Inhibition of tamoxifen's therapeutic effects by emodin in estrogen receptor-positive breast cancer cell lines

Purpose

This study was aimed to investigate the combination effect of endoxifen and emodin on estrogen receptor (ER) positive breast cancer cell lines and to explain the mechanism of the combination effect.

Methods

We conducted this study on MCF-7 (ER+/human epidermal growth factor receptor-2 [HER2]−), T47D (ER+/HER2−), ZR-75-1 (ER+/HER2+), and BT474 (ER+/HER2+) cell lines, which confirmed combination effect of endoxifen and emodin. Optimal concentrations for combination were determined to study the effects on proliferation of MCF-7 and ZR-75-1 cells. Analysis of the combination effect was carried out in the CompuSyn software. The combination of downstream mechanisms, and combined effects of other similar compounds were tested on the MCF-7 and ZR 75-1 cell lines. Protein expression was confirmed by western blot.

Results

The combination of endoxifen and emodin had antagonistic effects on MCF-7 and ZR-75-1cell lines (combination index > 1). We validated the antagonistic effect in T47D and BT474 cell lines. During the combined treatment, the results showed elevated amounts of cyclin D1 and phosphorylated extracellular signal-regulated kinase (pERK). Analysis of drug interactions showed antagonistic effect between endoxifen and chemical compounds similar to emodin, such as chrysophanol or rhein, in MCF-7 and ZR-75-1 cells.

Conclusion

Addition of emodin attenuated tamoxifen's treatment effect via cyclin D1 and pERK up-regulation in ER-positive breast cancer cell lines.

Engineering an "infectious" T(reg) biomimetic through chemoselective tethering of TGF-β1 to PEG brush surfaces

Modulation of immunological responses to allografts following transplantation is of pivotal importance to improving graft outcome and duration. Of the many approaches, harnessing the dominant tolerance induced by regulatory T cells (Treg) holds tremendous promise. Recent studies have highlighted the unique potency of cell surface-bound TGF-β1 on Treg for promoting infectious tolerance, i.e. to confer suppressive capacity from one cell to another. To mimic this characteristic, TGF-β1 was chemoselectively tethered to inert and viable polymer grafting platforms using Staudinger ligation. We report the synthesis and functional characterization of these engineered TGF-β1 surfaces. Inert beads tethered with TGF-β1 were capable of efficiently converting naïve CD4(+) CD62L(hi) T cells to functional Treg. Concordantly, translation of conjugation scheme from inert surfaces to viable cells also led to efficient generation of functional Treg. Further, the capacity of these platforms to generate antigen-specific Treg was demonstrated. These findings illustrate the unique faculty of tethered TGF-β1 biomaterial platforms to function as an "infectious" Treg and provide a compelling approach for generating tolerogenic microenvironments for allograft transplantation.

Regulation of epithelial proliferation by TGF-beta

The closely related mammalian TGF-betas (TGF-beta 1, TGF-beta 2 and TGF-beta 3) are potent inhibitors of proliferation of many cell types in vitro. TGF-beta 1 has been demonstrated to be growth inhibitory in vivo for epithelial, endothelial, myeloid and lymphoid cells. Utilizing skin keratinocytes as a model system for studying the mechanism of TGF-beta 1-induced growth inhibition, it has been demonstrated that TGF-beta 1 rapidly inhibits transcription of the c-myc gene. Antisense c-myc oligonucleotides inhibit proliferation of keratinocytes as effectively as does TGF-beta 1, indicating that TGF-beta 1 suppression of c-myc expression is an important component of this growth inhibition. Studies utilizing DNA tumour virus transforming gene constructs have shown that the retinoblastoma gene product, pRb, or a related protein, is needed for TGF-beta 1 suppression of c-myc transcription. Thus, TGF-beta 1 may act through a tumour suppressor gene product, pRb, to suppress transcription of a proto-oncogene, c-myc, and subsequently inhibit cell proliferation.

Second-trimester intra-abdominal bowel dilation in fetuses with gastroschisis predicts neonatal bowel atresia

OBJECTIVE

To determine in fetuses with gastroschisis the association between intra-abdominal bowel dilation in the second trimester and neonatal bowel atresia.

METHODS

We reviewed ultrasound and medical records of fetuses with gastroschisis from January 1998 to August 2004. Fetuses with intra-abdominal bowel dilation in the second trimester were identified and followed into the neonatal period.

RESULTS

We identified 58 mother-infant pairs showing fetal gastroschisis, with at least one prenatal ultrasound at our hospital and which were delivered there, or were transported there as newborns. Forty-eight of the 58 fetuses had no intra-abdominal bowel dilation and none of these neonates had bowel atresia. Ten of the 58 fetuses had intra-abdominal bowel dilation and all had bowel atresia at birth (P<0.0001). In eight cases in which ultrasound was performed at <25 weeks' gestation, intra-abdominal bowel dilation was already present.

CONCLUSION

Intra-abdominal bowel dilation in the second trimester predicts neonatal bowel atresia in fetuses with gastroschisis.

Periodontal pathogen detection in gingiva/tooth and tongue flora samples from 18- to 48-month-old children and periodontal status of their mothers

Few studies have detected periodontal pathogens in young children, and when detected the prevalence has been relatively low. In this epidemiological study, we determined the prevalence of periodontal pathogen colonization in young children and examined the relationship between periodontitis in mothers and detection of periodontal pathogens in their children aged 18-48 months. Children were selected and enrolled randomly into the study; tongue and gingival/tooth plaque samples were harvested and analyzed by DNA probe checkerboard assay for Porphyromonas gingivalis and Bacteroides forsythus. Clinical measurements included a gingival bleeding score in the children and a periodontal screening and recording (PSR) score in the mothers. Mothers having one or more periodontal sites with probing depths > 5.5 mm were classified as having periodontitis. In this population, 71% (66/93) of the 18- to 48-month-old children were infected with at least one periodontal pathogen. Detection rates for children were 68.8% for P. gingivalis and 29.0% for B. forsythus. About 13.8% (11/80) of children had gingival bleeding in response to a toothpick inserted interproximally. Children in whom B. forsythus was detected were about 6 times more likely to have gingival bleeding than other children. There was no relationship between bleeding and detection of P. gingivalis. 17.0% (16/94) of the mothers had periodontitis. When all mother-child pairs were considered, the periodontal status of the mother was found not to be a determinant for detection of periodontal pathogens in the floral samples from the children. However, the odds ratio that a daughter of a mother with periodontitis would be colonized was 5.2 for B. forsythus. A much higher proportion of children in this population were colonized by P. gingivalis and/or B. forsythus than has been previously reported for other populations. A modest level of association between manifestations of periodontitis in mothers and detection of B. forsythus in their daughters was observed.

Gender effects in auditory brainstem responses to air- and bone-conducted clicks in neonates

Examinations of gender differences in auditory brainstem response (ABR) wave V latencies and thresholds to air- and bone-conducted clicks were undertaken with neonates. Two hundred and two full-term neonates participated (i.e., 103 males and 99 females). Wave V latency measures for air- and bone-conducted click stimuli of 30, 45, and 60 dB nHL and 15 and 30 dB nHL, respectively, and thresholds to air- and bone-conducted clicks were determined. Female newborns displayed statistically significant shorter wave V latencies than male newborns for air-conducted click stimuli (i.e., approximately 0.2-0.3 ms; P=.0016). There were no significant gender differences in wave V latencies to bone-conducted click stimuli (P=.11). With respect to ABR thresholds, no statistically significant differences were observed for either air-conducted clicks (P=.054) or bone-conducted clicks (P=.18).

EDUCATIONAL OBJECTIVES

As a result of this activity, the participant will be able to (1) describe gender differences in ABR wave V latencies and thresholds to air- and bone-conducted clicks with neonates and (2) summarize possible explanations for observed gender differences in ABR wave V latencies and thresholds to air- and bone-conducted clicks with neonates.

Configuration of thiols dictates their ability to promote iron-induced reactive oxygen species generation

Iron catalyzes the production of reactive oxygen species (ROS) through the Fenton reaction. The modification of this phenomenon in the presence of various thiol compounds that are nominally reducing agents has been studied. Using the synaptosomal/mitochondrial (P2) fraction of rat cerebral cortex as a biological source of reactive oxygen species (ROS) production, we studied the influence of four compounds, glutathione (GSH), cysteine, N-acetyl-cysteine (NAC), and homocysteine on iron-induced ROS production. None of the thiol compounds alone, at the concentrations used, affected the basal rate of ROS production in the P2 fraction. GSH, homocysteine and NAC did not alter Fe-induced ROS generation, while cysteine greatly potentiated ROS formation. Measurement of the rate of ROS production in the presence of varying concentrations of cysteine together with 20 microM ferrous iron revealed a dose-response relationship. The mechanism whereby free cysteine, but not the cysteine-containing peptide GSH, homocysteine or NAC with a blocked amino group, exacerbates the pro-oxidant properties of ferrous iron probably involves formation of a complex between iron, a sulfhydryl and a free carboxyl residue located at a critical distance from the -SH group. Cysteine-iron interactions may, in part, account for the excessive toxicity of free cysteine in contrast to GSH and NAC.

BAPS prize-1999: Lung growth induced by prenatal tracheal occlusion and its modifying factors: a study in the rat model of congenital diaphragmatic hernia

BACKGROUND/PURPOSE

Prenatal tracheal occlusion (TO) has been shown to accelerate lung growth in animal models and models of pulmonary hypoplasia. However, these models may not mimic early events in human congenital diaphragmatic hernia (CDH). The authors previously have developed a model of TO in the rat. The purpose of this study was to apply this technique to characterize TO-induced lung growth in the early onset nitrofen-induced model of CDH, and to address the clinically important questions of the effect of timing of TO and maternal infusion of terbutaline on TO-induced lung growth.

METHODS

Left-sided CDH was induced in the fetuses of time-dated pregnant Sprague-Dawley rats by feeding 100 mg of nitrofen on day 9 of gestation. TO was performed via maternal laparotomy and hysterotomy at 19 days' gestation. At harvest (21.5 days' gestation), lungs from nitrofen-exposed fetuses without CDH (non-CDH), with CDH (CDH), and with CDH and TO (CDH-TO) were compared by analysis of wet and dry weight, DNA and protein content, and stereologic morphometry. A second study was performed to assess relative lung growth achieved by equal intervals of TO after "early" (19 days) versus "late" (20 days) gestational TO. Finally, the effect of maternal infusion of terbutaline, a commonly used tocolytic for fetal surgery, on TO-induced lung growth was analyzed.

RESULTS

Analysis of lung growth showed consistent and significant lung growth in CDH-TO lungs. Lung growth after TO was proliferative and characterized by an increase in parenchymal volume as manifest by increased total saccular number and surface area and radial saccular count. Although visceral reduction was partially achieved, herniated liver was reduced incompletely. The majority of lung growth occurred during the latter half of the TO period. Early gestational age at TO and maternal terbutaline administration adversely influenced lung growth in CDH-TO fetuses.

CONCLUSIONS

Prenatal TO induces dramatic lung growth in the early onset, nitrofen-induced rat model of CDH. TO is more effective later in gestation presumably because of the advanced stage of lung development and lung fluid production. This effect could be counterbalanced by the use of beta-mimetic tocolytic, which inhibits fetal lung fluid production late in gestation. Multiple factors including fetal lung fluid production and absorption, pharmacologic agents, space-occupying herniated viscera, and timing and duration of TO may be important clinical variables. The development of the rat model should facilitate further studies into the cellular and molecular mechanisms responsible for TO-induced lung growth.

An investigation of maternal stress after neonatal hearing screening

An investigation was undertaken to determine whether mothers whose infants failed a newborn hearing screening (MWIF) had significantly more stress and were consequently at risk for dysfunctional attachment than those mothers whose infants passed a newborn hearing screening (MWIP). The Parenting Stress Index (PSI; Abidin, 1995), a screening and diagnostic assessment questionnaire designed to measure the relative magnitude of stress in a parent-child dyad, was used. Twenty MWIP and 20 MWIF participated. The PSI was administered through a telephone interview approximately 1 month after participants' discharge while their infants were between their fourth and fifth week of life. In the case of MWIF, the interview occurred before their infant's hearing retest. No significant differences in Total Stress, Life Stress, Child Domain, and Parent Domain subscale raw scores of the PSI were found between MWIP and MWIF (p > .05). An examination of the individual PSI profiles of all participants for "high" and "low" normative percentile scores (i.e., percentile scores > or = 90th percentile and percentile scores < or = 0 percentile for the former and latter, respectively) revealed that the incidence of high scale/subscale percentile scores was essentially equivalent between groups. MWIP, however, displayed lower scale/subscale percentile scores. The results of the study suggest that those mothers whose infants receive a refer outcome after a newborn hearing screening demonstrate equivalent stress levels as those mothers whose infants received a pass.

Prospects for fetal gene therapy

Advances in prenatal diagnosis and gene transfer technology have allowed consideration of prenatal gene therapy. A compelling argument can be made for this strategy in treating genetic diseases that are fatal in the prenatal or perinatal period. In other diseases, the fetal environment may offer unique biological advantages that favor a prenatal gene therapy strategy over treatment after birth. Although issues of safety and efficacy must be resolved before clinical application, the development of fetal gene therapy may become a new molecular therapeutic arm in the field of prenatal intervention.

Decrease of glial fibrillary acidic protein in rat frontal cortex following aluminum treatment

Aluminum lactate was injected either intraperitoneally or stereotactically into the lateral cerebral ventricles of rats. Rats were killed at various times after treatment, and frontal cortex, hippocampus, and striatum were dissected out. Microtiter plate-based sandwich ELISA and immunohistochemistry were used to measure the glial fibrillary acidic protein (GFAP) concentration. GFAP levels were significantly decreased in frontal cortex 7 days after a single lateral ventricular injection of aluminum lactate and 14 days following systemic treatment. In contrast, neither hippocampus nor striatum exhibited any significant changes in the content of this astrocytic intermediate filament protein after aluminum treatment. Levels of a predominantly astroglial enzyme, glutamine synthetase, were also selectively reduced in the frontal cortex following intraventricular injection of aluminum. This depression exhibited a regional and temporal specificity similar to that found for GFAP. These results suggest a selective and progressive diminution of astrocytic responsivity in frontal cortex following either systemic or intraventricular aluminum dosing. The depression of GFAP levels reported here, which was found in the rat cerebral cortex 7-14 days after aluminum treatment in a species that does not form neurofilamentous aggregates, may reflect extended impairment of astrocytic function and suggests that these cells may be the primary targets of aluminum neurotoxicity.

The stabilization of ferrous iron by a toxic beta-amyloid fragment and by an aluminum salt

Aluminum is a recognized neurotoxin in dialysis encephalopathy and may also be implicated in the etiology of neurodegenerative disease, particularly Alzheimer's disease. Alzheimer's disease is suspected to be associated with oxidative stress, possibly due to the pro-oxidant properties of beta-amyloid present in the senile plaques. The underlying mechanism by which this occurs is not well understood although interactions between amyloid and iron have been proposed. The presence of low molecular weight iron compounds can stimulate free radical production in the brain. This study provides a possible explanation whereby both aluminum and beta-amyloid can potentiate free radical formation by stabilizing iron in its more damaging ferrous (Fe2+) form which can promote the Fenton reaction. The velocity, at which Fe2+ is spontaneously oxidized to Fe3+ at 37 degrees C in 20 mM Bis-Tris buffer at pH 5.8, was significantly slowed in the presence of aluminum salts. A parallel effect of prolongation of stability of soluble ferrous ion, was found in the presence of beta-amyloid fragment (25-35). Ascorbic acid, known to potentiate the pro-oxidant properties of iron, was also capable of markedly stabilizing ferrous ions.

Persistent postnatal transgene expression in both muscle and liver after fetal injection of recombinant adenovirus

BACKGROUND/PURPOSE

Immune responses to both vector and transgene antigens have limited the efficacy of postnatal gene therapy. We hypothesize that the fetal period may offer immunologic and developmental advantages for successful gene therapy. In this study we examined the efficacy, persistence, and immunologic effects of recombinant adenovirus after intramuscular delivery into fetal mice.

METHODS

E1-deleted adenovirus (AdCMVlacZ) containing the beta-galactosidase marker gene was used for injection. Fetal Balb/c mice (14 to 15 days' gestation) were injected with AdCMVlacZ in 10-microL volume in either the shoulder or hindlimb musculature. Animals were killed at 18 to 20 days' gestation and up to 4 months postnatally for analysis of transgene expression and adenoviral genome persistence.

RESULTS

Fetuses were injected with doses of AdCMVlacZ from 1 x 10(8) to 2 x 10(10) viral particles (n = 80). Optimal survival rate was 83% at 18 to 20 days' gestation and 55% at 4 weeks of age using a dose of 1 x 10(9) particles. Expression of beta-galactosidasae at 18 to 20 days localized to multiple muscle groups surrounding the site of injection, as well as bone marrow stroma, liver, lung, and dorsal root ganglia. Persistent muscle and liver transgene expression was observed for as long as 16 and 8 weeks, respectively, after injection. The pattern of liver expression was confined to discrete foci of hepatocytes, which appeared to increase in size in older animals. No histological evidence of muscle or liver inflammation was observed at any time after injection. No neutralizing antibodies were observed postnatally.

CONCLUSIONS

Our results confirm that gene therapy in the fetus may be advantageous. Distribution of vector in the fetus at the site of injection is clearly broader than in the adult setting. Furthermore, the absence of immune response and persistence of transgene expression suggests that fetal exposure to foreign transgene and vector antigens may induce tolerance. Although we have not proven genomic integration, the histological appearance of transgene expression in the liver supports this conclusion. By understanding the mechanisms that underlie persistent transgene expression, fetal gene therapy may become a feasible strategy for the treatment of fatal genetic diseases.

BAPS Prize--1997. Fetal gene therapy: efficacy, toxicity, and immunologic effects of early gestation recombinant adenovirus. British Association of Paediatric Surgeons

BACKGROUND/PURPOSE

Advancements in gene transfer technology and prenatal diagnosis have allowed investigators to consider an in utero gene therapy approach for fatal genetic diseases. The authors sought to develop fetoscopic techniques for gene delivery and investigate the efficacy and safety of recombinant adenoviral vectors in the fetus.

METHODS

Fetal sheep between 60 and 130 days' gestation (dGA) underwent either fetoscopic intratracheal injection or umbilical vein (UV) injection of recombinant adenovirus, AdCMVlacZ. At death, fetal organs were examined for beta-galactosidase expression, histopathology, and CD45 immunostaining. Fetal serum was compared with preimmune serum for transaminase levels and the presence of antiadenoviral neutralizing antibodies.

RESULTS

Fetoscopic intratracheal delivery of AdCMVlacZ in late-gestation sheep fetuses resulted in efficient alveolar gene transfer, but, antiadenoviral immunologic reactions limited the longevity of transgene expression to 14 days. This prompted an examination of whether early gestational exposure could induce tolerance in the fetus to adenoviral and transgene antigens. AdCMVlacZ (1 x 10(11) particles) was injected via UV into fetuses at 60 dGA. Within 3 days, beta-galactosidase expression was localized to the fetal liver, adrenal glands, kidneys, and endocardium. Although adrenal expression was nearly constant over 28 days, expression in fetal liver disappeared within 14 to 28 days. Loss of hepatic expression did not appear to be immune mediated because there was no evidence of hepatic inflammation or appearance of antiadenoviral neutralizing antibodies. Fetuses injected with AdCMVlacZ at 60 dGA were reinjected with 1 x 10(13) particles at 125 dGA and antiadenoviral humoral immune responses were recorded. Despite early-gestation adenovirus injection, fetuses still responded to the late-gestation adenoviral exposure, developing antiadenoviral neutralizing antibodies similar to control fetuses.

CONCLUSIONS

The authors developed fetoscopic access for pulmonary adenovirus delivery in late-gestation sheep. Although initial alveolar transduction was highly efficient, antiadenoviral immune responses limited the duration of transgene expression. In contrast, early-gestation adenoviral delivery did not elicit antiadenoviral immune responses despite achieving efficient transduction of many fetal tissues. Furthermore, early-gestation adenovirus delivery did not affect late-gestation antiadenoviral immune responses. These findings suggest that the early-gestation sheep fetus is not amenable to adenoviral tolerance induction by UV injection and that it is incompetent of immunologic response to adenovirus. For the purposes of in utero gene therapy, recombinant adenovirus may be applied optimally to genetic diseases requiring transient in utero expression.

Long-term correction of canine hemophilia B by gene transfer of blood coagulation factor IX mediated by adeno-associated viral vector

Hemophilia B is a severe X-linked bleeding diathesis caused by the absence of functional blood coagulation factor IX, and is an excellent candidate for treatment of a genetic disease by gene therapy. Using an adeno-associated viral vector, we demonstrate sustained expression (>17 months) of factor IX in a large-animal model at levels that would have a therapeutic effect in humans (up to 70 ng/ml, adequate to achieve phenotypic correction, in an animal injected with 8.5x10(12) vector particles/kg). The five hemophilia B dogs treated showed stable, vector dose-dependent partial correction of the whole blood clotting time and, at higher doses, of the activated partial thromboplastin time. In contrast to other viral gene delivery systems, this minimally invasive procedure, consisting of a series of percutaneous intramuscular injections at a single timepoint, was not associated with local or systemic toxicity. Efficient gene transfer to muscle was shown by immunofluorescence staining and DNA analysis of biopsied tissue. Immune responses against factor IX were either absent or transient. These data provide strong support for the feasibility of the approach for therapy of human subjects.

Tracheal occlusion in the fetal rat: a new experimental model for the study of accelerated lung growth

BACKGROUND

Prenatal tracheal occlusion accelerates fetal lung growth, but the mechanism of this phenomenon is unknown. Previous animal models have been limited by expense, lack of species-specific molecular probes, or the stage of lung development when studies could be performed. To provide a model that is more amenable to systematic analysis, we have developed an in vivo rat model of prenatal tracheal occlusion.

METHODS

Time-dated pregnant rats underwent laparotomy at 19 days' gestational age (term, 22 days). The fetal head and neck were exteriorized through a hysterotomy, and the trachea was ligated under a dissecting microscope. The fetus was returned to the amniotic cavity, and the uterine and maternal abdominal incisions were closed. The dam and the fetuses were killed at 21.5 days' gestational age, and the fetal lungs were assessed for lung growth and compared with nonoperated littermate controls.

RESULTS

Thirty-two of 50 manipulated fetuses survived. Of the 32 survivors, successful tracheal ligation was confirmed in 20, and these 20 fetuses were compared with 33 littermate controls. Fetal body weight (4.81+/-0.26 g v 4.87+/-0.41 g) and heart weight (0.05+/-0.01 g v 0.05+/-0.01 g) were not significantly different between ligated fetuses and littermate controls, whereas the wet lung weight (0.30+/-0.06 g v 0.13+/-0.02 g, P<.01), lung-to-body-weight ratio (6.34+/-1.16% v 2.64+/-0.41%, P<.01), dry lung weight (17.4+/-2.45 mg v 12.1+/-1.87 mg, P<.01), total lung DNA (1210+/-371 microg v 828+/-208 microg, P<.01), and total lung protein (14.3+/-5.3 mg v 8.7+/-1.7 mg, P<.01) were increased significantly in the ligated fetuses. The enlarged lung demonstrated normal histology findings after inflation fixation.

CONCLUSIONS

Prenatal tracheal occlusion during the canalicular stage of lung development accelerates lung growth in the rat. In comparison with other large animal models, this relatively inexpensive small animal model has the distinct advantages of a short gestation, a large number of fetuses per litter, the availability of a developmental model of congenital diaphragmatic hernia, and the availability of well-defined molecular probes to investigate the mechanism of tracheal occlusion-induced lung growth.

Increased cell proliferation and decreased apoptosis characterize congenital cystic adenomatoid malformation of the lung

BACKGROUND/PURPOSE

Congenital cystic adenomatoid malformations (CCAM) are lung lesions that demonstrate abnormalities of both mesenchymal and epithelial tissues. The pathogenesis of these tumors remains unknown. Because normal organogenesis requires a balance between cell proliferation and programmed cell death (apoptosis), the authors hypothesized that CCAM results from an increase in cell proliferation or a decrease in apoptosis within the developing lung, possibly mediated by keratinocyte growth factor (KGF).

METHODS

To examine cell cycle control in CCAM, we measured indices of cell proliferation and apoptosis in lesions requiring fetal (n = 4) or neonatal (n = 8) resection compared with those of normal fetal (14 to 28 weeks' gestation; n = 14) and neonatal (n = 3) human lung. Cell proliferation was analyzed by immunostaining for a proliferation marker (Ki-67). Apoptosis was examined using an in situ digoxigenin end-labeling technique to localize apoptotic bodies. The expression of KGF protein and KGF mRNA in CCAM and normal lung was examined using immunohistochemistry and semiquantitative reverse transcriptase-polymerase chain reaction (RT-PCR).

RESULTS

CCAM lesions in general showed a twofold increase in cell proliferation index (19.2% +/- 1.4% v 9.6% +/- 0.7%, P < .00005) and a fivefold decrease in apoptotic bodies (0.9 +/- 0.2 v 4.5 +/- 0.5, P < .0005) compared with age-matched normal lung. CCAMs that required resection before birth had the highest cell proliferation index. There were no differences in the expression of KGF protein or KGF mRNA in CCAM and normal lung.

CONCLUSIONS

These results demonstrate that CCAM differs from normal lung by increased cell proliferation and decreased apoptosis. The increased proliferation does not appear to be mediated by the pneumocyte mitogen KGF. An examination of factors that control cell proliferation and apoptosis in CCAM may provide further insight into the pathogenesis of this tumor.

Hyaluronan receptor expression increases in fetal excisional skin wounds and correlates with fibroplasia

BACKGROUND/PURPOSE

The midgestation fetus heals incisional skin wounds scarlessly, whereas large excisional wounds scar. High concentrations of hyaluronan (HA) are associated with scarless fetal as opposed to scar-forming adult wound repair. Because expression of the HA receptors, CD44 and RHAMM (Receptor for HA-Mediated Motility), has been associated with adult wound fibroplasia, the authors postulated that fetal excisional wounds would show increased expression of CD44 and RHAMM as compared with incisional wounds.

METHODS

Two models of fetal wound healing were examined. Fetal skin from human abortuses was heterotransplanted subcutaneously into severe combined immunodeficient (SCID) mice. Fourteen days after grafting, incisional or 2-mm excisional wounds were created (n = 6 per time-point). In addition, incisional and excisional (6 to 10 mm) wounds (n = 5 per time-point) were created on the backs of 70- to 75-day fetal lambs (term, 145 days). Tissue from both models was harvested at sequential time-points after injury. Wounds were studied histologically for fibroplasia and assayed for their HA content. CD44 and RHAMM expression were analyzed by immunohistochemistry and immunoblotting.

RESULTS

As expected, in both models, incisional wounds healed scarlessly, whereas excisional wounds showed fibroplasia. Incisional wounds of fetal lambs maintained a significantly higher HA content than excisional wounds 3 days after injury. Between 1 and 7 days in either human or sheep fetal wounds, immunostaining for CD44 and RHAMM markedly increased along the margins of excisional wounds as compared with incisional wounds and unwounded skin. Immunoblot analysis confirmed this increased HA receptor expression in both models.

CONCLUSIONS

HA receptor expression increased in both human and sheep fetal excisional wounds and correlated with fibroplasia and a reduced HA content. The authors speculate that strategies to limit the expression or function of HA receptors during postnatal wound repair may modify the development of scar.

Adeno-associated viral vector-mediated gene transfer of human blood coagulation factor IX into mouse liver

Recombinant adeno-associated virus vectors (AAV) were prepared in high titer (10(12) to 10(13) particles/mL) for the expression of human factor IX after in vivo transduction of murine hepatocytes. Injection of AAV-CMV-F.IX (expression from the human cytomegalovirus IE enhancer/promoter) into the portal vein of adult mice resulted in no detectable human factor IX in plasma, but in mice injected intravenously as newborns with the same vector, expression was initially 55 to 110 ng/mL. The expression in the liver was mostly transient, and plasma levels decreased to undetectable levels within 5 weeks. However, long-term expression of human F.IX was detected by immunofluorescence staining in 0.25% of hepatocytes 8 to 10 months postinjection. The loss of expression was likely caused by suppression of the CMV promoter, because polymerase chain reaction data showed no substantial loss of vector DNA in mouse liver. A second vector in which F.IX expression was controlled by the human EF1alpha promoter was constructed and injected into the portal vein of adult C57BL/6 mice at a dose of 6.3 x 10(10) particles. This resulted in therapeutic plasma levels (200 to 320 ng/mL) for a period of at least 6 months, whereas no human F.IX was detected in plasma of mice injected with AAV-CMV-F.IX. Doses of AAV-EF1alpha-F. IX of 2.7 x 10(11) particles resulted in plasma levels of 700 to 3, 200 ng/mL. Liver-derived expression of human F.IX from the AAV-EF1alpha-F.IX vector was confirmed by immunofluorescence staining. We conclude that recombinant AAV can efficiently transduce hepatocytes and direct stable expression of an F.IX transgene in mouse liver, but sustained expression is critically dependent on the choice of promoter.

Microchimerism and tolerance after in utero bone marrow transplantation in mice

BACKGROUND

Donor-specific tolerance has been induced after both fetal and neonatal hematopoietic stem cell (HSC) transplantation in mice. However, the relationship between hematopoietic microchimerism and tolerance in these models has not been defined due to the insensitivity of donor cell detection methodology. To address this problem we developed a semiquantitative polymerase chain reaction (PCR)-based assay for detection of microchimerism after major histocompatibility (MHC) class I disparate HSC transplantation. This assay was used to examine the relationship between microchimerism and tolerance after fetal and neonatal transplantation of fully allogeneic bone marrow cells.

MATERIALS AND METHODS

C57BL/6 mice (H2-Kb) were used as adult bone marrow donors and Balb/c mice (H2-Kd) were used as fetal or newborn recipients. A dose of 10(10) BM cells/kg was injected intraperitoneally into recipient animals. Peripheral blood of animals which survived beyond 3 weeks of age was analyzed by PCR for the presence of donor MHC class I DNA. Tolerance was tested by placement of donor-specific skin grafts after determination of chimerism status.

RESULTS

Our assay was found to be specific for H2-Kb donor cells in an H2-Kd background with a sensitivity of <0.0001%. Of 49 animals injected in utero 19 (38%) had donor DNA present in peripheral blood at low levels (<0.1%) whereas only 1 of 18 neonatally injected animals had detectable donor cells (P < 0.01). Tolerance to donor-specific skin grafts was found in 6 of 9 animals which were chimeric after in utero HSC transplantation whereas none of the 18 neonatally injected animals including the chimeric animal were tolerant.

CONCLUSIONS

Our results indicate the following. (<CITEREF RID="JR975255RF1">1) Hematopoietic microchimerism can be detected by PCR in peripheral blood after in utero injection of fully allogeneic HSCs. (<CITEREF RID="JR975255RF2">2) Fetal injections yield a higher incidence of microchimerism than newborn injections. (<CITEREF RID="JR975255RF3">3) Tolerance can be induced across a fully allogeneic barrier by in utero HSC transplantation and this is associated with the presence of peripheral blood microchimerism.

Fetoscopy

Fetoscopy involves the application of microlaparoscopic technology to fetal diagnosis and therapeutic intervention. Though fetoscopy presents many potential advantages over open fetal surgery, the primary one is that of decreased procedure-induced preterm labor and fetal loss from preterm delivery. The small uterine puncture sites required for fetoscopic surgery should, in theory, obviate the morbidity of a large hysterotomy. Fetoscopic instrumentation is small by design, but this has not limited the breadth of the interventional spectrum, because creative applications have been used for the treatment of twin-twin transfusion syndrome, twin reversed arterial perfusion sequence, hydronephrosis, congenital diaphragmatic hernia, fetal tumors, and myelomeningocele. This article examines the fetoscopic experience for these applications, involving over 150 cases. The results for many procedures are auspicious and will improve as further operative experience and newer fetoscopic technologies become available. However, as with any novel technology, responsible application must involve careful experimentation and an analysis of potential maternal and fetal benefits.

Epidermal integrin expression is upregulated rapidly in human fetal wound repair

BACKGROUND/PURPOSE

The fetus heals skin wounds rapidly and scarlessly. The mechanisms that mediate the rapid reepithelialization that is seen in this process are unknown. Integrins are a family of cell surface receptors that bind fibronectin, tenascin, collagen, and other extracellular matrix proteins that are deposited rapidly in fetal wounds. The authors hypothesized that epidermal integrin receptors specific for fibronectin and other wound matrix proteins are upregulated rapidly during human fetal repair.

METHODS

To investigate the spatial and temporal expression of integrins in scarless fetal repair, fetal skin from six human abortuses (16 to 23 weeks' gestation) was transplanted subcutaneously into severe combined immunodeficient mice. After graft take, full-thickness incisional wounds were made in the grafts, and grafts were harvested at various time-points from 4 hours to 28 days after wounding. Integrin receptor protein expression was analyzed at each time-point using immunohistochemistry with monoclonal antibodies specific for the receptors that bind fibronectin, tenascin, collagen, and laminin (alpha5, alpha(v), beta6, alpha2, alpha3, alpha6, and beta4).

RESULTS

In this model, wounded human fetal skin grafts reepithelialized rapidly (within 24 to 36 hours) and healed scarlessly. Within 4 hours of wounding, the grafts showed increased, suprabasal expression (alpha2, alpha3, alpha6, beta4) or neoexpression (alpha5, alpha(b), beta6) of integrins at the epidermal wound edge. This increased expression persisted until reepithelialization was complete.

CONCLUSIONS

Early upregulation of integrins in fetal wounds may permit rapid keratinocyte migration and reepithelialization, and may be important in limiting the induction of inflammatory mediators and scar.

Orthodontic treatment timing: a survey of orthodontists

There has been much debate with respect to the ideal time to initiate orthodontic treatment. Recent clinical trials have tested the effects of early orthodontic treatment. The purpose of this study was to understand orthodontists' perspectives on the best time to initiate treatment, factors that preclude early treatment, and experiences with compliance or adherence problems among their younger patients. Questionnaires were distributed to 335 practicing orthodontists throughout the United States. Respondents were first asked to indicate the best stage to initiate orthodontic treatment for 41 different types of occlusal deviations. They were then asked what conditions might preclude early orthodontic treatment. After one reminder, 137 questionnaires (41%) were returned. The sample consisted of practitioners with 3 to 52 years of experience and represented 46 different orthodontic training programs; 19% were female. The majority (92%) were in private practice. Among the 41 conditions listed, orthodontists would most likely treat 21 in the early mixed dentition, especially anterior crossbites (> 76%); 13 in the late mixed dentition, especially deepbite (> 60%) and mandibular inadequacy (> 59%); and 4 in either stage. Only two conditions would be treated in later stages (maxillary midline diastema, 43%; and congenitally missing teeth,39%). One third would postpone treating mandibular prognathism until adulthood. Patient variables that precluded treatment were behavior (98%) and compliance (96%) problems. Finances (76%) and family disruptions (57%) were less important deterrents to treatment. Orthodontists' experience with Phase I treatment influenced their decisions (p < 0.01). Orthodontists who have been in practice longer were more likely to treat temporomandibular joint sounds (p < 0.003) and deviations in opening (p < 0.002) than less experienced orthodontists; the latter were more likely to refer such patients to temporomandibular disorder specialists. These findings suggest that early orthodontic intervention is the norm, but practice characteristics affect treatment timing.

Fetoscopic gene therapy for congenital lung disease

Fetal gene therapy offers the promise of cure for certain genetic diseases, like cystic fibrosis and surfactant protein B deficiency. The authors hypothesized that a fetoscopic approach could attain a high level of organ-specific gene transfer to the fetal lung late in gestation. To test this hypothesis the authors examined the efficacy, specificity, and toxicity of recombinant adenovirus-mediated transfer of the beta-galactosidase marker gene to the lung of late gestation fetal sheep using a fetoscopic technique. Twelve fetal sheep of 125 to 135 days' gestation (term, 145 days) underwent fetoscopic bronchoscopy and intratracheal administration of a replication-deficient adenoviral vector that transduces the beta-galactosidase marker gene. Escape of administered virus was prevented by the fetoscopic deployment of a detachable silicone balloon in the fetal trachea. All fetuses survived until being killed at 2 days after vector delivery for the histopathologic assessment of vector efficacy and specificity. Optimal beta-galactosidase transgene expression was observed at a viral titer of 2 x 10(12) particles per milliliter of administered volume. Expression was greatest in the distal pulmonary parenchyma, particularly in type II pneumocytes, and extended out to the pleura. There was no evidence of gene transfer in either the large conducting airways or in any other fetal organ. The authors have developed a minimally invasive technique for the specific pulmonary delivery of gene therapy vectors to the fetus with no associated acute toxicity. Gene transfer to the late gestation fetus for the treatment of congenital pulmonary disease may be feasible through fetoscopy.

Myofibroblast persistence in fetal sheep wounds is associated with scar formation

The scarless repair capabilities of the fetus are influenced by the size of the wound and the gestational age of the fetus. Whereas small wounds heal scarlessly, large wounds in the same fetus heal with scar. Myofibroblasts are specialized fibroblasts that express alpha-smooth muscle actin (alpha-SMA), a contractile cytoskeletal protein. The authors hypothesized that small fetal wounds that heal scarlessly will have a relative absence of myofibroblasts, whereas large wounds that heal with scar will have abundant myofibroblasts. In this study, an incisional wound and four punch biopsy wounds of 2, 4, 6, and 10 mm diameter were placed on the backs of 60- to 90-day-gestation fetal sheep (term, 145 days). Fourteen days after wounding, the healed fetal wounds were harvested, the repair morphology was determined (scarless, transitional repair, or scar), and the expression of alpha-SMA was analyzed by immunohistochemistry. In the second part of this study the authors analyzed the temporal expression of alpha-SMA in fetal wounds at 1, 2, 3, and 7 days after wounding in 70-day-gestation fetal sheep. In the 14-day wounds, the authors found that alpha-SMA was not expressed in any incisional or 2-mm wound that healed scarlessly, but it was expressed in all wounds that healed with scar. Overall, alpha-SMA expression strongly correlated with increasing wound size (P < .005). Myofibroblasts were seen as early as 24 hours after wounding, and at 3 and 7 days all wounds showed strong expression of alpha-SMA. These results demonstrate that although myofibroblasts are induced early in fetal wound repair, by 14 days there is a notable lack of myofibroblasts in wounds that heal scarlessly and an abundance of myofibroblasts in those wounds that scar. By determining the factors that regulate the disappearance of the myofibroblast in scarless fetal wounds, the authors hope to gain new insights into the mechanisms of scarless fetal repair.

Wound size and gestational age modulate scar formation in fetal wound repair

The early-gestation fetus heals incisional skin wounds rapidly and scarlessly. The morphology with which the fetus heals excisional skin wounds remains unclear. To characterize excisional fetal wound repair, and to determine whether there is a developmentally regulated wound-size threshold beyond which fetal skin heals with scar, the authors created excisional wounds in fetal lambs of varying gestational age. Time-mated pregnant ewes carrying 22 fetuses at 60 to 90 days' gestation (term, 145 days) underwent laparotomy and hysterotomy. An incisional wound and four circular, punch biopsy wounds of 2, 4, 6, and 10 mm in diameter were placed on the back of each fetal lamb and marked with India ink. The wounds were harvested at 14 days' postwounding and examined grossly and microscopically after serial sectioning and histological staining. Morphological features of all wounds were graded. By 14 days' postwounding all fetal wounds had healed completely. for lambs at each gestational age, increasing wound size was strongly associated with an increase in the frequency of scar. Also, as gestational age increased from 60 to 90 days' gestation the frequency of scarless repair decreased. By understanding the cellular and molecular processes that mediate scar formation with increasing wound size and advancing gestational age, the authors hope to gain further insight into the mechanisms of scarless fetal wound repair.

Salivary binding antibodies induced by human immunodeficiency virus type 1 recombinant gp120 vaccine. The NIAID AIDS Vaccine Evaluation Group

Salivary binding antibodies induced by candidate human immunodeficiency virus type 1 (HIV-1) vaccines in healthy, HIV-1 uninfected volunteers were assessed in a clinical trial evaluating intramuscularly injected HIV-1MN recombinant gp120 (rgp120) vaccine alone or with HIV-1IIIB rgp120 vaccine. The two rgp120 vaccines induced envelope glycoprotein-specific immunoglobulin G (IgG) and IgA antibodies in whole saliva and serum.

Neonatal auditory brainstem responses recorded from four electrode montages

Simultaneous auditory brainstem responses (ABRs) to click stimuli at 30 and 60 dB nHL were recorded from 16 full term neonates with four electrode arrays: vertical (Cz-Nape of neck), ipsilateral (Cz-Mi), contralateral (Cz-Mc), and horizontal (Mc-Mi). Results indicated that ABR waveforms were morphologically similar to those recorded in adults: Waves I, III, and V were clearly identifiable and of the same polarity in 15 of 16 subjects 60 dB nHL and Wave V was clearly identifiable in 14 of 16 subjects at 30 dB nHL. Although ABR waves were identified in most cases, waveforms expression was variable with different electrode recording montages. It is suggested that if a clinician must choose one montage array for recording neonatal ABRs at high intensity levels for neurodiagnostic evaluations, the ipsilateral recording array is indicated since it displays the highest expression of wave components. For screening applications or threshold searching at lower stimulus levels, however, either the ipsilateral or vertical montage would be justified. Further, caution should be employed when interpreting ABR results in neonates recorded with unconventional montages due to the variable expression of wave components.

Infant hearing screening with an automated auditory brainstem response screener and the auditory brainstem response

From 1653 babies hospitalized in the Veterans General Hospital-Taipei from 1993 to 1995, 260 infants at risk of hearing impairment were selected. The risk criteria of hearing impairment for neonates were based on the recommendation of the US Joint Committee on Infant Hearing, 1990 Position Statement. All these infants were screened with the Algo-1 Plus, an automated auditory brainstem response (ABR) screener at a mean postconceptional age of 40.7 +/- 4.5 weeks. Thirty-nine cases (39/260, 15%) involving 57 ears (57/520, 11%), failed the screening. Except for one infant who died, the babies had an ABR test for both air- and bone-conducted stimuli and an otological examination. The case-specific incidence of conductive hearing deficit at the initial ABR test was 5.4%. The prevalence of sensorineural hearing deficits was between 2.3% confirmed and 3.1% including infants who did not have follow-up tests. The kappa-value that indicated agreement between the Algo-1 and ABR results was 0.64, and the overall efficiency of using Algo-1 to correctly identify pass or failure of the ABR was 83%.

Cystic neoplasms of the pancreas. A clinicopathologic study, including DNA flow cytometry

OBJECTIVE

To review the classification, clinical behavior, and appropriate therapy for cystic neoplasms of the pancreas. We examined patient demographics, clinical parameters, preoperative imaging modalities, histologic findings, and tumor DNA content to determine which best predict outcome.

DESIGN

Case series and survey of pathologic specimens.

SETTING

Tertiary care center.

PATIENTS

Twenty-two patients with cystic neoplasms of the pancreas treated at affiliates of Northwestern University Medical School, Chicago, Ill.

MAIN OUTCOME MEASURES

Predictive value of preoperative testing, tumor DNA content, patient survival.

RESULTS

In 20 patients undergoing computed tomographic scan, the tumor was visualized in every case. All other imaging studies evaluated were less likely to demonstrate the lesion. Eight of 10 patients with serous cystadenomas were alive with no evidence of disease at the time of this report; one patient was alive with local recurrence, and a second patient had died of unrelated causes. All patients with mucinous cystadenomas were alive with no evidence of disease. Three of seven patients with cystadenocarcinomas had aneuploid, high S-phase tumors, and one had a diploid, high S-phase tumor; all four died (mean survival, 4.8 months). Two patients with cystadenocarcinomas had diploid, low S-phase tumors; both were long-term survivors but died of their disease at 8.6 and 9.3 years.

CONCLUSIONS

(1) Computed tomographic scan is the most valuable diagnostic imaging study for preoperative evaluation of these patients. (2) Precise preoperative determination of tumor type is not possible. (3) DNA flow cytometry may help identify patients with aggressive tumors who may benefit from adjuvant chemoradiation.

Neonatal auditory brainstem response thresholds to air- and bone-conducted clicks: 0 to 96 hours postpartum

Auditory brainstem response (ABR) thresholds to air- and bone-conducted clicks were investigated in 40 full-term neonates. Subjects were divided into two groups of 20 according to postpartum age: less than 48 hours and between 49 and 96 hours. Mean ABR thresholds to air- and bone-conducted clicks for neonates less than 48 hours postpartum were 14.5 dB nHL (51.5 dB peak SPL) and 1.8 dB nHL (36.8 peak re: 1 microN), respectively, while those for neonates between 49 and 96 hours were 3.8 dB nHL (40.8 dB peak SPL) and 1.5 dB nHL (36.5 dB peak re: 1 microN), respectively. A significant difference was found between the two group mean ABR thresholds to air-conducted stimuli (p < .0001) but not for the bone-conducted stimuli (p < .8959). A statistically significant within-group difference was found between the ABR thresholds to air- and bone-conducted stimuli for only the neonates less than 48 hours of age (p < .0001). When the data was collapsed across groups, simple linear regression analyses revealed a statistically significant relation between postpartum age and ABR threshold to air-conducted stimuli (p < .0001) and a nonsignificant relation between postpartum age and ABR threshold to bone-conducted stimuli (p < .9744). These findings support the notion that some resolution of fluids and residuals in the middle ear occurs during the first 48 hours postpartum and that air-conducted stimuli are attenuated during that period. As such, a physiologic conductive deficit among the younger neonates is suggested.

Effect of high-pass filtering on the neonatal auditory brainstem response to air- and bone-conducted clicks

The effect of standard high-pass analog filtering on the neonatal auditory brainstem response (ABR) to air- and bone-conducted clicks at low intensity screening levels was investigated. Simultaneous three channel recorded ABRs were obtained from 20 neonates with filter settings of 30-3000, 100-3000, and 150-3000 Hz at intensity levels of 20, 30, and 40 dB nHL. Statistically significant reductions in wave V amplitude and decreases in wave V latency were observed for both transducers across all three low level stimulus intensities with the progressive increase in the high-pass filter cutoff (p < .05). These data support the advocacy of less restrictive high-pass filtering (e.g., 30 Hz) for neonatal and infant ABR screening to air- and bone-conducted clicks.

Tyrosine inhibits intestinal-phase gastric-acid secretion

BACKGROUND

Intestinal infusion of leucine augments the maximal gastric-acid secretory response to pentagastrin and serves as a bioassay for intestinal-phase acid secretion. Another action of leucine is to decrease tyrosine flux into neural tissues. We hypothesized that the mechanism of leucine-stimulated acid secretion involves its ability to alter tyrosine absorption.

METHODS

We administered tyrosine intrajejunally and intravenously to anesthetized, vagotomized rats during maximal pentagastrin stimulation and measured acid output in response to intrajejunal infusion of leucine.

RESULTS

Intrajejunal tyrosine produced a dose-dependent inhibition of leucine-stimulated acid secretion but only mild effects on acid secretion in response to pentagastrin alone. Intravenous tyrosine infusions also decreased acid secretion in response to intestinal leucine but required much higher doses.

CONCLUSIONS

Tyrosine exerts a specific inhibitory effect on leucine-stimulated acid secretion, which is mediated intraluminally. Because tyrosine is an important regulator of adrenergic nervous system activity, we speculate that the mechanism of leucine-stimulated acid secretion may involve modulation of the sympathetic nervous system, thereby affecting acid secretion.

Auditory brain stem responses to air- and bone-conducted clicks in the audiological assessment of at-risk infants

Auditory brain stem responses (ABRs) to air- and bone-conducted clicks were used to assess the auditory status of 170 at-risk neonates. During the perinatal period, 20.6% (35/170 cases) of the at-risk infants failed ABRs to air-conducted clicks at 30 dB nHL in at least one ear. Ear-specific results indicated an initial failure rate of 15.0% (51/340 ears). Approximately two-thirds (32/51 ears) of these initial failures showed purely conductive deficits, whereas the remaining one-third (19/51 ears) involved suspected sensorineural components. Follow-up audiological evaluations were performed for 87.1% (148 cases) of these at-risk infants at 4 mo and/or 1 yr corrected age. Based on the initial tests and follow-up assessments, the tentative operating characteristics of ABRs to both air- and bone-conducted clicks for identification of sensorineural deficits in at-risk neonates were calculated. It was found that the ABR to bone-conducted clicks yielded better specificity, predictive value of positive results, and overall efficiency. It is suggested that the ABR to bone-conducted stimuli should be viewed as a valuable addition in the assessment of cochlear reserve in infants who fail a newborn auditory screening to air-conducted stimuli.

Auditory brainstem response thresholds to air and bone conducted clicks in neonates and adults

Auditory brainstem response (ABR) thresholds to air and bone conducted clicks were investigated in 20 full-term neonates and 20 normal-hearing young adults. Results showed mean ABR thresholds to air and bone conducted clicks for neonates to be 3.75 dB nHL (40.75 peak SPL) and 1.25 dB nHL (36.25 dB peak re: 1 microN), respectively, and for adults 3.75 dB nHL (40.75 peak SPL) and 18.75 dB nHL (53.75 peak re: 1 microN), respectively. A significant difference was observed in mean ABR thresholds to bone conducted stimuli between neonates and adults (p < 0.0001) and among mean adult ABR thresholds to air and bone conducted stimuli (p < 0.0001). Nonsignificant differences were observed in mean ABR thresholds to air and bone conducted stimuli among neonates (p > 0.05) and in mean ABR thresholds to air conducted stimuli between neonates and adults (p = 1.00). It is speculated that the dissimilarity in the relationship of thresholds to air and bone conducted stimuli between neonates and adults reflects, in part, a difference in efficiency of signal delivery to the cochlea.

Test-retest variability of the auditory brainstem response to bone-conducted clicks in newborn infants

The variability of the auditory brainstem response (ABR) to bone- and air-conducted clicks was investigated utilizing a test-retest paradigm with 20 normal full-term newborn infants. ABRs to bone-conducted clicks at 15 and 30 dB nHL and air-conducted clicks at 30 dB nHL were obtained. The delivery of the bone-conducted signal was controlled. ABR wave V latencies were measured from each test-retest stimulus condition. The results indicated no statistically significant difference in test-retest variability of ABR wave V latencies or amplitudes between bone- and air-conducted clicks. ABRs to bone-conducted clicks, under controlled clinical conditions, are as reproducible and reliable as ABRs to air-conducted clicks in newborn infants.

Effect of vibrator to head coupling force on the auditory brain stem response to bone conducted clicks in newborn infants

The effect of vibrator to head coupling force on the auditory brain stem response (ABR) to bone conducted clicks in newborn infants was investigated. Twenty full term newborn infants were tested. ABRs to bone conducted clicks were obtained with four different coupling forces (225, 325, 425, and 525 g) at stimulus intensities of 15 and 30 dB nHL. ABRs to air conducted clicks were also obtained at 30 dB nHL. The results of this study indicated that ABR wave V latencies to bone conducted clicks in newborn infants were affected significantly when the vibrator to head coupling force shift exceeded 200 g. It is recommended that the coupling force be controlled and remain consistent when implementing ABR to bone conducted stimuli in newborn infants.

Effect of temporal area bone vibrator placement on auditory brain stem response in newborn infants

The effect of bone conduction vibratory placement on the temporal area, revealed by the auditory brain stem response (ABR), in newborn infants, was investigated. Twenty-five full term neonates were tested at 48 to 72 hours postparturition. ABR wave V latencies were obtained from three different temporal area postauricular vibrator placements at 15 and 30 dB nHL stimulus intensity levels. Results showed that significant ABR wave V latency shifts were observed with changes in the three vibrator placements (p less than 0.05). It is suggested that, with ABR testing in newborn infants using bone conducted stimuli, bone vibrator placement on the temporal area remain consistent.

Transforming growth factor beta 1-induced changes in cell migration, proliferation, and angiogenesis in the chicken chorioallantoic membrane

Application of TGF beta 1 (10-100 ng) to the chicken chorioallantoic membrane (CAM) for 72 h resulted in a dose-dependent, gross angiogenic response. The vascular effects induced by TGF beta 1 were qualitatively different than those induced by maximal doses of basic FGF (bFGF) (500 ng). While TGF beta 1 induced the formation of large blood vessels by 72 h, bFGF induced primarily small blood vessels. Histologic analysis revealed that TGF beta 1 stimulated pleiotropic cellular responses in the CAM. Increases in fibroblast and epithelial cell density in the area of TGF beta 1 delivery were observed as early as 4 h after TGF beta 1 treatment. By 8 h, these cell types also demonstrated altered morphology and marked inhibition of proliferation as evidenced by 3H-thymidine labeling. Thus, the TGF beta 1-stimulated accumulation of these cell types was the result of cellular chemotaxis from peripheral areas into the area of TGF beta 1 delivery. Microscopic angiogenesis in the form of capillary sprouts and increased endothelial cell density first became evident at 16 h. By 24 h, capillary cords appeared within the mesenchyme of the CAM, extending towards the point of TGF beta 1 delivery. 3H-thymidine labeling revealed that the growth of these capillary cords was due to endothelial cell proliferation. Finally, perivascular mononuclear inflammation did not become evident until 48 h of treatment, and its presence correlated spatially and temporally with the gross and histological remodelling of newly formed capillary cords into larger blood vessels. In summary, these data suggest that, in the chicken CAM, TGF beta 1 initiates a sequence of cellular responses that results in growth inhibition, cellular accumulation through migration, and microvascular angiogenesis.

Expression of and response to growth regulatory peptides by two human pancreatic carcinoma cell lines

Two human pancreatic adenocarcinoma cell lines (PANC 1 and MIA PACA 2) were examined for expression of growth factors that could potentially play a role either in growth regulation of the tumor cells, or in cells that comprise the stromal elements of tumors. Both cell lines expressed transforming growth factor-alpha (TGF alpha), basic fibroblast growth factor (bFGF), c-sis (PDGF B chain), TGF beta 1, and TGF beta 3 mRNA by Northern blot analysis. Only the PANC 1 cells, however, expressed the TGF beta 2 transcript. TGF beta-like competing activity was found in medium conditioned by either cell line, but TGF alpha-like [epidermal growth factor (EGF)-competing] activity was not detected in the medium from either cell line by radioreceptor assay. TGF alpha and EGF caused concentration-dependent stimulation of soft agar colony growth of the MIA PACA 2 cells, while only TGF alpha caused a significant but less dramatic stimulation of soft agar growth of the PANC 1 cells. Insulin stimulated the anchorage-independent growth of MIA PACA 2 but not PANC 1 cells. Likewise, bFGF also caused a concentration-dependent stimulation of MIA PACA 2 but not PANC 1 growth in soft agar, and PDGF had no effect on the growth of either cell line. TGF beta had no inhibitory or stimulatory effect on soft agar colony growth of either the PANC 1 or the MIA PACA 2 cells, although both cell lines exhibited high affinity, saturable TGF beta binding sites, and TGF beta 1 was capable of autoinduction of TGF beta 1 mRNA expression in PANC 1 cells. The ability to continue to respond to positive growth regulatory factors coupled with the loss of responsiveness to negative growth factors may be important in the pathogenicity of these aggressive tumors.

A developmental study of bone conduction auditory brain stem response in infants

Two studies, vibrator placement and masking, were performed to evaluate the developmental aspect of bone conduction auditory brain stem response (ABR) in human infants. Subject groups included newborns, 1-yr-olds, and adults. In the vibrator studies, ABRs were obtained from placements of the bone conduction vibrator on the frontal, occipital, and temporal bones. Results showed that temporal placements in neonates and 1-yr-olds produce significantly shorter wave V latencies of ABR than frontal or occipital placements. In adults, differences of wave V latencies from various vibrator placements were comparatively small. In the masking studies, ABRs were acquired from vibrator placements at the temporal bone in the presence of ipsilateral air conducted masking noise from the experimental groups. Results showed that interaural attenuations of bone conduction click stimuli are the largest in neonates, somewhat smaller from 1-yr-olds, and the smallest in adults. The findings of this research strongly suggest that temporal placements for bone conduction ABR should be used, in some instances, when testing infants and 1-yr-olds. The results of this study support the proposition that bone conduction ABR is a feasible and reliable diagnostic tool in testing infants.