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Biomedical subjects

A L Murphree

Publications and source records attributed to A L Murphree.

At least 55 records · Page 3Linked to original sources
PubMed1985

Photodynamic therapy of intraocular tumors: examination of hematoporphyrin derivative distribution and long-term damage in rabbit ocular tissue.

Studies were performed to determine the distribution of hematoporphyrin derivative (HPD) in ocular structures and to characterize long-term damage associated with ocular HPD photodynamic therapy. Pigmented rabbits with an amelanotic melanoma heterotransplanted to the iris were used to obtain quantitative tissue levels of HPD as well as to document HPD localization by fluorescence microscopy. HPD was administered i.v., and tissue concentrations of HPD were determined by spectrofluorometry following porphyrin extraction. Vascular structures such as the tumor, iris, and choroid-retina as well as the aqueous fluid from eyes containing tumors demonstrated rapid HPD localization. The sclera had minimal HPD uptake, and the drug was not detected in avascular structures such as the lens or cornea. HPD was cleared from all ocular structures except the tumor and choroid-retina by 24 h following injection. Fluorescence microscopy data indicate that HPD remained in the avascular photoreceptor cell outer segments of the retina. Long-term damage was documented in rabbits which received HPD photodynamic therapy to a 1-sq cm area of retina via transpupillary light delivery. Acute damage to the exposed area of retina (in the form of a chorioretinal scar) could be induced. This damage was permanent but not progressive. Lens opacities were not observed, and the cornea, aqueous, and vitreous remained clear on all test eyes. The results from these studies suggest that HPD photodynamic therapy may provide a selective and safe approach to the treatment of ocular tumors.

Animals↗
PubMed1984

Retinoblastoma: clues to human oncogenesis.

The retinoblastoma gene can be considered a model for a class of recessive human cancer genes that have a "suppressor" or "regulatory" function. The loss or inactivation of both alleles of this gene appears to be a primary mechanism in the development of retinoblastoma. Such a mechanism is in direct contrast to that of putative human oncogenes which are thought to induce tumorigenesis following activation or alteration. The high incidence of second primary tumors among patients who inherit one inactive retinoblastoma allele also suggests that this cancer gene plays a key role in the etiology of several other primary malignancies. Finally, the observation that extra nonrandom copies of specific chromosomal regions occur in some of these tumors provides circumstantial evidence that an "expressor" gene (possibly an oncogene) may be involved in retinoblastoma development.

Adenocarcinoma↗
PubMed1984

Hematoporphyrin derivative photoradiation induced damage to normal and tumor tissue of the pigmented rabbit eye.

Cytotoxicity induced by hematoporphyrin derivative (HpD) photoradiation in both normal and experimental tumor tissue of pigmented rabbit eyes has been examined. In addition, documentation of HpD induced fluorescence in ocular structures has also been obtained. Acute normal ocular tissue toxicity studies demonstrated that HpD (1-10 mg HpD/kg) followed 48 hours later by a transpupil irradiation of red light (635 nm, 36-90 J/cm2) resulted in demarcated areas of retinal damage. Long term (chronic) toxicity studies have shown that the initial damage to the retina was permanent but that no damage to the cornea, lens or vitreous could be observed during a 16 month follow-up. Visual and histological documentation have been obtained, following HpD photoradiation therapy (PRT), in rabbit eyes having heterotransplanted single nodule amelanotic melanomas. A toxic effect characterized by tumor blanching, edema and hemorrhage was observed within 24 hours of treatment. Histological examination obtained 24 hours following HpD PRT illustrated massive tumor tissue necrosis and vascular disruption. HpD PRT at clinically relevant doses was also shown to be effective in selectively curing the highly malignant amelanotic iris melanoma. It is concluded that HpD PRT may prove to be an effective modality for treating certain ocular tumors.

Animals↗
PubMed1983

Neonatal neuroblastoma metastatic to the iris.

A newborn infant was found to have Stage IVS retroperitoneal neuroblastoma. Multiple iris nodules were present at birth and regressed in synchrony with the primary tumor mass as chemotherapy was administered. A summary of the ocular manifestations of neuroblastoma is presented. A discussion of the possible significance of the iris lesions in this case is given. As far as we are aware, this is the first case report of neuroblastoma metastatic to the iris.

Female↗
PubMed1983

Patient with 13 chromosome deletion: evidence that the retinoblastoma gene is a recessive cancer gene.

Although a constitutional chromosomal deletion including 13q14 has been found to date in all retinoblastoma patients whose esterase D activity is 50 percent of normal, one female patient has been found who has 50 percent esterase D activity in all normal cells examined but no deletion of 13q14 at the 550-band level. Therefore, she has the smallest constitutional chromosomal deletion within 13q14 that is associated with susceptibility to retinoblastoma. Two stem lines were identified in a retinoblastoma from this patient, and each one had a missing 13 chromosome. No detectable esterase D activity was found in the tumor, indicating that the normal nondeleted 13 chromosome was lost in both stem lines. Thus the data from this patient not only show that there is a total loss of genetic information at the location of the retinoblastoma gene within the tumor, but also imply that recessive genes may play an important role in the development of certain human tumors including retinoblastoma.

Child, Preschool↗
PubMed1983

Gene for hereditary retinoblastoma assigned to human chromosome 13 by linkage to esterase D.

Evaluation of three families with hereditary retinoblastoma demonstrates close linkage of the gene for this tumor with the genetic locus for esterase D. These results assign the gene for the hereditary form of retinoblastoma to band q14 on chromosome 13, the same region which is affected in the chromosome deletion form of this eye tumor, and therefore suggest a common underlying mechanism in the pathogenesis of these two forms of retinoblastoma.

Chromosome Deletion↗
PubMed1983

Nonrandom chromosomal changes in untreated retinoblastomas.

The karyotypic patterns of 15 retinoblastomas were examined. Five tumors were found to have two distinct stem lines and, therefore, the chromosomal patterns of 20 tumor cell lines are reported. Three nonrandom chromosomal changes, namely, a loss of a chromosome #13, the presence of an i(6p), or a trisomy of 1q were observed. The potential importance of these chromosomal changes in tumor development is discussed, particularly the loss of a chromosome #13 or the gain of an i(6p). At least one of the three chromosomal changes was found in 75% of the tumor lines analyzed.

Aneuploidy↗
PubMed1983

Hematoporphyrin derivative photoradiation therapy for the treatment of intraocular tumors: examination of acute normal ocular tissue toxicity.

Preclinical studies designed to define potential side effects resulting from the use of hematoporphyrin derivative (HPD) photoradiation therapy (PRT) as a modality for treating intraocular tumors have been performed. Pigmented rabbits were used to evaluate acute normal ocular tissue toxicity following single HPD PRT treatments in which the light was directed through the pupil and onto a 1-sq cm area of the retina. The treatment procedure consisted of the i.v. administration of HPD (1 to 10 mg/kg) followed 48 hr later by a 15-min exposure of localized red light [635 +/- 5 nm; 40 to 400 milliwatts/sq cm] generated by a free running rhodamine B dye laser pumped by a 5-watt argon laser. Toxicity to normal retinal tissue was documented using fundus photography, fluorescein angiography, and histological examination. The results of this study demonstrated that ocular damage in the form of retinal edema, detachment, and necrosis could be induced by clinically relevant doses of HPD PRT. The area of retinal damage was limited to the treatment field in all but the highest doses of HPD PRT. The histological results were in agreement with the visual observations in that abrupt and demarcated transition areas between injured and normal-appearing retina were observed. Care will have to be used in the delivery of light to the treatment field if HPD PRT is to be utilized for treatment of intraocular tumors.

Animals↗
PubMed1982

Tissue distribution of 3H-hematoporphyrin derivative in athymic "nude" mice heterotransplanted with human retinoblastoma.

Quantitative uptake levels of tritium-labeled hematoporphyrin derivative (3H-HpD) have been obtained for normal and malignant tissue of athymic "nude" mice heterotransplanted intraocularly with human retinoblastoma. It was determined that eyes with tumor accumulated higher levels of 3H-HpD than those in control eyes. In addition, an improved therapeutic retention ratio of the drug (eyes with tumor compared with control eyes) was obtained at extended time intervals after administration.

Animals↗
PubMed1981

Total hyphema evacuation by vitrectomy instrumentation.

We describe our technique for the surgical removal of hyphema using the Ocutome vitrectomy system and report the results in 12 patients. Blood was removed successfully with just one operation in all 12 eyes. Eleven of the 12 eyes maintained intraocular tension of less than 20 mm Hg. Vision improved in 11 of 12 eyes and six had a vision of 6/18 or better. Permanent vision loss could not be attributed to the operative technique.

Adolescent↗
PubMed1980

Regional assignment of genes for human esterase D and retinoblastoma to chromosome band 13q14.

The expression of human esterase D was evaluated quantitatively and qualitatively in five persons with partial deletions or duplications of chromosome 13. The results showed that the locus of this enzyme is at band 13q14. Deletion of this same band in other subjects has been found previously to indicate a predisposition to the development of retinoblastoma, which was present in the four individuals in this study who had partial deletions of chromosome 13. Because of this close synteny, esterase D evaluation should aid in the diagnosis and genetic counseling of retinoblastoma.

Chromosome Deletion↗
PubMed1980

The nude mouse model for human retinoblastoma: a system for evaluation of retinoblastoma therapy.

We have critically examined the nude mouse model for human retinoblastoma to determine whether or not characteristics found in the parent tumor are retained in the mouse. We have demonstrated that most tumors grown in the anterior chamber of the nude mouse maintain a similar karyotype, show the same degree of differentiation and develop an adequate tumor blood supply when compared to the primary tumor from which they were obtained. Because of these findings, we suggest that this model may be particularly useful for evaluating new methods or combinations of treatment for human retinoblastoma.

Animals↗
PubMed1980

Tumor regression of human retinoblastoma in the nude mouse following photoradiation therapy: a preliminary report.

Retinoblastoma is the most common malignant intraocular neoplasm of childhood. Enucleation of both eyes is necessary in some advanced cases where radiotherpy and other modalities of treatment have failed. We present in this paper our initial observation that photoradiation therapy (the combination of the photosensitizing drug, hematoporphyrin derivative, and red light) produces marked tumor cytotoxicity in human retinoblastoma heterotransplanted into the anterior chamber of the nude mouse eye.

Animals↗
PubMed1976

Ocular findings in mannosidosis.

Three patients with typical features of mannosidosis and deficiency of alpha-mannosidase activity, who were examined ophthalmologically, had similar lenticular opacities. Corneal opacities were absent. Chamber angle and striking ophthalmoscopic anomalies occurred in two young patients who had normal electroretinograms. Two patients had strabismus. Conjunctival biopsy specimens morphologically confirmed the lysosomal nature of this disorder.

Carbohydrate Metabolism, Inborn Errors↗