Application of OCT-angiography to characterise the evolution of chorioretinal lesions in acute posterior multifocal placoid pigment epitheliopathy

PurposeThe aim of this study was to determine a sequence of structural changes in acute posterior multifocal placoid pigment epitheliopathy (APMPPE) using optical coherence tomography-angiography (OCT-A) and comparing with other imaging modalities.Patients and methodsPatients with a new diagnosis of acute-onset APMPPE referred to a regional specialist centre from October 2015 to October 2016 were included. Multimodal imaging employed on all patients from diagnosis included the following: fundus fluorescein angiography, indocyanine green angiography, fundus autofluorescence, spectral domain-OCT (SD-OCT), and OCT-A. All non-invasive imaging processes were repeated during follow-up.ResultsTen eyes of five patients were included in the study, three males and two females, with a mean age of 26.2 years (range: 21-32) and a mean follow-up of 6.4 months (range: 2.6-13.3). All patients presented with bilateral disease and macular involving lesions. OCT-A imaging of the choriocapillaris was supportive of hypoperfusion at the site of APMPPE lesions during the acute phase of this condition with normalisation of choroidal vasculature during follow-up. Multimodal imaging consistently highlighted four sequential phases from presentation to resolution of active disease.ConclusionsMultimodal imaging in patients with APMPPE in acute and long-term follow-up demonstrates a reversible choroidal hypoperfusion supporting the primary inciting pathology as a choriocapillaritis. The evolution shows resolution of the ischaemia through a defined sequence that results in persistent changes at the level of the retinal pigment epithelium and outer retina. OCT-A was able to detect preclinical changes and chart resolution at the level of the choriocapillaris.

Review of lateral orbital wall ossifying fibroma

Significant histological overlap exists between fibro-osseous lesions and diagnosis is made on a clinicopathological basis. Ossifying fibroma is a benign fibro-osseous neoplasm of the jaw and craniofacial complex that has generated a degree of controversy regarding diagnosis and classification, especially with respect to the psammomatoid variant. Orbital lesions mainly arise from the paranasal sinuses affecting the medial or inferior orbital wall. Lateral orbital wall ossifying fibroma is, therefore, a rare condition with only a single previous case report. We present a second case of lateral orbital wall ossifying fibroma and a review of the associated literature.

Nonarteritic anterior ischaemic optic neuropathy in Addison's disease

PURPOSE

To report three cases of Nonarteritic anterior ischaemic optic neuropathy (NAAION) in patients with Addison's disease.

METHODS

We present a retrospective review of patients presenting with NAAION with underlying Addison's disease.

RESULTS

Three eyes of two young patients presented with NAAION. Both patients had underlying Addison's disease with episodes of prolonged hypotension.

CONCLUSION

To our knowledge, this is the first published report of NAAION associated with Addison's disease. As hypotension may be one of the few situations, in which NAAION may be treatable and the visual loss reversible, it is important to recognize and treat sustained episodes of hypotension in these individuals.

The use of imiquimod in the treatment of periocular tumours

PURPOSE

To review our experience with 5% topical Imiquimod in the treatment of periocular tumours.

METHODS

Imiquimod, an imidazoquinoline, is an immune response modifier which has been shown to have potent anti-viral and anti-tumour activity. We present a retrospective case series of 5 patients who received topical Imiquimod for various eyelid tumours. Two patients were diagnosed with basal cell carcinoma of the eyelid, one patient with actinic keratosis, one with intraepidermal squamous cell carcinoma (Bowen's disease) and one patient had concomitant squamous cell carcinoma and intraepidermal squamous cell carcinoma.

RESULTS

All 5 patients, with various eyelid neoplastic/pre-neoplastic pathology, responded well with clinical resolution, to treatment with topical Imiquimod. There were few adverse reactions to periocular use of 5% Imiquimod, with only 1 patient developing a chemical conjunctivitis which resolved on dose reduction.

CONCLUSIONS

There is limited experience and published literature on the use of topical 5% Imiquimod in the treatment of periocular tumours. In our experience, it is a safe and effective treatment for periocular lesions, including actinic keratosis, intraepidermal squamous cell carcinoma, basal cell carcinoma and squamous cell carcinoma. To our knowledge, this is the first published description of the successful use of 5% Imiquimod in treating moderately differentiated squamous cell carcinoma of the eyelid.

Lacrimal gland uptake of gallium (67Ga) citrate in patients without ocular pathology

PURPOSE

To report a series of patients with bilateral lacrimal gland uptake of Gallium (67Ga) Citrate in patients without ocular pathology and to assess the degree to which this can be a normal phenomenon.

METHODS

We present an index case of lacrimal gland uptake of Gallium (67Ga) Citrate in a patient without lacrimal pathology and a subsequent retrospective review of all Gallium scans performed at the Bristol Royal Infirmary, UK from 2002 to 2008. Patients who demonstrated Ga67 uptake within the lacrimal glands were identified and case notes from all scans were retrieved and reviewed. The notes were analysed to determine the rationale for the gallium investigation as well as whether there was any preexisting ocular pathology.

RESULTS

Retrospective review demonstrated that 21 gallium scans were performed from 2002 to 2008, from which 4 patients demonstrated bilateral lacrimal gland Ga67 uptake with no evidence of past or current lacrimal/ocular pathology. On the basis of our review, we report that bilateral gallium uptake is not a specific finding, occurring in normal individuals with no history or symptoms of ocular or orbital pathology.

Thyroid function in patients with proteinuria

BACKGROUND

Patients with proteinuria may suffer from substantial losses of functional proteins such as hormones and hormone-binding proteins. A limited number of studies have reported urinary losses of thyroid hormones and thyroxin-binding globulin. Overt hypothyroidism attributable to these urinary losses has been described. However, the impact of proteinuria on thyroid function parameters has not been studied in a large patient cohort.

METHODS

We evaluated thyroid function parameters in patients with proteinurea who are negative to thyroxine peroxidase antibodies (TPOAbs). Values of free thyroxin and thyroid-stimulating hormone (TSH) were compared with data from age- and gender-matched controls derived from the Nijmegen Biomedical Study, a population-based survey conducted in our hospital.

RESULTS

We evaluated 159 patients. There were 111 males and 48 females. Median (IQR) age was 52 (40 to 62) years, serum creatinine concentration 99 (82 to 134) micromol/l, serum albumin concentration 29 (22 to 35) g/l, and proteinuria 6.6 (3.1 to 10.9) g/10 mmol creatinine. Median TSH was significantly higher in the patients than the controls (1.81 mU/l vs 1.34 mU/l, p.<0.001); however, overt hypothyroidism was observed in only one patient.

CONCLUSION

Patients with proteinuria have higher TSH levels, consistent with urinary loss of thyroid hormones. However, these urinary losses do not result in overt, clinically relevant, hypothyroidism. The role of subclinical hypothyroidism in these patients needs further evaluation.

Evaluation of a new cataract surgery referral pathway

AIMS

To compare the quality of referrals and listing rates of direct optometric referrals vs traditional GP referrals for cataract surgery.

METHODS

A retrospective cohort of 124 patients referred for cataract surgery was identified (62 via optometric pathway and 62 via GP pathway). The quality of the referral was assessed by establishing if it contained adequate information relating to the College of Optometrists' referral framework document. Age, sex, drug history, listing rate, operative rate, and visual acuity (best corrected) at referral and at the postoperative visit were recorded and compared between the two referral pathways using the Fisher's exact test.

RESULTS

Optometric referrals, relative to GP referrals, were more likely to include information relating to objective visual loss (100 vs 87%, P=0.0061) and to counsel the patient (97 vs 18%, P=0.0001). GP referrals, relative to optometric referrals, were more likely to comment on personal circumstances (32 vs 3%, P=0.0001), past medical history (95 vs 68%, P=0.0001), and drug history (94 vs 69%, P=0.0009). Operative rates were higher for the optometric direct referrals relative to GP referrals (87 vs 69%, P=0.0284). There was no difference in the visual acuity before or after surgery between the pathways.

CONCLUSIONS

Optometric direct cataract referrals provide better information on objectively measured vision and better delivery of preoperative counselling. Traditional GP referrals contain better medical history, drug information, and details of personal circumstances. Rates of surgery were slightly higher with optometric referrals.

Antitumor effects of ajulemic acid (CT3), a synthetic non-psychoactive cannabinoid

One of the endogenous transformation products of tetrahydrocannabinol (THC) is THC-11-oic acid, and ajulemic acid (AJA; dimethylheptyl-THC-11-oic acid) is a side-chain synthetic analog of THC-11-oic acid. In preclinical studies, AJA has been found to be a potent anti-inflammatory agent without psychoactive properties. Based on recent reports suggesting antitumor effects of cannabinoids (CBs), we assessed the potential of AJA as an antitumor agent. AJA proved to be approximately one-half as potent as THC in inhibiting tumor growth in vitro against a variety of neoplastic cell lines. However, its in vitro effects lasted longer. The antitumor effect was stereospecific, suggesting receptor mediation. Unlike THC, however, whose effect was blocked by both CB(1) and CB(2) receptor antagonists, the effect of AJA was inhibited by only the CB(2) antagonist. Additionally, incubation of C6 glioma cells with AJA resulted in the formation of lipid droplets, the number of which increased over time; this effect was noted to a much greater extent after AJA than after THC and was not seen in WI-38 cells, a human normal fibroblast cell line. Analysis of incorporation of radiolabeled fatty acids revealed a marked accumulation of triglycerides in AJA-treated cells at concentrations that produced tumor growth inhibition. Finally, AJA, administered p.o. to nude mice at a dosage several orders of magnitude below that which produces toxicity, inhibited the growth of subcutaneously implanted U87 human glioma cells modestly but significantly. We conclude that AJA acts to produce significant antitumor activity and effects its actions primarily via CB(2) receptors. Its very favorable toxicity profile, including lack of psychoactivity, makes it suitable for chronic usage. Further studies are warranted to determine its optimal role as an antitumor agent.

Association of increased phosphatidylinositol 3-kinase signaling with increased invasiveness and gelatinase activity in malignant gliomas

OBJECT

Glioblastoma multiforme is the most malignant of the primary brain tumors and aggressively infiltrates surrounding brain tissue, resulting in distant foci within the central nervous system, thereby rendering this tumor surgically incurable. The recent findings that both phosphatidylinositol 3-kinase (PI 3-K) and the phosphatase and tensin homolog (PTEN) regulate tumor cell invasiveness have led the authors to surmise that these lipid signaling molecules might play a role in regulating matrix metalloproteinases (MMPs), which are essential for tumor cell invasion.

METHODS

Using the C6 glioma cell line, which does not express measurable amounts of PTEN protein and in which in vitro invasiveness is MMP dependent, the authors determined that in vitro glioma cell invasiveness was significantly reduced when cells were preincubated overnight with LY294002 or wortmannin, two specific inhibitors of PI 3-K signaling. Next, using gelatin zymography, it was noted that these compounds significantly inhibited MMP-2 and MMP-9 activities. Moreover, the decrease in MMP activity correlated with the decrease in PI 3-K activity, as assessed by Akt phosphorylation. Finally, using semiquantitative reverse transcriptase-polymerase chain reaction, the authors demonstrated that LY294002 decreased messenger (m)RNA levels for both MMPs. Thus, these in vitro data indicate that PI 3-K signaling modulates gelatinase activity at the level of mRNA. Using immunostaining of phosphorylated Akt (p-Akt) as a measure of PI 3-K activity, the authors next assessed rat brains implanted with C6 cells. Compared with surrounding brain, there was marked p-Akt staining in C6 glioma cells and in neurons immediately adjacent to the tumor, but not in normal brain. The p-Akt staining in tumors was especially intense in perivascular areas. Using double-labeling techniques, colocalization of p-Akt with MMP-2 and MMP-9 was also noted in perivascular tumor areas.

CONCLUSIONS

The increase in p-Akt staining within these PTEN-deficient gliomas is consistent with what would be predicted from unchecked PI 3-K signaling. Furthermore, the immunohistochemically detected colocalization of p-Akt and MMP-2 and MMP-9 supports the authors' in vitro studies and the proposed linkage between PI 3-K signaling and MMP activity in gliomas.

The Ras-ERK pathway is required for the induction of neuronal nitric oxide synthase in differentiating PC12 cells

We have studied the role of MAP kinase pathways in neuronal nitric oxide synthase (nNOS) induction during the differentiation of PC12 cells. In nerve growth factor (NGF)-treated PC12 cells, we find nNOS induced at RNA and protein levels, resulting in increased NOS activity. We note that neither nNOS mRNA, nNOS protein nor NOS activity is induced by NGF treatment in cells that have been infected with a dominant negative Ras adenovirus. We have also used drugs that block MAP kinase pathways and assessed their ability to inhibit nNOS induction. Even though U0126 and PD98059 are both MEK inhibitors, we find that U0126, but not PD98059, blocks induction of nNOS protein and NOS activity in NGF-treated PC12 cells. Also, the p38 kinase inhibitor, SB203580, does not block nNOS induction in our clone of PC12 cells. Since the JNK pathway is not activated in NGF-treated PC12 cells, we conclude that the Ras-ERK pathway and not the p38 or JNK pathway is required for nNOS induction in NGF-treated PC12 cells. We find that U0126 is much more effective than PD98059 in blocking the Ras-ERK pathway, thereby explaining the discrepancy in nNOS inhibition. We conclude that the Ras-ERK pathway is required for nNOS induction.

PTEN: a newly identified regulator of neuronal differentiation

Even though phosphorylation of phosphatidylinositols by phosphoinositide 3-kinase has an important and pervasive role in the nervous system, little is known about the phosphatases that reverse this reaction. Recently, such a phosphatase, PTEN, was cloned as a tumor suppressor for gliomas. We now know that PTEN is a tumor suppressor for many tumor types and is a phosphatidylinositol phosphatase specific for the 3-position of the inositol ring. PTEN is expressed in most, if not all, neurons and is localized in the nucleus and cytoplasm. PTEN is not evident in neural processes or synapses. PTEN is induced during neuronal differentiation and is required for survival of differentiating neuronal cells. In summary, PTEN is a regulatory molecule with multiple functions at multiple subcellular sites. Further studies are required to determine which downstream pathways are regulated by PTEN, by which mechanisms PTEN activity is regulated, which stimuli regulate PTEN activity, and why a molecule that inhibits several survival pathways is induced during neurogenesis.

Cell-cycle arrest in TrkA-expressing NIH3T3 cells involves nitric oxide synthase

We have examined nerve growth factor (NGF)-triggered signaling in two NIH3T3 cell lines exogenously expressing the NGF receptor, TrkA. TRK1 cells cease to proliferate and extend long processes in response to NGF, while E25 cells continue to proliferate in the presence of NGF. These two cell lines express similar levels of TrkA and respond to NGF with rapid elevation of mitogen-activated protein kinase (MAPK) activity. MAPK activation is slightly more sustained for E25 cells than for TRK1 cells, although sustained activation of MAPK has been suggested to cause cell-cycle arrest. As judged by NADPH-diaphorase staining, nitric oxide synthase (NOS) activity is increased in TRK1 cells upon exposure to NGF. In contrast, diaphorase staining in E25 cells is unaffected by NGF treatment. Immunocytochemistry shows that levels of the brain NOS (bNOS) isoform are increased in TRK1, but not E25, cells exposed to NGF. Furthermore, Western blots show that NGF elevated cyclin-dependent kinase inhibitor, p21(WAF1), in TRK1 cells only. NGF-induced p21(WAF1) expression, cell-cycle arrest and process extension are abolished by N-nitro-L-arginine methyl ester (L-NAME), a competitive inhibitor of NOS. The inactive enantiomer, D-NAME, did not inhibit these responses. Furthermore, even though E25 cells do not respond to NGF or nitric oxide donors, they do undergo a morphological change in response to NGF plus a nitric oxide donor. Therefore, NOS and p21(WAF1) are induced only in the TrkA-expressing NIH3T3 cell line that undergoes cell-cycle arrest and morphological changes in response to NGF. These results demonstrate that sustained activation of MAPK is not the sole determining factor for NGF-induced cell-cycle arrest and implicate NO in the cascade of events leading to NGF-induced morphological changes and cell-cycle arrest.

Neurotrophin channeling of neural progenitor cell differentiation

The act of defining neuropoietic progenitor/stem cells is still in its early phases. Epidermal growth factor (EGF) stimulates extended proliferation of aggregates of subventricular striatal cells, taken from E15 mouse striatum, termed neurospheres in liquid culture. We have shown here and in previous work, using either immunohistochemistry or RT-PCR, that neurosphere cells express 13 cytokines (32 tested) and 20 cytokine receptors (28 tested), with 11 potential paracrine and nine potential autocrine loops. The neurotrophin receptors, Trk A, B, and C, were all expressed. Using a newly developed FACS single cell deposition technique, we evaluated the capacity of single EGF stimulated neurosphere cells to respond to the ligands for Trk A and B, nerve growth factor (NGF), and brain-derived neurotrophin factor (BDNF). Addition of NGF or BDNF to EGF for 14 days had no effect, but removal of EGF at day 14 with subsequent addition of BDNF or NGF resulted in an increase in neuronal and astroglial, but not oligodendrocyte, colony cells at 21 and 28 days of culture for BDNF, and of both cell types at 28 days for NGF. Tri-lineage colonies increased at day 21 with BDNF and at day 28 for both NGF and BDNF. Gross colony morphology also showed changes with neurotrophin addition, forming multiple individual cell balls or filamentous spreads. When EGF was withdrawn, a threshold effect was observed, with small, but not large, colonies ceasing growth. BDNF and NGF showed no effects on cell proliferation when compared to EGF controls, as determined by 5'-bromo-2-deoxyuridine (BrdU) incorporation and thus, they appear to affect differentiation of progenitor cells. These data indicate a sequential action of cytokines with EGF maintaining viability and proliferation and blocking differentiation. Removal of EGF is then permissive for the differentiating effects of BDNF and NGF. These data further indicate that the majority of EGF neurosphere clones have neurotrophin dependent tri-lineage potential.

A role for nuclear PTEN in neuronal differentiation

Mutations of phosphatase and tensin homolog deleted on chromosome 10 (PTEN), a protein and lipid phosphatase, have been associated with gliomas, macrocephaly, and mental deficiencies. We have assessed PTEN's role in the nervous system and find that PTEN is expressed in mouse brain late in development, starting at approximately postnatal day 0. In adult brain, PTEN is preferentially expressed in neurons and is especially evident in Purkinje neurons, olfactory mitral neurons, and large pyramidal neurons. To analyze the function of PTEN in neuronal differentiation, we used two well established model systems-pheochromocytoma cells and cultured CNS stem cells. PTEN is expressed during neurotrophin-induced differentiation and is detected in both the nucleus and cytoplasm. Suppression of PTEN levels with antisense oligonucleotides does not block initiation of neuronal differentiation. Instead, PTEN antisense leads to death of the resulting, immature neurons, probably during neurite extension. In contrast, PTEN is not required for astrocytic differentiation. These observations indicate that PTEN acts at multiple sites in the cell, regulating the transition of differentiating neuroblasts to postmitotic neurons.

Identification of arfophilin, a target protein for GTP-bound class II ADP-ribosylation factors

Yeast two-hybrid screening of a human kidney cDNA library using the GTP-bound form of a class II ADP-ribosylation factor (ARF5) identified a novel ARF5-binding protein with a calculated molecular mass of 82.4 kDa, which was named arfophilin. Northern hybridization analysis showed high level arfophilin mRNA expression in human heart and skeletal muscle. Arfophilin bound only to the active, GTP-bound form of ARF5 and did not bind to GTP-ARF3, which is a class I ARF. The N terminus of ARF5 (1-17 amino acids) was essential for binding to arfophilin. The GTP-bound form of ARF5 with amino acid residues in the N terminus mutated to those in ARF4 (another class II ARF) also bound to arfophilin, suggesting it is a target protein for GTP-bound forms of class II ARFs. The binding site for ARF on arfophilin was localized to the C terminus (residues 612-756), which contains putative coiled-coil structures. Recombinant arfophilin overexpressed in CHO-K1 cells was localized in the cytosol and translocated to a membrane fraction in association with GTP-bound ARF5. ARF5 containing the N terminus of ARF3 did not promote translocation indicating that class II ARFs are specific carriers for arfophilin.

Allocation of crania to groups via the "new morphometry"

An investigation regarding the variation in cranial morphology between American blacks and whites was conducted using triangulation schemes of inter-landmark distances and converting these to three dimensional coordinate data. A least squares superimposition method and Euclidean distance analysis were utilized to obtain parameters for classifying individuals in our sample, consisting of 19 black and nineteen white crania from the William M. Bass, III Donated and Forensic collections curated at the University of Tennessee, Knoxville. Thirty-six caliper measurements were collected on each skull based on 14 homologous cranial landmarks (nasion, bregma, lambda, prosthion, subspinale, basion, frontomalare (left and right), zygoorbitale (left and right), zygotemporale (left and right), and left and right asterion). The results are compared to traditional discriminant analysis. The classification results using the new morphometry are comparable to traditional discriminant analysis. However, the new morphometry can provide information as to the specific location of morphological variation that cannot be obtained with discriminant analysis.

Association with the SRC family tyrosyl kinase LYN triggers a conformational change in the catalytic region of human cAMP-specific phosphodiesterase HSPDE4A4B. Consequences for rolipram inhibition

The cAMP-specific phosphodiesterase (PDE) HSPDE 4A4B(pde46) selectively bound SH3 domains of SRC family tyrosyl kinases. Such an interaction profoundly changed the inhibition of PDE4 activity caused by the PDE4-selective inhibitor rolipram and mimicked the enhanced rolipram inhibition seen for particulate, compared with cytosolic pde46 expressed in COS7 cells. Particulate pde46 co-localized with LYN kinase in COS7 cells. The unique N-terminal and LR2 regions of pde46 contained the sites for SH3 binding. Altered rolipram inhibition was triggered by SH3 domain interaction with the LR2 region. Purified LYN SH3 and human PDE4A LR2 could be co-immunoprecipitated, indicating a direct interaction. Protein kinase A-phosphorylated pde46 remained able to bind LYN SH3. pde46 was found to be associated with SRC kinase in the cytosol of COS1 cells, leading to aberrant kinetics of rolipram inhibition. It is suggested that pde46 may be associated with SRC family tyrosyl kinases in intact cells and that the ensuing SH3 domain interaction with the LR2 region of pde46 alters the conformation of the PDE catalytic unit, as detected by altered rolipram inhibition. Interaction between pde46 and SRC family tyrosyl kinases highlights a potentially novel regulatory system and point of signaling system cross-talk.

An unusual case of multiple mesosternal foramina

We present an unusual example of multiple mesosternal foramina (MMF). The alignment of the paired defects is unlike any previously described. Although single sternal defects are often encountered, paired defects are quite uncommon. This is the first documented example of bilateral paired defects in the sternum.

Mobility of TrkA is regulated by phosphorylation and interactions with the low-affinity NGF receptor

The nerve growth factor (NGF) receptor is a complex of two proteins, gp75 and the tyrosine kinase TrkA. Using fluorescence recovery after photobleaching, we have studied the diffusion properties of the TrkA receptor. For PC12 cells that express both gp75 and TrkA, TrkA was relatively immobile with only 28 +/- 1% of receptor molecules free to diffuse with D = (3.64 +/- 0.23) x 10(-9) cm2/s. Addition of NGF decreased the mobile fraction to 21 +/- 1% with D = (4.11 +/- 0.18) x 10(-9) cm2/s. Using the Sf9 baculovirus expression system, we were able to study TrkA in the absence and presence of gp75. On Sf9 cells, TrkA showed a mobile fraction of 46 +/- 2% with D = (2.64 +/- 0.21) x 10(-9) cm2/s in the absence of gp75 and 43 +/- 2% with D = (2.31 +/- 0.25) x 10(-9) cm2/s in its presence. Thus, gp75 did not alter TrkA mobility. Addition of NGF to the medium approximately halved the mobile fraction for TrkA in both the absence and presence of gp75. However, using a kinase-deficient mutant of TrkA, we found that ligand-induced immobilization requires an active kinase in the absence of gp75 but not in its presence. In addition, using point mutations at specific TrkA autophosphorylation sites, we determined that mobility is controlled by multiple phosphorylation sites, but the SHC binding site at Y490 may be particularly important for ligand-induced immobilization of TrkA. Therefore, two mechanisms lead to NGF-induced immobilization of TrkA--the first resulting from autophosphorylation of TrkA and the second occurring through TrkA's association with gp75.

Cranial thickness in American females and males

To date, numerous studies have examined the range of cranial thickness variation in modern humans. The purpose of this investigation is to present a new method that would be easier to replicate, and to examine sex and age variation in cranial thickness in a white sample. The method consists of excising four cranial segments from the frontal and parietal regions. The sample consists of 165 specimens collected at autopsy and 15 calvarial specimens. An increase in cranial thickness with age was observed. The results suggest that cranial thickness is not sexually dimorphic outside the onset of hyperostosis frontalis interna (HFI).

Intracellular compartmentalization of PDE4 cyclic AMP-specific phosphodiesterases

The PDE4 cyclic AMP-specific phosphodiesterase family comprises a large number of different isoforms encoded by four distinct genes, with additional complexity arising through alternate mRNA splicing. This generates a number of distinct PDE4 isoforms with unique N-terminal regions. The range of such splice variants emanating from the four PDE4 genes appears to be highly conserved across species. One key role for such regions appears to be their potential to target isoforms to specific intracellular sites. Evidence for such a targeting role for these N-terminal regions can be gleaned by a variety of techniques. These include subcellular fractionation, confocal microscopy, binding assays to show association with proteins having src homology 3 (SH3) domains, and generation of chimeric constructs of these N-terminal regions with proteins that are normally expressed in the cytosol.

Molecular cloning and transient expression in COS7 cells of a novel human PDE4B cAMP-specific phosphodiesterase, HSPDE4B3

5'-Rapid amplification of cDNA ends, done on poly(A)+ RNA from human U87 cells, was used to identify 420 bp of novel 5' sequence of a PDE4B cAMP-specific phosphodiesterase (PDE). This identified an open reading frame encoding a putative 721-residue 'long-form' PDE4B splice variant, which we term HSPDE4B3. HSPDE4B3 differs from the two known PDE4B forms by virtue of its unique 79-residue N-terminal region, compared with the unique N-terminal regions of 94 and 39 residues found in HSPDE4B1 and HSPDE4B2 respectively. In transfected COS7 cells the two long forms, HSPDE4B1 and HSPDE4B3, had molecular masses of approx. 104 and approx. 103 kDa respectively. Expressed in COS-7 cells, the three HSPDE4B isoforms were found in the high-speed supernatant (cytosol) fraction as well as both the high-speed pellet (P2) and low-speed pellet (P1) fractions. All isoforms showed similar Km values for cAMP hydrolysis (1.5-2.6 microM). The maximal activities of the soluble cytosolic activity of the two long forms were very similar, whereas that of the short form, HSPDE4B2, was approx. 4-fold higher. Particulate-associated HSPDE4B1 and HSPDE4B2 were less active (approx. 40%) than their cytosol forms, whereas particulate HSPDE4B3 was similar in activity to its cytosolic form. Particulate and cytosolic forms of HSPDE4B1 and HSPDE4B3 were similarly inhibited by rolipram {4-[3-(cyclopentoxyl)-4-methoxyphenyl]-2-pyrrolidone}, the selective inhibitor of PDE4 (IC50 0.05-0.1 microM), whereas particulate-associated HSPDE4B2 was profoundly (approx. 10-fold) more sensitive (IC50 0.02 microM) to rolipram inhibition than its cytosolic form (IC50 0.2 microM). The various particulate-associated HSPDE4B isoforms showed very different susceptibilities to solubilization with the detergent Triton X-100 and high NaCl concentration. A novel cDNA, called pRPDE74, was obtained by screening a rat olfactory lobe cDNA library. This contained an open reading frame encoding a 721-residue protein that showed approx. 96% amino acid identity with HSPDE4B3 and is proposed to reflect the rat homologue of this human enzyme and is thus called RNPDE4B3. Alternative splicing of mRNA generated from both the human and rat PDE4B genes produces long and short splice variants that have unique N-terminal splice regions. It is suggested that these alternatively spliced regions determine changes in the maximal catalytic activity of the isoforms, their susceptibility to inhibition by rolipram and mode of interaction with particulate fractions.

A novel, nerve growth factor-activated pathway involving nitric oxide, p53, and p21WAF1 regulates neuronal differentiation of PC12 cells

During development, neuronal differentiation is closely coupled with cessation of proliferation. We use nerve growth factor (NGF)-induced differentiation of PC12 pheochromocytoma cells as a model and find a novel signal transduction pathway that blocks cell proliferation. Treatment of PC12 cells with NGF leads to induction of nitric oxide synthase (NOS) (Peunova, N., and Enikolopov, G. (1995) Nature 375, 68-73). The resulting nitric oxide (NO) acts as a second messenger, activating the p21(WAF1) promoter and inducing expression of p21(WAF1) cyclin-dependent kinase inhibitor. NO activates the p21(WAF1) promoter by p53-dependent and p53-independent mechanisms. Blocking production of NO with an inhibitor of NOS reduces accumulation of p53, activation of the p21(WAF1) promoter, expression of neuronal markers, and neurite extension. To determine whether p21(WAF1) is required for neurite extension, we prepared a PC12 line with an inducible p21(WAF1) expression vector. Blocking NOS with an inhibitor decreases neurite extension, but induction of p21(WAF1) with isopropyl-1-thio-beta-D-galactopyranoside restored this response. Levels of p21(WAF1) induced by isopropyl-1-thio-beta-D-galactopyranoside were similar to those induced by NGF. Therefore, we have identified a signal transduction pathway that is activated by NGF; proceeds through NOS, p53, and p21(WAF1) to block cell proliferation; and is required for neuronal differentiation by PC12 cells.

Embryonic precursor cells that express Trk receptors: induction of different cell fates by NGF, BDNF, NT-3, and CNTF

Epidermal growth factor (EGF)-treated neurosphere cultures from embryonal striatum contain multipotential cells capable of neuronal, astrocytic, and oligodendroglial differentiation. In this study, we tested whether these neural precursor cells differentiate in the presence of neurotrophic factors. We first assayed neurosphere cells for expression of neurotrophin receptors. TrkA, TrkB, TrkC, and gp75 were detected by immunofluorescence microscopy in 60-80% of cells. In addition, the ciliary neurotrophic factor receptor alpha was expressed in 50-60% of cells. In the presence of the mitogen, EGF, treatment of stem cells with neurotrophic factors had no apparent effect. Removal of EGF from cells resulted in cessation of cell proliferation and pronounced astrocytic (glial fibrillary acidic protein+) differentiation. Neuronal (neurofilament+) and oligodendroglial (galactocerebroside+) cells appeared in cultures treated with neurotrophic factors. Nerve growth factor (NGF) resulted in bipolar neuronal cells, and brain-derived neurotrophic factor led to multipolar neuronal cells. Treatment with neurotrophin-3 or ciliary neurotrophic factor resulted in bipolar neuronal cells and oligodendrocytes. Neuronal differentiation in the presence of NGF was enhanced by extracellular matrix, and the resulting neuronal cells expressed choline acetyltransferase and, to a lesser degree, tyrosine hydroxylase. These studies demonstrate that neurotrophic factors influence the fates of these multipotential precursor cells. Indeed, the true utility of multipotential precursor cells is the production of different types of cells in different situations. Local cues, such as neurotrophic factors and extracellular matrix, may regulate production of different types of neural cells during development or in response to other stimuli, such as injury.

TrkA expression decreases the in vivo aggressiveness of C6 glioma cells

We stably expressed the nerve growth factor receptor trkA or a truncated trkA lacking the kinase domain (trkA delta) in a highly tumorigenic rat glioma cell line, C6. Survival of rats with large intrastriatal inocula of C6trkA cells was significantly longer than for rats bearing C6 or C6trkA delta cells. Histological studies revealed that C6trkA cells were much less invasive than C6 or C6trkA delta cells and had a greater rate of apoptosis. There was no apparent induction of differentiation of C6 cells by trkA. Therefore, unlike what is observed in neuroblastomas, trkA decreases tumorigenicity by modulating invasiveness and tumor cell death independent of inducing differentiation. This novel mechanism suggests a new therapeutic strategy for malignant gliomas.

Role of Rho family proteins in phospholipase D activation by growth factors

Treatment of fibroblasts with growth factors results in activation of phospholipase D (PLD). In order to determine the role of the Rho family of small GTPases in growth factor-mediated PLD activation, we used cells transfected with wild type and mutant Rac1. In response to epidermal growth factor (EGF), PLD activity was greatly increased in Rat1 fibroblasts expressing wild type Rac1 (wtRac1), and completely abrogated in cells expressing dominant negative N17Rac1, consistent with Rac1 mediating the action of this growth factor. In contrast, in cells treated with platelet-derived growth factor (PDGF) or phorbol ester, the wtRac1 cells showed little or no enhancement of PLD activity, and the response was not affected in the N17Rac1 cells, implying that Rac1 played a minimal role in the activation of PLD by PDGF or protein kinase C. Both growth factors produced an attenuated PLD response in cells expressing constitutively active V12Rac1, but these cells showed other changes, including altered morphology, increased basal PLD, and decreased growth factor receptor autophosphorylation. The effects of EGF and PDGF on phosphoinositide phospholipase C activity were not enhanced in cells expressing wtRac1 or inhibited in those expressing N17Rac1. In cells expressing constitutively active V12Rac1, basal phosphoinositide phospholipase C was elevated, but there were no significant effects of EGF or PDGF. We used C3 transferase of Clostridium botulinum, which ADP-ribosylates and inactivates RhoA, to investigate the involvement of RhoA in the activation of PLD by PDGF. Cells expressing wtRac1 and N17Rac1 showed a decreased PLD in response to PDGF when treated with C3 transferase, indicating a role for RhoA. In summary, these data indicate a major role for Rac1 in the activation of PLD by EGF, but not PDGF or protein kinase C.

Distal mucus fistula following resection for perforated sigmoid diverticular disease

A retrospective study of 62 consecutive patients undergoing resection of perforated diverticular disease was undertaken to assess influence of distal stump closure (DSC) or creating a distal mucus fistula (DMF) on subsequent restoration of bowel continuity. Forty-one patients underwent DSC and 21 DMF. Mean operating time and hospital stay were 164 min and 30 days for patients undergoing DSC compared with 142 min and 18 days for those undergoing DMF. Of the 54 survivors, 44 underwent reversal (25/35; DSC, 19/19; DMF). Mean operative time and hospital stay was 208 min and 17 days for DSC compared to 143 min and 10 days for DMF (P = 0.0003). Overall mortality and morbidity of either groups were comparable. Distal mucus fistula can often be safely created following resection of perforated sigmoid diverticulitis. This may result in higher reversal rates and significantly reduces the operating time and hospital stay without compromising the outcome.

A comparison of the effects of oral conjugated equine estrogen and transdermal estradiol-17 beta combined with an oral progestin on quality of life in postmenopausal women

OBJECTIVE

To compare the effect of transdermal estradiol-17 beta and oral conjugated equine estrogen when combined with an oral progestin on quality of life in post-menopausal women.

DESIGN

Randomized controlled double-blind trial. A randomization error lead to the exclusion of six subjects but the soundness of the remaining randomization was confirmed.

SETTING

Large urban community.

PATIENTS

Women 2-7 years after menopause with a uterus and ovaries, and not currently using hormone replacement therapy. Seventy-four women completed the trial.

INTERVENTIONS

After baseline measures of quality of life, subjects were randomly assigned to either continuous oral conjugated equine estrogen 0.625 mg daily or continuous transdermal estradiol-17 beta 50 mcg twice weekly, for four 4-week cycles. Medroxyprogesterone acetate 10 mg oral tablets was administered to both groups for the last 12 days of each cycle.

OUTCOMES MEASURED

Quality of life was determined using the Menopause-Specific Quality of Life Questionnaire. Tolerability was determined by a specifically designed list of adverse effects. Both measures were recorded at base-line and in mid-cycle during the second, third and fourth cycles of treatment.

RESULTS

There were no statistically significant differences in any of the domains at baseline between the oral and transdermal treatment groups. In the vasomotor domain-scores for the oral and transdermal groups improved from baseline levels of 3.14 and 3.09, respectively, to 1.32 and 1.23; physical domain scores improved from 2.45 and 2.73 to 2.04 and 1.78; psychosocial domain scores improved from 2.72 and 3.04 to 2.21 and 1.94; sexual domain scores improved from 2.32 and 2.16 to 1.64 and 1.30. There were no statistically significant group differences or time/group interactions. Both forms of therapy were equally well tolerated.

CONCLUSIONS

Improvement in all domains, measured by the Menopause-Specific Quality of Life Questionnaire, was observed in both the oral and transdermal groups. In the absence of a placebo control group, the improvements observed cannot be attributed solely to the therapy. Neither form of therapy offered an advantage over the other in respect to improvement in quality of life.

Caliber estimation from cranial entrance defect measurements

Caliber estimation from entrance defects has long been rejected by forensic scientists. This appears to be a consequence of soft tissue perspective of forensic pathologists. This study examined the relation between caliber and cranial entrance defects and maximum cranial thickness. The calibers considered in this inquiry were .22, .25, .32, and .38. The sample consisted of 73 specimens obtained at autopsy (thirty-seven of .22 caliber, five of .25, six of .32, and twenty-five of .38). To test the strength of the relation between caliber, minimum diameter, and maximum thickness Pearson correlation coefficients were conducted. The strongest relationship was observed between caliber and minimum diameter. A relationship between minimum diameter and maximum thickness was also observed. To test the null hypothesis that the mean minimum diameter is not significantly different between calibers an analysis of variance procedure was performed. The ANOVA yielded a strong relationship between dependent variable minimum diameter and caliber. Multiple regression analysis measuring the association between minimum diameter, caliber, and maximum thickness was also conducted. The Pr > F .0001 suggests that the overall model is significant. Discriminant functions and canonical variables were obtained. Classification was first performed by using two values small and large calibers. The large caliber group consisted of .38, while the small caliber group included .22, .25, and .32. The correct classification rate using crossvalidation for large caliber is 86.96%, and 93.33% for the group small caliber. A narrower classification was also performed by using three values, .23 caliber (.22 and .25 calibers grouped), .32, and .38 as the criterion variable groups also using minimum diameter and maximum thickness as predictors. The correct classification rate using crossvalidation is 82.02% for .23 caliber, 73.94% for .38 caliber, and 16.67% for .32 caliber defects. The discriminant functions can be used with appropriate caution to classify observations into groups defined by caliber using minimum diameter and maximum thickness as the predictors. Caution is suggested when attempting to estimate caliber from defects that are not produced from the perpendicular entrance of a bullet.

The cyclin-dependent kinase inhibitor p21 (WAF1) is required for survival of differentiating neuroblastoma cells

We are employing recent advances in the understanding of the cell cycle to study the inverse relationship between proliferation and neuronal differentiation. Nerve growth factor and aphidicolin, an inhibitor of DNA polymerases, synergistically induce neuronal differentiation of SH-SY5Y neuroblastoma cells and the expression of p21WAF1, an inhibitor of cyclin-dependent kinases. The differentiated cells continue to express p21WAF1, even after removal of aphidicolin from the culture medium. The p21WAF1 protein coimmunoprecipitates with cyclin E and inhibits cyclin E-associated protein kinase activity. Each of three antisense oligonucleotides complementary to p21WAF1 mRNA partially blocks expression of p21WAF1 and promotes programmed cell death. These data indicate that p21WAF1 expression is required for survival of these differentiating neuroblastoma cells. Thus, the problem of neuronal differentiation can now be understood in the context of negative regulators of the cell cycle.

The neurotrophin receptor, gp75, forms a complex with the receptor tyrosine kinase TrkA

The high-affinity NGF receptor is thought to be a complex of two receptors , gp75 and the tyrosine kinase TrkA, but direct biochemical evidence for such an association had been lacking. In this report, we demonstrate the existence of such a gp75-TrkA complex by a copatching technique. Gp75 on the surface of intact cells is patched with an anti-gp75 antibody and fluorescent secondary antibody, the cells are then fixed to prevent further antibody-induced redistributions, and the distribution of TrkA is probed with and anti-TrkA antibody and fluorescent secondary antibody. We utilize a baculovirus-insect cell expression of wild-type and mutated NGF receptors. TrkA and gp75 copatch in both the absence and presence of NGF. The association is specific, since gp75 does not copatch with other tyrosine kinase receptors, including TrkB, platelet-derived growth factor receptor-beta, and Torso (Tor). To determine which domains of TrkA are required for copatching, we used a series of TrkA-Tor chimeric receptors and show that the extracellular domain of TrkA is sufficient for copatching with gp75. A chimeric receptor with TrkA transmembrane and intracellular domains show partial copatching with gp75. Deletion of the intracellular domain of gp75 decreases but does not eliminate copatching. A point mutation which inactivates the TrkA kinase has no effect on copatching, indicating that this enzymatic activity is not required for association with gp75. Hence, although interactions between the gp75 and TrkA extracellular domains are sufficient for complex formation, interactions involving other receptor domains also play a role.

Differential biological effects of K252 kinase inhibitors are related to membrane solubility but not to permeability

K252a and K252b are related protein kinase inhibitors that, dependent on conditions, can either inhibit or potentiate the effects of neurotrophic factors. K252a, an ester, is more potent and more cytotoxic on intact cells than K252b, a carboxylic acid. To understand better why these drugs elicit different degrees of biological responses, we analyzed their hydrophobicity, cell permeability, and subcellular distribution. As judged by partitioning between organic and aqueous phases, both compounds are hydrophobic. The partition coefficients were 15.6:1 (organic/aqueous phases) for K252a and 4.4:1 for K252b. The ratio of fluorescence excitation at 352 nm to that at 340 nm for the K252 compounds in the organic alcohol 1-decanol versus water provides a simple assay of binding of these compounds to phospholipid membranes. This ratio shifted for K252a, but not K252b, in the presence of phospholipid vesicles, indicating that K252a dissolved in the hydrophobic interior of the membrane. Using quantitative video fluorescence microscopy, we found that K252a strongly labeled both Sf9 insect cells and PC12 rat pheochromocytoma cells, probably staining intracellular membranes. The uptake of K252a was rapid and apparently irreversible. K252b also quickly entered Sf9 and PC12 cells, but staining was much weaker. Hence, K252a and K252b are similar in that they both rapidly enter cells but greatly differ in their membrane solubility.

Regulation of phospholipase D in HL60 cells. Evidence for a cytosolic phospholipase D

Phospholipase D (PLD) activity that was stimulated by guanosine 5'-O-(3-thiotriphosphate) (GTP gamma S) was detected in cytosol and membranes of HL60 cells. GTP gamma S-stimulated PLD activity was detected in the membranes when exogenous labeled phosphatidylcholine was used in the presence of phosphatidylethanolamine and phosphatidylinositol 4,5-bisphosphate, but not when [3H]myristic acid-labeled endogenous substrate was used. Cytosolic PLD co-chromatographed with small GTP-binding proteins on anion-exchange columns, but subsequent chromatography separated these. Reconstitution studies demonstrated ADP ribosylation factor (ARF) as a regulator of cytosolic PLD, whereas the Rho proteins RhoA and CDC42Hs were ineffective. The cytosolic enzyme showed very little activity in the absence of GTP gamma S and was stimulated by 2 mM Ca2+, whereas the membrane enzyme had significant basal activity and was inhibited by Ca2+. Rho-specific GDP dissociation inhibitor inhibited GTP gamma S stimulation of membrane PLD activity in the presence and absence of cytosol. The stimulation in GDP dissociation inhibitor-treated membranes could be partially recovered by the addition of recombinant Rho proteins (RhoA, Rac1, CDC42Hs). RhoA and Rac1 were also stimulatory in untreated membranes. However, Western blot analysis of membranes showed the presence of RhoA, but not Rac1 or CDC42Hs, suggesting that RhoA was the endogenous small GTP-binding protein involved in GTP-dependent PLD activity in membranes in the absence of cytosol. ARF also stimulated the membrane PLD in the presence of GTP gamma S, and the combination of RhoA and ARF showed a synergistic effect. These results show the presence of ARF-dependent PLD activity in both cytosol and membranes. The membranes contain another PLD activity for which the endogenous regulator appears to be RhoA. The data suggest the existence of at least two different PLD isozymes in HL60 cells.

Interaction with TrkA immobilizes gp75 in the high affinity nerve growth factor receptor complex

It has been proposed that the high affinity nerve growth factor (NGF) receptor required for NGF response is a complex of two receptor proteins, gp75 and the tyrosine kinase TrkA, but direct biochemical or biophysical evidence has been lacking. We have previously shown using fluorescence recovery after photobleaching that gp75 is highly mobile on NGF-nonresponsive cells, but relatively immobile on NGF-responsive cells. In this report, we show that a physical interaction with TrkA causes gp75 immobilization. We found that gp75 is relatively mobile on TrkA negative nnr5 cells, a PC12 variant which is nonresponsive to NGF. In contrast, on T14 nnr5 cells (which bear a TrkA expression vector) gp75 is relatively immobile. Similarly, using baculoviruses to express gp75 and TrkA on Sf9 insect cells, we found that TrkA immobilizes gp75 molecules. The related receptor, TrkB, caused a more modest immobilization of gp75. Immobilization was found to require intact TrkA kinase and gp75 cytoplasmic domains, paralleling the requirements of high affinity binding of NGF. Analysis of gp75 diffusion coefficients indicates that mutated gp75 and TrkA molecules may form a complex, even in the absence of the ability to bind NGF with high affinity.

TrkA neurogenic receptor regulates differentiation of neuroblastoma cells

We examined events associated with neuronal differentiation of neuroblastoma cell line SH-SY5Y. Treatment with nerve growth factor (NGF) and aphidicolin, an inhibitor of DNA polymerases alpha and delta, induces terminal differentiation of SH-SY5Y cells. Following 3-4 days of treatment with NGF + aphidicolin, the cells irreversibly ceased proliferation and differentiated. There was a succession of events preceding differentiation. Down-regulation of c-myc was an early event occurring after less than 1 day of treatment with NGF + aphidicolin. Upregulation of the trkA and low-affinity NGF receptors (LNGFR) occurred after 3 days of NGF + aphidicolin treatment and required treatment with both NGF and aphidicolin. To test the role of TrkA in neuroblastic differentiation, we transfected SH-SY5Y cells with a TrkA-expression plasmid. In response to NGF in the absence of aphidicolin, the TrkA-transformant line ceased proliferation and irreversibly differentiated. SH-SY5Y cells bearing a control plasmid displayed only modest, reversible differentiation and did not cease cell proliferation in response to NGF. Hence, expression of NGF receptors is upregulated during differentiation of SH-SY5Y cells, and overexpression of TrkA enhances NGF-induced differentiation.

Retrograde axonal transport and lesion-induced upregulation of the TrkA high-affinity NGF receptor

Long-term physiological responses of nerve growth factor (NGF) and other neurotrophins require gene regulation and likely depend on retrograde axonal transport of NGF or a signaling molecule activated by ligand-receptor interaction. The low-affinity neurotrophin receptor p75LANR is retrogradely transported, but this receptor is not sufficient for NGF-dependent cell survival or differentiation. In this study we examined the distribution and transport of the TrkA NGF receptor using two anti-peptide polyclonal antibodies and a monoclonal antibody, all of which are TrkA specific. We find that (1) in the adult rat brain TrkA-like immunoreactivity is similar with all antibodies in striatal and basal forebrain neurons, (2) TrkA is upregulated in neuronal and nonneuronal cells near the sites of injury, and (3) TrkA immunoreactivity builds up within the proximal and distal segments of transected fimbrial axons, which is consistent with its transport in the anterograde and retrograde directions. Thus, TrkA may itself be, or be a component of, the neurotrophic intraaxonal messenger by which NGF regulates gene expression in sensitive neurons.

Activation of rat liver phospholipase D by the small GTP-binding protein RhoA

Stimulation of phospholipase D by guanosine 5'-O-(3-thiotriphosphate) (GTP gamma S) in rat liver plasma membranes indicates the involvement of GTP-binding proteins. We used RhoGDI, an inhibitor of GDP dissociation from small GTP-binding proteins of the Rho family, to determine the involvement of these proteins. Incubation, and subsequent washing, of plasma membranes with RhoGDI dose-dependently diminished GTP gamma S-stimulated phospholipase D activity, as determined by accumulation of phosphatidylethanol in the presence of ethanol. Incubation with RhoGDI also caused a rapid and dose-dependent appearance of RhoA in the wash, which was associated with the inhibition of phospholipase D. RhoGDI also rapidly extracted Cdc42 from membranes, but Rac1 was not extracted. Full reconstitution of GTP gamma S-stimulated phospholipase D in RhoGDI-washed membranes was achieved with recombinant RhoA. There was partial reconstitution with Rac1 and no enhancement with Cdc42 or ADP-ribosylation factor. The response to RhoA was dose-dependent (EC50 = 0.5 microM). ADP-ribosylation of RhoA by Clostridium botulinum C3 exoenzyme did not affect its ability to recover GTP gamma S-stimulated phospholipase D activity in RhoGDI-washed membranes. These findings support a role for GTP-binding proteins of the Rho family in the activation of membrane-associated phospholipase D and implicate RhoA as the major protein involved.

Down-regulation of c-myc oncogene during NGF-induced differentiation of neuroblastoma cell lines

There may be a close relationship between myc oncogenes and carcinogenesis of human neuroblastoma. In previous studies, we were able to induce differentiation of certain neuroblastoma cell lines with NGF. In order to study gene regulation during differentiation, N-myc and c-myc cDNA probes were hybridized with RNA extracted from different cell lines before and after NGF treatment. It was found that cell lines which expressed N-myc did not express c-myc while those with c-myc did not express N-myc except for SHEP cell line which had neither c-myc nor N-myc expression. In NGF-induced differentiated neuroblastoma cells, c-myc oncogene was down-regulated in comparison with the control samples. The time course of c-myc down-regulation was concomitant with the appearance of morphological differentiation. In situ hybridization also showed remarkable reduction of c-myc oncogene expression in NGF-induced differentiated cells as compared with the untreated control cells. These results indicate that down-regulation of c-myc oncogene may be a key event during NGF-induced differentiation and over-expression of c-myc oncogene may, at least partially, be responsible for the genesis of neuroblastoma.

Purification and properties of phospholipase A1 from bovine brain

Phospholipase A1 (PLA1) was isolated from a soluble fraction of bovine brain. The purification included sequential DEAE-Sephacel, phenyl-Sepharose FF, and heparin-Sepharose CL-6B column chromatography. Mono Q, Sephacryl S-300, and Mono S high resolution column chromatography in the presence of the detergent 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonic acid (10 mM) and glycerol (10%, v/v) was required to further separate the enzyme from contaminating material. The purified PLA1 eluted from the Sephacryl S-300HR column in a volume corresponding to a molecular mass of 365 kDa and migrated as two bands (M(r) = 112,000 and 95,000) when separated by polyacrylamide gel electrophoresis in sodium dodecyl sulfate. Chromatofocusing, hydroxylapatite, and lectin affinity column chromatography and nondenaturing polyacrylamide gel electrophoresis were unsuccessful in separating the two electrophoretic bands, implying a close association or similarity. The purified enzyme was stable in solutions containing detergent and glycerol and was insensitive to metal chelators, dithiothreitol, phenylmethylsulfonyl fluoride, and diisopropyl fluorophosphate, but was inactivated by heat (60 degrees C) and ZnCl2. At pH 7.5, the purified enzyme showed highest specific activity, 23.8 mumol/min-mg, when 1-palmitoyl-2-[1-14C]arachidonoyl-phosphatidylethanolamine was the substrate. The rate of catalysis was optimal at a pH of 9.0 and could be enhanced 2-fold by Ca2+, Mg2+, and Sr2+, but not Mn2+. The enzyme catalyzed the specific hydrolysis of acyl groups from the sn-1 position of a broad range of phospholipid substrates, including lysophospholipids, and accounts for most of the soluble phospholipase A1 activity of bovine brain.

Circular dichroism and crosslinking studies of the interaction between four neurotrophins and the extracellular domain of the low-affinity neurotrophin receptor

Interactions between the purified recombinant receptor extracellular domain (RED) of the human low-affinity neurotrophin receptor (LANR) and recombinant human brain-derived neurotrophic factor, neurotrophin-3 (NT-3) and neuotrophin-4/5 have been studied by chemical crosslinking and circular dichroism. Conformational changes subsequent to binding have been shown by these procedures. First, relative affinities of the neurotrophins for RED were determined by binding competition assays in which radioiodinated nerve growth factor (NGF) from mouse submaxillary gland was crosslinked to RED in the presence of varying amounts of unlabeled neurotrophin competitors. RED bound each of the 3 recombinant human neurotrophins with affinities that were indistinguishable from authentic mouse NGF. These results are the first measurement of binding of the neurotrophin family to their common receptor using purified components. In order to study the effect of binding on the conformation of the proteins, CD measurements were made before and after mixing neurotrophins and RED, as had previously been done with NGF and RED (Timm DE, Vissavajjhala P, Ross AH, Neet KE, 1992, Protein Sci 1:1023-1031). Similar changes in CD spectra occurred upon combination of each of the neurotrophins and RED, with negative changes near 220-225 nm and positive changes near 190-200 nm; however, significant differences existed among the various neurotrophin-RED difference spectra. The NT-3/RED complex showed the largest spectral change and NGF the smallest. Thus, specific conformational changes in secondary structure of neurotrophin, RED, or both accompany the binding of each neurotrophin to the extracellular domain of the LANR.

Purification of a 110-kDa phosphoinositide phospholipase C that is activated by G-protein beta gamma-subunits

We report the purification from bovine brain cytosol of a 110-kDa phosphoinositide-specific phospholipase C (PLC-110) that was markedly stimulated by G-protein beta gamma-subunits. The enzyme was purified approximately 2000-fold with a yield of 4%. On the basis of size and immunological cross-reactivity, PLC-110 was distinct from 150-kDa PLC-beta 1, 145-kDa PLC-gamma 1, and 85-kDa PLC-delta 1. An antiserum to a peptide corresponding to a conserved PLC Y domain sequence cross-reacted with PLC-110. PLC-110 was also recognized by two antisera selective for NH2-terminal and internal sequences in PLC-beta 3, but not by a third peptide antiserum to the COOH terminus of this enzyme, suggesting that PLC-110 is related to PLC-beta 3. Reconstitution of purified PLC-110 with beta gamma-subunits produced greater than 100-fold activation, indicating activation was observed at approximately 60 nM beta gamma and full activation at approximately 500 nM beta gamma. PLC-110 maximally hydrolyzed phosphatidylinositol 4-phosphate and phosphatidylinositol 4,5-bisphosphate at 1 microM Ca2+, but showed no activity toward phosphatidylinositol at Ca2+ concentrations up to 1 mM. Concentrations of purified guanosine 5'-O-(3-thiotriphosphate)-liganded alpha q that fully activated PLC-beta 1 failed to stimulate PLC-110. This observation indicates that the site at which beta gamma interacts with PLC-110 is distinct from that at which alpha q regulates the activity of PLC-beta isozymes.

Comparison of transdermal and oral sequential gestagen in combination with transdermal estradiol: effects on bleeding patterns and endometrial histology

OBJECTIVE

To assess prospectively the effect on bleeding patterns, transformation of the endometrium, and rate of endometrial hyperplasia of transdermal norethisterone acetate when administered sequentially in combination with transdermal estradiol (E2), and to compare it to a regimen using oral medroxyprogesterone acetate.

METHODS

Two hundred eighteen women were randomized to receive either transdermal E2 0.05 mg/day for 14 days followed by transdermal E2 0.05 mg/day plus transdermal norethisterone acetate 0.25 mg/day for 14 days, or transdermal E2 0.05 mg/day for 25 days with the addition of oral medroxyprogesterone acetate 10 mg/day on days 16-25, followed by a 3-day treatment-free period. Treatment was planned for 13 cycles of 28 days. The subjects kept daily bleeding diaries, and endometrial biopsies were taken before and at the end of treatment.

RESULTS

The mean duration of bleeding (regular) induced by the gestagen was 7.33 days in the transdermal gestagen-treated group, which was 1.54 days longer than in the oral gestagen-treated group (P = .0001). The mean cycle day of onset was 25.74. Bleeding was spotting or light in the transdermal group in 77% of the days in which bleeding occurred. When comparing the two groups, there were no differences in the overall mean cycle day of onset or in the intensity of gestagen-induced bleeding. Breakthrough (irregular) bleeding episodes occurred in 42% of the transdermal subjects, lasted a mean of 4.18 days, and were spotting or light in 87% of the days when they occurred. There were no differences between the treatment groups. There was only one case (1.3%) of confirmed simple hyperplasia and five cases of failure of gestagenic transformation of the endometrium in 77 women treated for a mean of 367 days with transdermal gestagen.

CONCLUSION

A transdermal system delivering a combination of E2 and norethisterone acetate for 14 days in sequence with E2 delivered transdermally for 14 days produced bleeding patterns that are clinically acceptable and comparable to those produced by oral medroxyprogesterone acetate given in sequence with E2 delivered transdermally for 25 days. The use of the combination system was not associated with a significant risk of endometrial hyperplasia.