Surgical treatment of adjacent instability after lumbar spine fusion

STUDY DESIGN

This study is a retrospective review of 39 patients with previous instrumented lumbar fusion who underwent secondary spine surgery for lumbar adjacent instability. To the authors' knowledge, this is the largest study of surgical treatment of lumbar adjacent instability in the literature to date.

OBJECT

This study evaluated the feasibility of adjacent instability treated with medial facetectomy, fusion with autologous bone grafting, and pedicle screw instrumentation.

SUMMARY OF BACKGROUND DATA

The surgical treatment of adjacent instability has seldom been discussed. Revision spine fusions are challenged by high pseudarthrosis rates.

METHODS

Thirty-nine patients with previous lumbar fusion underwent second lumbar spine surgery for adjacent instability. All were treated with autogenous posterolateral arthrodesis and transpedicle screw fixation in addition to decompressive laminectomy. Medical records, radiographs, and pain scores were obtained.

RESULTS

The clinical results were excellent or good in 76.9% of patients, and the radiographic fusion was successful in 37 (94.9%) of patients. Flat back was noted in 8 (20.5%) of patients. In 5 patients (12.8%), neighboring segment breakdown again developed, and 2 of those patients underwent a third lumbar fusion. Dural tear during operation occurred in 2 patients. One patient experienced cauda equina syndrome but recovered bladder function 1 month later.

CONCLUSION

Autogenous posterolateral arthrodesis combined with pedicle screw fixation led to successful radiologic and clinical outcome in patients with lumbar adjacent instability. Adequate decompression of the adjacent stenosis requires medial facetectomy, thus preventing aggressive nerve root manipulation and reducing the incidence of dural tear.

Analysis of minimal sequences on JC virus VP1 required for capsid assembly

Human JC virus (JCV) belongs to the family of Polyomaviridae. The viral capsid is composed of 72 capsomeres. Five VP1 molecules make up a capsomere structure. To investigate the minimal sequences on JCV VP1 polypeptide required for capsid assembly, the first 12 (Delta N12) and 19 (Delta N19) amino acids at the N-terminus and the last 16 (Delta C16), 17 (Delta C17), and 31 (Delta C31) amino acids at the C-terminus of VP1 were truncated and expressed in E. coli. The VP1 proteins of Delta N12 and Delta C16 were able to self-assemble into a virus-like particle similar to that of wild-type (WT) VP1. However, the mutant proteins of Delta N19, Delta C17, and Delta C31 formed a pentameric capsomere structure as demonstrated by a 10-50% sucrose gradient centrifugation and electron microscopy. These results suggest that the 12 amino-terminal and 16 carboxy-terminal amino acids of VP1 are dispensable for the formation of virus-like particles, and further truncation at either end of VP1 leads to the loss of this property.

Destructive spondyloarthropathy mimicking spondylitis in long-term hemodialysis patients

A 63-year-old man with end-stage renal disease (ESRD) who had been undergoing hemodialysis for 18 years suffered persistent neck pain, progressive quadriparesis, and a deteriorating ataxic gait during the 6 months before admission. A sudden onset of aggravating quadriparesis and an inability to ambulate occurred during his trip to Sydney, Australia, 1 week before this admission. Vertebral tuberculosis osteomyelitis of the C5/6 segment was considered and treated in a hospital there. Findings from cervical magnetic resonance imaging (MRI; low signal intensity on both T1- and T2-weighted images) were diagnostic of destructive spondyloarthropathy (DSA) and distinguishable from spinal osteomyelitis preoperatively. Amyloid masses, mainly composed of B-2 microglobulin, filled in disc and paradiscal ligaments, with adjacent end-plate destruction by cytokine-mediated reactive inflammation, and appeared to be mostly related to the pathogenesis of DSA. The cervical spine, especially C5/6, is the most common site of DSA. Spinal instability and neurologic compression cause the clinical symptoms and signs. Adequate decompression and successful cervical fusion ensure the best therapeutic results.

Potential benefits of restrictions on the transport of teenage passengers by 16 and 17 year old drivers

OBJECTIVES

The presence of passengers is associated with fatal motor vehicle crashes of teenage drivers. A restriction against newly licensed teenage drivers carrying passengers has been included in some, but not all, graduated licensing systems. The purpose of this study was to predict the net effects on all types of road users, including vehicle occupants and non-occupants, of possible prohibitions against 16-17 year old drivers carrying passengers.

METHODS

Two national datasets, a census of fatal crashes and a sample of trips in the United States, were used to compute 1995 road user death rates. Potential effects of restrictions on drivers ages 16-17 carrying passengers younger than 20 were estimated, based on road user death rates and potential choices made by passengers who would have traveled with 16-17 year old drivers if there were no restrictions.

RESULTS

There were 1,181 road user deaths in 1995 involving drivers ages 16-17 whose passengers were all younger than age 20. The predicted number of lives in the United States that would be saved annually ranges from 83 to 493 (corresponding to reductions of 7-42% in road user deaths) for drivers ages 16 and 17 combined. Similar percentages of reductions (8-44%) were predicted solely for 16 year old drivers. Assuming passenger restrictions would apply to all 16 year old drivers and at least one third of 17 year old drivers, an estimated 60-344 fewer deaths per year may occur if restrictions are mandated.

CONCLUSIONS

Restrictions on carrying passengers younger than 20 should be considered for inclusion in graduated licensing systems. Even if fewer than half the drivers obey the restrictions, a substantial reduction in road user deaths would be expected. Further evaluation based on real world experience is needed to confirm their efficacy.

Dietary intake of soybean protein and menstrual cycle length in pre-menopausal Singapore Chinese women

BACKGROUND

Intake of soybean protein was associated with a reduced risk of breast cancer in a case-control study. It has also been demonstrated to increase menstrual cycle length in an experimental setting.

OBJECTIVE

To ascertain whether the association of soybean protein intakes with menstrual cycle length persists in an uncontrolled community setting.

DESIGN

Cross-sectional food frequency dietary survey, menstrual cycle survey and prospective collection of menstrual cycle data.

SETTING

A hospital clinic and a nursing college.

SUBJECTS

Two hundred menstruating women.

RESULTS

An association (P = 0.034) of higher intakes of soybean protein with increased menstrual cycle length, as recorded by self report and by prospectively recording three consecutive cycles, was observed. The risk of menstrual cycle length being greater than the median, when comparing the upper quartile (8.7-35.2 g x day(-1)) of soybean intake and the lowest quartile (0.1-3.3 g x day(-1)) was double, and this approached statistical significance (OR = 2.02, 95% CI = 0.88-4.64 and OR = 1.93, 95% CI = 0.82-4.56 for self-reported cycle length and cycle length as recorded by diary, respectively). In terms of the absolute association with cycle length, subjects in the upper quartile of soybean intake demonstrated a cycle length 1-2 days longer than did subjects in the lowest quartile.

CONCLUSIONS

It is likely that the association between dietary intake of soybean protein and length of menstrual cycle prevails in the community setting. This is shown using both self-reported cycle length and cycle length as recorded in a prospective diary.

A role for p75 neurotrophin receptor in the control of apoptosis-driven hair follicle regression

To examine the mechanisms that underlie the neurotrophin-induced, apoptosis-driven hair follicle involution (catagen), the expression and function of p75 neurotrophin receptor (p75NTR), which is implicated in apoptosis control, were studied during spontaneous catagen development in murine skin. By RT-PCR, high steady-state p75NTR mRNA skin levels were found during the anagen-catagen transition of the hair follicle. By immunohistochemistry, p75NTR alone was strongly expressed in TUNEL+/Bcl2- keratinocytes of the regressing outer root sheath, but both p75NTR and TrkB and/or TrkC were expressed by the nonregressing TUNEL-/Bcl2+ secondary hair germ keratinocytes. To determine whether p75NTR is functionally involved in catagen control, spontaneous catagen development was compared in vivo between p75NTR knockout (-/-) and wild-type mice. There was significant catagen retardation in p75NTR knockout mice as compared to wild-type controls (P<0.05). Instead, transgenic mice-overexpressing NGF (promoter: K14) showed substantial acceleration of catagen (P<0.001). Although NGF, brain-derived neurotrophic factor (BDNF), and neurotrophin 3 (NT-3) accelerated catagen in the organ-cultured skin of C57BL/6 mice, these neurotrophins failed to promote catagen development in the organ-cultured p75NTR null skin. These findings suggest that p75NTR signaling is involved in the control of kerotinocyte apoptosis during catagen and that pharmacological manipulation of p75NTR signaling may prove useful for the treatment of hair disorders that display premature entry into catagen.

Relationships of mortality with the fine and coarse fractions of long-term ambient PM10 concentrations in nonsmokers

In a cohort of 6338 California Seventh-day Adventists, we previously observed for males associations between long-term concentrations of particulate matter (PM) with an aerodynamic diameter less than 10 microm (PM10) and 15-year mortality due to all natural causes (ANC) and lung cancer (LC) listed as underlying causes of death and due to nonmalignant respiratory disease listed as either the underlying or a contributing (CRC) cause of death. The purpose of this analysis was to determine whether these outcomes were more strongly associated with the fine (PM2.5) or the coarse (PM2.5-10) fractions of PM10. For participants who lived near an airport (n=3769), daily PM2.5 concentrations were estimated from airport visibility, and on a monthly basis, PM2.5-10 concentrations were calculated as the differences between PM10 and PM2.5. Associations between ANC, CRC, and LC mortality (1977-1992) and mean PM10, PM2.5, and PM2.5-10 concentrations at study baseline (1973-1977) were assessed using Cox proportional hazards models. Magnitudes of the PM10 associations for the males of this subgroup were similar to those for the males in the entire cohort although not statistically significant due to the smaller numbers. In single-pollutant models, for an interquartile range (IQR) increase in PM10 (29.5 microg/m3), the rate ratios (RRs) and 95% confidence intervals (CI) were 1.15 (0.94, 1.41) for ANC, 1.48 (0.93, 2.34) for CRC, and 1.84 (0.59, 5.67) for LC. For an IQR increase in PM2.5 (24.3 microg/m3), corresponding RRs (95% CI) were 1.22 (0.95, 1.58), 1.64 (0.93, 2.90), and 2.23 (0.56, 8.94), and for an IQR increase in PM2.5-10 (9.7 microg/m3), corresponding RRs (95% CI) were 1.05 (0.92, 1.20), 1.19 (0.88, 1.62), and 1.25 (0.63, 2.49), respectively. When both PM25 and PM2.5-10 were entered into the same model, the PM2.5 estimates remained stable while those of PM2.5-10 decreased. We concluded that previously observed associations of long-term ambient PM10 concentration with mortality for males were best explained by a relationship of mortality with the fine fraction of PM10 rather than with the coarse fraction of PM10.

Gene delivery via polyomavirus major capsid protein VP(1), isolated from recombinant Escherichia coli

In this study we attempted to investigate the feasibility of transferring exogenous DNA into the recipient host via polyomavirus major capsid protein VP(1) pseudocapsids generated from recombinant Escherichia coli, designated PyVP(1,E), both in vitro and in vivo. NIH-3T3 and FR3T3 cells were transfected with pCMV beta and pPyMT-1 plasmid DNA, respectively. In vitro DNA transfection was carried out via Pseudofect- and PyVP(1,E)-mediated methods, or by co-precipitation with calcium phosphate. Expression of beta-galactosidase and PyMT reporter genes was examined by Western-blot analysis. Parallel experiments were performed in vivo by direct injection of pCMV beta and pPyMT-1 plasmid DNA, complexed with PyVP(1,E), into the livers of Wistar rats, followed by Western-blot analysis and histochemical staining. The results obtained from in vitro transfection experiments showed that expression of the reporter genes can be detected in the recipient cells at 48 h post-transfection. PyVP(1,E) was shown to exhibit similarly efficient in vitro DNA transfection properties to Pseudofect, which was obtained from recombinant baculovirus.

Interaction of combined administration of intrathecal morphine with subcutaneous morphine or buprenorphine

AIM

To analyze the mode of interaction of combined administration of intrathecal morphine with subcutaneous morphine or buprenorphine.

METHODS

Different groups of rats were scheduled to undergo administration of intrathecal (ith) morphine, subcutaneous (s.c.) morphine, s.c. buprenorphine, and the combinations of ith morphine with s.c. morphine or buprenorphine in a series of dose ratios. Nociceptive responses of hind paws of each animal were measured by means of "plantar stimulation" test. The test latency was converted to the percent of maximal possible effect (% MPE).

RESULT

Morphine ith, morphine s.c., buprenorphine s.c., as well as combinations in all dose ratios increased the % MPE in a dose-dependent manner. Isobolograms showed that the ED50 points determined for the combinations were plotted significantly left to the theoretical additive line.

CONCLUSION

The combination of morphine ith with either morphine s.c. or buprenorphine s.c. resulted in a synergistic effect. This interaction might be due to the activation of the synergistic antinociceptive mechanisms between supraspinal and spinal levels.

Carrying passengers as a risk factor for crashes fatal to 16- and 17-year-old drivers

CONTEXT

Injuries from motor vehicle crashes are the leading cause of death among teenagers. Carrying passengers has been identified as a possible risk factor for these crashes.

OBJECTIVE

To determine whether the presence of passengers is associated with an increased risk of crashes fatal to 16- and 17-year-old drivers and whether the risk varies by time of day and age and sex of drivers and passengers. DESIGN AND SETTING INCIDENCE: study of data from the Fatality Analysis Reporting System and General Estimates System (1992-1997), as well as the Nationwide Personal Transportation Survey (1995).

SUBJECTS

Drivers aged 16 and 17 years who drove passenger cars, vans, or pickup trucks.

MAIN OUTCOME MEASURE

Driver deaths per 10 million trips by number of passengers, driver age and sex, and time of day; and driver deaths per 1000 crashes by passenger age and sex.

RESULTS

Compared with drivers of the same age without passengers, the relative risk of death per 10 million trips was 1.39 (95% confidence interval [CI], 1.24-1.55) for 16-year-old drivers with 1 passenger, 1.86 (95% CI, 1.56-2.20) for those with 2 passengers, and 2.82 (95% CI, 2.27-3.50) for those with 3 or more passengers. The relative risk of death was 1.48 (95% CI, 1.35-1.62) for 17-year-old drivers with 1 passenger, 2.58 (95% CI, 2.24-2.95) for those with 2 passengers, and 3.07 (95% CI, 2.50-3.77) for those with 3 or more passengers. The risk of death increased significantly for drivers transporting passengers irrespective of the time of day or sex of the driver, although male drivers were at greater risk. Driver deaths per 1000 crashes increased for 16- and 17-year-olds transporting male passengers or passengers younger than 30 years.

CONCLUSION

Our data indicate that the risk of fatal injury for a 16- or 17-year-old driver increases with the number of passengers. This result supports inclusion of restrictions on carrying passengers in graduated licensing systems for young drivers.

Three-dimensional computer-assisted simulation combining facial skeleton with facial morphology for orthognathic surgery

The purpose of this study was to use a 3-dimensional (3D) computer-aided design (CAD) simulation system to plan surgical procedures and predict postoperative changes in orthognathic surgery patients. A computer-generated imaging model was developed by combining a 3D reconstructed cephalometric skeletal image and a laser-scanned facial surface image. Moreover, postoperative data were studied and linked to the simulator model for programming and executing simulated surgical procedures. Interactive editing capabilities allow surgeons to operate CAD surgical simulation, and predicted results can be presented graphically and numerically. The results indicate that the integration of 3D images and CAD techniques have a potential for simulating surgery and providing graphic information to patients in obtaining an informed consent.

Anterior reconstructive spinal surgery with Zielke instrumentation for metastatic malignancies of the spine

From March 1984 to April 1996, 60 consecutive patients with spinal metastasis underwent palliative surgery by anterior corpectomy and Zielke instrumentation. Their ages ranged from 21 to 76 years (mean 54 years). Thirty-two patients had metastasis to the thoracic spine, 20 to the lumbar spine, and 8 had both thoracic and lumbar metastases. The primary malignancies were lung cancer in 12 patients, colorectal cancer in 10, hepatoma in 9, thyroid cancer in 7, breast cancer in 3, and cancers of the stomach, kidney, nasopharynx, long bones, skin, and cervix in 1 patient each. A primary carcinoma was never identified in 13 patients. In the present series, 4 patients died within 1 month, and 56 patients were followed-up. All maintained spinal stability postoperatively. Forty of 52 patients with severe pain obtained significant symptomatic relief for 3 months or more, and 33 of the 46 paralyzed patients gained neural improvement. Sphincter dysfunction became better in 10 patients, and none became worse. We conclude that anterior corpectomy to decompress neural encroachment with instrumental reconstruction to stabilize the collapsed spine is a good adjunctive treatment in these highly selected patients.

A comparative study of human muscle and brain creatine kinases expressed in Escherichia coli

We report the expression of the human muscle (CK-MM) and brain (CK-BB) creatine kinases in Escherichia coli. The proteins have been purified to apparent homogeneity and several of their physical and kinetic properties investigated. In the process, we have conclusively verified the correct DNA sequence of the genes encoding the respective isozymes, and determined the correct primary structure and mass of the gene products. Alignment of the primary sequences of these two enzymes shows 81% sequence identity with each other, and no obvious gross structural differences. However, Western blot analyses demonstrated the general lack of antigenic cross-reactivity between these isozymes. Preliminary kinetic analyses show the K(m) and k(cat) values for the creatine and MgATP substrates are similar to values reported for other isozymes from various tissues and organisms. The human muscle and brain CKs do not, however, exhibit the synergism of substrate binding that is observed, for example, in rabbit muscle creatine kinase.

Identification of a mammalian angiopoietin-related protein expressed specifically in liver

Based on searches of EST databases for signal sequences and amphipathic helices, we have identified and cloned an angiopoietin-like gene, ANGPTL3. Multiple tissue Northern blots show that ANGPTL3 is expressed principally in the liver. ANGPTL3 is expressed early during liver development, and expression is maintained in adult liver. Human ANGPTL3 is a 460-amino-acid polypeptide with the characteristic structure of angiopoietins: a signal peptide, an extended helical domain predicted to form dimeric or trimeric coiled-coils, a short linker peptide, and a globular fibrinogen homology domain (FHD). Murine ANGPTL3 is a 455-acid polypeptide encoded by seven exons on mouse chromosome 4, spanning about 11 kb of DNA. ANGPTL3 contains the four conserved cysteines implicated in the intramolecular disulfide bonds within the FHD, but it does not contain two other cysteines that are found within the FHD of angiopoietins 1, 2, and 4. ANGPTL3 also does not contain the characteristic calcium binding motif found in the other angiopoietins. By radiation hybrid mapping and the use of surrounding genes, human ANGPTL3 maps to the 1p31 region.

[Transformation of common wheat (Triticum aestivum L.) with herbicide-resistant EPSPs gene]

The herbicide-resistant EPSPs (5-enolpyruvylshikimate-3-phosphate synthase) gene was transformed into about 1,000 young spikes and 800 young embryos of wheat variety, Jinghua 1, with gene gun. Thirty-eight and four regenerated plants were obtained respectively screened with glyphosate. All regenerated plants were analysed by PCR and/or Southern blotting. The results indicated that EPSPs gene was integrated stably into the genome of Jinghua 1, and some of the transformants showed fertile. So herbicide-resistant EPSPs gene could be used as selective marker in the transformation of monocotyledon cereal crops, such as wheat.

A role for p75 neurotrophin receptor in the control of hair follicle morphogenesis

During hair follicle (HF) morphogenesis, p75 neurotrophin receptor (p75NTR) reportedly is the first growth factor receptor found to be expressed by those fibroblasts that later develop into the dermal papilla (DP) of the HF. However, the functional role of p75NTR in HF morphogenesis is still unknown. Studying HF development in fetal and neonatal C57BL/6 murine back skin, we show that p75NTR-immunoreactivity (IR) is prominently expressed by DP fibroblasts as well as by skin nerves during the early steps of HF development. In contrast, p75NTR-IR disappears from the DP in the fully developed HF and it is expressed only in the epithelial outer root sheath of the HF. Compared to age-matched wild-type animals, p75NTR knockout (-/-) mice show significant acceleration of HF morphogenesis, and DP fibroblasts of p75NTR knockout mice show reduced proliferative activity in situ, indicating alterations in their transition from proliferation to differentiation. Although no significant differences in the expression of adhesion molecules (NCAM), selected morphogens (TGFbeta-2, HGF/SF, FGF-2, KGF), or their receptors (TGFbetaR-II, m-met, FGFR-1) were seen between DP of p75NTR knockout and wild-type mice, p75NTR mutants showed a prominent upregulation of FGFR-2, a high-affinity receptor for KGF, in both follicular DP and epithelium. Furthermore, the administration of anti-KGF neutralizing antibody significantly inhibited acceleration of HF morphogenesis in p75NTR knockout mice in vivo. These observations suggest that p75NTR plays an important role during HF morphogenesis, functioning as a receptor that negatively controls HF development, most likely via alterations in DP fibroblast proliferation/differentiation and via downregulation of KGF/FGFR-2 signaling in the HF.

Combined spinal epidural for labour analgesia--duration, efficacy and side effects of adding sufentanil or fentanyl to bupivacaine intrathecally vs plain bupivacaine

AIM OF STUDY

The aim of the study was to evaluate the efficacy and side effects of adding sufentanil 10 micrograms, fentanyl 10 micrograms or a control of 1 mL saline to 2.5 mg bupivacaine given intrathecally via combined spinal epidural (CSE) for labour pain relief in the first stage.

METHOD

Sixty ASA I or II patients who requested for epidural analgesia were randomised to three groups. CSE was performed with a 16G Touhy needle and 27G Whitacre needle.

RESULTS

Patients in the sufentanil/bupivacaine group had a significantly longer duration of analgesia (162.9 min +/- 63.4) compared with fentanyl/bupivacaine (110.0 min +/- 44.6) compared with plain bupivacaine (70.0 min +/- 32.1). Pruritus was significant in patients with sufentanil (80%) and fentanyl (47.4%) but did not occur with plain bupivacaine. There was no significant difference in the incidence of nausea or vomiting, hypotension and motor blockade although blood pressures in the sufentanil group were consistently lower than the other two groups. Pain scores were lowest in the sufentanil group. Fetal heart rate changes and Apgar scores were not significantly different between the groups.

CONCLUSION

In combined spinal epidural for labour analgesia, adding sufentanil 10 micrograms to intrathecal bupivacaine 2.5 mg provided fast onset and good analgesia for a longer duration compared with adding fentanyl 10 micrograms and with plain bupivacaine. The main side effect was pruritus. Neonatal outcome was similar.

Acute postoperative aggravation of radiculopathy as a complication of free fat transplantation in lumbar disc surgery: case report

This case report illustrates a rare case of motor weakness caused by a free fat graft herniation. A 40-year-old woman who had undergone surgery for a herniated lumbar intervertebral disc experienced right lower leg weakness. On magnetic resonance image (MRI) a herniated free fat graft was noted. An emergent operation was performed and the herniated fat graft was removed. Postoperatively, the patient recovered well with improvement of the motor weakness. MRI is a good method for diagnosis of fat graft herniation. The mechanisms of this complication have been documented, and the size of the fat graft plays an important role. The methods for prevention of this herniation are also discussed. Although the transplantation of adipose tissue has many advantages, including the prevention of postoperative epidural fibrosis, great care is needed when applying a fat graft intra-operatively. When a postoperative neurologic deficit develops, herniation of the fat graft must be considered. An emergent operation is the treatment of choice for this particular complication.

Three-dimensional virtual imaging of facial skeleton and dental morphologic condition for treatment planning in orthognathic surgery

The improvement of esthetics and function, including the occlusal relationship, needs to be carefully considered in treatment planning for the success of orthognathic surgery. Conventional lateral cephalograms and dental study casts have been used usually for the assessment of skeletal morphologic condition and occlusion, respectively, in planning procedures. However, these traditional techniques do not allow for simultaneous evaluation of the skeletal morphologic condition and the occlusal harmony. A new technique has been developed that combines the conventional clinical diagnostic materials, cephalograms, and dental study casts to produce a 3-dimensional virtual image for routine practice. A 3-dimensional graphic image of dental study casts was generated with a laser surface scanner. A 3-dimensional skeletal image was constructed based on the coordinates of anatomic landmarks registered on frontal and lateral cephalograms. The image of the study cast was then set up with the 3-dimensional skeletal image to create a 3-dimensional dataset of the virtual image. The 3-dimensional virtual image, combining the cephalometric and the dental study cast information, permits simultaneous display of skeletal morphologic condition and occlusal relationship. This 3-dimensional virtual imaging can be helpful in planning orthodontic-surgical treatment and in providing graphic information to the patient. This article describes the technique and outline. A clinical application with this imaging technique is also demonstrated.

Noggin is a mesenchymally derived stimulator of hair-follicle induction

The induction of developmental structures derived from the ectoderm, such as the neural tube or tooth, occurs through neutralization of the inhibitory activity of members of the bone-morphogenetic protein (BMP) family by BMP antagonists. Here we show that, during hair-follicle development, the neural inducer and BMP-neutralizing protein Noggin is expressed in the follicular mesenchyme, that noggin-knockout mice show significant retardation of hair-follicle induction, and that Noggin neutralizes the inhibitory action of BMP-4 and stimulates hair-follicle induction in embryonic skin organ culture. As a crucial mesenchymal signal that stimulates hair-follicle induction, Noggin operates through antagonistic interactions with BMP-4, which result in upregulation of the transcription factor Lef-1 and the cell-adhesion molecule NCAM, as well as through BMP4-independent downregulation of the 75 kD neurotrophin receptor in the developing hair follicle.

Binding and uptake of cationic lipid:pDNA complexes by polarized airway epithelial cells

To better understand the barriers associated with cationic lipid-mediated gene transfer to polarized epithelial cells, Fischer rat thyroid (FRT) cells and polarized normal human bronchial epithelial (NHBE) cells grown on filter supports at an air-liquid interface were used to study the binding and uptake of cationic lipid:plasmid DNA (pDNA) complexes. The efficiencies of binding and uptake of cationic lipid:pDNA complexes by these cell systems were monitored using fluorescence microscopy of fluorescently tagged lipid or pDNA probes. Fluorescent probe bound to the cell surface was differentiated from internalized probe by adding trypan blue, which quenched the fluorescence of bound but not internalized probes. For proliferating cells, binding and internalization of the cationic lipid:pDNA complexes were determined to be efficient. In contrast, little binding or internalization of the complexes was observed using polarized epithelial cells. However, after aspirating a small area of cells from the filter support, virtually all of the cells adjoining this newly formed edge bound and internalized the cationic lipid:pDNA complexes. To determine if their uptake in edge cells was related to the ability of the complexes to access the basolateral membranes of these cells, the binding and uptake of complexes was monitored in polarized NHBE cells that had been pretreated with EGTA or Ca2+-free media, strategies known to disrupt tight junctions. Cells treated in this manner bound and internalized cationic lipid:pDNA complexes efficiently and also expressed significant levels of transgene product. Control cells with intact tight junctions neither bound complexes nor expressed significant transgene product. These data confirm and extend earlier observations that the polarized apical membranes of airway epithelial cells are resistant to transfection by lipid:pDNA complexes. Further, in contrast to previous studies that have shown the entry step of complexes is not an important barrier for COS and HeLa cells, binding and entry of complexes in polarized NHBE cells appear to be rate limiting. These findings suggest that strategies designed to open the tight junctions of polarized epithelial cells may improve gene delivery to these cells for diseases such as cystic fibrosis (CF).