Biomedical subjects

J Bruner

Publications and source records attributed to J Bruner.

At least 19 recordsLinked to original sources

PubMed2003

Prenatal management of gastroschisis: the place of the amnioexchange procedure.

Gastroschisis is a malformation of the anterior abdominal wall that consists of a right paraumbilical defect with bowel loops bathed in the amniotic fluid. The survival rate is now greater than 90% and the prognosis relies mainly on morbidity attributable to bowel dysfunction. Recent research has examined gastrointestinal waste present in amniotic fluid that induces bowel toxicity and an inflammatory process. The amnioexchange procedure (changing the amniotic fluid regularly) involves a new therapeutic approach: reducing bowel injuries in the fetuses. This article shows that there is an inflammatory reaction in human gastroschisis and in the authors' model, and that the clinical and biological data plead for the practice of amnioexchange in human beings. A randomized, controlled study is now needed.

Amniotic Fluid↗

PubMed2002

Phase II study of accelerated fractionation radiation therapy with carboplatin followed by PCV chemotherapy for the treatment of anaplastic gliomas.

PURPOSE: To conduct a Phase II one-arm study to evaluate the long-term efficacy and safety of accelerated fractionated radiotherapy combined with i.v. carboplatin for patients with previously untreated anaplastic gliomas. METHODS AND MATERIALS: Between 1988 and 1992, 90 patients received 1.9-2.0-Gy radiation 3 times a day with 2-h infusions of 33 g/m(2) carboplatin for two 5-day cycles separated by 2 weeks. After radiotherapy, patients received procarbazine, lomustine (CCNU), and vincristine (PCV) for 1 year or until the tumor progressed. RESULTS: Ninety patients were evaluable for analysis. Histologically, 69 had anaplastic astrocytoma; 14, anaplastic oligoastrocytoma; and 7, anaplastic oligodendroglioma. Gross total resection was performed in 20 (22%), subtotal resection in 45 (50%), and biopsy in 25 (28%); reoperation (total or subtotal resection) was performed in 50 (56%) patients. A multivariate analysis showed that a younger age (p = 0.026), Karnofsky performance score (KPS; p = 0.009), and brain necrosis (p = 0.0002) were predictive of a better survival. Results from analysis of extent of surgery (biopsy, subtotal resection, gross total resection) approached significance (p = 0.058). Radiation dose, irradiated tumor volume, and techniques used (boost and fields) were not significant variables. The median survival (MS) of all anaplastic glioma patients was 28.1 months; for anaplastic astrocytoma patients, MS was 28.7 months and 40.8 months for the combined anaplastic oligodendroglioma/oligoastrocytoma patients. Long-term survival occurred in 25% of anaplastic glioma patients who were alive 8.6 years after treatment was initiated. Treatment-induced necrosis was documented by surgery or autopsy in 19 (21%) patients; 21 (23%) had a mixed pattern of necrosis and tumor; and an additional 13 (14%) patients who did not have surgical or autopsy demonstration of predominant radiation necrosis had magnetic resonance imaging (MRI) evidence of radiation necrosis. Serious clinical neurologic deterioration and/or dementia requiring full-time caregiver attention were observed in 9 (10%) patients. CONCLUSION: When comparable selection criteria are applied, the rate of MS in this study is inferior to results attainable with current radiation and chemotherapy approaches, although the rates of long-term survival are comparable. Theoretically, patients failing therapy and dying earlier than anticipated may be because of excessive central nervous system (CNS) toxicity resulting from the combination of accelerated fractionated irradiation, intensive carboplatin chemotherapy before each radiation fraction, and postirradiation PCV chemotherapy. On the other hand, patients with treatment-induced necrosis survived significantly longer than patients who did not demonstrate MRI or histologic evidence of necrosis (MS, 106 months vs. 18-33 months).

Adolescent↗

PubMed2001

Multicenter phase II trial of temozolomide in patients with glioblastoma multiforme at first relapse.

BACKGROUND: Recurrent glioblastoma multiforme (GBM) is resistant to most therapeutic endeavors, with low response rates and survival rarely exceeding six months. There are no clearly established chemotherapeutic regimens and the aim of treatment is palliation with improvement in the quality of life. PATIENTS AND METHODS: We report an open-label, uncontrolled, multicenter phase II trial of temozolomide in 138 patients (intent-to-treat [ITT] population) with glioblastoma multiforme at first relapse and a Karnofsky performance status (KPS) > or = 70. One hundred twenty-eight patients were histologically confirmed with GBM or gliosarcoma (GS) by independent central review. Chemotherapy-naïve patients were treated with temozolomide 200 mg/m2/day orally for the first five days of a 28-day cycle. Patients previously treated with nitrosourea-containing adjuvant chemotherapy received 150 mg/m2/day for the first five days of a 28-day cycle. In the absence of grade 3 or 4 toxicity, patients on the 150 mg/m2 dose schedule were eligible for a 200 mg/m2 dose on the next cycle. RESULTS: The primary endpoint was six-month progression-free survival assessed with strict radiological and clinical criteria. Secondary endpoints included radiological response and Health-related Quality of Life (HQL). Progression-free survival at six months was 18% (95% confidence interval (CI): 11%-26%) for the eligible-histology population. Median progression-free survival and median overall survival were 2.1 months and 5.4 months, respectively. The six-month survival rate was 46%. The objective response rate (complete response and partial response) determined by independent central review of gadolinium-enhanced magnetic resonance imaging (MRI) scans was 8% for both the ITT and eligible-histology populations, with an additional 43% and 45% of patients, respectively, having stable disease (SD). Objectively assessed response and maintenance of a progression-free status were both associated with HQL benefits (characterized by improvements over baseline in HQL domains). Temozolomide had an acceptable safety profile, with only 9% of therapy cycles requiring a dose reduction due to thrombocytopenia. There was no evidence of cumulative hematologic toxicity. CONCLUSIONS: Temozolomide demonstrated modest clinical efficacy, with an acceptable safety profile and measurable improvement in quality of life in patients with recurrent GBM. The use of this drug should be explored further in an adjuvant setting and in combination with other agents.

Adult↗

PubMed2000

Effect of brefeldin A on acetylcholine release from glioma C6BU-1 cells.

The glial C6BU-1 cell line, loaded with acetylcholine can release this neurotransmitter. This study was aimed at determining whether disruption of the Golgi-vesicular traffic by brefeldin A would change the acetylcholine release from these cells and affect proteins involved in transmitter release like the 15 kDa proteolipid, common to V-ATPase and mediatophore. Cells were treated for 24 or 36 h with brefeldin A (35.7 microM). The observed changes in cell morphology were typical for brefeldin A treated cells in which protein membrane supply has been stopped. Inhibition of membrane protein supply was confirmed in the present work. Moreover, the 15 kDa proteolipid also decayed to a very low level in the cell membrane fraction. The release of acetylcholine evoked by a calcium challenge and a calcium ionophore, or by electrical pulses decreased markedly. The life time of the release mechanism was of the order of 36 h and half decayed in 24 h. In addition, the electrically evoked release became much shorter. Considering that C6BU-1 cells are able to release large amounts of ACh and their membranes contain a sizeable amount of the 15 kDa proteolipid, these results suggest that this proteolipid may be one of the proteins forming the membrane complex responsible for transmitter release, at least in these cells.

Acetylcholine↗

PubMed2000

A phase II study of temozolomide vs. procarbazine in patients with glioblastoma multiforme at first relapse.

A randomized, multicentre, open-label, phase II study compared temozolomide (TMZ), an oral second-generation alkylating agent, and procarbazine (PCB) in 225 patients with glioblastoma multiforme at first relapse. Primary objectives were to determine progression-free survival (PFS) at 6 months and safety for TMZ and PCB in adult patients who failed conventional treatment. Secondary objectives were to assess overall survival and health-related quality of life (HRQL). TMZ was given orally at 200 mg/m(2)/day or 150 mg/m(2)/day (prior chemotherapy) for 5 days, repeated every 28 days. PCB was given orally at 150 mg/m(2)/day or 125 mg/m(2)/day (prior chemotherapy) for 28 days, repeated every 56 days. HRQL was assessed using the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire (EORTC QLQ-C30 [+3]) and the Brain Cancer Module 20 (BCM20). The 6-month PFS rate for patients who received TMZ was 21%, which met the protocol objective. The 6-month PFS rate for those who received PCB was 8% (P = 0.008, for the comparison). Overall PFS significantly improved with TMZ, with a median PFS of 12.4 weeks in the TMZ group and 8.32 weeks in the PCB group (P = 0.0063). The 6-month overall survival rate for TMZ patients was 60% vs. 44% for PCB patients (P = 0.019). Freedom from disease progression was associated with maintenance of HRQL, regardless of treatment received. TMZ had an acceptable safety profile; most adverse events were mild or moderate in severity.

Adult↗

PubMed2000

Diet- or warfarin-induced vitamin K insufficiency elevates circulating undercarboxylated osteocalcin without altering skeletal status in growing female rats.

To further characterize the skeletal role of vitamin K (K), markers of bone turnover, density, and strength were evaluated in rats with diet- or warfarin (W)-induced K insufficiency. One hundred two, 7-week-old, female rats were randomly assigned to low K (phylloquinone [K1], 20 microg/kg diet), control K (K1, 1300 microg/kg diet), low-dose W (W, 1.5 mg/kg control diet), or high-dose W plus K (W/K1, 10/100 mg/kg diet). Femur bone mineral content (BMC) and bone mineral density (BMD), plasma prothrombin time (PT) and prothrombin concentration (PC), and serum total alkaline phosphatase (ALP) and skeletal alkaline phosphatase (sALP) were measured at baseline and days 20, 40, 60, and 80. Serum total osteocalcin (OC) and undercarboxylated osteocalcin (ucOC) and femur length (FL) were measured at baseline and day 80. Left femur OC was measured and biomechanical testing of the right femur and third lumbar vertebral body was performed at day 80. Low dietary K elevated circulating ucOC (17% higher than control; p < 0.0001) at day 80. Furthermore, in both W groups, essentially all circulating OC was undercarboxylated and femur OC was lower than control (p < 0.0001). However, there was no change in femur percent ucOC, suggesting deposition of less newly synthesized OC. No between group differences were observed in PT, ALP, sALP, FL, BMC, BMD, or bone strength. In conclusion, skeletal K insufficiency can be induced by W or diet manipulation. This does not hinder peak bone mass attainment in female rats; however, W causes less newly synthesized OC to be deposited in bone.

Absorptiometry, Photon↗

PubMed2000

The urodynamic profile of myelodysplasia in childhood with spinal closure during gestation.

PURPOSE: Spinal dysraphism is the most common cause of neurogenic bladder dysfunction in newborns. Urodynamic findings in these patients include uninhibited bladder contractions, bladder areflexia, decreased compliance and detrusor-sphincter dyssynergia. Early urodynamic studies are recommended for spina bifida to help identify bladder characteristics that may cause a risk of upper tract deterioration. We recently evaluated a new early type of intervention involving closure of the neural tube defect during gestation in 25 patients at our institution. We hypothesize that this procedure results in decreased exposure of the spinal cord to amniotic fluid, which may improve neurological function. To date we have evaluated 16 of the 25 patients with video urodynamics. We compared the results to those in the literature on patients with myelomeningocele and without prenatal intervention. MATERIALS AND METHODS: We performed urodynamic testing in 16 patients with a mean age of 6.5 months, including cystometrography, fluoroscopic evaluation of filling and voiding, pelvic floor electromyography and post-void residual urine measurement. In addition, we retrospectively reviewed renal ultrasound, voiding cystourethrography, catheterization need, number of urinary tract infections and medication in these cases. RESULTS: Uninhibited detrusor contractions and an areflexic bladder were identified in 6% and 43% of patients, respectively, while 19% had decreased compliance and 75% had leak point pressure greater than 40 cm. water. Mean bladder capacity was 40 cc and 31% of patients had much lower capacity than expected for age. Previous renal ultrasound and voiding cystourethrography showed evidence of upper tract dilatation and reflux in 2 cases, respectively. Intermittent catheterization and anticholinergic therapy were required by 1 patient each and 1 had a significant urinary tract infection. CONCLUSIONS: Urodynamic findings in this population are comparable to those previously reported in the literature in patients with spina bifida without prenatal closure of the spinal defect. The lower incidence of urinary tract infection and reflux in our study probably represents more aggressive early urological management rather than neurological improvement. These urodynamic studies were performed early in life and future evaluation may ultimately reveal improved bladder function compared with that in others with myelodysplasia. However, at this time we recommend that patients who undergo spinal cord defect closure during gestation be evaluated and treated in the same manner as those with myelomeningocele but without fetal intervention.

Child↗

PubMed1999

Central region-of-interest analysis of lumbar spine densitometry demonstrates lower bone mass in older rhesus monkeys.

Osteoarthritis (OA) spuriously elevates spine bone mineral density (BMD) as measured by dual-energy X-ray absorptiometry (DXA). This study documents spinal OA prevalence in adult female rhesus monkeys, and evaluates a custom central region-of-interest (CROI) analysis technique designed to minimize OA effects on BMD measurement. Lumbar spine radiographs were obtained on 71 animals, age 10-37 years. OA degree was blindly scored as none, minimal, or moderate/severe. Moderate/severe OA was not observed before age 19, but was present in 66% of older animals. Subsequently, lumbar spine (L2-4) BMD was determined by standard DXA analysis and manual placement of 0.92 cm2 CROIs in two groups of female rhesus monkeys. One group (eight control, eight postovariectomy, ages 10-19 years) was assessed longitudinally, the second (n = 90, ages 10-37) cross-sectionally. Measured bone loss following ovariectomy (8.1% standard analysis, 11.5 % CROI) was comparable with both techniques. By contrast, CROI demonstrated lower bone mass with age (p < 0.0001), whereas only a trend (p = 0.06) was observed with standard analysis. When World Health Organization criteria were applied, 42% of animals > or = age 19 years were classified as osteopenic/osteoporotic by standard analysis compared with 67% by CROI. All "normal" animals reclassified as osteopenic/osteoporotic by CROI had OA. In conclusion, female rhesus monkeys often develop spinal OA with advancing age. CROI analysis demonstrated lower bone density in older monkeys and was as sensitive to estrogen-depletion bone loss as standard methodology. This suggests that alternative analysis techniques, such as CROI, may be more appropriate to evaluate bone density in nonhuman primates, and potentially in people.

Absorptiometry, Photon↗

PubMed1999

Receptor potentials and electrical properties of nonspiking stretch-receptive neurons in the sand crab Emerita analoga (Anomura, Hippidae).

Receptor potentials and electrical properties of nonspiking stretch-receptive neurons in the sand crab Emerita analoga (Anomura, Hippidae). Four nonspiking, monopolar neurons with central somata and large peripheral dendrites constitute the sole innervation of the telson-uropod elastic strand stretch receptor in Emerita analoga. We characterized their responses to stretch and current injection, using two-electrode current clamp, in intact cells and in two types of isolated peripheral dendritic segments, one that included and one that excluded the dendritic termini (mechanosensory membrane). The membrane potentials of intact cells at rest (mean +/- SD: -57 +/- 4. 4 mV, n = 30), recorded in peripheral or neuropil processes, are similar to the membrane potentials of isolated dendritic segments and always less negative than membrane potentials of motoneurons and interneurons recorded in the same preparations. Ion substitution experiments indicate that the membrane potential is influenced strongly by Na+ conductance, probably localized in the mechanotransducing terminals within the elastic strand. The form of the receptor potential in response to ramp-hold-release stretch remains the same as stretch amplitude is varied and is not dependent on initial membrane potential (-70 to -30 mV) or recording site: initial depolarization (slope follows ramp of applied stretch), terminated by rapid, partial repolarization to a plateau (delayed depolarization) that is intermediate between the peak depolarization and the initial potential and sustained for the duration of the stretch. Responses to depolarizing current pulses are similar to stretch-evoked receptor potentials, except for small amplitude stimuli: an initial peak occurs only in response to stretch and probably reflects elastic recoil of the extracellular matrix surrounding the dendritic terminals. The rapid, partial repolarization depends on holding potential and is abolished by 4-aminopyridine (4-AP; 10 mM), implicating a fast-activating, fast-inactivating K+ conductance; TEA (60 mM) abolishes the remaining slow repolarization to the plateau. In intact cells, but not dendritic segments, regenerative depolarizations can arise in response to stretch or depolarizing current pulses; they are reduced by CdCl2 (10 microM) in the saline containing TEA and 4-AP and probably reflect current spread from Ca2+ influx at presynaptic terminals in the ganglion. We found no evidence for other voltage-activated conductances. Unlike morphologically similar "nonspiking" thoracic receptors of other species, E. analoga's nonspiking neurons are electrically compact and do not boost the analogue afferent signal by voltage-activated inward currents. The most prominent (only?) voltage-activated extra-ganglionic conductances are for potassium; by reducing the slope of the stretch-plateau depolarization curve, they extend each neuron's functional range to the full range of sensitivity of the receptor.

4-Aminopyridine↗

PubMed1999

Multicenter phase II trial of temozolomide in patients with anaplastic astrocytoma or anaplastic oligoastrocytoma at first relapse. Temodal Brain Tumor Group.

PURPOSE: To determine the antitumor efficacy and safety profile of temozolomide in patients with malignant astrocytoma at first relapse. PATIENTS AND METHODS: This open-label, multicenter, phase II trial enrolled 162 patients (intent-to-treat [ITT] population). After central histologic review, 111 patients were confirmed to have had an anaplastic astrocytoma (AA) or anaplastic mixed oligoastrocytoma. Chemotherapy-naive patients were treated with temozolomide 200 mg/m(2)/d. Patients previously treated with chemotherapy received temozolomide 150 mg/m(2)/d; the dose could be increased to 200 mg/m(2)/d in the absence of grade 3/4 toxicity. Therapy was administered orally on the first 5 days of a 28-day cycle. RESULTS: Progression-free survival (PFS) at 6 months, the primary protocol end point, was 46% (95% confidence interval, 38% to 54%). The median PFS was 5.4 months, and PFS at 12 months was 24%. The median overall survival was 13.6 months, and the 6- and 12-month survival rates were 75% and 56%, respectively. The objective response rate determined by independent central review of gadolinium-enhanced magnetic resonance imaging scans of the ITT population was 35% (8% complete response [CR], 27% partial response [PR]), with an additional 26% of patients with stable disease (SD). The median PFS for patients with SD was 4.4 months, with 33% progression-free at 6 months. Maintenance of progression-free status and objectively assessed response (CR/PR/SD) were both associated with health-related quality-of-life (HQL) benefits. Adverse events were mild to moderate, with hematologic side effects occurring in less than 10% of patients. CONCLUSION: Temozolomide demonstrated good single-agent activity, an acceptable safety profile, and documented HQL benefits in patients with recurrent AA.

Adult↗

PubMed1998

Pediatric oligodendrogliomas.

Pediatric oligodendrogliomas are infrequently occurring brain tumors and frequently thought of as benign. The literature examining treatment and outcome in this select population is sparse. A retrospective analysis of pediatric oligodendrogliomas treated at MD Anderson Cancer Center between 1973 and 1992 was performed. Oligodendrogliomas were histologically graded according to the method of Smith. Survival data were estimated with Kaplan-Meier curves. Mean follow-up was 39.7 months. Nineteen children had histologically verified oligodendrogliomas and mixed oligodendroglioma/astrocytoma (M:F = 11:8; age range 1-18 years, mean = 13.1). Presenting symptoms included seizures (n = 10), headache (n = 3), visual field defects (n = 2), weakness (n = 2), cranial nerve palsy (n = 1) and decreased school performance (n = 1). All patients underwent craniotomy: 13 subtotal resections, 5 gross total resections and 1 biopsy. Twelve children had adjuvant therapy including radiation (n = 12), chemotherapy (n = 5) or both (n = 5). The 5-year survival was 65%. Seizure frequency was reduced in 30%. Children with oligodendrogliomas do not have a benign course, but younger children (<12 years) have a better prognosis. Histologic classification correlates with survival. Completeness of resection was not found to be a factor relating to survival. No conclusions can be drawn concerning adjuvant therapy because of selection bias.

Adolescent↗

PubMed1998

Zoledronate prevents the development of absolute osteopenia following ovariectomy in adult rhesus monkeys.

This study assessed effects of the bisphosphonate zoledronate (ZLN) on bone density and biochemical markers of bone turnover in ovariectomized (OVX) adult female rhesus monkeys. Forty monkeys were randomly assigned to one control or four OVX groups. The control and one OVX group received saline, and the other three OVX groups received ZLN (0.5, 2.5, or 12.5 microg/kg) by a single weekly subcutaneous injection for 69 weeks. Bone mass of the total body (TB), lumbar spine (LS), distal and central radius (dual-energy X-ray absorptiometry), and skeletal turnover markers were measured at baseline and at 13, 26, 39, 52, and 69 weeks of treatment. Increased skeletal turnover and decreased bone mass (LS and TB) were demonstrable by 13 weeks post-OVX. Maximal bone loss (7-8%) at these sites occurred by 39 weeks after OVX and persisted for the study duration. Long-term ZLN treatment was well tolerated and prevented increased skeletal turnover and bone loss in a dose-dependent fashion. Progressive turnover suppression was not observed with any ZLN dose. In conclusion, after OVX, adult rhesus monkeys develop persistent increased bone turnover and absolute osteopenia of the LS and TB, making them an outstanding model of skeletal behavior in perimenopausal women. These OVX-related skeletal changes are dose-dependently blocked by ZLN.

Absorptiometry, Photon↗

PubMed1997

MOPP chemotherapy without irradiation as primary postsurgical therapy for brain tumors in infants and young children.

Infants and young children who have brain tumors have a poor rate of survival and high treatment associated morbidity. A trial of mechlorethamine, vincristine (oncovin), procarbazine, and prednisone (MOPP) was performed to test the hypothesis that replacing radiotherapy with chemotherapy would improve survival and decrease long term morbidity of infants who have brain tumors. Between 1976 and 1988, 17 consecutive children less than 36 months old when diagnosed with medulloblastoma or ependymoma were treated with MOPP chemotherapy as primary therapy following surgical excision or biopsy of the tumor. Radiotherapy was reserved for recurrent disease. Ten of 17 children have survived without evidence of disease: medulloblastoma eight of 12 with median survival time of 10.6 years (range, 6.2 to 15.2 yrs); and ependymoma, 2 of 5 (at 13.0 and 16.0 yrs). Four of the 10 children with medulloblastoma and ependymoma who relapsed are now disease free at 7.5, 11.7, 12.2 and 13.5 yrs post relapse after receiving salvage therapy with cisplatin (n = 1) or irradiation (n = 3). All relapses occurred within 26 months of diagnosis. Data on growth demonstrated height less than the 5th percentile in all children who received cranial irradiation compared to 25 to 95th percentile for nonirradiated children. Intellectual ability for the group who did not require radiation was within normal range (mean IQ 100.1) and stable across annual assessments. Those who required radiation had lower IOs which continued to decline over time (mean IQ 85 at mean age of 5.8 years, declining to 63 at 10 years). In young children with brain tumors, primary chemotherapy with MOPP, omitting radiotherapy, provides improved neurodevelopmental outcome and survival.

Antineoplastic Combined Chemotherapy Protocols↗

PubMed1996

Validation of an immunoassay for canine thyroid-stimulating hormone and changes in serum concentration following induction of hypothyroidism in dogs.

OBJECTIVE: To validate a new immunoradiometric assay for canine thyroid-stimulating hormone (cTSH) and to document changes in serum cTSH concentration during induction of hypothyroidism in dogs. ANIMALS: Six healthy adult male Beagles. PROCEDURE: Sensitivity, specificity, precision, and accuracy of the cTSH assay were evaluated in vitro. Hypothyroidism was induced in dogs by i.v. administration of sodium iodide I 131 solution. Subsequently, L-thyroxine was administered orally to normalize serum thyroxine concentrations. RESULTS: The cTSH assay appeared to be specific and was sufficiently sensitive to detect cTSH in the serum of these dogs prior to induction of hypothyroidism. There was a 35-fold increase in mean serum cTSH concentration following induction of hypothyroidism, and 35 days after initiation of thyroid replacement therapy, mean serum cTSH concentration was not significantly greater than mean baseline value. CLINICAL IMPLICATIONS: Assay of serum cTSH is likely to prove helpful in the differential diagnosis of primary, secondary, and tertiary hypothyroidism in dogs, and in monitoring response to thyroid hormone replacement treatment.

Animals↗

PubMed1996

Adenovirus-mediated p16/CDKN2 gene transfer induces growth arrest and modifies the transformed phenotype of glioma cells.

The p16 (MTS1/CDKN2) gene localized at the 9p21 chromosomal region encodes for a cell cycle inhibitor protein and is altered in many human cancers. The frequency of p16 alterations in gliomas exceeds 50%. To restore the missing wild-type p16 gene efficiently in glioma cells an adenovirus vector carrying the full length coding sequence of the wild-type p16 cDNA, Ad5RSV-p16, was constructed. Three human glioma cell lines, U251 MG, U-87 MG and D54 MG, that did not express endogenous p16/CDKN2 gene and were easily infected with adenovirus vectors were selected for these experiments. Introduction of the Ad5RSV-p16 in these malignant glioma cell lines directed the biosynthesis of functional p16 protein in the majority of the exposed cells, significantly inhibited cell growth, influenced cell morphology and modified the transformed phenotype of cells including the ability to form colonies in soft agar. Flow cytometric studies revealed that the majority of the Ad5RSV-p16 infected glioma cells were arrested in the G0-G1 phases of the cell cycle. These results suggest that p16/CDKN2 inactivation is a significant factor in the genesis and progression of gliomas and that the restoration of the wild-type p16 protein could have clinical and therapeutic utility.

Adenoviridae↗

PubMed1996

Mutations of the p16 gene in gliomas.

In the present study we investigated the frequency of p16 gene exon 2 mutations in 35 malignant gliomas, using either direct sequencing of the PCR products or cloning into the pCRII vector and sequencing of the cloned PCR products. No mutations were detected during direct sequencing of the PCR products. However, after sequencing of individual clones, we found multiple mutations in 5 tumors involving codons 73(GCC to ACC, Ala to Thr), 76 (GCC to GTC, Ala to Val), 85(GCT to ACT, Ala to Thr), 98(CAC to TAC, His to Tyr), 102 (GCG to GTG, Ala to Val), 106 (GTG to ATG, Val to Met), 107 (CGC to TGC, Arg to Cys), 127 (GCA to GTA, Ala to Val), 128 (CGG to TGG, Arg to Trp) and 136 (GGC to GAC, Gly to Asp). Mutations were found only in glioblastomas and were either C to T or G to A transitions. Each mutation was detected in a small percentage of tumor cells (1.3-22%) using individual colony sequencing and southern hybridization with mutant oligonucleotides, consistent with the heterogenous cell population of glioblastomas. The presence of p16 gene mutations only in glioblastomas suggests that they are late events in glioma development.

Adult↗

PubMed1996

Enhancement of quantal transmitter release and mediatophore expression by cyclic AMP in fibroblasts loaded with acetylcholine.

Neuronal properties such as neurotransmitter uptake and release can be expressed in non-neuronal cells. We show here that fibroblasts-mouse cell line L-M(TK-)-are able to take up acetylcholine from the external medium and to release it in response to a calcium influx. Release was assessed biochemically by a luminescence method, but it was also elicited from individual fibroblasts and recorded in real-time using a Xenopus myocyte as an acetylcholine detector. After treatment for three to six days with dibutyryl-cyclic AMP, the cells changed their shape and acetylcholine release was greatly enhanced. Surprisingly, in differentiated fibroblasts the time-course transmitter release exhibited a high degree of variability even for the successive responses evoked from the same cell; many currents recorded in myocytes on electrical stimulation of fibroblasts had an extremely long duration (up to 1 s or more). This suggested that the release sites were kept open for a very long time. Cyclic AMP treatment also caused a marked increase in the expression of mediatophore 16,000 mol. wt proteolipid in fibroblast membranes. Mediatophore is an acetylcholine-translocating protein which is abundant in cholinergic presynaptic plasma membranes. It is concluded that cyclic AMP differentiation of fibroblasts prolongs the duration of acetylcholine release at individual sites and enhances the expression of the 16,000 mol. wt proteolipid-forming mediatophore.

Acetylcholine↗

PubMed1996

Combination of 6-thioguanine, procarbazine, lomustine, and hydroxyurea for patients with recurrent malignant gliomas.

OBJECTIVE: To determine the efficacy of the combination of 6-thioguanine, procarbazine, lomustine, and hydroxyurea for patients with recurrent malignant gliomas after failure of either previous radiotherapy alone or previous radiotherapy plus nitrosourea-based chemotherapy. METHODS: Seventy-seven patients with recurrent malignant gliomas were studied. 6-Thioguanine was administered for 4 days before lomustine, and procarbazine was administered for 1 day before and 2 days after lomustine to potentiate lomustine's antitumor effect. Hydroxyurea was initiated 1 day before lomustine and continued for a total of 3 days. RESULTS: Thirty patients with glioblastomas and 47 patients with anaplastic gliomas were eligible for evaluation. In the glioblastoma group, 2 of 30 patients had a partial response and 8 of 30 patients had stable disease. This group of patients who responded and had stable disease included 6 of 10 patients who had not undergone previous chemotherapy but only 4 of 20 who had undergone previous chemotherapy. The overall median time to disease progression for the glioblastoma group was 9 weeks. In the anaplastic glioma group, 11 of 47 patients had a partial response and 25 of 47 had stable disease, including 23 of 30 without previous chemotherapy and 13 of 17 who had undergone previous chemotherapy. The median time to disease progression for the whole anaplastic glioma group was 24 weeks; however, the time to disease progression was 50 weeks for responding patients who had not undergone previous chemotherapy and 25 weeks for those who had undergone previous chemotherapy. CONCLUSION: Our results indicate that chemotherapy with a combination of 6-thioguanine, procarbazine, lomustine, and hydroxyurea is active for patients with recurrent anaplastic gliomas and glioblastomas not previously treated with nitrosourea-based chemotherapy but is inactive for patients with glioblastomas previously treated with chemotherapy.

Adolescent↗