Growth factor-induced osteogenesis in a novel radiolucent bone chamber.

Treatment of large bone defects is currently performed using mainly autograft or allograft bone. There are important drawbacks to bone grafting, such as limited availability, donor site morbidity in the case of autograft and inferior performance of allografts. Therefore, there is a great need for a suitable bone graft substitute. In order to evaluate efficiently newly developed biomaterials and factors intended for orthopaedic surgery, the bone chamber is a very suitable model. To allow longitudinal investigation of bone growth with µCT, a new bone chamber made of radiolucent polyether ether ketone (PEEK) was developed and studied for its feasibility. Therefore, PEEK bone chambers were placed on rat tibiae, and filled with vehicle (Matrigel without growth factors, negative controls), with bone morphogenetic protein 2 (BMP-2, positive controls), or a mix of growth factors combining BMP-2, vascular endothelial growth factor and the chemokine stromal cell-derived factor 1α, all laden on gelatin microspheres for controlled release (combined growth factors). Growth factor presence led to a significant increase in bone formation after 8 weeks, which subsided after 12 weeks, underlining the importance of longitudinal analysis. We conclude that the PEEK-bone chamber is a suitable translational animal model to assess orthotopic bone formation in a longitudinal manner.

Direct effect of nicotine on mesolimbic dopamine release in rat nucleus accumbens shell.

Nicotine stimulates dopamine (DA) cell firing via a local action at somatodendritic sites in the ventral tegmental area (VTA), increasing DA release in the nucleus accumbens (NAcc). Additionally, nicotine may also modulate DA release via a direct effect in the NAcc. This study examined the contribution of the latter mechanism on NAcc DA release by applying nicotine systemically, as well as locally in the VTA and NAcc shell region in rats. Furthermore, the effect of i.v. nicotine on cell firing rate of dopaminergic neurons in the VTA was measured. Systemic administration of nicotine (0.32mg/kg s.c.) increased extracellular DA levels in the NAcc to ∼1.5 fold of baseline, while DA levels in the VTA remained unaffected. A similar DA increase was observed after local NAcc infusion of nicotine (1µM and 10µM). However, 10-1000-fold higher nicotine concentrations were required in the VTA to produce a comparable 150% increase in extracellular DA levels in the ipsilateral NAcc. Additionally, electrophysiological experiments showed that the dopaminergic firing rate in the VTA showed a trend towards an increase after a nicotine dose of 0.1mg/kg i.v. Taken together these data indicate that the effects of nicotine on DA release at the level of the NAcc might be more important for the rewarding effects than originally proposed.

Mapping of the mouse actin capping protein beta subunit gene.

BACKGROUND: Capping protein (CP), a heterodimer of alpha and beta subunits, is found in all eukaryotes. CP binds to the barbed ends of actin filaments in vitro and controls actin assembly and cell motility in vivo. Vertebrates have three isoforms of CPbeta produced by alternatively splicing from one gene; lower organisms have one gene and one isoform. RESULTS: We isolated genomic clones corresponding to the beta subunit of mouse CP and identified its chromosomal location by interspecies backcross mapping. CONCLUSIONS: The CPbeta gene (Cappb1) mapped to Chromosome 4 between Cdc42 and D4Mit312. Three mouse mutations, snubnose, curly tail, and cribriform degeneration, map in the vicinity of the beta gene.

Vertebrate isoforms of actin capping protein beta have distinct functions In vivo.

Actin capping protein (CP) binds barbed ends of actin filaments to regulate actin assembly. CP is an alpha/beta heterodimer. Vertebrates have conserved isoforms of each subunit. Muscle cells contain two beta isoforms. beta1 is at the Z-line; beta2 is at the intercalated disc and cell periphery in general. To investigate the functions of the isoforms, we replaced one isoform with another using expression in hearts of transgenic mice. Mice expressing beta2 had a severe phenotype with juvenile lethality. Myofibril architecture was severely disrupted. The beta2 did not localize to the Z-line. Therefore, beta1 has a distinct function that includes interactions at the Z-line. Mice expressing beta1 showed altered morphology of the intercalated disc, without the lethality or myofibril disruption of the beta2-expressing mice. The in vivo function of CP is presumed to involve binding barbed ends of actin filaments. To test this hypothesis, we expressed a beta1 mutant that poorly binds actin. These mice showed both myofibril disruption and intercalated disc remodeling, as predicted. Therefore, CPbeta1 and CPbeta2 each have a distinct function that cannot be provided by the other isoform. CPbeta1 attaches actin filaments to the Z-line, and CPbeta2 organizes the actin at the intercalated discs.

Childhood imbalance and chronic otitis media with effusion: effect of tympanostomy tube insertion on standardized tests of balance and locomotion.

The goal of this study was to investigate the role of chronic otitis media with effusion as a cause of childhood imbalance. Nineteen 4- to 6-year-old children with chronic otitis media with effusion and 14 matched control children underwent a series of laboratory tests, including two standardized tests of balance and locomotion: the Peabody Developmental Motor Scales (PDMS) and the Bruininks-Oseretsky Test of Motor Proficiency (BOTMP). The children in the chronic otitis media with effusion group underwent tympanostomy tube insertion. Both groups underwent the same battery of tests within 6 to 8 weeks of initial testing. Analysis of variance for the PDMS and BOTMP demonstrated significantly lower performance in the balance subscales for the otitis group before (P < .01). Both otitis and control groups improved when retested. The improvement was greater and approaching significance in the otitis group on the PDMS and BOTMP (P = .056 and .097, respectively). It is concluded that chronic otitis media with effusion significantly affects balance and coordination skills in 4- to 6-year-old children. These skills improve after tympanostomy tube insertion at a rate greater than that of the control group.

Antenatal thyrotropin-releasing hormone to prevent lung disease in preterm infants. North American Thyrotropin-Releasing Hormone Study Group.

BACKGROUND: Pulmonary disease is common in preterm infants, despite antenatal glucocorticoid therapy. The addition of antenatal thyrotropin-releasing hormone therapy has been reported to decrease pulmonary morbidity in these infants. METHODS: We enrolled 996 women at 13 North American centers who were in preterm labor at <30 weeks' gestation in a double-blind, placebo-controlled, randomized trial of antenatal thyrotropin-releasing hormone, given intravenously in four doses of 400 microg each at eight-hour intervals. The primary outcome was chronic lung disease or death of the infant on or before the 28th day after delivery, and secondary outcomes were respiratory distress syndrome and chronic lung disease or death at 36 weeks' postmenstrual age. Complete data were available for 981 women and their 1134 live-born infants. The 769 infants born at < or = 32 weeks' gestation were defined as the group at risk. RESULTS: There were no significant differences between the at-risk treatment and placebo groups in mean (+/-SD) birth weight (1109+/-354 vs. 1097+/-355 g), gestational age (27.9+/-2.1 vs. 27.9+/-2.1 weeks), sex, or race. The frequencies of respiratory distress syndrome (66 percent vs. 65 percent), death at 28 days (11 percent vs. 11 percent), chronic lung disease or death at 28 days (45 percent vs. 42 percent) and at 36 weeks (32 percent vs. 34 percent), and other neonatal complications as well as the severity of lung disease were not significantly different in the at-risk treatment and placebo groups. Similarly, there were no differences in outcome between the treatment and placebo groups for the infants born at >32 weeks' gestation. CONCLUSIONS: In preterm infants at risk for lung disease, antenatal administration of thyrotropin-releasing hormone and glucocorticoid is no more beneficial than glucocorticoid alone.

Identification of a naturally occurring ligand for thymic positive selection.

In the thymus, positive and negative selection shape the T cell repertoire. It has previously been shown that positive selection, like negative selection, is the result of the interaction of the TCR with self-peptides bound to MHC. However, little is known about the number or nature of the self-peptide ligands that mediate positive selection in vivo. We devised a novel assay with enhanced sensitivity for low affinity TCR ligands to identify self-peptides that may be biologically relevant. At least eight K(b)-bound self-peptides were detected by this assay using thymocytes bearing the OT-I TCR (specific for OVAp/K(b)). The sequence of one of these peptides was determined using the recently developed technique of membrane preconcentration-capillary electrophoresis-tandem mass spectrometry. This peptide, CP alpha1, has limited sequence similarity to OVAp, yet was found to induce positive selection of OT-I thymocytes in fetal thymic organ culture.

Efficacy of ototopical ciprofloxacin in pediatric patients with otorrhea.

OBJECTIVE: The objective of this study was to evaluate the efficacy and safety of topical ciprofloxacin in patients with recurrent otorrhea that was unresponsive to other antibiotics. METHODS: Pediatric patients with otorrhea and confirmed Pseudomonas aeruginosa in the ear fluid were enrolled. Topical ciprofloxacin, three drops three times daily for 14 days, was prescribed with aural care. Efficacy and safety were evaluated on days 7 and 14. A phone follow-up was conducted monthly thereafter for 8.6 months. RESULTS: Twenty-nine pediatric patients were enrolled. On day 14, 18 were cured, 8 were improved, 2 were changed to an alternate therapy and cured, and 1 showed no improvement, perhaps due to a small external ear canal. Two additional patients were cured at day 21. None of the patients reported any adverse effects. Twelve patients had no recurrence at 3 to 15 months after the study. CONCLUSION: The use of topical ciprofloxacin in pediatric patients was curative in nearly 70% of patients with otorrhea associated with P. aeruginosa who were previously unresponsive to other antimicrobials. No adverse reactions were reported in the study population.

Mapping of the mouse actin capping protein alpha subunit genes and pseudogenes.

Capping protein (CP), a heterodimer of alpha and beta subunits, is found in all eukaryotes. CP binds to the barbed ends of actin filaments in vitro and controls actin assembly and cell motility in vivo. Vertebrates have three alpha isoforms (alpha 1, alpha 2, alpha 3) produced from different genes, whereas lower organisms have only one gene and one isoform. We isolated genomic clones corresponding to the alpha subunits of mouse CP and found three alpha 1 genes, two of which are pseudogenes, and a single gene for both alpha 2 and alpha 3. Their chromosomal locations were identified by interspecies backcross mapping. The alpha 1 gene (Cappa1) mapped to chromosome 3 between D3Mit11 and D3Mit13. The alpha 1 pseudogenes (Cappa1-ps1 and Cappa1-ps2) mapped to Chromosomes 1 and 9, respectively. The alpha 2 gene (Cappa2) mapped to Chromosome 6 near Ptn. The alpha 3 gene (Cappa3) also mapped to Chromosome 6, approximately 68 cM distal from Cappa2 near Kras2. One mouse mutation, de, maps in the vicinity of the alpha 1 gene. No known mouse mutations map to regions near the alpha 2 or alpha 3 genes.

Vertebrates have conserved capping protein alpha isoforms with specific expression patterns.

Capping protein (CP), a ubiquitous actin binding protein composed of an alpha and a beta subunit, is important for actin assembly and cell motility. Lower organisms have one gene and one isoform of each subunit. Chickens have two very similar alpha-subunit isoforms. To determine if vertebrates in general contain multiple alpha isoforms and if those alpha isoforms have conserved sequences, we isolated and analyzed alpha subunit cDNA's in mice and humans. Both mice and humans also have two alpha isoforms. Phylogenetic analysis of the alpha isoform sequences reveals that vertebrates have two highly conserved subfamilies, alpha1 and alpha2. The alpha1 and alpha2 subfamilies are very similar to each other but can be defined and distinguished from each other by a small number of key amino acid residues. In addition, 3' untranslated cDNA sequences are conserved within the isoform subfamilies. To investigate the function of the alpha isoforms, we examined their expression in mouse cells and tissues. Endothelial cells contain only the alpha2 isoform, and erythrocytes contain almost exclusively the alpha1 isoform. Most tissues have both alpha1 and alpha2 isoforms but the ratio of alpha1:alpha2 varies widely. Together, these findings support the hypothesis that the CP alpha isoforms have conserved, unique and essential roles in vertebrates.

Comparison of the structure and expression of odd-skipped and two related genes that encode a new family of zinc finger proteins in Drosophila.

The odd-skipped (odd) gene, which was identified on the basis of a pair-rule segmentation phenotype in mutant embryos, is initially expressed in the Drosophila embryo in seven pair-rule stripes, but later exhibits a segment polarity-like pattern for which no phenotypic correlate is apparent. We have molecularly characterized two embryonically expressed odd-cognate genes, sob and bowel (bowl), that encode proteins with highly conserved C2H2 zinc fingers. While the Sob and Bowl proteins each contain five tandem fingers, the Odd protein lacks a fifth (C-terminal) finger and is also less conserved among the four common fingers. Reminiscent of many segmentation gene paralogues, the closely linked odd and sob genes are expressed during embryogenesis in similar striped patterns; in contrast, the less-tightly linked bowl gene is expressed in a distinctly different pattern at the termini of the early embryo. Although our results indicate that odd and sob are more likely than bowl to share overlapping developmental roles, some functional divergence between the Odd and Sob proteins is suggested by the absence of homology outside the zinc fingers, and also by amino acid substitutions in the Odd zinc fingers at positions that appear to be constrained in Sob and Bowl

Topical ciprofloxacin for otorrhea after tympanostomy tube placement.

OBJECTIVE: To evaluate the efficacy, systemic absorption, and safety of ototopically administered ciprofloxacin in children with otorrhea associated with tympanostomy tube placement. DESIGN: Nonrandomized, open-label pilot trial with pharmacokinetic determination of the systemic absorption of ototopical ciprofloxacin. SETTING: A pediatric otolaryngology clinic affiliated with Columbus (Ohio) Children's Hospital. PATIENTS: Patients aged 3 to 8 years were enrolled if they had persistent otorrhea associated with tympanostomy tube placement. Other inclusion criteria were culture of Pseudomonas aeruginosa from the drainage material; failure of previous oral antibiotic therapy; and ability to participate in bone conduction audiometry. INTERVENTION: Participants received 3 drops (approximately 60 microL) of 0.3% ototopical ciprofloxacin hydrochloride (Ciloxan, Alcon Laboratories Inc, Forth Worth, Tex), three times a day, for 14 days. Bone conduction audiometry was performed at baseline and on day 14. Patients were examined on days 7 and 14 for efficacy of treatment (improvement, cure, failure) and adverse effects. On day 7, blood samples were drawn just before and 1 hour after the dose was given. Concentrations of ciprofloxacin were measured by high-performance liquid chromatography, with a 5 ng/mL limit of detection. Telephone follow-up was performed on day 44. Parents were asked about adverse effects at days 7, 14, and 44. RESULTS: Mean duration of ear drainage at baseline was 10.7 months (0.75 to 36 months). Ten of 11 infected ears (nine of 10 patients) were improved or cured at day 7. Ten of 11 ears were completely cured at days 14 and 44. No adverse effects were noted or reported by the children's parents. One child had abnormal bone conduction audiometry results at baseline. The results of bone conduction audiometry on day 14 were normal in all children. Trough concentrations of ciprofloxacin were determined in eight of 10 children; and peak concentrations were determined in seven of 10 children. Ciprofloxacin was not detected in the plasma of any child. CONCLUSION: Topical ciprofloxacin was found to be safe and effective in treating otorrhea in children who did not respond to other treatments.

Home from hospital: a survey of hospital discharge arrangements in Northamptonshire.

The timeliness and adequacy of inpatient discharge communication between hospitals and general practitioners (GPs) in Northamptonshire was examined by a postal questionnaire survey of GPs of patients recently discharged from hospital, with the aim of improving the co-ordination of discharge procedures, and hence improving continuity of care. The questionnaire measured when and how the GP was informed of the discharge, and examined the adequacy of medical, therapeutic and social details in the discharge documents sent out by the hospital. It was found that 67 per cent of discharges had been notified to the GP by the hospital within five days of discharge. With notable exceptions the discharge documents were considered timely. General practitioners were less satisfied with the adequacy of discharge communication in terms of 'social' topics such as transport needs, social services back-up, and whether a patient with a malignancy knew about his or her diagnosis. The GPs of patients under geriatricians were more satisfied with the quality of discharge documents. Comparison with an earlier study suggested that the speed of communication and involvement of GPs in discharge in Northamptonshire is not as satisfactory as that found in Oxford in 1986. It was concluded that within the county there appear to be models of good practice in terms of discharge communication with GPs. These standards should be adopted by other specialties to match or improve on existing good practice.

The surgery of benign and malignant neoplasms adjacent to or involving the skull base.

A group of patients who have undergone resection of benign and malignant neoplasms, either adjacent to or through the skull base, were evaluated to determine whether the long-term results justify the risks of such surgery. A total of 37 patients underwent 55 operations in a 6.5-year period from December 1979 to July 1986 at The Ohio State University. An analysis of the operative, perioperative, and long-term complications demonstrates that surgery is well-tolerated. The disease-free interval and survival rates for both benign and malignant neoplasms are encouraging and demonstrate curative potential even for those patients presenting with recurrent malignancies extending through the base of the skull. The interdisciplinary approach evaluated in this study is an effective modality in the treatment of skull base tumors, conferring a favorable risk-benefit ratio.

Pneumocystis antigen appearance during immunosuppression.

The sequential appearance of Pneumocystis carinii (Pc) antigens during the progression of immunosuppression in rats was studied using the immunoblotting technique and specific immunologic probes. Putative Pc soluble antigens, with molecular weights of approximately 70 and 90 kd, were detected as early as 2 wk after initiation of immunosuppression in rats using a pool of monoclonal antibodies produced to Pc isolated from lungs using enzymatic digestion. Monoclonal antibodies produced to Pc isolated by massaging the lung tissue using a Stomacher apparatus and infection-derived sera did not detect soluble antigens until at least the 6th wk of immunosuppression. Analysis of Pc pellets obtained from Stomacher- and lavage-processed lungs revealed that the lower molecular weight antigens (less than or equal to 40, 45 and possibly 55-60 kd) were recognized early during the immunosuppression process.

Ultrasonographic evaluation of intraventricular hemorrhage in premature infants.

Ultrasound and computerized tomographic (CT) methods were used in detecting hydrocephalus and intraventricular hemorrhage (IVH) in three premature infants, with excellent anatomic and pathologic correlation. Ultrasonography may offer an advantageous alternative to CT scanning in evaluating suspected IVH and/or posthemorrhagic hydrocephalus in critically ill infants.

Meningeal sarcoma of the spinal cord in a newborn.

In a newborn infant, spinal rigidity and signs of cervical cord compression developed. Myelography suggested the presence of a spinal cord neoplasm, and pathologic studies confirmed the diagnosis of a pleomorphic cellular sarcoma originating from the leptomeninges of the thoracic spinal cord. A review of neonatal spinal cord neoplasms disclosed a high incidence of developmental tumors in this age group and, therefore, the need for early diagnosis, since many of these tumors are amenable to radiation therapy and surgical removal.

An outbreak og gastroenteritis due to E. coli 0142 in a neonatal nursery.

A nursery outbreak of gastroenteritis casued by Escherichia coli 0142/K86/H6 is described. Over a period of nine months, 59 epidemiologically linked cases of diarrhea occurred, including 21 intractable cases with four deaths. The epidemic strain, which was not agglutinated by commerical diagnostic antisera, was isolated from the hands of personnel in five instances directly incriminated hand carriage as the mode of spread. Acquisition of illness, which was especially high among low-birth-weight infants less than 17 days old, did not correlate with any treatment modality investigated and appeared to be related to a host factor. Noninvasive small intestinal colonization, production of enterotoxin, and multiple antibiotic resistance of the epidemic strain were demonstrated and helped to explain the intractability of clinical illness in many infants, despite intensive parenteral antibiotic therapy. Surveys of fecal coliforms on the hands of nursery personnel revealed no change in prevalence after introduction of a policy of "triple" handwashing with 3 percent hexachlorophene soap, but a significant decrease occurred during the use of disposable gloves. The frequent occurrence of E. coli 0142 in throat swabs of affected infants suggested that pharyngeal colonization may serve as an important diagnostic clue in E. coli diarrhea.