Evaluation of locally manufactured patient-specific custom made implants for cranial defects using a silicone mould.

BACKGROUND: Cranial vault defects can pose a significant problem for neurosurgeons where autologous bone is no longer available for cranioplasty. Numerous materials exist to create implants which include polymethyl methacrylate (PMMA) and titanium. A technique using 3-dimensional CT scan reconstruction of a cranial defect and creating a silicon mould which can be autoclaved in theatre to create a PMMA implant was developed. OBJECTIVE: The aim of this study is to evaluate the efficacy, cosmetic result, safety and cost-effectiveness of this procedure and compare this to existing techniques. METHOD: An ambispective study was performed in patients requiring cranioplasty with a custom made implant. Patients were assessed for risk factors and cosmetic outcome, surgical technique was described and complications and cost compared to existing literature between 2010 and 2016. RESULTS: Thirty retrospective and 30 consecutive prospective patients were recruited into the study. Overall sepsis rate was 8.3%. All septic cases had superficial sepsis of which 2 grafts were removed due to cerebrospinal fluid leakage resulting in wound breakdown. A 100% accurate implant to defect ratio was achieved leading to a high satisfaction rate. Average cost was 5 times cheaper than the closest market related product. CONCLUSION: Patient specific moulds using PMMA to create custom implants are safe, have excellent cosmetic results and are a very cost-effective option to manage cranial defects. Accurate planning strategies for large craniotomies, where bone will potentially be discarded, add to surgical effectiveness and cost-saving to the patient.

Comparative outcomes of ulnar nerve transposition versus neurolysis in patients with entrapment neuropathy at the cubital tunnel: a 20-year analysis.

BACKGROUND: Entrapment neuropathy of the ulnar nerve at the level of the elbow is the shared domain of multiple surgical specialties. A wide variety of operative methods for its surgical management have been reported. Our hospital utilizes neurolysis (NL) and subcutaneous transposition (AST). The aim of this paper was to compare the clinical outcomes in patients treated by ulnar nerve transposition versus neurolysis over a 20-year period. METHODS: We included patients who underwent either neurolysis or an ulnar nerve transposition. A retrospective analysis was performed which included 480 patients at our institution between January 1992 and December 2012. In total, physical and electronic records for 480 patients were reviewed. Three-hundred and one underwent ulnar nerve transposition and 179 underwent ulnar nerve neurolysis . RESULTS: In the AST group 201/301 patients suffered from parasthesiae pre-operatively and 156/301 had pain at and around the cubital tunnel. Paresis of the ulnar nerve innervated muscles was present in 99/301 patients. At the 3-month follow-up appointment, 187/201 patients with parasthesiae and 113/156 patients with local pain had resolution of their symptoms. In the NL group 151/179 patients had parasthesiae pre-operatively and 126/179 had pain at and around the cubital tunnel. Paresis of the ulnar nerve innervated muscles was present in 56/179 patients. At the 3-month follow-up appointment, 141/151 patients with parasthesiae and 117/126 patients with local pain had resolution of their symptoms. CONCLUSIONS: In cases of ulnar nerve compression at the cubital tunnel, both neurolysis and transposition are effective in improving clinical outcome. The only statistically significant advantage of neurolysis over transposition seems to be relief of localized elbow pain. We recommend neurolysis as the preferred procedure.

Fluid intake, genetic variants of UDP-glucuronosyltransferases, and bladder cancer risk.

BACKGROUND: Results of studies of fluid consumption and its association with bladder cancer have been inconsistent. Few studies have considered modification effects from genetic variants that may interact with the type of consumed fluids. UDP-glucuronosyltransferases (UGTs), which are membrane-bound conjugating enzymes, catalyse the transformation of hydrophobic substrates to more water-soluble glucuronides to facilitate renal or biliary excretion. Whether genetic variants in UGTs could modulate the association between fluid intake and bladder cancer has not been studied. METHODS: We conducted a case-control study with 1007 patients with histopathologically confirmed bladder cancer and 1299 healthy matched controls. Fluid intake and epidemiologic data were collected via in-person interview. Multivariate unconditional logistic regression was used to estimate odds ratios (ORs) and the 95% confidence intervals (95% CI). RESULTS: After adjustment for potential confounders, high quantity of total fluid intake (> or =2789 vs. <1696 ml per day) conferred a 41% increased risk of bladder cancer (OR=1.41; 95% CI=1.10-1.81). Specific fluids such as regular soft drinks and decaffeinated coffee were also associated with increased risks, whereas tea, wine, and liquor were associated with decreased risks. Among 83 single-nucleotide polymorphisms in the UGT gene family, 18 were significantly associated with bladder cancer risk. The most significant one was rs7571337, with the variant genotype conferring a 29% reduction in risk (OR=0.71; 95% CI=0.56-0.90). CONCLUSIONS: Total and specific fluid intakes are associated with bladder cancer risk in the study population and that genetic variants of UGT genes could modulate the effects. These results facilitate identification of high-risk individuals and have important implications in bladder cancer prevention.

Cellular signals underlying ß-adrenergic receptor mediated salivary gland enlargement.

We examined the cellular signaling pathways involved in parotid gland enlargement induced by repeated isoproterenol administration in rats. Immunoblot analysis revealed early (1h) activation of the mitogen activated protein kinase (MAPK) ERK1/2, and progressive activation of epidermal growth factor receptor (EGFR), p38MAPK and p70S6 kinase (p70S6K) during 72h of isoproterenol treatment. Expression of ß-adrenergic receptors (ARs) of the ß2, but not ß1, subtype increased over time in parallel with increases in the proliferation marker PCNA and parotid gland weight. Levels of ß2-AR mRNA, assessed by quantitative RT-PCR and Northern blot analysis, were upregulated in parotid glands of isoproterenol treated rats. cAMP response element binding protein (CREB), a positive regulator of ß2-AR transcription, was activated at 1h after isoproterenol administration, as evidenced by increased nuclear translocation and DNA binding using immunohistochemical staining and electrophoretic mobility shift assay. ELISA of NF-κB, also a ß2-AR transcriptional regulator, revealed an increase in p65 and p50 subunits in nuclear protein extracts from parotid glands of isoproterenol treated rats. Together, these results demonstrate that ß-adrenergic stimulation activates diverse cell survival and progrowth signaling pathways, including cAMP and EGFR linked activation of ERK1/2, p38MAPK, and p70S6K, and also induction of ß2-ARs, possibly mediated by CREB and NF-κB, resulting in salivary gland enlargement. We propose that during isoproterenol treatment activation of the ß1-AR, the predominant ß-AR subtype in unstimulated salivary glands, initiates proliferative signaling cascades, and that upregulation of the ß2-AR plays an essential role in later stages of salivary gland growth.

The evolution of neurosurgery: how has our practice changed?

INTRODUCTION: Neurosurgery is a rapdily evolving speciality and has often taken a lead in adopting new technologies. Advancing technology however is not the only force driving change in this discipline. Other factors include an escalation in patient expectations, an increasing (and ageing) population and the prevailing economic conditions. The aim of our study was to analyse the trends in neurosurgical practice over a 10-year period. MATERIALS AND METHODS: The details of every neurosurgical procedure performed at Wellington Regional Hospital from 2001 to 2011 were prospectively recorded in a relational database. This was then retrospectively interrogated to provide data for this study. RESULTS: Neurosurgical practice has clearly evolved over the last decade. Predictable changes include a trend towards coiling rather than clipping of cerebral aneurysms, an increasing number of tumour resections (particularly for malignant glioma) coupled with the increased use of image guidance and endoscopy. The number of operations on the cervical spine has also increased although overall the number of procedures for spinal degenerative conditions has declined, perhaps reflecting local practice. The rates of craniotomy for trauma and burr holes for chronic subdural haematoma have remained essentially unchanged. We have demonstrated a significant increase in annual case-load that is disproportionate to any change in population size. Collaboration between specialties is increasingly evident. CONCLUSION: The most important changes have occured in the fields of neuro-oncology, vascular neurosurgery and spinal surgery. Inter-specialty collaboration is establishing itself as a model of care. These data may guide resource allocation for a population increasing both in number and in age.

Biology of BCG response in non-muscle invasive bladder cancer - 2021 IBCN Updates Part III.

Bacillus Calmette-Guerin (BCG) remains the only FDA-approved first-line therapy in patients with high-risk non-muscle invasive bladder cancer. Recurrences, even after adequate BCG therapy, are common and the efficacy of second-line therapies remains modest. Therefore, early identification of patients likely to recur and treatment after recurrence remain critical unmet needs in the clinical care of bladder cancer patients. To address these deficits, a better understanding of the mechanisms of resistance to BCG-therapy is needed. The virtual update of the International Bladder Cancer Network (IBCN) on the biology of response to BCG focused on potential mechanisms and markers of resistance to intravesical BCG therapy. The insights from this meeting will be highlighted and put into context of previously reported mechanisms of resistance to BCG in this review.

HPV-positive clinically advanced squamous cell carcinoma of the urinary bladder (aBSCC): A comprehensive genomic profiling (CGP) study.

BACKGROUND: Advanced bladder squamous cell carcinoma (aBSCC) is an uncommon form of urinary bladder malignancy when compared with the much higher urothelial carcinoma incidence. We studied the genomic alteration (GA) landscape in a series of aBSCC based on the association with human papilloma virus (HPV) to determine if differences in GA would be observed between the positive and negative groups. METHODS: Using a hybrid capture-based FDA-approved CGP assay, a series of 171 aBSCC were sequenced to evaluate all classes of GA. Tumor mutational burden (TMB) was determined on up to 1.1 Mbp of sequenced DNA and microsatellite instability (MSI) was determined on up to 114 loci. Programmed cell death ligand -1 (PD-L1) expression was determined by IHC (Dako 22C3) with negative expression when PD-L1 was 0, lower expression of positivity set at 1 to 49%, and higher expression set at ≥50% expression. RESULTS: Overall, 11 (6.4%) of the aBSCC were found to harbor HPV sequences (10 HPV16 and 1 HPV 11). HPV+ status was identified slightly more often in women (NS) and in younger patients (P = 0.04); 2 female patients with aBSCC had a prior history of SCC including 1 anal SCC and 1 vaginal SCC. HPV+ aBSCC had fewer GA/tumor (P < 0.0001), more inactivating mutations in RB1 (P = 0.032), and fewer inactivating GA in CDKN2A (P < 0.0001), CDKN2B (P = 0.05), TERT promoter (P = 0.0004) and TP53 (P < 0.0001). GA in genes associated with urothelial carcinoma including FGFR2 and FGFR3 were similar in both HPV+ and HPV- aBSCC groups. MTAP loss (homozygous deletion) which has emerged as a biomarker for PRMT5 inhibitor-based clinical trials was not identified in any of the 11 HPV+ aBSCC cases, which was significantly lower than the 28% positive frequency of MTAP loss in the HPV- aBSCC group (P < 0.0001). MTOR and PIK3CA pathway GA were not significantly different in the 2 groups. Putative biomarkers associated with immunotherapy (IO) response, including MSI and TMB status, were also similar in the 2 groups. PD-L1 expression data was available for a subset of both HPV+ and HPV- cases and showed high frequencies of positive staining which was not different in the 2 groups. CONCLUSIONS: HPV+ aBSCC tends to occur more often in younger patients. As reported in other HPV-associated squamous cell carcinomas, HPV+ aBSCC demonstrates significantly reduced frequencies of inactivating mutations in cell cycle regulatory genes with similar GA in MTOR and PIK3CA pathways. The implication of HPV in the pathogenesis of bladder cancer remains unknown but warrants further exploration and clinical validation.

Severe adhesive arachnoiditis resulting in progressive paraplegia following obstetric spinal anaesthesia: a case report and review.

A 27-year-old woman developed severe adhesive arachnoiditis after an obstetric spinal anaesthetic with bupivacaine and fentanyl, complicated by back pain and headache. No other precipitating cause could be identified. She presented one week postpartum with communicating hydrocephalus and syringomyelia and underwent ventriculoperitoneal shunting and foramen magnum decompression. Two months later, she developed rapid, progressive paraplegia and sphincter dysfunction. Attempted treatments included exploratory laminectomy, external drainage of the syrinx and intravenous steroids, but these were unsuccessful and the patient remains significantly disabled 21 months later. We discuss the pathophysiology of adhesive arachnoiditis following central neuraxial anaesthesia and possible causative factors, including contamination of the injectate, intrathecal blood and local anaesthetic neurotoxicity, with reference to other published cases. In the absence of more conclusive data, practitioners of central neuraxial anaesthesia can only continue to ensure meticulous, aseptic, atraumatic technique and avoid all potential sources of contamination. It seems appropriate to discuss with patients the possibility of delayed, permanent neurological deficit while taking informed consent.

La maladie de Grisel treated by combined C1-2 transarticular and C1 lateral mass screw fixation.

The authors describe a novel posterior approach to atlantoaxial stabilization combining C1-2 transarticular and C1 lateral mass screws with vertical connecting rods to create a strong construct with four-point fixation. They present here a case of atlanto-axial instability secondary to infection, Grisel's syndrome, necessitating instrumented stabilization after a period of close clinical and radiological observation following the initial cervical decompression and evacuation of retropharyngeal and epidural abscesses.

Management of bladder cancer.

Bladder cancer is the fourth most common cancer in men and is increasing in incidence in women as well. Bladder cancer has a broad range of behavior and presentations, with different prognoses and treatments. Laboratory research has made strides in elucidating pathways of this cancer, and identifying novel therapeutic targets. This short review provides a summary of the current knowledge of the management of bladder cancer.

Retraction: Staged Surgical Management in the Treatment of Primary Epidural Hydatidosis of the Spine: A Case Series and Review.

[This retracts the article DOI: 10.7759/cureus.401.].

CSF protein concentration associated with ventriculoperitoneal shunt obstruction in tuberculous meningitis.

INTRODUCTION: Hydrocephalus occurs in 85% of patients with tuberculous meningitis (TBM). Ventriculoperitoneal shunt (VPS) insertion is first-line treatment for relieving increased intercranial pressure. VPS obstruction secondary to increased protein levels in cerebrospinal fluid (CSF) is a known complication. OBJECTIVE: To ascertain if there is a difference in protein levels 1) between cranial and lumbar CSF, and to quantify levels associated with VPS obstruction, and 2) obtained from lumbar puncture vs. ventricular CSF. METHOD: A 30-year retrospective analysis was undertaken. CSF protein levels were statistically analysed to determine correlation between these levels and VPS obstruction. RESULTS: Of 214 children and 376 adults who underwent VPS insertion for TBM, respectively 27.5% and 25.5% sustained blocked VPS. The mean protein level in CSF collected from the non-obstructed group was 1.76 g/l, compared to 2.94 g/l in the obstructed group. The mean CSF protein level from intraoperative ventricular vs. lumbar puncture samples in the VPS obstruction group was respectively 2.471 g/l and 2.474 g/l. CONCLUSION: Patients with increased protein levels in CSF are at a high risk of VPS blockage. In these patients, temporary measures should be employed until CSF protein levels decrease.

Retraction: Thoracic Vertebral Actinomycosis Secondary to a Pulmonary Origin.

[This retracts the article DOI: 10.7759/cureus.391.].

Phospholipase C-gamma1: regulation of enzyme function and role in growth factor-dependent signal transduction.

Phospholipase C(gamma)1 (PLC-gamma1), a tyrosine kinase substrate, is a multi-domain molecule that modulates the intracellular levels of the second messenger molecules: Ca2+ and diacylglycerol. Although a wide variety of growth factor receptor tyrosine kinases phosphorylate and activate PLC-gamma1, the biological role and necessity of this signal transduction element in mitogenesis has remained unclear. Recent results, however, point to a more essential role than was suggested by initial studies. Also, biochemical studies have indicated a putative means for the intramolecular repression of PLC-gamma1 activity and provide a means for interpreting activation signals through a derepression mechanism.

Proteus mirabilis abscess involving the entire neural axis.

Intramedullary spinal cord abscesses are rare and potentially devastating lesions usually associated with other infective processes such as bacterial endocarditis, or pulmonary or urogenital infection. We describe a 2-year-old girl who presented with an infected dermal sinus leading to an intraspinal abscess. This abscess eventually spread and involved the entire neural axis leaving her quadriparetic. Drainage of the abscess resulted in recovery and the child regained normal function of her limbs. To our knowledge this is the first documented case of an intramedullary abscess involving the entire neural axis.

Mitochondrial oligomers boost glycolysis in cancer stem cells to facilitate blebbishield-mediated transformation after apoptosis.

Apoptosis culminates in secondary necrosis due to lack of ATP. Cancer stem cells form spheres after apoptosis by evoking the blebbishield emergency program. Hence, determining how blebbishields avoid secondary necrosis is crucial. Here we demonstrate that N-Myc and VEGFR2 control transformation from blebbishields, during which oligomers of K-Ras, p27, BAD, Bax, and Bak boost glycolysis to avoid secondary necrosis. Non-apoptotic cancer cells also utilize oligomers to boost glycolysis, which differentiates the glycolytic function of oligomers from their apoptotic action. Smac mimetic in combination with TNF-α or TRAIL but not in combination with FasL abrogates transformation from blebbishields by inducing secondary necrosis. Thus blebbishield-mediated transformation is dependent on glycolysis, and Smac mimetics represent potential candidates to abrogate the blebbishield emergency program.

Hypoxia prevents induction of aromatase expression in human trophoblast cells in culture: potential inhibitory role of the hypoxia-inducible transcription factor Mash-2 (mammalian achaete-scute homologous protein-2).

The human placenta has a remarkable capacity to aromatize C19-steroids, produced by the fetal adrenals, to estrogens. This reaction is catalyzed by aromatase P450 (P450arom), encoded by the CYP19 gene. In placenta, CYP19 gene expression is restricted to the syncytiotrophoblast layer. Cytotrophoblasts isolated from human placenta, when placed in monolayer culture in 20% O2, spontaneously fuse to form syncytiotrophoblast. These morphological changes are associated with a marked induction of aromatase activity and CYP19 gene expression. When cytotrophoblasts are cultured in an atmosphere containing 2% O2, they manifest increased rates of DNA synthesis and fail to fuse and form syncytiotrophoblast. The objective of the present study was to utilize cytotrophoblasts isolated from midterm human placenta to analyze the effects of O2 on CYP19 gene expression and the molecular mechanisms that mediate these effects. We observed that when trophoblast cells were maintained in 2% O2, there was only a modest induction of CYP19 expression as a function of time in culture, and aromatase activity was barely detectable. However, when cytotrophoblasts that had been maintained in 2% O2 for 3 days were placed in a 20% O2 environment, there was a rapid onset of cell fusion and induction of P450arom mRNA and aromatase activity. In addition, mRNAs for the helix-loop-helix factors Mash-2 (mammalian achaete-scute homologous protein-2) and Id1 (inhibitor of differentiation 1) were readily detectable in freshly isolated cytotrophoblasts and were markedly decreased upon differentiation to syncytiotrophoblast in 20% O2. By contrast, when cytotrophoblasts were cultured in 2% O2, mRNA levels for Mash-2 and Id1 remained elevated. Interestingly, overexpression of Mash-2 in primary cultures of human trophoblast cells markedly inhibited cell fusion and the spontaneous induction of P450arom mRNA levels and caused a marked decrease in expression of co-transfected fusion gene constructs containing either 125, 201, 246, or 501 bp of DNA flanking the 5'-end of the placenta-specific exon (exon I.1) of the human CYP19 gene linked to the human GH (hGH) structural gene, as reporter. In studies using BeWo, a human choriocarcinoma cell line, overexpression of Mash-2 also inhibited expression of cotransfected CYP19I.1:hGH fusion gene constructs. The findings that Mash-2 had no effect on the expression of a CYP19I.1(-42):hGH fusion gene in primary cultures of human trophoblast and BeWo cells suggest that Mash-2 exerts its inhibitory effects directly or indirectly though CYP19I.1 5'-flanking sequences that lie between -42 and -125 bp. By contrast, neither Id1 nor Id2 had an effect on CYP19I. 1 promoter activity in the transfected BeWo cells. These findings suggest that Mash-2 may serve as a hypoxia-induced transcription factor that prevents differentiation to syncytiotrophoblast and aromatase induction in human trophoblast cultured under low O2 conditions.

Characterization of the regulatory regions of the human aromatase (P450arom) gene involved in placenta-specific expression.

Aromatase P450 (P450arom), a product of the CYP19 gene, catalyzes the conversion of C19-steroids to estrogens. Human P450arom is expressed in placental syncytiotrophoblast, ovarian granulosa cells, and adipose stromal cells by use of tissue-specific promoters that are located 5' of unique untranslated first exons. Mononuclear cytotrophoblasts isolated from midterm human placenta spontaneously fuse in culture to form multinucleated syncytiotrophoblast. These morphological changes are associated with a marked induction of P450arom gene expression. The majority of P450arom transcripts in placental syncytiotrophoblast contain sequences encoded by exon I.1, which lies more than 35 kb upstream of the translation initiation site in exon II. To functionally map genomic sequences required for placenta-specific P450arom expression, fusion genes containing various amounts of DNA flanking the 5'-end of placenta-specific exon I.1 linked to the human GH (hGH) gene, as reporter, were introduced into primary cultures of human trophoblast cells and other cell types. Since the trophoblast cells manifest high levels of aromatase P450 expression, we believe that this provides a physiologically relevant system for characterizing the regulatory regions of this gene. Expression of the fusion genes increased as a function of time in culture in concert with syncytiotrophoblast differentiation and induction of aromatase activity and of P450arom gene expression. P450arom-hGH fusion genes containing 923 and 501 bp of exon I.1 5'-flanking DNA were expressed at comparable levels; these levels were more than 3-fold greater than those of fusion genes containing 2400 bp of exon I.1 5'-flanking DNA, suggesting the presence of an upstream silencer element(s). Expression of these fusion genes was undetectable in cell lines that do not express aromatase or that express aromatase utilizing a nonplacental P450arom promoter. By contrast, P450arom I.1-hGH fusion genes containing 246, 201, or 125 bp of exon I.1 5'-flanking sequence were expressed both in trophoblast cells and in other cell lines. These findings demonstrate that 501 bp of exon I.1 5'-flanking DNA contain response elements required for trophoblast-specific expression of P450arom. These results also suggest the presence of regulatory elements between -501 bp and -246 bp of exon I.1 5'-flanking sequence that bind inhibitory transcription factors expressed in nontrophoblast cells. Deletion and site-directed mutagenesis experiments further suggest that cis-acting elements, including a GC box and two hexameric sequences present within 246 bp of sequence flanking the 5'-end of exon I.1, contribute to the high levels of P450arom promoter activity in primary cultures of placental cells. By competitive and supershift electrophoretic mobility shift assays, it was observed that the ubiquitously expressed transcription factor Sp1 comprises one of the proteins binding to the GC box in the 5'-flanking sequence of P450arom exon I.1.

Reconstructive challenges in the extended endoscopic transclival approach.

OBJECTIVE: We wanted to present our experience with the extended endoscopic approach to clival pathology, focusing on cerebrospinal fluid leak and reconstruction challenges. METHODS: We examined a consecutive series of 37 patients undergoing the extended endoscopic approach for skull base tumours, 9 patients with clival pathology. Patients were examined for the incidence of post-operative cerebrospinal fluid leak in relation to tumour pathology, location, size, reconstruction and lumbar drain. RESULTS: The overall incidence of post-operative cerebrospinal fluid leak was 10.8 per cent. Seventy-five per cent of patients who had a post-operative cerebrospinal fluid leak underwent a transclival approach (p < 0.05). All patients with clival pathology who underwent an intradural dissection had a post-operative cerebrospinal fluid leak (p < 0.05). CONCLUSION: Post-operative cerebrospinal fluid leak rates after the extended endoscopic approach have improved significantly after advancements including the vascularised nasoseptal flap. Despite this, transclival approaches continue to pose much difficulty. Further investigation is necessary to develop technical improvements that can meet the unique challenges associated with this region.

Identification of the regulatory regions of the human aromatase P450 (CYP19) gene involved in placenta-specific expression.

Expression of the human CYP19 gene in placental syncytiotrophoblast, ovarian granulosa and luteal cells and adipose stromal cells is regulated by tissue-specific promoters which lie upstream of unique untranslated first exons. In placenta, the majority of CYP19 mRNA transcripts contain 5'-sequences encoded by exon I.1 which lies >35 kb upstream of the translation initiation sequence in exon II. Mononuclear cytotrophoblasts isolated from midterm human placenta spontaneously fuse in culture to form multinucleated syncytiotrophoblast. These morphological changes are associated with a marked induction of CYP19 gene expression. To functionally define genomic regions required for placenta-specific expression, fusion genes containing various amounts of exon I.1 5'-flanking sequence linked to the human growth hormone (hGH) structural gene, as reporter, were introduced into human trophoblast cells in primary monolayer culture and into transgenic mice. Our findings using transfected cells and transgenic mice suggest that sequences between -501 and -42 bp upstream of exon I.1 contain a positive enhancer element(s) that mediates the actions of trophoblast-specific transcription factors, as well as a negative element(s) that binds inhibitory transcription factors in other cell types. Our findings from transgenic studies further indicate that mouse placenta contains the necessary transcription factors required to activate the human CYP19 promoter although mouse placenta does not express endogenous aromatase.