five girls and three boys) ranging in age from 1 day to 3 years 4 months with midline subscalp lesions underwent radiologic examination with CT or MR imaging. In all cases, the lesions were surgically excised and subjected to pathologic examination. Imaging studies and medical records were reviewed retrospectively.

RESULTS

Six of eight children had vertical embryonic positioning of the straight sinus with a prominent superior cerebellar cistern. A "spinning-top" configuration of the tentorial incisura, a "cigar-shaped" CSF tract within the interhemispheric fissure, fenestration of the superior sagittal sinus, and "peaking" of the tentorium were associated findings helpful in making this diagnosis. Two of the eight children had findings indistinguishable from focal dermoid, six were developmentally normal, one had mild motor delay, and one died at the age of 3 years. Pathologic examination revealed glial, meningeal (arachnoid), fibrous, and dermal elements.

CONCLUSION

Characteristic findings on MR images and CT scans provide clues to the diagnosis of atretic cephalocele. However, even in the presence of abnormal imaging findings, these children may be developmentally normal.

Evidence for a role for galectin-1 in pre-mRNA splicing

Galectins are a family of beta-galactoside-binding proteins that contain characteristic amino acid sequences in the carbohydrate recognition domain (CRD) of the polypeptide. The polypeptide of galectin-1 contains a single domain, the CRD. The polypeptide of galectin-3 has two domains, a carboxyl-terminal CRD fused onto a proline- and glycine-rich amino-terminal domain. In previous studies, we showed that galectin-3 is a required factor in the splicing of nuclear pre-mRNA, assayed in a cell-free system. We now document that (i) nuclear extracts derived from HeLa cells contain both galectins-1 and -3; (ii) depletion of both galectins from the nuclear extract either by lactose affinity adsorption or by double-antibody adsorption results in a concomitant loss of splicing activity; (iii) depletion of either galectin-1 or galectin-3 by specific antibody adsorption fails to remove all of the splicing activity, and the residual splicing activity is still saccharide inhibitable; (iv) either galectin-1 or galectin-3 alone is sufficient to reconstitute, at least partially, the splicing activity of nuclear extracts depleted of both galectins; and (v) although the carbohydrate recognition domain of galectin-3 (or galectin-1) is sufficient to restore splicing activity to a galectin-depleted nuclear extract, the concentration required for reconstitution is greater than that of the full-length galectin-3 polypeptide. Consistent with these functional results, double-immunofluorescence analyses show that within the nucleus, galectin-3 colocalizes with the speckled structures observed with splicing factor SC35. Similar results are also obtained with galectin-1, although in this case, there are areas of galectin-1 devoid of SC35 and vice versa. Thus, nuclear galectins exhibit functional redundancy in their splicing activity and partition, at least partially, in the nucleoplasm with another known splicing factor.

Hypertensive encephalopathy in children

We present five cases of hypertensive encephalopathy in children, three with MR imaging findings and two with CT findings alone. One of the five patients had MR perfusion imaging, which showed perfusion abnormalities that support the concept of vasodilation as the major contributor to the syndrome. Hypertensive encephalopathy is rarely reported in children, and its true prevalence may be underestimated. Characteristic lesions in the severely hypertensive child should be recognized as manifestations of hypertensive encephalopathy, and subsequent clinical management should focus on treatment of the hypertension and/or its underlying causes.

Adolescent parenting: outcomes and maternal perceptions

OBJECTIVE

To describe selected outcomes and maternal perceptions of adolescent parenting.

DESIGN

Qualitative and quantitative methods, interview, and two standardized instruments were combined in this follow-up study of adolescents who received perinatal services between 1985 and 1988.

SETTING

Data were collected in the mothers' homes.

PARTICIPANTS

Mothers who were randomly selected for an earlier chart outcome audit (N = 98) and could be located (n = 19).

MAIN OUTCOME MEASURES

Subsequent pregnancies; school completion; children's development, indicated by the Developmental Profile II (DPII); parental attitudes, indicated by the Adult-Adolescent Parenting Inventory (AAPI); and maternal perceptions.

RESULTS

Responses revealed irregular use of contraceptives as one reason for the initial pregnancy and for subsequent unplanned pregnancies. Sixteen mothers completed high school, and 18 intend to complete postsecondary programs. The DPII indicated age-appropriate development of the children. AAPI scores for 84% of the mothers indicated nonnurturing attitudes. Mothers described family support, motherhood, and their children.

CONCLUSIONS

Research is needed with larger samples and to test interventions to promote regular use of contraception. Findings support the need for research-based programs to educate and promote the development of adolescent mothers and their children.

Identification of galectin-3 as a factor in pre-mRNA splicing

Galectin-3 (M(r) approximately 35,000) is a galactose/lactose-specific lectin found in association with ribonucleoprotein complexes in many animal cells. Cell-free-splicing assays have been carried out to study the requirement for galectin-3 in RNA processing by HeLa cell nuclear extracts by using 32P-labeled MINX as the pre-mRNA substrate. Addition of saccharides that bind galectin-3 with high affinity inhibited product formation in the splicing assay, while addition of carbohydrates that do not bind to the lectin did not inhibit product formation. Nuclear extracts depleted of galectin-3 by affinity adsorption on a lactose-agarose column were deficient in splicing activity. Extracts subjected to parallel adsorption on control cellobiose-agarose retained splicing activity. The activity of the galectin-3-depleted extract could be reconstituted by the addition of purified recombinant galectin-3, whereas the addition of other lectins, either with a similar saccharide binding specificity (soybean agglutinin) or with a different specificity (wheat germ agglutinin), did not restore splicing activity. The formation of splicing complexes was also sensitive to galectin-3 depletion and reconstitution. Together, these results define a requirement for galectin-3 in pre-mRNA splicing and identify it as a splicing factor.

Evaluation of a clinic for pregnant adolescents

A random retrospective review of the Teen Obstetrical Parenting Perinatal Services (TOPPS) clinic medical records for 1985 to 1989 was completed on 120 adolescent mothers (30 charts for each year). The purpose of this study was to evaluate maternal and infant outcomes related to the goals of the TOPPS clinic located at University Hospital on the UAMS campus in Little Rock, Arkansas. The clinic was cofounded by Lee Lee Doyle, Ph.D., who is now professor of obstetrics/gynecology at UAMS, and Betty Rouse, R.N., M.N.Sc., who is a clinical associate professor at UAMS, College of Nursing. The outcomes measured were nutritional status as measured by maternal weight gain, infant birth weight, gestational age and Apgar scores. Referrals to appropriate agencies during pregnancy were also reviewed. Analysis of the data revealed that 31% of clients received documented nutritional counseling, 60.2% of the babies were healthy (88% term and 87% appropriate for gestational age), and documented referrals (i.e. WIC, AFDC, Medicaid, etc.) were made in 32% of the cases. Conclusions were that both mothers and infants had positive outcomes. Documentation of referrals needs to be improved or rationale stated for non-referral.

Phenotypic conversion of TK-deficient cells following electroporation of functional TK enzyme

The ability to phenotypically rescue a mutant (Rat-3, thymidine kinase-deficient) cell line by electroporation of functional TK enzyme has been investigated. Extracts of electroporated cells showed a 35-fold increase in TK enzyme levels under conditions where greater than 90% of the cells remained viable. The electroporated enzyme was intracellular, as demonstrated by the fact that cells were able to utilize exogenous [3H]thymidine for DNA synthesis. By in situ autoradiography, 82% of electroporated cells contained functional enzyme and incorporated [3H]thymidine into DNA. Thus, this technique can efficiently provide a missing metabolic function to cultured mammalian cells.

The toddler's cuboid fracture

The authors describe two proved and two presumed cases of cuboid fractures in toddlers. These children were seen because of their inability to bear weight on the affected foot following a fall. Initial radiographs were normal; however, early scintigraphy revealed focal uptake in the cuboid. Follow-up radiographs demonstrated characteristic sclerosis of the base of the cuboid. Cuboid fractures are another example of a toddler's injury that may be difficult to diagnose at initial physical and radiographic examination.

Chest radiographs in the evaluation of the febrile infant

Chest radiographs are often considered an essential part of the workup of the febrile infant. Anteroposterior and lateral radiographs of the chest are frequently obtained in this group of patients, irrespective of respiratory tract symptoms and/or signs. A total of 226 children (less than or equal to 2 years old) with and without signs and symptoms of lower respiratory tract infections were examined to assess the yield of chest radiographs. The radiograph was considered positive only if a focal parenchymal infiltrate was present. Hyperinflation or bronchial thickening was not included as a positive finding because these children usually do not receive antibiotics despite the fact that viral illness or reactive airway disease may be present. In a retrospective study of 105 infants, confidence intervals for yield were established for children with (95% Cl = 12%, 32%) and without (95% Cl = 0%, 14%) symptoms or signs of lower respiratory tract infection. In a prospective study of 121 infants without chest symptoms or signs, confidence levels for positive yield were better defined (95% Cl = 0%, 3%). The data suggest that obtaining chest radiographs to look for parenchymal infiltrates treatable with antibiotics in infants less than 2 years old is necessary only in those infants who have clinical evidence of lower respiratory tract illness.

RNA metabolism in nuclei: adenovirus and heat shock alter intranuclear RNA compartmentalization

Nuclear RNA compartmentalization has received little attention as an area where regulation of gene expression could occur. RNA transcription and processing occur in association with the nuclear matrix, a salt-insoluble proteinaceous network that fills the nuclear space and is contiguous with the peripheral lamina and pore complexes. Described here are experiments that determine the fate of nuclear RNA after it has completed these matrix-associated maturation steps. Continuous label experiments indicate that after nuclear RNA is processed it changes its state of attachment in the nucleus so that it is now removed from the nucleus in the high salt extraction step of matrix isolation. It is this salt-extractable RNA that will be transported to the cytoplasm. Late in adenovirus infection and following heat shock, when transport of cellular RNA is decreased, cellular transcripts do not make the transition from the matrix-associated to the salt-extractable nuclear pool. The implication of these data for the regulation of gene expression is discussed.

Reconstitution of the U1 small nuclear ribonucleoprotein particle

Although the U1 small nuclear ribonucleoprotein particle (snRNP) was the first mRNA-splicing cofactor to be identified, the manner in which it functions in splicing is not precisely understood. Among the information required to understand how U1 snRNP participates in splicing, it will be necessary to know its structure. Here we describe the in vitro reconstitution of a particle that possesses the properties of native U1 snRNP. 32P-labeled U1 RNA was transcribed from an SP6 promoter-human U1 gene clone and incubated in a HeLa S100 fraction. A U1 particle formed which displayed the same sedimentation coefficient (approximately 10S) and buoyant density (1.40 g/cm3) as native U1 snRNP. The latter value reflects the ability to withstand isopycnic banding in Cs2SO4 without prior fixation, a property shared by native U1 snRNP. The reconstituted U1 particle reacted with both the Sm and RNP monoclonal antibodies, showing that these two classes of snRNP proteins were present. Moreover, the reconstituted U1 snRNP particle was found to display the characteristic Mg2+ switch of nuclease sensitivity previously described for native U1 snRNP: an open, nuclease-sensitive conformation at a low Mg2+ concentration (3 mM) and a more compact, nuclease-resistant organization at a higher concentration (15 mM). The majority of the U1 RNA in the reconstituted particle did not contain hypermethylated caps, pseudouridine, or ribose 2-O-methylation, showing that these enigmatic posttranscriptional modifications are not essential for reconstitution of the U1 snRNP particle. The extreme 3' end (18 nucleotides) of U1 RNA was required for reconstitution, but loop II (nucleotides 64 to 77) was not. Interestingly, the 5' end (15 nucleotides) of U1 RNA that recognizes pre-mRNA 5' splice sites was not required for U1 snRNP reconstruction.

Puerperal renal vein thrombosis

A case of renal vein thrombosis occurring one week post partum with unknown etiology and excellent recovery is described. Review of the literature reveals this disorder is rare in the nonpregnant woman and even rarer in pregnancy. Survival has greatly improved with anticoagulant use. Diagnosis, prognosis, and treatment are discussed.

Evidence for mannose-mediated adherence of Candida albicans to human buccal cells in vitro

Various lectins and sugars were used to study the possible role of saccharide-containing moieties on the surface of Candida albicans and human buccal cells in the adherence of this yeast to mucosal surfaces. The lectins possessed affinities for several different sugar moieties and were used to pretreat C. albicans or buccal cells before mixing and incubating in the adherence assay. It was found that concanavalin A, a lectin that recognizes mannose and glucose, inhibited adherence of the pretreated yeasts to buccal cells and also inhibited adherence of pretreated buccal cells to nonpretreated yeast cells. Adherence was restored by preincubating the concanavalin A with a mannose derivative, but preincubation of concanavalin A with other sugars did not produce this effect. Lectins that do not recognize mannose had no effect on adherence. The presence of alpha-D-methyl mannopyranoside in the incubation medium during the assay inhibited adherence, whereas other sugars did not. Germinated yeasts adhered to buccal cells more effectively than nongerminated cells and were more susceptible to adherence inhibition by concanavalin A than were nongerminated yeasts. Thus, mannose-containing moieties on the surface of C. albicans and buccal cells could mediate the adherence of this yeast to human epithelium.

RNA metabolism in isolated nuclei: processing and transport of immunoglobulin light chain sequences

Transport of prelabeled RNA from isolated myeloma nuclei is studied using conditions that permit RNA synthesis. Cytosol and spermidine are not required to maintain nuclear stability and inhibited RNA release. Omission of ATP or GTP decreased release 25 to 40%. The stimulatory effect of ATP or GTP is not due to hydrolysis of the triphosphates by the nuclear envelope NTPase, since addition of quercetin (an inhibitor of this NTPase) has no effect on the quantity of RNA released. The size distribution and percentage of poly A-containing species released from nuclei incubated with or without ATP or the other rNTPs are identical. Hybridization analysis of nuclear RNA before the transport assay revealed mature and precursor k light chain mRNA sequences. Following the transport assay, a significant fraction of k mRNA precursors is chased into mature k mRNA which is found both in nuclear-retained and released RNA.

RNA metabolism in isolated nuclei: effect of temperature on RNA transport from intact and membrane-denuded nuclei

The kinetics of RNA transport from intact (both inner and outer nuclear membranes present) and membrane-denuded myeloma nuclei were monitored at temperatures between 10 and 37 degrees C. A linear rate for RNA transport was calculated and the log of RNA transported from membrane-denuded nuclei was greater than that transported from intact nuclei and ii) RNA transport from both nuclear preparations exhibited straight line Arrhenius plots. We conclude the nuclear envelope (or a nuclear matrix element) modulates the amount of RNA transported from nuclei and that nuclear membrane thermal phase transitions do not alter the apparent energy of activation for the transport process.

Serum protein binding of drugs during and after pregnancy in humans

The serum protein binding of three weakly acidic drugs (salicylic acid, sulfisoxazole, and phenytoin), one week base (diazepam), and one steroid (dexamethasone) was determined in pregnant women at seven time periods during pregnancy and at two periods post partum, as well as in a group of nonpregnant women of childbearing age. The serum free fraction values (ratio of concentrations, free to total drug) of all drugs rose during pregnancy, primarily after 15 wk of gestation, and remained elevated for at least 1 to 5 days post partum. Pregnancy had the greatest effect on protein binding of sulfisoxazole, diazepam, and salicylic acid. The magnitude of this effect is such that quantitatively significant changes in the pharmacokinetic and pharmacodynamic characteristics of certain drugs may be expected to occur during pregnancy (in addition to possible changes caused by other pregnancy-related effects such as altered activity of drug-metabolizing enzyme systems). All drugs but dexamethasone exhibited significant negative correlations between free fraction values and serum albumin concentrations during pregnancy. The serum protein binding of salicylic acid, but not the other drugs tested, was more extensive in nonpregnant women who were not taking oral contraceptives than in those who were.

Prevention of hyaline membrane disease with plasminogen. A cooperative study

In a double-blind, randomized study, 500 premature infants were treated with plasminogen or placebo intravenously within 60 minutes of birth. There was a substantial decrease in severe clinical respiratory distress, death caused by hyaline membrane disease, and total mortality in the plasminogen-treated infants as compared to the controls.

RNA transport in isolated myeloma nuclei. Transport from membrane-denuded nuclei

Nuclei prepared from MOPC-21 cells were treated with the nonionic detergents Triton X-100 or Nonidet P-40. Chemical analysis revealed that nearly 90% of the nuclear phospholipid was removed by detergent treatment. The membrane-denuded nuclei remained intact with preservation of nuclear pore complexes as demonstrated by electron microscopy. Ribonucleic acid transport from detergent-treated nuclei proceeded at the same rate and to the same extent as in control nuclei. Normal nuclear restriction of nucleic acids was unaltered by removal of the nuclear membranes. The effect of temperature on transport of RNA from freshly isolated myeloma nuclei with intact nuclear envelopes was studied. No temperature transition was associated with the transport process. These data indicate that the transport of macromolecules from isolated myeloma nuclei is independent of the nuclear membrane.

Polysome isolation of sepharose column chromatography

Polysomes from the mouse myeloma MOPC-21 were purified by gel filtration of Sepharose 6B, 4B and 2B columns. All three columns eliminated nearly all intracellular material smaller than 40 S subunits. In addition, passage through 4B and 2B columns substantially reduced the amount of subunits and monosomes in the preparations. Purified polysomes retained structural integrity when stored at -85 degrees C for at least nine weeks.

The conversion of gibberellin A1 to gibberellin A 8 by a cell-free enzyme system

An enzyme system which catalyzes hydroxylation of (3)[H]gibberellin A1 ([(3)H]GA1) to [(3)H]GA8 was obtained from homogenates of germinating bean (Phaseolus vulgaris L.) seed. The system remained in the supernatant after centrifugation at 95000×g for 2 h. Hydroxylation occurred at one of the specifically (3)H-labeled positions (C-2) and, concomitantly, produced [(3)H]water whic was used to measure formation of [(3)H]GA8. NADPH and/or ascorbate are cofactors utilized by this enzyme. EDTA effectively inhibited the system, suggesting a cation requirement.