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Biomedical subjects

D H Char

Publications and source records attributed to D H Char.

At least 91 records · Page 5Linked to original sources
PubMed1990

Uveal melanoma in relation to ultraviolet light exposure and host factors.

We conducted a case-control interview study among 1277 subjects (407 patients, 870 controls selected by using random digit dial) in 11 western United States to determine whether uveal melanoma and cutaneous melanoma shared common risk factors. After adjustment for other factors, the risk of uveal melanoma was increased for those with green, gray, or hazel eyes [relative risk (RR) = 2.5, P less than 0.001] or blue eyes (RR = 2.2, P less than 0.001) when compared to brown. A tendency to sunburn after 0.5 h midday summer sun exposure increased risk for uveal melanoma (burn with tanning RR = 1.5, P = 0.02; burn with little tanning RR = 1.8, P less than 0.001; burn with no tanning RR = 1.7, P = 0.002); as did exposure to UV or black lights (RR = 3.7, P = 0.003); and welding burn, sunburn of the eye, or snow blindness (RR = 7.2, P less than 0.001). An association with uveal melanoma was also noted with an increasing number of large nevi (P = 0.04 for trend), although the individual risk estimates were not remarkable. These data suggest that host factors and exposure to UV light are risk factors for uveal melanoma.

Adult↗
PubMed1990

Five-year follow-up of helium ion therapy for uveal melanoma.

One hundred sixty-four patients with uveal melanoma were treated with helium ion irradiation prior to May 1984, and the data were analyzed in June 1989. Most uveal melanomas were large, with a mean tumor thickness of 6.5 mm; approximately 60% of the patients had tumors that extended anterior to the equator. A complete follow-up was obtained for all patients. One hundred twelve patients were alive at the time of this report; 18% of the patients developed clinical and laboratory evidence of metastases and eventually died of widespread tumor. Eighty-four percent of eyes were retained. Data were analyzed with a number of parametric and nonparametric techniques. Larger tumors and those located in close proximity to the optic nerve and fovea had a higher incidence of most complications, especially visual loss.

Adult↗
PubMed1990

Metastatic ciliary body carcinoid tumor.

A 50-year-old man with a history of systemic carcinoid had decreased right eye vision and a darkly pigmented cilio-choroidal mass. Results of ultrasonographic and fluorescein angiographic examinations were consistent with a malignant melanoma. Fine-needle aspiration biopsy of the lesion identified it as a carcinoid metastasis. The patient refused both radiation and enucleation; complete excision with a cyclochoroidectomy was performed. Histopathologic examination showed a carcinoid neoplasm covered by marked hyperplasia of the retinal pigment epithelium that produced the pigmented appearance of the lesion.

Biopsy, Needle↗
PubMed1990

Ultrasonographic measurement of uveal melanoma thickness: interobserver variability.

We retrospectively reviewed ultrasonographic data on 32 uveal melanomas that had been studied both at a referral institution and at our centre within a six-week period. Generally there were good correlations between ultrasonographic measurements of tumour thickness. The mean absolute difference in ultrasound measurements of tumour thickness was 0.64 mm (range 0-2.2 mm); the mean tumour thickness was 5.2 mm (range 3.5-10.2 mm). Tumour diameter, location, the relative ultrasonographic experience with uveal melanoma, type of equipment, and tumour thickness all affected the interobserver variation of measurement.

Humans↗
PubMed1990

Flow cytometry measurement of nuclear RNA content in uveal melanoma.

We retrospectively studied the nuclear RNA content in uveal melanomas with known, long-term follow-up. Thirty patients had spindle cell melanomas, 25 had mixed cell tumors, and 9 had epithelioid cell neoplasms. Epithelioid cell types had a higher nuclear RNA content compared to mixed or spindle cell types (p less than 0.05). Using the Cox proportional hazards model, the nuclear RNA content appeared to be an independent prognostic indicator in uveal melanomas, and an increased nuclear RNA content was associated with a worse prognosis (p = 0.001).

DNA, Neoplasm↗
PubMed1990

Fluorescein angiography in ciliary body melanomas.

We retrospectively studied the value of iris fluorescein angiography in predicitng benignity or malignancy in 10 cases of ciliary body melanoma with iris extension. No correlation between fluorescein-angiographic appearance and histopathologic features was observed. Fluorescein angiography adds little to the management of ciliary body melanomas with iris extension.

Adult↗
PubMed1990

31P magnetic resonance spectroscopy of animal uveal melanoma.

Scleral surface coils were used to obtain in vivo magnetic resonance spectra (MRS) of Greene melanoma implanted in the rabbit uvea. Well-localized tumor spectra (4.7 Tesla) with good signal-to-noise ratios (S/N) were obtained from the tumor with a "single-pulse" sequence in less than 1 hour. Tumor localization was confirmed with one-dimensional spectroscopic imaging studies. Serial 31P spectra were obtained during tumor growth and after both optimal and suboptimal hyperthermia. Early 31P MRS change is correlated with tumor treatment response and preceded histologic evidence of cell destruction. Twenty-four to 48 hours after successful treatment, the inorganic phosphate/nucleoside triphosphate (NTP), and phosphomonoester/NTP ratios were significantly increased from 1.2 +/- 0.1 to 1.7 +/- 0.1 and 1.3 +/- 0.1 to 1.8 +/- 0.2, respectively. In contrast, untreated or ineffectively treated tumors showed little change. Interpretation of 31P MRS data in this animal uveal melanoma model after the first week was complicated by decreased S/N, increased contamination from contiguous tissues, ingrowth of fibroblasts, macrophages, and intratumor hemorrhage.

Animals↗
PubMed1990

Microwave hyperthermia for choroidal melanoma in rabbits.

Radiation has provided excellent local control rates in choroidal melanoma, but significant impairment in visual acuity has occurred in 30-60% of patients due in part to the development of radiation vasculopathy in the fovea and optic disc. Hyperthermia has been shown to have a synergistic effect when added to radiation therapy in human malignancies. The use of hyperthermia in ocular melanoma may allow a reduction in the total radiation dose necessary to achieve local control. A 2450-MHz microwave plaque applicator with integral surface cooling was used to deliver hyperthermia treatments to rabbit eyes containing choroidal melanomas. Extensive thermal mapping was done in acute eyes. In 18 survival animals, a single 23-G needle thermocouple probe with three sensors was inserted into the tumor. Target temperatures of 41.0-46.0 degrees C were maintained for 1 hour. All tumor-bearing eyes were followed for 1 month after treatment, or until tumor growth was noted, with serial ultrasound measurements and visual examinations. A 92% response rate was obtained in tumors treated at temperatures greater than 43.0 degrees C for 1 hour with no significant toxicity. Heat alone has significant tumoricidal properties in this animal model.

Animals↗
PubMed1989

Analysis of radiation failure after uveal melanoma brachytherapy.

We analyzed the number of cycling cells in the DNA synthesis phase and in mitosis in two uveal melanomas unsuccessfully treated with iodine 125 brachytherapy. In one patient, the tumor appeared to have been radioresistant, whereas the other patient had a clinically inapparent area of tumor that was not included in the tumoricidal radiation field. In the first patient, there was uniform tumor cell cycling, whereas the second patient had cycling cells predominantly in the area that did not receive optimal radiation. This gradient of cycling tumor cells in the second patient was observed with both standard histologic examination (mitoses per high-powered field) and bromodeoxyuridine staining (DNA synthesis). The bromodeoxyuridine technique was significantly more sensitive than standard histologic examination in the detection of cycling cells.

Aged↗
PubMed1989

The effect of silicone nasolacrimal intubation on epiphora after helium ion irradiation of uveal melanomas.

We evaluated prophylactic silicone tube intubation of the nasolacrimal drainage system prior to helium ion irradiation of uveal melanomas located on the nasal side of the globe. Twelve patients received silicone tubes and were compared to a control group of 12 patients with irradiated nasal tumors without silicone tubes. Symptoms of nasolacrimal duct obstruction and epiphora were evaluated by means of a questionnaire. All patients had nasolacrimal duct irrigation. Patients intubated before irradiation maintained patency (11 of 12), whereas those in the control group did not (zero of 12) (P less than .0014); ten of 12 control patients had closure of both superior and inferior puncta. No significant difference in symptoms of epiphora was observed between the two groups.

Helium↗
PubMed1989

Effect of various doses of radiation for uveal melanoma on regression, visual acuity, complications, and survival.

We reviewed 284 choroidal and ciliary body melanomas treated with 50, 60, 70, or 80 gray equivalents (GyE) of helium ion radiation. Multivariate methods of data analysis were used to adjust for differences between dose groups with respect to the characteristics of patients (and their tumors). Radiation dose level did not affect survival, complications, visual outcome, or tumor regression in this model. The minimum radiation dose necessary to achieve tumor control with charged particles may be less than 50 GyE.

Dose-Response Relationship, Radiation↗
PubMed1989

DNA cell cycle studies in uveal melanoma.

We histologically studied uveal melanomas treated with surgery only (enucleation or ciliochoroidectomy), low-dose (20 Gy) preenucleation radiation followed by enucleation, or enucleated melanomas after high-dose (50 to 80 Gy) charged-particle beam therapy. There was significantly less bromodeoxyuridine uptake in irradiated vs nonradiated melanomas (P less than .0001). Similarly, tissue culture growth of irradiated tumors was significantly less (P less than .007). These data demonstrate destruction of reproductive integrity of helium ion-irradiated melanomas. The incorporation of bromodeoxyuridine and fine needle aspiration biopsy techniques may be useful in the delineation of successfully irradiated tumors from tumors with apparent growth secondary to radiation vasculopathy.

Adult↗
PubMed1989

Solitary intraocular lymphoma as an initial presentation of widespread disease.

A patient presented with a large peripapillary choroidal mass as the initial manifestation of widespread, poorly differentiated, large cell lymphoma. The choroidal tumor had clinical and ultrasonographic characteristics of a uveal malignant melanoma. A systemic evaluation and fine-needle aspiration biopsy specimens of the abdomen and choroid established the diagnosis of a lymphoma. On rare occasion, other neoplasms can simulate the diagnostic pattern of uveal melanoma, and fine-needle aspiration biopsy can be crucial in establishing the correct diagnosis.

Abdominal Neoplasms↗
PubMed1989

Iris melanoma with increased intraocular pressure. Differentiation of focal solitary tumors from diffuse or multiple tumors.

A 70-year-old man presented with an apparent focal iris ciliary body mass and increased intraocular pressure. Fine needle aspiration biopsy 180 degrees from the main lesion demonstrated uveal melanoma cells in the angle. The eye was enucleated, and multiple separate iris and ciliary body melanomas were noted. This case demonstrates the usefulness of fine needle aspiration biopsy for both diagnosis and optimum therapy in selected cases.

Aged↗
PubMed1989

Bromodeoxyuridine uptake in the assessment of hyperthermic therapy for intraocular tumor.

Assessment of uveal melanoma response after many nonenucleation therapies is difficult with current modalities, since tumor regression is usually delayed. The goal of most treatments, including ionizing radiation or radiation and adjunct hyperthermia, is to destroy the reproductive capacity of the tumor. Cell cycling analysis with bromodeoxyuridine, a thymidine analogue only incorporated during DNA synthesis, was a useful indication of tumor control after hyperthermia was used to treat a Greene intraocular melanoma model. Cell cycling decreased from a mean of 16% before therapy to less than 1% in all the successfully treated tumors. Cell cycling changes preceded histologic evidence of cell death. In contrast, tumors that grew after insufficient treatment had increased cell cycling to a mean of 25%. Cell cycling studies with bromodeoxyuridine represent a sensitive gauge of the reproductive integrity of the tumor.

Animals↗