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Biomedical subjects

J R Parker

Publications and source records attributed to J R Parker.

At least 19 recordsLinked to original sources
PubMed2001

Phase III, randomized, double-blind, cross-over comparison of gadoteridol and gadopentetate dimeglumine in magnetic resonance imaging of patients with intracranial lesions.

This study compares the efficacy and safety of gadoteridol with that of gadopentetate dimeglumine for enhanced MRI in subjects with intracranial lesions. A total of 92 subjects at three European centres underwent one MRI study enhanced with 0.1 mmol/kg gadoteridol and another with 0.1 mmol/kg gadopentetate dimeglumine. Contrast agents were assigned in random order, separated by 3-7 days. Eighty subjects were evaluated for efficacy. The presence of pathology, degree of enhancement, location and number of lesions, as well as additional information gained, were compared for each subject's unenhanced and enhanced scans for both the gadoteridol and gadopentetate dimeglumine examination. Safety was evaluated in all treated subjects by means of pre- and post-dose vital signs, laboratory tests and by monitoring for adverse events. There was no significant difference in the number of lesions visualized pre- and post-contrast for the two contrast agents. A high degree of correlation was noted between the two blinded readers. When post-contrast image sets were compared between contrast agents, there was no significant difference in superiority of one agent over the other for any of the evaluators (P > 0.05). No significant differences for any safety parameter were noted between the two agents. Gadoteridol and gadopentetate dimeglumine are effective and well tolerated for use in contrast-enhanced MRI of the CNS at a dose of 0.1 mmol/kg.

Adolescent↗
PubMed2001

Antineuronal nuclei immunohistochemical staining patterns in childhood ependymomas.

NeuN, the mouse-derived monoclonal antibody to the reportedly neuron-specific nuclear protein, has been observed to react with many different types of normal, postmitotic neurons throughout the central and peripheral nervous systems. We retrospectively examined 23 surgical specimens (collected from 20 patients) originally diagnosed at our institution between 1983 and 1999 as ependymoma (9), myxopapillary ependymoma (1), anaplastic/malignant ependymoma (10), and primitive neuroectodermal tumor with ependymal differentiation (3). The ependymomas included lesions from the spine (3), cerebrum (5), and posterior fossa (15). Representative formalin-fixed, paraffin-embedded sections from each tumor were subjected to immunohistochemical staining with antibody against NeuN (Chemicon International, Inc, Temecula, CA). Five astrocytomas, four primitive neuroectodermal tumors, and normal cerebral cortex and ependyma from autopsy brains of premature newborns, term infants, and older children served as controls. Thirteen ependymal tumors had positive nuclear staining ranging from rare tumor cells to numerous groups of cells; of these, 9 were anaplastic ependymomas and had the most staining. These studies suggest that some ependymomas arise from a pluripotential neuroglial cell.

Antibodies, Monoclonal↗
PubMed2000

Paget's disease of the vulva: pathology, pattern of involvement, and prognosis.

OBJECTIVE: The aim of this study was to determine prognostic factors and risk factors for recurrence in patients with Paget's disease of the vulva. METHODS: The medical records of 76 patients with a diagnosis of Paget's disease of the vulva were retrospectively reviewed. The diagnosis in each case was confirmed by reviewing the pathology. Patients were then divided into four groups by diagnosis: intraepithelial Paget's disease (IEP) (n = 46), invasive Paget's disease (IP) (n = 9), intraepithelial Paget's disease with underlying adenocarcinoma (IEPUA) (n = 13), and intraepithelial Paget's disease with a coexisting cancer (CCA) (n = 8). Comorbid conditions, location of disease, pathologic diagnosis, method of treatment, margin status, and current status of the patient were evaluated. Descriptive statistical data and univariate analysis were generated using the Statview statistical package. RESULTS: A diagnosis of IEPUA, IP, or CCA predicted a poor survival (P = 0. 0017). Patients who had received chemotherapy or radiation as treatment had a poor survival (P < 0.0001 and 0.0002). Patients with clitoral Paget's disease had a higher incidence of death from disease (P = 0.026). When death from all causes was considered, patients treated with wide local excision (WLE) had a significantly longer survival than patients treated with other more radical treatments (P = 0.02). Risk factors for recurrence included treatment with WLE (P = 0.004). CONCLUSIONS: Patients with IP, IEPUA, or CCA have a poorer prognosis than patients with IEP. Location of Paget's disease is important for prognosis; and patients with clitoral Paget's disease may require more aggressive treatment. WLE is associated with a higher risk of recurrence, but overall patients with WLE tend to survive longer than patients treated more radically.

Aged↗
PubMed2000

Persian leopard (Panthera pardus) attack in Oklahoma: case report.

The authors report a fatal case of a Persian leopard (Panthera pardus) attack in an animal sanctuary in Oklahoma. The victim was a 53-year-old Costa Rican woman who was attempting to feed the animal when she was attacked and killed. Autopsy, radiography, fingerprint analysis, microbiologic cultures, and dental impressions were used to evaluate the case. These simple techniques can be applied to similar cases involving wild and domestic animal attacks.

Animals↗
PubMed1999

A multisite phase III study of the safety and efficacy of a new manganese chloride-based gastrointestinal contrast agent for MRI of the abdomen and pelvis.

The purpose of this study was to evaluate the safety and efficacy of a manganese chloride-based oral magnetic resonance (MR) contrast agent during a Phase III multisite clinical trial. Two hundred seventeen patients were enrolled who were already scheduled for MRI of the abdomen and/or pelvis. In this group of patients, it was postulated that the use of an oral agent would better allow discrimination of pathology from bowel. Patients with known gastrointestinal pathology including peptic ulcer disease, inflammatory bowel disease, obstruction, or perforation were excluded to minimize confounding variables that could affect the safety assessment. Of these 217 patients, 18 received up to 900 mL of placebo, and 199 patients were given up to 900 mL of a manganese chloride-based oral contrast agent, LumenHance (Bracco Diagnostics, Inc.). Safety was determined by comparing pre- and post-dose physical examinations, vital signs, and laboratory examinations and by documenting adverse events. Efficacy was assessed by unblinded site investigators and two blinded reviewers who compared pre- and post-dose T1- and T2-weighted MRI scans of the abdomen and/or pelvis. In 111 (57%) of the 195 cases evaluated for efficacy by site investigators (unblinded readers), MRI after LumenHance provided additional diagnostic information. Increased information was found by two blinded readers in 52% and 51% of patients, respectively. In 44/195 cases (23%) unblinded readers felt the additional information would have changed patient diagnosis and in 50 patients (26%), it would have changed management and/or therapy. Potential changes in patient diagnosis or management/therapy were seen by the two blinded readers in 8-20% of patients. No clinically significant post-dose laboratory changes were seen. Forty-eight patients (24%) receiving LumenHance and four patients (22%) receiving placebo experienced one or more adverse events. Gastrointestinal tract side effects were most common, seen in 29 (15%) of LumenHance patients and in 3 (17%) of the placebo patients. LumenHance is a safe and efficacious oral gastrointestinal contrast agent for MRI of the abdomen and pelvis.

Abdomen↗
PubMed1999

Safety and pharmacokinetic profile of gadobenate dimeglumine in subjects with renal impairment.

RATIONALE AND OBJECTIVES: To determine the safety and pharmacokinetics of gadobenate dimeglumine in a group of subjects with moderate or severe renal impairment. METHODS: The safety and pharmacokinetic profile of gadobenate dimeglumine, a gadolinium (Gd3+) chelate complex in development as a contrast agent for MRI, were evaluated in a placebo-controlled, double-blind, multicenter trial. Subjects with moderate or severe renal impairment (creatinine clearances of 31 to 60 or 10 to 30 mL/min, respectively) received a 0.2-mmol/kg intravenous bolus of Gd3+ or saline placebo. Blood samples (up to 72 hours) and urine and fecal samples (up to 216 hours) were assayed for total Gd3+ content by inductively coupled plasma atomic emission spectroscopy. Gd3+ blood concentration/time data were analyzed nonparametrically and parametrically using the software program WinNonlin VI.1. RESULTS: Mean (SD) values for Gd3+ area under the curve, blood clearance, steady-state volume of distribution, renal clearance, and creatinine clearance for the moderate group were 862 (392) micrograms.h/mL, 56 (25) mL/min, 21 (5) L, 47 (23) mL/min, and 46 (16) mL/min. Values for the severe group were 1347 (366) micrograms.h/mL, 31 (7) mL/min, 19 (6) L, 22 (7) mL/min, and 21 (8) mL/min. No Gd(3+)-related adverse events occurred. Mean values for Gd3+ recovery in urine and feces for moderate and severe groups were 74% and 6%, and 69% and 8% of the dose, respectively. Linear regression analysis demonstrated a significant relation between the level of renal function and blood clearance of Gd3+. CONCLUSIONS: Although mean blood clearance and renal clearance values progressively declined with increasing degree of renal impairment, based on the safety profile and the fact that the administered dose was double the standard dose used for MRI purposes, there appears to be no need for dose reduction in this population.

Adult↗
PubMed1999

Benign nevus cell aggregates in the thymus: a case report.

Aggregates of benign nevus cells occurring in lymph nodes are a well-described incidental finding. Nevus cell aggregates (NCAs) can mimic foci of metastatic carcinoma or other disease processes, so the surgical pathologist should be familiar with this lesion. The purpose of this report is to describe the potential diagnostic difficulties created by benign NCAs within the thymus of a 32-year-old man with dysplastic nevus syndrome and malignant melanoma involving mediastinal lymph nodes and the right lung. Morphologically, the NCAs in this case elicited the differential diagnoses of metastatic melanoma and thymoma. Immunohistochemical studies helped to establish the correct diagnosis by demonstrating reactivity for S-100 protein and negative staining for keratin and HMB-45. Unlike malignant melanomas, NCAs show no p53 protein immunoreactivity, and low proliferative activity was detected by Ki-67 antigen immunostaining. Although melanocytic cells were rarely reported in thymic neoplasms, we are not aware of any previous reports of NCAs occurring in the normal thymus.

Adult↗
PubMed1997

Primary endodermal sinus tumor of the vulva: a case report and review of the literature.

BACKGROUND: Extragonadal endodermal sinus tumors arising in the external genitalia represent an exceedingly rare malignancy in women. Six cases of endodermal sinus tumors of the vulva have been reported to date, with three cases failing to respond to conservative surgery and vincristine-based chemotherapy. We report a seventh case of vulvar endodermal sinus tumor that was treated with radical surgery and platinum-based chemotherapy. CASE: RT is an 18-year-old female who presented with a vulvar mass that was diagnosed as endodermal sinus tumor at the time of biopsy. She was subsequently treated with modified radical vulvectomy and ipsilateral groin lymphadenectomy, followed by bleomycin, etoposide, and cisplatin chemotherapeutic regimen. She has since remained free of disease for 18 months as evidenced by serum alpha-fetoprotein and physical exam at 18 months. CONCLUSIONS: Vulvar endodermal sinus tumors represent a very small number of germ cell tumors in women. Based on the previous accounts, this disease appears to be more fatal than endodermal sinus tumor arising at other sites. These tumors also have a predilection for local metastasis. Due to the previous accounts, we chose to treat this patient with radical surgery and platinum-based chemotherapy. This treatment regimen has resulted in a disease-free state for 18 months.

Adult↗
PubMed1997

Worldwide clinical safety assessment of gadoteridol injection: an update.

Gadoteridol injection is a low molecular weight chelate complex of gadolinium (III) which is useful as a contrast agent for magnetic resonance imaging. A total of 2481 adult and pediatric subjects were studied with gadoteridol at doses from 0.025 to 0.3 mmol/kg in phase I-IIIb clinical trials in Europe and the United States. The study population had a mean age of 49 years, and included 119 patients under 18 years of age and 747 patients over 60 years of age. After 2656 administered injections of gadoteridol a total of 233 adverse events were recorded in 176 exposures, an incidence rate of 6.6 % irrespective of relationship to drug administration. The most frequently reported adverse events were nausea (1.5 %), taste perversion (0.9 %), and headache (0.6 %). All other adverse events occurred with an incidence of 0.5 % or less. This report confirms the excellent safety profile of gadoteridol in healthy subjects and patients with a variety of known or suspected pathologies.

Adolescent↗
PubMed1997

Indication-related dosing for magnetic resonance contrast media.

This presentation reviews the issue of contrast media dosing and imaging protocols for the optimal MR imaging detection and characterization of pathology. The cumulative clinical experience gained in performing contrast-enhanced MR examinations with gadolinium chelates indicates that a dose of 0.1 mmol/kg body weight provides safe and effective enhancement of most CNS pathology. Doses lower than 0.1 mmol/kg have been shown to be inadequate for delineating all but selected types of CNS pathology, such as masses with a high lesion to background ratio on post-contrast images (acoustic neuromas) or lesions located in areas in which the normal tissue very rapidly takes up contrast agent (e. g. microadenomas in the pituitary gland). Recent clinical studies have suggested a role for high dose gadolinium administration (up to 0.3 mmol/kg) for the optimal detection and delineation of cerebral metastases or other small or poorly enhancing lesions. Differences in the histopathologic characteristics (capillary permeability, vascularity, location, size) of specific diseased tissues may require varying doses or even a different contrast agent to be used for optimal imaging results. As new MR contrast agents and new scanning techniques are introduced, the specific diagnostic question posed will likely determine the choice of pulse sequence, contrast agent and dose used.

Contrast Media↗
PubMed1997

The spectrum of pediatric injuries after a bomb blast.

The spectrum of pediatric injuries seen after a bomb blast is poorly documented. The pathophysiology of blast injuries differ significantly from other forms of trauma and typically result in large numbers of distinctly patterned injuries. On April 19, 1995, a truck bomb was detonated directly adjacent to the Alfred P. Murrah Federal Building in Oklahoma City, Oklahoma. A total of 816 adults and children were injured or killed as a direct result of the blast. Twenty infants and children were seated by the window of the second floor day care center at the time of the explosion. The injuries incurred by all children involved in the blast were studied. Nineteen children, 16 of whom were in the day care center, died as a direct result of the blast. The injury patterns among the 19 dead children included a 90% (17 of 19) incidence of skull fractures, 15 of those with cerebral evisceration (skull capping); 37% with abdominal or thoracic injuries; 31% amputations; 47% arm fractures, 26% leg fractures; 21% burns; and 100% with extensive cutaneous contusions, avulsions, and lacerations. Forty-seven children sustained nonfatal injuries with only seven children requiring hospitalization. The injuries sustained by the seven hospitalized children included two open, depressed skull fractures, with partially extruded brain, two closed head injuries, three arm fractures, one leg fracture, one arterial injury, one splenic injury, five tympanic membrane perforations, three corneal abrasions, and four burn cases (1 > 40% body surface area [BSA]). After a bomb blast, pediatric patients sustain a high incidence of cranial injuries. Fractures and traumatic amputations are common. Intraabdominal and thoracic injuries occur frequently in the deceased but infrequently in survivors.

Adolescent↗
PubMed1997

Comparison of general and epidural anesthesia in patients undergoing primary unilateral THR.

One hundred ninety-five consecutive patients underwent 195 primary unilateral total hip arthroplasties between January 1988 and December 1993. Patients were divided into three groups based on the type of anesthesia utilized for their procedure. Group I consisted of 108 patients (59 women and 49 men; average age 56 years) who had general endotracheal anesthesia alone. Group II consisted of 70 patients (41 women and 29 men, average age 58 years) who had general endotracheal anesthesia with epidural augmentation intraoperatively and postoperatively. Group III consisted of 17 patients (6 women and 11 men, average age 62 years) who had epidural anesthesia only. Data were analyzed by anesthesia group to compare a variety of clinically relevant factors. No statistically significant differences among groups were noted regarding average age at surgery, the underlying diagnoses leading to joint replacement, the number of preexisting medical conditions, length of hospitalization, nonsurgical operating room time, intraoperative blood transfusions, intraoperative femur fractures, deep venous thrombosis, deep infections, death, or the prevalence of postoperative urinary tract infections. Postoperative urinary tract infections correlated with duration of Foley catheterization, but not the duration of epidural catheterization. Significant differences among anesthesia groups were observed for two factors: 1) estimated intraoperative blood loss was highest for Group I (P < .05) and was primarily a function of surgical time (P < .0001), and 2) postoperative Hemovac output (over the first and second postoperative 24-hour periods) was greatest for Group II (P < .05). Epidural anesthesia appears to be a safe modality in patients undergoing primary unilateral total hip replacement.

Adult↗
PubMed1997

Cellular hemangioma of the posterior mediastinum: unusual presentation of a rare vascular neoplasm.

Cellular hemangiomas arising in the posterior mediastinum (or paravertebral sulcus) are rare tumors even in childhood. We report one such tumor which arose within a sympathetic ganglion in an infant with associated congenital heart disease (ventricular septal defect) and severe congestive heart failure. The tumor was discovered incidentally at cardiac catheterization when tumor blush was observed in the apex of the left chest. This benign mass was completely resected prior to repair of the cardiac defect. We speculate that it may have contributed to the congestive heart failure.

Cardiac Catheterization↗