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Biomedical subjects

P L Robertson

Publications and source records attributed to P L Robertson.

At least 19 recordsLinked to original sources
PubMed2006

Inflammatory arthritis-like and other MR findings in wrists of asymptomatic subjects.

OBJECTIVE: To describe magnetic resonance (MR) imaging findings in the wrists of asymptomatic subjects that might be confused with pathologic findings. DESIGN: MR examination of the dominant wrist was performed in 30 asymptomatic volunteers aged 22-49 years using pre-contrast and post-contrast sequences in the coronal and axial planes. The bases of the metacarpals, the carpus and the distal radius and ulna were evaluated by two musculoskeletal radiologists for lesions, notches, blood vessels and synovial enhancement. RESULTS: There were 24 bright osseous lesions (erosions, intraosseous ganglia, oedema or cysts) in 14 subjects. Intraosseous blood vessels were seen in all but one wrist examined, most commonly in the capitate and lunate bones. Enhancement was present in 26 of 27 notches identified at the base of the second metacarpal and less commonly in the capitate, hamate and triquetral notches. A small joint effusion was present in 14 subjects. Joint or soft-tissue enhancement was identified in 16 wrists. CONCLUSIONS: Many MR abnormalities and variants may be detected in the wrists of asymptomatic subjects. Many of these could be confused with pathologic findings usually associated with inflammatory arthritis.

Adult↗
PubMed2002

Scotin, a novel p53-inducible proapoptotic protein located in the ER and the nuclear membrane.

p53 is a transcription factor that induces growth arrest or apoptosis in response to cellular stress. To identify new p53-inducible proapoptotic genes, we compared, by differential display, the expression of genes in spleen or thymus of normal and p53 nullizygote mice after gamma-irradiation of whole animals. We report the identification and characterization of human and mouse Scotin homologues, a novel gene directly transactivated by p53. The Scotin protein is localized to the ER and the nuclear membrane. Scotin can induce apoptosis in a caspase-dependent manner. Inhibition of endogenous Scotin expression increases resistance to p53-dependent apoptosis induced by DNA damage, suggesting that Scotin plays a role in p53-dependent apoptosis. The discovery of Scotin brings to light a role of the ER in p53-dependent apoptosis.

Amino Acid Sequence↗
PubMed2000

Diffusion magnetic resonance imaging: an early surrogate marker of therapeutic efficacy in brain tumors.

BACKGROUND: A surrogate marker for treatment response that can be observed earlier than comparison of sequential magnetic resonance imaging (MRI) scans, which depends on relatively slow changes in tumor volume, may improve survival of brain tumor patients by providing more time for secondary therapeutic interventions. Previous studies in animals with the use of diffusion MRI revealed rapid changes in tumor water diffusion values after successful therapeutic intervention. METHODS: The present study examined the sensitivity of diffusion MRI measurements in orthotopic rat brain tumors derived from implanted rat 9L glioma cells. The effectiveness of therapy for individual brain cancer patients was evaluated by measuring changes in tumor volume on neuroimaging studies conducted 6--8 weeks after the conclusion of a treatment cycle. RESULTS: Diffusion MRI could detect water diffusion changes in orthotopic 9L gliomas after doses of 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU or carmustine) that resulted in as little as 0.2 log cell kill, a measure of tumor cell death. Mean apparent diffusion coefficients in tumors were found to be correlated with and highly sensitive to changes in tumor cellularity (r =.78; two-sided P =.041). The feasibility of serial diffusion MRI in the clinical management of primary brain tumor patients was also demonstrated. Increased diffusion values could be detected in human brain tumors shortly after treatment initiation. The magnitude of the diffusion changes corresponded with clinical outcome. CONCLUSIONS: These results suggest that diffusion MRI will provide an early surrogate marker for quantification of treatment response in patients with brain tumors.

Adolescent↗
PubMed1998

Pediatric brain tumors.

Brain tumors are the most common solid neoplasms in childhood. This article reviews the current classification, clinical presentations, diagnostic procedures, and principles of treatment of pediatric brain tumors. The specific presentation, treatment, and prognosis of the most common, individual types of pediatric brain tumors are discussed.

Brain Neoplasms↗
PubMed1998

Survival and prognostic factors following radiation therapy and chemotherapy for ependymomas in children: a report of the Children's Cancer Group.

OBJECT: Ependymomas in children continue to generate controversy regarding their histological diagnosis and grading. optimal management, and possible prognostic factors. To increase our knowledge of these tumors the authors addressed these issues in a cohort of children with prospectively staged ependymomas treated with radiotherapy and chemotherapy. METHODS: Children between the ages of 2 and 17.3 years harboring an intracranial ependymoma confirmed by a central review of the tumor's pathological characteristics were treated according to Children's Cancer Group Protocol 921 from 1986 to 1992. Treatment following surgery and postoperative tumor staging (including brain computerized tomography or magnetic resonance [MR] imaging, spinal MR imaging or myelography, and cerebrospinal fluid cytological investigation) included craniospinal irradiation with a local boost to the primary tumor and patient randomization to receive adjuvant chemotherapy with either 1) CCNU, vincristine, and prednisone, or 2) the eight-drugs-in-1-day regimen. Centralized review of the tumor pathological characteristics revealed 20 ependymomas and 12 anaplastic ependymomas in the 32 children included in the study. Diagnoses made at the individual institutions included anaplastic (malignant) ependymoma (15 patients), ependymoma (four patients), ependymoblastoma (nine patients), ependymoastrocytoma (one patient), and primitive neuroectodermal tumor (three patients), which were discordant with the centralized review diagnosis in 22 of 32 cases. Only three of the 32 patients had metastatic disease (two with M and one with M3 stages). At surgery, 47% of tumors were estimated to be totally resected. Among the 14 of 17 patients who suffered a relapse and were evaluated for site of relapse, 10 (71%) had an isolated local relapse, three (21%) had concurrent local and metastatic relapse, and only one (7%) had an isolated metastatic relapse. Kaplan-Meier estimates of 5-year progression-free survival (PFS) and overall survival rates were 50 +/- 10% and 64 +/- 9%, respectively. CONCLUSIONS: Predictors of PFS duration included an estimate of the extent of resection made at surgery (total compared with less than total, p = 0.0001) and the amount of residual tumor on postoperative imaging as verified by centralized radiological review (< or = 1.5 cm2 compared with > 1.5 cm2, p < 0.0001). No other factors, including centrally reviewed tumor histopathological type, location, metastasis and tumor (M and T) stages, patient age, race, gender, or chemotherapy treatment regimen significantly correlated with PFS duration. The pattern of predominantly local relapse and the important influence of residual tumor or the extent of resection on PFS duration confirms a prevailing impression that local disease control is the major factor in the prediction of outcome of ependymoma. Survival rates were comparable with those reported by other investigators who have treated patients with similar doses of radiation and no chemotherapy.

Adolescent↗
PubMed1997

Lymphocytic hypophysitis presenting with diabetes insipidus in a 14-year-old girl: case report and review of the literature.

UNLABELLED: Lymphocytic hypophysitis is a rare disorder predominantly affecting females during the antepartum or postpartum period. It is characterized by destruction and lymphocytic infiltration of the pituitary gland, probably by an autoimmune process, leading to a pituitary mass lesion and/or various degrees of hypopituitarism. The lesion is usually confined to the adenohypophysis. Posterior pituitary gland or stalk involvement is rare, although patients presenting with diabetes insipidus have been reported. We describe a girl aged 13 years 9 months with lymphocytic hypophysitis who presented with diabetes insipidus and secondary amenorrhea. MRI of the brain revealed a 1 cm enhancing mass in the pituitary stalk. A biopsy of the mass by right pterional craniotomy showed lymphocytic infiltration without neoplastic cells or granuloma formation. To our knowledge, this is the youngest reported patient with a diagnosis of lymphocytic hypophysitis. In this case report, her clinical presentation is discussed along with a review of the literature. CONCLUSION: We present the first childhood case of lymphocytic hypophysitis which is an autoimmune inflammatory disorder of the pituitary gland. Although this is a rare condition in adults, it also needs to be considered in the pediatric population. Conservative management is preferred unless there are signs of increased intracranial pressure. Most importantly, close monitoring for multiple hormone deficiencies is indicated in this condition.

Adolescent↗
PubMed1997

Leptomeningeal fibrosis and the delayed diagnosis of a central nervous system neoplasm (primitive neuroectodermal tumor).

We report a unique case of histologically confirmed meningeal fibrosis in a child who had progressive ischemic neurologic symptoms before the delayed diagnosis of an intracranial primitive neuroectodermal tumor (PNET) was made > 1 year after initial presentation. This pathology has previously been described after neurosurgical procedures, subarachnoid hemorrhage, cranial irradiation, and with no known etiology, but has never been reported in association with a central nervous system neoplasm. In a 6-year-old boy with headaches of several months' duration MRI demonstrated hydrocephalus, a right cerebellopontine angle cyst, and dural enhancement. Biopsies of the thickened meninges taken when the cyst was surgically fenestrated demonstrated only fibrosis with no evidence of infection, hemorrhage, or neoplasm. In the next 6 months, the child had two acute stroke-like episodes with alternating hemiparesis that gradually improved. There were ischemic changes in the diencephalon on MRI. Repeat dural biopsies were unchanged. One year after the initial operation, a left hemiparesis recurred and MRI demonstrated multiple intracranial masses in the cerebral cortex, cerebellum, suprasellar area, and cauda equina. After surgical resection, the cortical mass was found to be a PNET. All the lesions regressed after treatment with radiation and chemotherapy. We hypothesize that the meningeal fibrosis represented a "desmoplastic" reaction to an occult PNET, similar to the fibrous proliferation with cerebellar desmoplastic medulloblastoma except for the extent of the meningeal involvement and the long undetected parenchymal tumor. The mechanism of the ischemic brain injury was most likely vascular involvement by the fibrotic process, either directly or by predisposition to vasoconstriction.

Brain Neoplasms↗
PubMed1997

Improved prognosis of intracranial non-germinoma germ cell tumors with multimodality therapy.

The 5 year survival for patients with malignant intracranial non-germinoma germ cell tumors (NGGCT) which include endodermal sinus tumors, embryonal carcinomas, choriocarcinomas and immature teratomas is less than 25% following a small resection and radiotherapy. In an effort to improve the survival of these patients, an approach using an attempt at radical resection where feasible followed by multi-modality 'sandwich' therapy (chemotherapy-radiation-chemotherapy) was used to treat 18 newly diagnosed patients between 1986 and 1994 in a multi-institution study. Fourteen patients had histologically proven NGGCT and four were presumed NGGCT because of markedly elevated concentrations of serum and/or CSF alpha fetoprotoin (AFP) and/or beta human chorionic gonadatrophin (b-HCG). The primary tumor was confined to the pineal region in 12 patients, the suprasellar region in five, and a cerebral hemisphere in one. None of the patients had central nervous system metastases at diagnosis by MRI imaging of the spine and CSF cytology. Radical surgical resection was performed initially in 11 patients (gross total -6, subtotal -5): four had a biopsy and three had no surgery. All patients then received 3 or 4 cycles of neoadjuvant chemotherapy with cisplatin (100 mg/m2/cycle) and VP-16 (500 mg/m2/cycle). Of the 12 patients with evaluable disease there were 9 responses to the neoadjuvant chemotherapy (5 CR, 4 PR); 2 patients had stable disease and I progressed during chemotherapy. Six patients with no evaluable disease after a gross total resection had a continuous complete response. Seventeen patients received radiation therapy (involved field -11, involved field + craniospinal -4, involved field + whole brain -2). Twelve patients received 4 cycles post-radiation chemotherapy with vinblastine (6.5 mg/m2/cycle). bleomycin (15 U/m2/cycle), VP-16 (300 mg/m2/cycle, carboplatin (450 mg/m2/cycle). A total of four patients have died (3-progressive/recurrent disease, 1-metabolic). Four year actuarial event-free and total survival rates are 67% and 74%. This multi-modality adjuvant therapy approach appears to dramatically improve the outcome of malignant intracranial NGGCT.

Adolescent↗
PubMed1997

A phase I study of high-dose tamoxifen for the treatment of refractory malignant gliomas of childhood.

Recent studies have indicated that the proliferation of malignant gliomas is in part dependent on excessive activation of protein kinase C (PKC)-mediated pathways. Conversely, inhibiting PKC may provide a novel approach for blocking glioma growth. The antiestrogen tamoxifen, a moderately potent PKC inhibitor, has been shown in vitro to block the proliferation of malignant glioma cell lines at concentrations several-fold higher than those typically attained during the treatment of breast cancer; such serum concentrations may be achieved with doses > 40 mg/m2 b.i.d. The safety and efficacy of these high doses for producing disease control in patients with malignant gliomas has recently been noted anecdotally, although a rigorous study of this agent has been lacking. To address this issue, we examined the safety and efficacy of high-dose tamoxifen in a series of children with malignant gliomas that had progressed after conventional therapy. An initial group was treated with 60 mg/m2 p.o. b.i.d. and a second group with 100 mg/m2 b.i.d. Steady-state serum tamoxifen and metabolite levels were measured in most patients. Toxicity with the regimen was minimal; two patients treated at the higher dose required reduction to the lower dose because of asymptomatic prolongation of the QT interval on an electrocardiogram. Although none of the patients exhibited clear-cut tumor regression, 4 of 14 patients had stabilization of previously progressive disease for at least 3 months; the longest survivor lived for 17 months after beginning tamoxifen. The moderate efficacy of this agent in otherwise end-stage disease coupled with its low toxicity and the relative ease of oral administration provides a rationale for proceeding with larger studies of this agent in patients with malignant gliomas, possibly as a means for potentiating the effects of conventional chemotherapeutic agents, which to date have shown limited efficacy in the treatment of these tumors.

Administration, Oral↗
PubMed1996

Successful treatment of childhood pilocytic astrocytomas metastatic to the leptomeninges with high-dose cyclophosphamide.

Leptomeningeal dissemination of childhood pilocytic astrocytoma (PA) is a rare event with little information available regarding therapy. We report here four children with disseminated PA whom we treated with high doses of cyclophosphamide with clinical benefit. The patients were aged 2.5 to 8 years. Three patients presented with PA localized in the posterior fossa, initially treated with surgical resection (n = 3) and radiotherapy (n = 1). Leptomeningeal dissemination occurred at 32, 44, and 8 months from diagnosis, respectively. The fourth patient presented with an optic pathway tumor with leptomeningeal dissemination at diagnosis. At commencement of cyclophosphamide therapy, disease was present in the subarachnoid space (intracranial, n = 2; spinal, n = 4), cerebral ventricles (n = 2), and primary site (n = 3). Histology was identical at diagnosis and recurrence in the two biopsied cases and cerebrospinal fluid was negative in all cases. Treatment was with cyclophosphamide 4-5 g/m2/cycle given every 4 weeks for a total of two cycles (n = 1) and four cycles (n = 3). One patient achieved disease stabilization (duration 27 months at the time of publication) and three patients experienced significant reductions in tumor burden. Subsequent intrathecal therapy was administered to two patients. Two patients developed disease progression at 10 and 9 months from cessation of chemotherapy. The one re-treated patient responded to further, lower dose, cyclophosphamide. This is the first report of the use of high dose cyclophosphamide for disseminated PA. The recurrence of disease in two cases with a further response to lower dose cyclophosphamide has implications for the optimal duration of therapy for these low grade, aggressive tumors.

Antineoplastic Agents, Alkylating↗
PubMed1996

Valproic acid and thrombocytopenia in children: a case-controlled retrospective study.

Thrombocytopenia in association with valproic acid (VPA) therapy has been reported in patients of various ages with incidences ranging from 1 to 32%. To evaluate this association in a pediatric population, we retrospectively studied 167 children treated with VPA at our institution between 1989 and 1993. Ninety-one patients on VPA monotherapy and 76 on VPA polytherapy (VPA plus 1 to 3 other antiepileptic drugs) were compared with 92 age- and sex-matched control patients treated with antiepileptic drugs other than VPA. Study variables included patient age, most recent platelet count, VPA dose, dose/kg, and serum VPA level. Thrombocytopenia, defined as a platelet count < 200 x 10(3)/mm3, was present in 21.6% of the children treated with VPA (26.4% in those on VPA monotherapy and 15.8% in those on VPA polytherapy) but in only 5.4% of controls untreated with VPA. Serum VPA level was the highest risk factor for the development of thrombocytopenia in these patients (P = .0001) and greater age also independently predicted thrombocytopenia. The dose of VPA or dose/kg were not independent predictors of thrombocytopenia (P = .0025). The degree of thrombocytopenia was mild among these patients, reflected in the absence of significant difference in mean platelet count between the three groups and the absence of any bleeding complication or excessive bruising. We conclude from these findings that the risk for children developing severe thrombocytopenia with bleeding complications while taking VPA is low and that mild thrombocytopenia does not necessarily mandate discontinuing the drug. Because higher serum VPA levels do predict thrombocytopenia, platelet counts should be closely monitored after dose escalation in such patients.

Adolescent↗
PubMed1995

Colour-assisted compression ultrasound in the diagnosis of calf deep venous thrombosis.

OBJECTIVE: To determine sensitivity and specificity of colour-assisted compression ultrasound (CUS) in the diagnosis of deep venous thrombosis (DVT) isolated to the calf veins. DESIGN: Prospective comparison of CUS with contrast venography in patients undergoing both procedures, with blinded evaluation of results. SETTING: Alfred Hospital, Melbourne (an urban tertiary referral hospital), between November 1990 and May 1992. SUBJECTS: Patients presenting for contrast venography with signs or symptoms of lower limb DVT. OUTCOME MEASURES: Presence of DVT; technical adequacy of examination. RESULTS: 92 of 402 patients (104 limbs) were examined. DVT was detected by venography in 43 limbs and was isolated to the calf veins in 19. It was diagnosed by CUS for eight of these 19. Calf CUS was technically inadequate in 26 limbs. Sensitivity and specificity of CUS for isolated calf DVT were 67% (95% confidence interval [CI], 40%-94%) and 93% (95% CI, 83%-100%), respectively, when the CUS was adequate. The low sensitivity of CUS was related to small size of the thrombi, inadequate studies because of previous DVT or very swollen limbs and technical errors. CONCLUSION: CUS is accurate for detecting larger isolated calf DVT when the calf study is adequate. Including the calf veins as well as the femoropopliteal veins in the initial CUS examination for symptomatic suspected lower limb DVT may reduce the need for follow-up CUS.

Adolescent↗
PubMed1995

Rotator cuff disorders: interobserver and intraobserver variation in diagnosis with MR imaging.

PURPOSE: To determine interobserver and intraobserver variation in the interpretation of magnetic resonance (MR) images in rotator cuff disorders. MATERIALS AND METHODS: MR images of the shoulder in 97 patients were retrospectively reviewed twice, with a 3-week interval. Surgical findings indicated a full-thickness tear in 29 patients, grade 1 impingement in 19 (tendinitis), and grade 2 impingement (partial tear) in 26. The control population comprised 23 asymptomatic volunteers or patients. RESULTS: All observers were accurate in the diagnosis of a full-thickness tear (89%-98%), with good intraobserver (kappa = 0.67-0.84) and interobserver agreement (kappa = 0.74-0.92). In diagnoses of tendinitis, partial tear, and normal cuff, there were wide ranges of sensitivity (13%-74%) and specificity (72%-93%), as well as poor interobserver (kappa = 0.12-0.60) and intraobserver agreement (kappa = 0.35-0.78). CONCLUSION: Full-thickness tears of the rotator cuff can be accurately identified at MR imaging with little observer variation. Consistent differentiation of normal rotator cuff, tendinitis, and partial thickness tears is more difficult.

Female↗
PubMed1995

Pediatric midbrain tumors: a benign subgroup of brainstem gliomas.

The presentation, radiographic findings and course of 17 children with MRI-documented intrinsic midbrain lesions are reviewed. The anatomic centers of all the lesions were tectal, peritectal, or tegmental. Lesions centered at the pineal gland were excluded. Signs of increased intracranial pressure from hydrocephalus requiring shunt placement were present in 14 patients. Histopathological diagnosis was confirmed in three tumors; these were low grade astrocytomas and all received focal irradiation, as did one unbiopsied tumor. The remaining 13 patients with no histopathological diagnosis received no therapy other than shunt placement in 11. All but one of the lesions have remained clinically and radiographically stable, with a 4-year progression-free and total survival of 94 and 100%, respectively. We conclude that mass lesions originating in the upper midbrain are a subset of intrinsic brainstem tumors with a relatively benign course, usually presenting with hydrocephalus after infancy. They may remain stable for considerable periods and may require no further therapy after treatment of hydrocephalus. Surgical biopsy and/or resection can usually be reserved for progressive or atypical lesions which may also require further adjuvant therapy.

Adolescent↗
PubMed1994

Chronic respiratory failure in limb-girdle muscular dystrophy: successful long-term therapy with nasal bilevel positive airway pressure.

Chronic respiratory failure is a major factor contributing to mortality in progressive neuromuscular disorders. Among the muscular dystrophies, respiratory failure most commonly occurs with Duchenne dystrophy, while in Becker, limb-girdle, and facioscapulo-humeral dystrophies, respiratory failure is infrequent and generally occurs in the more severe cases that have progressed to a nonambulatory, advanced functional stage. We report two brothers with a myopathic disease in which the distribution of weakness, initial clinical course, heredity, and muscle pathology most closely resembled a limb-girdle type of dystrophy. Both brothers, however, presented with chronic alveolar hypoventilation and respiratory failure when their locomotor disabilities were still mild. Respiratory failure was reversed, and satisfactory ventilation has been maintained for more than a year using a type of non-invasive intermittent positive pressure ventilation, with a bilevel positive airway pressure device (Bi-PAP), administered through a nasal mask during sleeping hours. These cases demonstrate an unusual presentation of limb-girdle dystrophy, and document that nocturnal, nasal administration of continuous airway pressure using the Bi-PAP device may be sufficient to maintain adequate long-term ventilation in some patients with neuromuscular causes of respiratory failure, and thus significantly improve quality of life and delay the need for more complex or invasive forms of assisted ventilation.

Adolescent↗
PubMed1994

Comparison of ultrasound and blood pool scintigraphy in the diagnosis of lower limb deep venous thrombosis.

We report a prospective, blinded comparison of compression ultrasound (US) and Tc-99m erythrocyte-labelled venous blood pool scintigraphy (BPS) in patients presenting with symptoms of deep venous thrombosis (DVT). Contrast venography (CV) was used as the gold standard. Ninety-eight lower limbs of 76 patients were examined. DVT was present at CV in 38 of 98 limbs and was isolated to the calf veins in eight. Sensitivity and specificity of ultrasound for femoropopliteal thrombus were 81.5% and 96% and of venous blood pool scintigraphy were 55% and 96%. For deep venous thrombosis in the whole limb sensitivity and specificity of ultrasound were 74% and 90% and of venous blood pool scintigraphy were 61% and 88%. In the calf sensitivity and specificity of US were 61% and 94% and of venous blood pool scintigraphy were 61% and 89%. Excluding equivocal venous blood pool scintigraphy results, the predictive values of a positive and negative venous blood pool scintigraphy study for the whole limb were 84% and 86%. The predictive values of a positive and negative ultrasound where the examination was adequate were 82% and 86%. US is a more sensitive alternative to CV than BPS for femoropopliteal DVT. When neither US nor CV can be performed, BPS remains a useful initial test for DVT, provided it is unequivocally positive or negative.

Adolescent↗