Sleep deprivation disturbs uterine contractility and structure in pregnant rats: role of matrix metalloproteinase 9 and transforming growth factor-β

Sleep deprivation (SD) during pregnancy can impact the delivery procedure, with prolongation of the labor duration. Matrix metalloproteinase-9 (MMP9) and transforming growth factor-β (TGF-β) are regulators of uterine remodeling. Their dysregulation is vital for abnormal placentation and uterine enlargement in complicated pregnancies. Therefore, this study aims to explore the outcome of SD throughout pregnancy on ex vivo uterine contractility, MMP9 and TGF-β, and uterine microscopic structure. A total of 24 pregnant rats were divided into two groups. From the first day of pregnancy, animals were exposed to partial SD/6 h/day. Uterine in vitro contractile responses to oxytocin, acetylcholine, and nifedipine were assessed. Additionally, uterine levels of superoxide dismutase and malondialdehyde and uterine mRNA expression of MMP9, TGF-β, and apoptotic biomarkers were analyzed. The results showed that SD significantly reduced uterine contractile responses to oxytocin and acetylcholine, while it augmented the relaxing effect of nifedipine. In addition, it significantly increased oxidative stress status, MMP9, TGF-β, and apoptotic biomarkers' mRNA expression. All were accompanied by degeneration of endometrial glands, vacuolization with apoptotic nuclei, and increased area% of collagen fibers. Finally, increased uterine MMP9 and TGF-β mRNA expression during SD clarified their potential role in modulating uterine contractility and structure.

Impact of Melatonin on Full-Term Fetal Brain Development and Transforming Growth Factor-β Level in a Rat Model of Preeclampsia

Preeclampsia (PE) is a leading cause of stroke and cognitive impairment in the offspring. Melatonin is involved in the outcome of normal pregnancy. Its receptors are widespread in the embryo. This study aimed to investigate the fetal neuroprotective effect of melatonin in experimentally induced PE. After induction of pregnancy in 18 female rats, they were divided into three equal groups. PE was induced in groups II and III by injection of deoxycorticosterone acetate and drinking isotonic saline. Melatonin was supplied to group III orally (10 mg/kg body weight) throughout pregnancy. Pregnancy was terminated on day 20, and macroanatomical investigation of three fetuses from each pregnant rat and their placentae was performed. Placental and brain homogenates were analyzed for malondialdehyde (MDA), placental growth factor (PLGF), tumor necrosis factor-α (TNF-α), and brain transforming growth factor-β (TGF-β). Histopathological analysis of fetal brain sections was performed. Melatonin improved placental, fetal, and brain weight; significantly reduced fetal death rate; significantly increased PLGF, placental and brain superoxide dismutase, and brain TGF-β; and significantly decreased placental TNF-α and brain MDA. Brain micromorphological study found normal glial cells and neuropil in the melatonin-treated group and a loss of neuronal cell outlines with an accumulation of cellular debris in the untreated group. In conclusion, melatonin approximately showed a neuroprotective activity by managing PE-induced oxidative stress in the placenta and fetal cerebral cortex of rats.

Determining the Diagnostic Utility of Lumbar Punctures in Computed Tomography Negative Suspected Subarachnoid Hemorrhage: A Systematic Review and Meta-analysis

BACKGROUND

While headache is a common neurologic symptom, subarachnoid hemorrhage (SAH) is a rare and potentially catastrophic cause of sudden-onset severe headache. The utility of the imaging modalities and interventional procedures are central to the investigation of the causes of headache; however, they are not without their limitations, risks, and complications.

METHODS

A meta-analysis in accordance with the Preferred Reporting for Systematic Reviews and Meta-analysis guidelines was conducted searching PubMed, EMBASE, and Google Scholar. Patients investigated for suspected subarachnoid hemorrhage (SAH) with a negative computed tomography (CT) and positive lumbar puncture (LP) and final diagnosis of SAH were included. The sensitivity of LP in the context of a negative CT and vsubsequent imaging confirming the cause of SAH (computed tomography angiography, magnetic resonance angiography, digital subtraction angiography [DSA]) was quantified. The pooled data were analyzed using the DerSimonian-Laid random effects model.

RESULTS

Four studies with 2782 patients who presented with headache suspicious for SAH were included with an initial negative CT report and a subsequent LP to rule out SAH. All included studies had an observational prospective cohort design. A combined pooled proportion of 0.383 (0.077, 0.756); 0.086 (0.007, 0.238); and 0.22 (0.04, 0.49) for LP+, DSA+, and DSA/computed tomography angiography+ investigations were estimated with a 95% confidence interval.

CONCLUSIONS

The current clinical workflow of an LP after a negative CT head for a patient presenting with a sudden-onset severe headache is observed to have a high enough proportion to warrant its continued use despite the sensitivity of modern CT scanners of ≥97%.

The Role of Anterior Cervical Discectomy and Fusion on Relieving Axial Neck Pain in Patients With Single-Level Disease: A Systematic Review and Meta-Analysis

STUDY DESIGN

Systematic review and meta-analysis.

OBJECTIVES

This study aims to evaluate the effects of anterior cervical decompression and fusion (ACDF) on axial neck pain in adult patients receiving surgery for myelopathy, radiculopathy, or a combination of both.

METHODS

Two independent reviewers completed a librarian-assisted search of 4 databases. Visual Analogue Scale (VAS) and Neck Disability Index (NDI) scores were extracted preoperatively and at 3, 6, 12, 24, 36, 48, and 48+ months postoperatively for ACDF groups and pooled using a random-effects model.

RESULTS

Of 17 850 eligible studies, 37 were included for analysis, totaling 2138 patients analyzed with VAS and 2477 with NDI score. Individual VAS mean differences were reduced at 6 weeks (-2.5 [95% confidence interval (CI): -3.5 to -1.6]), 3 months (-2.9 [-3.7 to -2.2]), 6 months (-3.2 [-3.9 to -2.6]), 12 months (-3.7 [-4.3 to -3.1]), 24 months (-4.0 [-4.4 to -3.5]), 48 months (-4.6 [-5.5 to -3.8]), and >48 months (-4.7 [-5.8 to -3.6]) follow-up (P < .0001 for all endpoints). Individual NDI mean differences were reduced at 6 weeks (-26.7 [-30.9 to -22.6]), 3 months (-29.8 [-32.7 to -26.8]), 6 months (-31.2 [-35.5 to -26.8)], 12 months (-29.3 [-33.2 to -25.4]), 24 months (-28.9 [-32.6 to -25.2]), 48 months (-33.1 [-37.4 to -28.7]), and >48 months (-37.6 [-45.9 to -29.3]) follow-up (P < .0001 for all endpoints).

CONCLUSIONS

ACDF is associated with a significant reduction in axial neck pain compared with preoperative values in patients being treated specifically for myelopathy or radiculopathy. This influences the preoperative discussions surgeons may have with patients regarding their expectations for surgery. The effects seen are stable over time and represent a clinically significant reduction in axial neck pain.

Correction to: Preservation of olfaction in anterior midline skull base meningiomas: a comprehensive approach

Result is incorrect.

Preservation of olfaction in anterior midline skull base meningiomas: a comprehensive approach

BACKGROUND

Olfaction is an undervalued sense in neurosurgery. Attempted surgical resection of anterior cranial fossa meningiomas puts the olfactory pathway at risk. Preservation of olfaction may increase the postoperative quality of life. Objective assessment of olfaction may inform clinical decision-making and influence the selection of operative approaches for surgical resection.

METHODS

We reviewed all patients who underwent surgical resection for midline anterior skull base meningiomas from July 1, 2014, through December 31, 2017. Patient demographics, tumor size, operative approach, pre- and postoperative deficits, and Simpson grade were collected and analyzed. Postoperative olfaction was assessed by clinical evaluation as well as objective evaluation using the University of Pennsylvania Smell Identification Test (UPSIT).

RESULTS

Twenty-eight patients (10 male, 18 female) were included with an average age of 53.8 years (range 27-80 years). Twenty-six patients underwent craniotomy for resection, while 2 patients had endoscopic approaches. Average tumor volume was 402.1 cm³ (6.6-2507.7 cm³). Preoperatively, five patients (17.8%) presented with olfactory impairment. Objectively, 50% of patients (14/28) consented and completed the UPSIT. The average postoperative UPSIT score was 25.8/40 (9/40-38/40). Two patients not identified on clinical assessment alone demonstrated postoperative olfactory deficit on UPSIT (2/14).

CONCLUSION

There are limited published studies evaluating olfaction in patients who undergo skull-based approaches for anterior fossa meningiomas. Our series showed the highest olfaction preservation rate (87.5%) using a comprehensive strategy and multitude of surgical approaches based on the olfactory function and tumor characteristics.

The Effect of Preoperative Direct Ligation of Ethmoidal Arteries on the Perioperative Outcomes of Large Anterior Skull Base Meningiomas Surgery: A Clinical Study

BACKGROUND

Anterior skull base meningiomas often grow to a large size (≥4 cm) before detection. Their blood supply is mostly provided by the anterior and posterior ethmoidal arteries. Because of their vascularity, intraoperative bleeding can be a challenging prospect that increases the risk of perioperative complications. Preoperative ethmoidal arteries ligation has been used to aid in limiting blood loss. Our objective was to assess the effect of preoperative arterial ligation on the perioperative course of large (≥4 cm) to giant (≥6 cm) anterior skull base meningiomas.

METHODS

We retrospectively searched our database for large anterior skull base meningiomas (≥4 cm). We analyzed differences in intraoperative blood loss, operative time, intraoperative transfusion, and hematologic parameters between patients who did not undergo preoperative ethmoidal arteries ligation (Group 1) and those who did (Group 2).

RESULTS

Average estimated blood loss (EBL) was 825 mL (Group 1) versus 350 mL (Group 2) (P = 0.42), decrease in hemoglobin was 4 g/dL versus 3.2 g/dL (P = 0.53), decrease in hematocrit was 12.4% versus 9.6% (P = 0.64), and average operative time was 656 minutes versus 598 minutes (P = 0.58). EBL per volume yielded a ratio of 10.6 mL/cm³ versus 4.1 mL/cm³ (P = 0.06).

CONCLUSIONS

Ethmoidal arteries ligation may have a benefit in large-to-giant anterior skull base meningiomas surgery. Our results showed a decrease in EBL and lesser decrease in pre- and postoperative hemoglobin and hematocrit levels as compared with cases in which no vascular ligation was performed when corrected for tumor volume.

Spinal Dural Repair: A Canadian Questionnaire

STUDY DESIGN

Questionnaire.

OBJECTIVES

Iatrogenic dural tear is a complication of spinal surgery with significant morbidity and cost to the health care system. The optimal management is unclear, and therefore we aimed to survey current practices among Canadian practitioners.

METHODS

A questionnaire was administered to members of the Canadian Neurological Surgical Society designed to explore methods of closure of iatrogenic durotomy.

RESULTS

Spinal surgeons were surveyed anonymously with a 55% response rate (n = 91). For pinhole-sized tears, there is no agreement in the methods of closure, with a trend toward sealant fixation (36.7%). Medium- and large-sized tears are predominantly closed with sutures and sealant (67% and 80%, respectively). Anterior tears are managed without primary closure (40.2%), or using sealant alone (48%). Posterior tears are treated with a combination of sutures and sealant (73.8%). Nerve root tears are treated with either sealant alone (50%), or sutures and sealant (37.8%). Tisseal is the preferred sealant (79.7%) over alternatives. With the exception of pin-hole sized tears (39.5%) most respondents recommended bed rest for at least 24 hours in the setting of medium (73.2%) and large (89.1%) dural tears.

CONCLUSIONS

This study elucidates the areas of uncertainty with regard to iatrogenic dural tear management. There is disagreement regarding management of anterior and nerve root tears, pinhole-sized tears in any location of the spine, and whether patients should be admitted to hospital or should be on bed rest following a pinhole-sized dural tear. There is a need for a robust comparative research study of dural repair strategies.

Tuberculum Meningioma: Orbitopterional Approach

This is a case of an extensive tuberculum sella meningioma involving the circle of Willis down to the basilar artery that presented with bilateral visual loss worse on the right than left side. A one-piece right orbitopterional approach along the worse eye was used to gain access to the three cranial fossae. The orbitotomy facilitates access to the midline structures and contralateral base of the tumor with minimal brain retraction. Tumor resection is initiated by first identifying the tumor capsule, followed by piecemeal debulking via ultrasonic aspiration. Early decompression of the ipsilateral optic nerve was performed. Gross total resection of the tumor was achieved through multiple windows as follows: prechiasmatic, opticocarotid, and carotid oculomotor. Sharp dissection is performed around critical neurovascular structures to reduce strain and vascular injury. The circle of Willis including the small perforators was completely preserved. Postoperative examination at follow-up demonstrated improvement in vision less on the right side and resolution of postoperative partial third nerve palsy.

The link to the video can be found at: https://youtu.be/XfEh8CjkvA0 .

Sublaminar wire migration into the medulla oblongata: a case report

Atlantoaxial procedures have been developed in an effort to ensure solid C1-C2 fusion. However, techniques that involve sublaminar wiring have the potential for neural structure injury. We present the management of a patient who previously underwent Gallie fusion 10 years ago and is presenting with a dislodged titanium wire that has migrated into the medulla oblongata. A 52-year-old female patient known with rheumatoid arthritis presented with truncal ataxia and food regurgitation 10 years after undergoing a C1-C2 Gallie fusion. A computerized tomography (CT) scan revealed that a wire from her Gallie fusion procedure migrated into the medulla oblongata. The patient underwent foramen magnum decompression with C1 bilateral laminectomy, instrumentation, and removal of a migrated wire. Six months later, a CT scan showed that all occipital screws were pulled out. In the revision surgery, new occipital screws were placed with a resultant significant improvement in patient's gait postoperatively. Wire migration as a differential diagnosis should be considered in patients presenting with neurological dysfunction who underwent surgical treatment with sublaminar wire fusion techniques.

Endoscopic Third Ventriculostomy: Outcome Analysis of an Anterior Entry Point

BACKGROUND

Endoscopic third ventriculostomy (ETV) is a safe and effective treatment for hydrocephalus. An entry point located 4 cm anterior to the coronal suture, 3 cm anterior to Kocher point, and approximately 9 cm from the pupil at the midpupillary line has been used successfully for the last 20 years in our center. We aimed to evaluate this alternative anterior entry point routinely used for ETV, with or without concurrent endoscopic biopsy.

METHODS

Patients undergoing this proposed entry point were examined to evaluate its safety and efficacy. Factors such as patients' age, sex, hydrocephalus etiology, tumor location and pathology, and complication rate were examined through regression analyses to evaluate their impact on tumor biopsy and ETV success rates, and the need for subsequent ventricular shunting.

RESULTS

A total of 131 patients were included in the study. ETV was successful in 125 (95.4%) patients. Of these, 26 (19.8%) patients required a biopsy, which was successful in 21 (80.8%) cases. A complication was observed in 10 (7.6%) patients, with a trend toward complications occurring after ETV failure. There was no association between ETV success rate and patients' age (P = 0.5) or sex (P = 0.99).

CONCLUSIONS

The anterior entry point is a safe and effective method for ETV, especially when considering concurrent ventricular tumor biopsy. This entry point may be considered as a more minimally invasive procedure when using rigid endoscopy and may also eliminate the need for a flexible scope.

Facial Nerve Outcome after Vestibular Schwannoma Resection: A Comparative Meta-Analysis of Endoscopic versus Open Retrosigmoid Approach

The minimal access retrosigmoid endoscopic approach to vestibular schwannoma (VS) resection has been used with promising results. However, it has not been compared with the standard open approach in the literature. We performed a meta-analysis review for all articles describing both approaches for VS from 1996 to 2011. We found 1861 articles. After review and discussion, we narrowed our study to 25 articles, 4 endoscopic and 21 open. The total number of patients was 3026 for open and 790 for endoscopic. The mean tumor sizes in the open and endoscopic series were 2.5 cm and 2.7 cm, respectively. Good facial nerve outcome was achieved in 67% of the open series patients and in 94% of the endoscopic series patients. Other outcomes in the open and endoscopic series were the following: gross total resection, 91% versus 97%; functional hearing, 22.6% versus 46%; wound infection, 1.3% versus 2.6%; and recurrence, 5.4% versus 2.2%. We acknowledge the limitations of our study, but we can state that the endoscopic approach is not inferior to the standard open approach. In expert hands the endoscopic approach can offer as good a result as the open, with potential benefits such as less pain and a shorter length of stay in the hospital. There is a need for more controlled studies for a definitive comparison.

Cervical spine clearance in obtunded patients after blunt traumatic injury: a systematic review

BACKGROUND

Cervical spine clearance protocols are controversial for unconscious patients after blunt traumatic injury and negative findings on computed tomography (CT).

PURPOSE

To review evidence about the utility of different cervical spine clearance protocols in excluding significant cervical spine injury after negative CT results in obtunded adults with blunt traumatic injury.

DATA SOURCES

MEDLINE, EMBASE, CINAHL, Google Scholar, and the Cochrane Library were searched from January 2000 through November 2014.

STUDY SELECTION

English-language studies that examined patients with negative CT results having confirmatory routine testing with magnetic resonance imaging (MRI), dynamic radiography, or clinical examination and that reported outcome measures of missed cervical spine injury, need for operative stabilization, or prolonged use of cervical collars.

DATA EXTRACTION

Independent reviewers evaluated the quality of studies and abstracted the data according to a predefined protocol.

DATA SYNTHESIS

Of 28 observational studies (3627 patients) that met eligibility criteria, 7 were prospective studies (1686 patients) with low risk of bias and well-interpreted, high-quality CT scans. These 7 studies showed that 0% of significant injuries were missed after negative CT results. The overall studies using confirmatory routine testing with MRI showed incidence rates of 0% to 1.5% for cervical spine instability (16 studies; 1799 patients), 0% to 7.3% for need for operative fixation (17 studies; 1555 patients), and 0% to 29.5% for prolonged collar use (16 studies; 1453 patients).

LIMITATIONS

Most studies were retrospective. Approaches to management of soft tissue changes with collars varied markedly.

CONCLUSION

Cervical spine clearance in obtunded adults after blunt traumatic injury with negative results from a well-interpreted, high-quality CT scan is probably a safe and efficient practice.

PRIMARY FUNDING SOURCE

None.

Surgical outcomes and natural history of intramedullary spinal cord cavernous malformations: a single-center series and meta-analysis of individual patient data

Object

Information pertaining to the natural history of intramedullary spinal cord cavernous malformations (ISCCMs) and patient outcomes after surgery is scarce. To evaluate factors associated with favorable outcomes for patients with surgically and conservatively managed ISCCMs, the authors performed a systematic review and metaanalysis of the literature. In addition, they included their single-center series of ISCCMs.

Methods

The authors searched MEDLINE, EMBASE, CINAHL, Google Scholar, and The Cochrane Library for studies published through June 2013 that reported cases of ISCCMs. Data from all eligible studies were used to examine the epidemiology, clinical features, and neurological outcomes of patients with surgically managed and conservatively treated ISCCMs. To evaluate several variables as predictors of favorable neurological outcomes, the authors conducted a meta-analysis of individual patient data and performed univariate and multivariate logistic regression analyses. Variables included patient age, patient sex, lesion spinal level, lesion size, cerebral cavernomas, family history of cavernous malformations, clinical course, presenting symptoms, treatment strategy (operative or conservative), symptom duration, surgical approach, spinal location, and extent of resection. In addition, they performed a meta-analysis to determine a pooled estimate of the annual hemorrhage rate of ISCCMs.

Results

Eligibility criteria were met by 40 studies, totaling 632 patients, including the authors' institutional series of 24 patients. Mean patient age was 39.1 years (range 2–80 years), and the male-to-female ratio was 1.1:1. Spinal levels of cavernomas were cervical (38%), cervicothoracic (2.4%), thoracic (55.2%), thoracolumbar (0.6%), lumbar (2.1%), and conus medullaris (1.7%). Average cavernoma size was 9.2 mm. Associated cerebral cavernomas occurred in 16.5% of patients, and a family history of cavernous malformation was found for 11.9% of evaluated patients. Clinical course was acute with stepwise progression for 45.4% of patients and slowly progressive for 54.6%. Symptoms were motor (60.5%), sensory (57.8%), pain (33.8%), bladder and/or bowel (23.6%), respiratory distress (0.5%), or absent (asymptomatic; 0.9%). The calculated pooled annual rate of hemorrhage was 2.1% (95% CI 1.3%–3.3%). Most (89.9%) patients underwent resection, and 10.1% underwent conservative management (observation). Outcomes were better for those who underwent resection than for those who underwent conservative management (OR 2.79, 95% CI 1.46–5.33, p = 0.002). A positive correlation with improved neurological outcomes was found for resection within 3 months of symptom onset (OR 2.11, 95% CI 1.31–3.41, p = 0.002), hemilaminectomy approach (OR 3.20, 95% CI 1.16–8.86, p = 0.03), and gross-total resection (OR 3.61, 95% CI 1.24–10.52, p = 0.02). Better outcomes were predicted by an acute clinical course (OR 1.72, 95% CI 1.10–2.68, p = 0.02) and motor symptoms (OR 1.76, 95% CI 1.08–2.86, p = 0.02); poor neurological recovery was predicted by sensory symptoms (OR 0.58, 95% CI 0.35–0.98, p = 0.04). Rates of neurological improvement after resection were no higher for patients with superficial ISCCMs than for those with deep-seated ISCCMs (OR 1.36, 95% CI 0.71–2.60, p = 0.36).

Conclusions

Intramedullary spinal cord cavernous malformations tend to be clinically progressive. The authors' findings support an operative management plan for patients with a symptomatic ISCCM. Surgical goals include gross-total resection through a more minimally invasive hemilaminectomy approach within 3 months of presentation.

Novel method to produce 109Cd via proton irradiation of electroplated silver on a gold-coated copper backing

Silver electrodeposition on gold layer was carried out by the alkaline plating baths to produce cadmium-109 via natAg(p, n)109Cd nuclear reaction. Gold was electrodeposited on copper backing in the beginning; the bath content consisted of 17.7 gl−1 KCN, 6.6 gl−1 Au, 6.6 gl−1 K2CO3 and 3.3 gl−1 Na2CO3 while acidity and temperature of the bath adjusted at 10 and 45°C respectively. A DC current density of ca 2.08 mA · cm−2 was used to electroplate gold. A gold layer of 63 μm thickness with suitable morphology was obtained after the electrodeposition. Silver was electrodeposited on the gold layer with 100% efficiency using a cyanide bath. The silver target was irradiated with 15 MeV proton beam and current of 150 μA; the 109Cd production yield was 2.0 μCi/μA · h (0.074 MBq/μA · h). The target material was dissolved by 14 M HNO3. Cadmium-109 in the dissolved target solution was separated from silver by evaporation process. Cadmium recovered with more than 88% efficiency involved non-detected silver impurity.

Efficacy of hepatitis B vaccine in a cohortcommunity-based study in Riyadh and Hail regions of Saudi Arabia

BACKGROUND

Saudi Arabia used to be hyperendemic for HBV infection. Most of infection occurs in early life. HBV vaccine was, therefore, introduced in 1989 as the seventh primary immunogen of the EPI Program. This study is conducted to evaluate the efficacy of this program in Riyadh and Hail Regions.

METHOD AND PATIENTS

A cohort follow-up study of children from Riyadh and Hail, who had been vaccinated in 1989, evaluated in 1991 and tested for HBV markers six years later.

RESULTS

The files of 303 children from Riyadh and Hail, who were investigated in 1991 retrieved and only 119, were available for testing. Fifty percent of the children have still a protective anti-HBs tittre. One vaccinated child was found to be positive for HBsAg. According to this study, the efficacy rate against HBsAg carriage is 88%.

CONCLUSION

This study demonstrates the tremendous effect of HB vaccine on the HBV infection of Saudi children in these two regions.

Specific targeting of folate-dendrimer MRI contrast agents to the high affinity folate receptor expressed in ovarian tumor xenografts

The need to develop target-specific MRI contrast agents to aid in disease characterization remains highly essential. In this study, we present a generation four polyamidoamine (PAMAM) folate-dendrimer that specifically targets the high affinity folate receptor (hFR) overexpressed on more than 80% of ovarian tumors. In vitro, mouse erythroleukemia cells expressing the hFR bind the radiolabeled folate-dendrimer chelate resulting in over 2700% increase in binding compared with untreated cells. The binding was inhibited by free folic acid to levels observed on folate-receptor-negative cells. In vivo, ovarian tumor xenografts resulted in a 33% contrast enhancement, following the folate-dendrimer chelate administration, that was significantly different compared with results obtained with a non-specific, extracellular fluid space agent, Gd-HP-DO3A. In addition, this contrast enhancement was absent in saline-treated animals, folate-receptor-negative tumors, and was inhibited by free folic acid. Results suggest that a macromolecular, dendrimeric MRI agent with high molecular relaxivities (1646 mM(-1) s(-1)) can be used in specifically targeting the hFR on tumor cells and ovarian tumors.

Development of a tumor-targeting MR contrast agent using the high-affinity folate receptor: work in progress

RATIONALE AND OBJECTIVES

Macromolecular contrast agents enhance tumors by means of active or passive targeting. Active targeting requires surface receptors. Many tumors of epithelial origin express the high-affinity folate receptor (hFR), including ovarian tumors. The objective of this research was to enhance tumors that express hFR using macromolecular contrast agents conjugated to folic acid.

METHODS

The authors prepared a folate-conjugated dendrimer polychelate by attaching folic acid to a fourth-generation ammonia-core polyamidoamine dendrimer. The remaining amines were reacted with 2-(4-isothiocyanatobenzyl)-6-methyldiethylenetriamine pentaacetic acid. Relaxivity measurements (r1 and r2) and MRI were conducted at 4.7 T.

RESULTS

The dendrimer r2 exceeded that of Gd-HP-DO3A by 8.2 times at 4.7 T. It increased the tumor percentage contrast enhancement, 24 hours after injection, of T2-weighted images by 33%.

CONCLUSIONS

This new agent accumulates in tumors expressing hFR. These results do not differentiate between active and passive targeting mechanisms. Receptor-negative tumors suggest a mechanism other than a nonspecific blood pool effect.