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Biomedical subjects

R M White

Publications and source records attributed to R M White.

At least 55 records · Page 3Linked to original sources
PubMed1990

Selective real-time measurement of styrene vapor using a surface-acoustic-wave sensor with a regenerable organoplatinum coating.

The performance of a coated surface-acoustic-wave (SAW) sensor for monitoring styrene vapor is investigated. The effects of several organic co-contaminants and atmospheric humidity are described, and regeneration of the sensor coating is demonstrated. The dual-SAW delay-line oscillator employs a reagent coating of trans-PtCl2(ethylene)(pyridine) to trap styrene via ethylene substitution. The rate of change of the sensor frequency is used to provide real-time measurement of styrene vapor concentrations. No effect on the response to styrene is observed upon simultaneous exposure to each of several olefin and non-olefin solvent vapors used with styrene in industrial processes. Butadiene, however, presents a reversible negative interference by successfully competing with styrene for reaction with the trapping agent. The response to styrene exhibits a moderate positive humidity dependence. Following prolonged exposure, the original complex can be regenerated in situ by exposure to ethylene gas, permitting repeated use of the sensor. An emphasis is placed on the application of the sensor to workplace air monitoring.

Chemical Phenomena↗
PubMed1990

[Encephalic lesions in neurofibromatosis: clinical manifestations and typical magnetic resonance findings].

Neurofibromatosis is the commonest neuroectodermal disease. It is characterized by dysplasias and/or tumors of organs and tissues derived from the embryonic ectoderm, mesoderm and endoderm, and most frequently presents with nervous system and cutaneous lesions. It can be classified as neurofibromatosis type 1 (NF-1 or von Recklinghausen disease) and neurofibromatosis type 2 (NF-2 or bilateral acoustic neurofibromatosis). In order to assess clinical presentation of the disease and diagnostic value of Magnetic Resonance Imaging (MRI), the authors retrospectively evaluated the clinical records and the cranial MR studies of 21 patients with neurofibromatosis (18 with NF-1 and 3 with NF-2). Distinctive abnormalities between the two types were found in both clinical presentation and MR studies. Clinically, NF-1 patients presented most often with blindness, while NF-2 patients were deaf and had fewer cutaneous lesions. The evaluation of MR studies showed that NF-1 patients were more likely to be affected with intracranial gliomas, predominantly of the optic pathways. Moreover, foci of prolonged T2 relaxation were frequently observed, primarily in the globus pallidus of the basal ganglia and in the dentate nucleus of the cerebellum. Some of the foci in the globi pallidi exhibited increased signal intensity on T1-weighted images as well. NF-2 patients more frequently presented with bilateral acoustic schwannomas, meningiomas and cerebral white matter foci of prolonged T2 relaxation, but they did not have dentate and basal ganglia lesions. The authors conclude that as a rule the manifestations of NF-1 and NF-2 on cranial MRI are separate and distinct; they do not overlap. MRI is an useful clinical tool for the diagnosis and the follow-up of patients with neurofibromatosis.

Adolescent↗
PubMed1989

Interaction of 5'-deoxy-5-fluorouridine and methotrexate. A basis for reduced methotrexate toxicity.

Methotrexate (MTX) toxicity is reduced significantly by a non-toxic dose of 5'-deoxy-5-fluorouridine (5'dFUr). Changes in the hematopoietic system (platelets, erythrocytes, leukocytes, and hematocrit), ileal tissue, and body weight were used as parameters to assess toxicity. MTX treatment alone resulted in: (a) a reduction of body weight; (b) significantly morphological changes in ileal tissue; and (c) a marked decrease in the hematopoietic parameters. Sequential treatment with MTX followed by 5'dFUr resulted in reversal of MTX depression of animal body weight and ileal tissue necrosis, and partial reversal in MTX toxicity to the hematopoietic system. Also, for all parameters studied, there were no significant differences between scheduling of MTX after a priming dose of 5'dFUr, 5'dFUr alone, and control. Hence, this study suggests that 5'dFUr is a pharmacological antidote for MTX toxicity, and, therefore, 5'dFUr in combination with MTX may provide a basis whereby more intense and effective MTX therapy may be given.

Animals↗
PubMed1989

Status of drugs-of-abuse testing in urine under blind conditions: an AACC study.

We report results of a blind study designed to determine the accuracy of drugs-of-abuse testing in urine as done in 31 laboratories across the United States. The drugs studied were amphetamines, cannabinoids, cocaine, opiates, and phencyclidine. These laboratories confirmed all positive drug results with a different analytical method. Ten urine samples were sent to each laboratory, which resulted in 1486 trials. There were no false-positive results. The overall accuracy rate was 97%. Our study demonstrates that urine drug testing can be accurate when performed by qualified staff, using up-to-date screening and confirmation methods, appropriate quality-assurance measures, and a chain of custody.

Chemistry, Clinical↗
PubMed1988

Cutaneous involvement of multiple myeloma and extramedullary plasmacytoma.

We recently performed a retrospective clinicopathologic study of five patients with cutaneous involvement of multiple myeloma or extramedullary plasmacytoma. Cutaneous nodules without extension from an underlying bony focus of disease developed in each case. In two cases skin lesions occurred in the more common setting of advanced disease, but in two others skin lesions provided early clues to the diagnosis. In three patients the appearance of skin lesions heralded a rapidly deteriorating clinical course, but two other patients had reasonably long survivals despite cutaneous disease (6 and 3 years, respectively). Two histopathologic configurations were identified in cutaneous lesions: nodular and infiltrative. Both patients with the latter form had multiple myeloma. In all cases tumor cells were pyroninophilic. Immunoperoxidase studies on fixed, paraffin-embedded tissues confirmed the electrophoretic findings in two cases, but findings were equivocal in three others. In one case, cells were positive for epithelial membrane antigen, and in another, alpha 1-antichymotrypsin-positive cells were observed in the centers of tumor islands. Cutaneous involvement with plasma cell neoplasms is recognized infrequently. Immunohistochemical techniques may prove to be valuable in evaluating these cases, but they are not without technical and interpretative difficulties.

Aged↗
PubMed1987

Human neuroelectric patterns predict performance accuracy.

In seven right-handed adults, the brain electrical patterns before accurate performance differed from the patterns before inaccurate performance. Activity overlying the left frontal cortex and the motor and parietal cortices contralateral to the performing hand preceded accurate left- or right-hand performance. Additional strong activity overlying midline motor and premotor cortices preceded left-hand performance. These measurements suggest that brief, spatially distributed neural activity patterns, or "preparatory sets," in distinct cognitive, somesthetic-motor, and integrative motor areas of the human brain may be essential precursors of accurate visuomotor performance.

Adult↗
PubMed1987

Type II insulin-like growth factor receptor is present in rat serum.

We previously identified in fetal rat serum a component capable of specifically binding radiolabeled insulin-like growth factor type II (IGF-II) that is considerably larger than both the fetal (40 kDa) and the adult (150 kDa) carrier proteins. We now present immunologic and affinity crosslinking data to show that this binding species is the type II IGF receptor. Rat serum was gel-filtered on a Sephadex G-200 column (0.05 M NH4HCO3, pH 8), and 125I-labeled IGF-II (125I-IGF-II) binding was measured in individual column fractions. 125I-IGF-II binding activity was found in the void volume of the column in addition to the carrier protein regions. Competitive binding studies using 125I-IGF-II and binding activity from the Sephadex G-200 void volume showed the characteristics of the type II receptor: IGF-II was more potent than IGF-I, and insulin did not compete. Moreover, a specific anti-type II IGF receptor antibody (no. 3637) completely blocked 125I-IGF-II binding. 125I-IGF-I did not bind to the void volume pool, demonstrating the absence of the type I IGF receptor in rat serum. Affinity crosslinking of 125I-IGF-II to the Sephadex G-200 void volume material demonstrated a specific band at 210 kDa without reduction and at 240 kDa after reduction of disulfide bonds. The serum type II IGF receptor size was confirmed by immunoblotting the void volume material with antiserum 3637, which revealed a band slightly smaller (approximately 10 kDa) than the type II IGF receptor from rat placental membranes. Immunoquantitation by immunoblotting using pure type II IGF receptor from rat placental membranes as standard showed a developmental pattern. In fetal rat serum (19-days gestation) and in sera from 3-, 10-, and 20-day-old rats, the concentrations of receptor protein were similar (1-5 micrograms/ml). The level of the type II IGF receptor in serum declined dramatically between age 20 and 40 days, but the receptor was still measurable at age 12 mo. We conclude that the type II IGF receptor is present in rat serum and is developmentally regulated.

Animals↗
PubMed1987

Liver transplant rejection: angiographic findings in 35 patients.

Rejection, the leading cause of liver allograft dysfunction, is usually detected by liver biopsy. The purpose of this study was to determine if there are angiographic findings that correlate with this posttransplantation complication. In a retrospective study, the angiograms of 35 patients with histologically proven allograft rejection were reviewed. The examinations were done because of suspected posttransplantation vascular complications. Abnormal hepatic arteriograms were observed in 30 (86%). Eleven (37%) of the 30 had hepatic artery thrombosis (all had acute rejection). Nineteen (63%) of the 30 had varying degrees of intrahepatic arterial narrowing (14 had acute and five had chronic rejection). Additional findings in patients with acute rejection included stretching of the intrahepatic arterial tree (five cases) and slow flow, poor peripheral arterial filling, and a decrease in the number of intrahepatic arteries (10 cases total). Intrahepatic branch vessel stenoses and occlusions were seen in four patients with chronic rejection. We conclude that there is good correlations between the angiographic findings and histologic evidence of rejection. Although angiography is not advocated as a test for transplant rejection, detection of certain findings raises the possibility of rejection.

Adult↗
PubMed1987

Status of drugs-of-abuse testing in urine: An AACC study.

The study demonstrates that, in May 1987, testing urine for drugs of abuse can be accurate. All laboratories challenged in this study currently perform such testing under contract and are involved in monthly proficiency testing and in-service training (AACC's Surveys Plus and In-Service Training Program in Toxicology). The laboratories were challenged to detect drugs at the concentrations at which they accept business. We suspect that when results of studies of this kind have been reported previously, the laboratories may have been scored inaccurately because they used technology designed to detect higher concentrations of the drugs than were weighed into the study specimens. This points up the need for laboratories and clients to be specific about the threshold concentrations used to report positives and policies for reporting positives detected below those concentrations.

Amphetamines↗
PubMed1986

Lymphomatoid papulosis.

In this review, we discuss the clinical and histologic features of lymphomatoid papulosis, a cutaneous disorder characterized by recurrent eruptions of self-healing papules and small nodules with histologic findings suggestive of malignant lymphoma. Possible causes of this peculiar disease are discussed in the light of recent investigation. Recognition is important to avoid misdiagnosis and overly aggressive therapy, but it should be remembered that a small number of cases have been reported to progress to malignant lymphoma.

Adult↗
PubMed1986

Distant skin metastases in a long-term survivor of malignant ameloblastoma.

We report a case of distant cutaneous metastases in a 68-year-old patient with malignant ameloblastoma of the mandible. The metastatic lesions were first noted approximately 31 years after resection of the primary tumor. Metastases to lung, pleura, bone, and brain had also occurred. Histochemical findings differ from those described in adamantinoid basal cell carcinoma. Cutaneous metastasis probably resulted from hematogenous dissemination. To our knowledge, this is the first report of such an occurrence in English language literature.

Aged↗
PubMed1985

Cutaneous involvement in Hodgkin's disease.

Among 465 patients with Hodgkin's disease seen from 1951 through 1980, there were 16 (3.4%) who had histologically verified "specific" cutaneous involvement with Hodgkin's disease. The most common clinical presentation was of single or multiple dermal or subcutaneous nodules. Three patients had skin lesions at first presentation. In all instances, it was possible to classify the cutaneous histologic pattern using the Rye Classification. In addition, one patient was seen in whom disease was confined to a localized area of skin and subcutaneous tissue. This case was difficult to classify, although there were some histologic features suggestive of lymphocyte-depletion Hodgkin's disease. The findings indicate three mechanisms of cutaneous involvement: (1) retrograde lymphatic spread, distal to involved lymph nodes (11 patients); (2) direct extension from an underlying nodal focus (3 patients); and (3) hematogenous dissemination (2 patients). Cutaneous involvement usually represents, or accompanies, Stage IV disease, and carries an ominous prognosis. The problems inherent in the diagnosis of primary cutaneous Hodgkin's disease are discussed.

Adolescent↗
PubMed1985

Early gastric cancer. Recent experience.

Early gastric cancer (EGC) is defined as carcinoma in which malignant invasion is limited to the mucosa or submucosa. Records of pathologic examinations from the Hospital of the University of Pennsylvania show that EGC comprised 6% of all gastric carcinomas diagnosed between 1977 and 1983 (7/118 cases) compared with 8.2% of gastric carcinomas diagnosed between 1965 and 1977 (12/147 cases). Double contrast radiographic techniques and fiberoptic endoscopy became widely available at our institution in 1976. Thus, the application of these techniques to symptomatic patients has not improved our ability to diagnose EGC. In contrast, the incidence of EGC in Japan has risen from 5% to 35% with the widespread use of these diagnostic techniques. This discrepancy can be attributed to mass screening of asymptomatic patients in Japan because of the unusually high prevalence of gastric carcinoma in that country. American radiologists and endoscopists should therefore recognize that they are unlikely to experience a significant increase in the detection of EGC as long as these examinations are performed predominantly on symptomatic patients.

Adenocarcinoma↗
PubMed1985

Efficacy of fenoprofen in the treatment of primary dysmenorrhea.

We compared fenoprofen calcium, 200 mg; fenoprofen calcium, 400 mg; aspirin, 650 mg; and a placebo in 85 women for the relief of primary dysmenorrhea in a double-blind, clinical trial. The usefulness of these drugs was judged from data obtained over four consecutive menstrual periods on: restriction of daily activity, pain intensity scores, need for rescue analgesics, withdrawal due to lack of efficacy, and adverse events. Both fenoprofen, 200 mg, and fenoprofen, 400 mg, offered significant (P less than .01) pain relief when compared to placebo and aspirin. Analyses of data on 1, 2 and 3 indicated that aspirin was not significantly different from placebo. The aspirin-treated group reported the greatest number of adverse reactions, but the differences between the four groups were not statistically significant. Our study lends support to the concept of a "plateau analgesic effect" of nonsteroidal antiinflammatory drugs (NSAIDs): fenoprofen, 200 mg, appears to be as effective as fenoprofen, 400 mg. When this type of drug fails to provide relief for a woman suffering from primary dysmenorrhea, switching to another NSAID may be more appropriate than increasing the dosage and the probability of dosage-related side effects.

Adolescent↗
PubMed1984

Pygmy mouse fibroblasts in tissue culture: evaluation of multiplication stimulating activity (MSA) receptors and growth responses to MSA.

The pygmy mouse has been proposed as a model for growth hormone resistance; it has normal serum somatomedin levels and does not respond to growth hormone treatment. In order to determine if the growth impairment is caused by a defect in somatomedin binding or in postreceptor action of somatomedin we compared fibroblasts derived from pygmy mice with those from normal appearing littermates. Using multiplication-stimulating activity (MSA) as a model somatomedin we found a normal Ka of binding to the cell surface MSA receptor but a significantly increased number of MSA receptors on the fibroblasts derived from pygmy mice. Studies of thymidine incorporation into DNA failed to demonstrate a difference between pygmy and normal fibroblasts in their responses to MSA alone, but there was a significantly greater thymidine incorporation into the DNA of normal fibroblasts when both competence factor (platelet-derived growth factor) and progression factors (somatomedins and growth hormone deficient platelet-poor plasma) were present in the test medium. On the other hand, cell proliferation studies did not demonstrate a consistent difference in the growth rate of normal versus pygmy fibroblasts. The data support the conclusion that the imparied growth of the pygmy mouse in vivo may be caused by factors which lie outside of the growth hormone-somatomedin pathway.

Animals↗
PubMed1983

The effect of growth hormone administration on lipids and lipoproteins in growth hormone-deficient patients.

Plasma lipids, lipoproteins, and lipoprotein cholesterol levels were studied in a group (n = 8) of prepubertal growth hormone-deficient patients before and after growth hormone (GH) administration. Determination of plasma lipoproteins by a sensitive agarose gel electrophoretic technique demonstrated: (a) in the patients with two prebeta bands an intensification of the fast prebeta lipoprotein fraction after growth hormone administration; and (b) in the patients with one prebeta band the appearance of a second prebeta band after growth hormone administration. The mean (+/- SD) plasma triglyceride level before GH was 86 +/- 60 mg/dl and 158 +/- 95 mg/dl after GH (P less than 0.01). Mean (+/- SD) plasma cholesterol level before GH was 196 +/- 25 mg/dl and 174 +/- 28 mg/dl after GH (P less than 0.05). High-density lipoprotein cholesterol concentrations decreased significantly (P less than 0.001) from mean (+/- SD) 55 +/- 12 mg/dl before GH to 37 +/- 10 mg/dl after GH. Very-low-density lipoprotein cholesterol concentrations increased significantly (P less than 0.05) from mean (+/- SD) 13 +/- 12 mg/dl before GH to 23 +/- 15 mg/dl after GH. Low-density lipoprotein cholesterol concentrations decreased (N.S.) from mean (+/- SD) 123 +/- 15 mg/dl before GH to 114 +/- 15 mg/dl after GH. These lipid and lipoprotein changes could be mediated through the insulin antagonism, hyperinsulinemia, and a decrease in lipoprotein lipase activity caused by growth hormone.

Adolescent↗