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Biomedical subjects

H H Engelhard

Publications and source records attributed to H H Engelhard.

31 records · Page 2Linked to original sources
PubMed1993

A quantitative analysis of modulations occurring in cellular c-myc protein content, %S phase and growth balance under growth-inhibitory conditions.

The c-myc protein was one of the first proto-oncogene products to be linked to the increased proliferative activity of neoplastic cells. However, few studies have attempted to quantify changes occurring in cellular c-myc protein content in response to growth-inhibitory conditions, or to relate such changes to total cellular protein (TCP) levels, %S phase cells and/or cellular growth balance. Knowledge of such relationships is important for determining the biological relevance of the c-myc protein as a marker for proliferating cells. In this study, a dual-laser flow cytometric technique employing three fluorescent dyes was used to quantify cellular changes in c-myc protein, TCP, DNA and growth balance in exponentially-growing and serum deprived U118MG, A-172 and HL-60 cells. Results obtained by flow cytometry were verified using other techniques. Changes in c-myc protein content were found to occur independently of changes in TCP, %S phase or cellular growth balance, and varied between cell lines. These results indicate that cellular c-myc protein determinations convey information that is unique from other indicators of cellular growth and proliferation. Such information may be linked, however, to the nutritional status and origin of the cells being assayed.

Brain Neoplasms↗
PubMed1992

Abdominal pain resulting from cerebrospinal fluid pseudocyst and cholelithiasis.

Patients treated with ventriculoperitoneal (VP) shunt procedures for hydrocephalus may have abdominal pain related to complications stemming from the shunt tubing itself or to other intra-abdominal disease. In patients with VP shunts, usually children, lack of absorption of cerebrospinal fluid (CSF) may produce a painful abdominal CSF pseudocyst. We have reported the rare occurrence of a CSF pseudocyst in an adult. The patient was also found to have cholelithiasis.

Abdominal Pain↗
PubMed1992

Imaging and movement of iron-oxide-bound antibody microparticles in brain and cerebrospinal fluid.

Therapy with monoclonal antibody conjugates has been proposed for patients with malignant intracranial tumors and meningeal carcinomatosis. One obstacle to successful immunotherapy has been the inability of adequate quantities of antibody to reach and bind malignant cells. The use of superparamagnetic antibody microparticles offers a potential solution to the problem of inadequate antibody delivery. In this report, studies of the imaging characteristics and magnetically-induced movement of iron oxide-bound antibody (IOAb) microparticles [BioMag] are described. 1 mg/ml IOAb was readily visualized using conventional CT scan technique, but produced image artifacts on MRI. Rapid movement of IOAb in vitro was noted to occur in response to a magnetic field gradient. This property was exploited in in vivo studies using laboratory animals. IOAb injected into the intrathecal space of sedated rats could be transported through the CSF and localized to the medial aspect of one cerebral hemisphere or the other, using an external magnet. Construction of specific microparticles may allow for improved delivery of therapeutic substances to specific sites within CSF pathways.

Animals↗
PubMed1991

Simultaneous quantification of c-myc oncoprotein, total cellular protein, and DNA content using multiparameter flow cytometry.

Variations in total cellular protein content can confound interpretation of the significance of modulations of specific cellular proteins. In an effort to overcome this problem, a technique is described for the simultaneous measurement of a specific cellular protein, total cellular protein, and DNA content. The method utilizes dual-laser (uv and 488 nm) excitation and three fluorescent dyes: FITC, SR101, and DAPI. FITC-labelled antibody coupled with indirect immunofluorescence was used to quantify the c-myc oncoprotein, whereas SR101 and DAPI were used to measure total cellular protein and cellular DNA, respectively. Flow cytometric measurements of c-myc oncoprotein were compared to densitometric readings of p64c-myc. SR101 protein determinations were compared to those obtained by the Lowry technique. Results indicated that flow cytometric measurements correlated well with those obtained by the biochemical methods. The usefulness of the technique was further examined following treatment of exponentially growing HL-60 cells with 2.5 micrograms/ml cycloheximide for 0 to 12 h. Cycloheximide treatment was found to cause a significant decrease in c-myc oncoprotein content within 2 h (P less than 0.05), a relative increase in the proportion of G0/G1 cells and a modest decrease in total cellular protein. This technique appears to provide a rapid, quantitative approach, useful for investigating alterations in cellular growth balance occurring with cell differentiation, neoplastic transformation, or cell treatment with radiation or cytostatic drugs.

Cell Cycle↗
PubMed1991

Glioblastoma multiforme occurring in a patient following exposure to polychlorinated biphenyls.

Polychlorinated biphenyls have been shown to be carcinogens in animal studies. Because of lipid solubility and lack of biodegradation, they are known to deposit preferentially in fat and nervous tissue. In this report, we describe a 31-year-old male with prolonged polychlorinated biphenyls exposure who developed glioblastoma multiforme. Fat biopsy documented the presence of markedly elevated PCB levels. A co-worker also developed a malignant astrocytoma. The nature of PCBs and their role in human carcinogenesis are discussed. The possibility of an etiologic link between PCBs and brain tumors should be further investigated.

Adult↗
PubMed1989

Paraplegia resulting from thoracolumbar stenosis in a seven-month-old achondroplastic dwarf.

In young achondroplastic children, neurological manifestations have been found to include macrocephaly, hydrocephalus or ventriculomegaly and cervicomedullary compression. Occasionally in the second decade, lumbar radiculopathy or paraparesis resulting from severe thoracolumbar kyphosis develops. In this paper, we report the unique case of an achondroplastic dwarf who developed paraplegia due to thoracolumbar spinal cord compression at the age of 7 months. Compromise of the spinal canal was found to be due not to bony stenosis, but to a second layer of fibrous tissue, histologically identical to the dura. Treatment consisting of decompressive laminectomy and resection of the constricting tissue allowed the child to recover completely. Clinical, radiographic and pathological findings are discussed.

Achondroplasia↗
PubMed1989

Quantification of the c-myc oncoprotein in human glioblastoma cells and tumor tissue.

The identification of a quantifiable oncoprotein marker in glial cells could lead to its use as an aid in the diagnosis, grading, and treatment of tumours of glial origin. In this study, monoclonal antibodies to the c-myc oncoprotein were used in conjunction with immunofluorescence microscopy, flow cytometry, and immunoblot analysis to quantitate and characterize the expression of this oncoprotein in neoplastic and benign cultured glial cells and brain-tumor tissue. Flow cytometric analysis revealed that the c-myc oncoprotein was highly expressed in neoplastic cell lines and in glioblastoma tumor specimens. In contrast, anti-c-myc oncoprotein staining was not present in a non-neoplastic glial cell line or in a benign brain tissue specimen. Immunoblot analysis revealed two distinct c-myc oncoprotein bands, having molecular weights of 64 and 75 kD. Densitometric determinations of the relative levels of the 64-kD protein were in good agreement with the determinations made by flow cytometry. Flow cytometry was also used to relate the quantity of the c-myc oncoprotein present in the cells to their cell cycle phase. In the malignant cultured cells, the protein underwent an approximate twofold increase as the cells progressed from G1/G0 to G2/M in the cell cycle. The present results suggest that the c-myc oncoprotein may prove to be a useful marker for the proliferation status and/or malignancy of glial cells.

Brain Neoplasms↗
PubMed1988

Flow cytometric DNA analysis of medulloblastoma. Prognostic implication of aneuploidy.

Paraffin-embedded surgical specimens from 26 infants and children with medulloblastomas treated between 1972 and 1981 were examined for DNA ploidy by flow cytometry (FCM). All patients received a standard treatment (a combination of maximum debulking of medulloblastoma and postoperative craniospinal irradiation with a posterior fossa boost of 5000 rad or more). They were studied to correlate the results of the findings of FCM DNA analysis with their final outcome, DNA ploidy, and extent of tumor resection. All seven patients with totally resected aneuploid medulloblastoma are alive, whereas only one of six patients with subtotally resected diploid medulloblastoma is alive (P = 0.0047). The current study suggests both DNA ploidy and extent of surgical resection are the most important determinant of patients' prognosis. Patients in selected group, particularly those with subtotally resected diploid tumor, are advised to undergo aggressive adjuvant chemotherapy.

Adolescent↗
PubMed1987

Developing a clinical algorithm for early management of cervical spine injury in child trauma victims.

To define a subset of injured children for whom emergency cervical spine radiography may be unnecessary, we performed a retrospective chart and radiologic review. Two entry methods were used: All injured children, from birth through 16 years, who had received cervical spine radiographs at The Children's Memorial Hospital from September 1983, to September 1984, were included. All patients from birth to 16 years with proven or suspected cases of cervical spine injury who had received cervical spine radiographs and who had been treated at either the Children's Memorial Hospital or the Northwestern University Spine Trauma Unit during period 1974 to 1984 also were included. Each child's chart was reviewed, and 84 clinical variables were recorded. All radiographs were reviewed by a pediatric neuroradiologist. Of 206 children studied, 59 had cervical spine injuries. A clinical algorithm was derived using the following eight variables: neck pain; neck tenderness; limitation of neck mobility; history of trauma to the neck; and abnormalities of reflexes, strength, sensation, or mental status. The following decision rule was selected: Positive findings in any of these eight variables mandates cervical spine radiography. This algorithm correctly identified 58 of 59 children with cervical spine injury, yielding a sensitivity of 98% and specificity of 54%. Cervical spine radiographs could have been avoided in 79 children (38% of the entire sample). This algorithm performed better than did models derived from logistic regression analysis of the same data. Validation trials are required prior to the implementation of this or other clinical decision algorithms in practice.

Accidents↗