PubMed Health⌕ Search

Biomedical subjects

M T Benson

Publications and source records attributed to M T Benson.

At least 37 records · Page 2Linked to original sources
PubMed1992

The expression of class I major histocompatibility antigens by human retinal pigment epithelium in vitro.

Since the expression of class I major histocompatibility antigens by the retinal pigment epithelium (RPE) may be important with regard to ocular immune responses, we investigated this using flow cytometry and compared the RPE cells with the colon carcinoma cell line SW742. Six cultured RPE cell lines were examined. All showed strong basal expression of class I antigen. However, this expression was not maximal, and all the RPE lines tested showed a marked capacity for up-regulation of expression by culture in the presence of interferon-alpha, interferon-gamma, or tumour necrosis factor alpha, cytokines involved in immunological responses.

Antibodies, Monoclonal↗
PubMed1992

Hemi-naevus of Ota: perturbation of neural crest differentiation as a likely mechanism.

We present a case of oculodermal melanosis that involves the lower eyelid and lower half of the globe in a very clearly defined fashion. We suggest that such a lesion is the result of a local change in embryonic environment occurring during a well-defined stage of ocular development, such that differentiation of neural crest cells into a melanocytic phenotype is favoured.

Adult↗
PubMed1992

Aggressive toxoplasma retinitis.

Toxoplasma infection is a common cause of infectious uveitis. It usually produces a characteristic fundal appearance, with evidence of previous inflammation. However, it may occur in an atypical and aggressive form. Steroids administered to salvage vision may then worsen the clinical course. Retinal biopsy may be diagnostic in cases where doubt exists. We illustrate these points with two cases.

Aged↗
PubMed1992

Congenital anomalies of the branchial apparatus: embryology and pathologic anatomy.

Various congenital anomalies of branchial origin are found in the neck region. Understanding the varied radiologic appearances of these anomalies is greatly aided by familiarity with their embryologic origins. By considering the anatomic location and radiologic appearance, the precise embryologic origin can be accurately predicted. Defects of the branchial apparatus include branchial, thymic, and parathyroid anomalies, which may manifest as cysts, sinuses, fistulas, and ectopic glands. The embryologic model is used to explain the origins of all branchial apparatus anomalies. The most accepted theory proposes that vestigial remnants result from incomplete obliteration of the branchial apparatus or buried cell rests, and, thus, if cells are trapped in the branchial apparatus during the embryologic stage, they can form branchial cysts later in life. By understanding the embryologic basis for these defects, the radiologist is better able to interpret the findings encountered with the various imaging modalities used in the evaluation of these anomalies.

Branchial Region↗
PubMed1992

Congenital malformations of the cervicothoracic lymphatic system: embryology and pathogenesis.

Familiarity with the embryology of the lymphatic system is helpful in understanding the pathogenesis and radiologic appearance of lymphangiomas of the cervicothoracic region. By considering anatomic location and radiologic appearance, one can predict the type of lymphangioma present, the primordial lymph sac from which the malformation arose, and when it formed in embryonic life. Cystic hygromas are composed of large, dilated lymphatic spaces. They form when a primordial lymph sac fails to reestablish communication with the central venous system from which it arose. These lesions may also result from an aberrant bud arising from a primordial lymph sac. Cavernous and capillary lymphangiomas are composed of smaller lymphatic channels. They form from abnormally sequestered buds of the developing lymphatic mesenchyme responsible for the fine meshwork of terminal branches in the periphery of the embryo. Their growth may be inhibited by the relatively tougher tissues in the periphery (eg, skin and muscle) compared with the relatively loose fatty connective tissue in which cystic hygromas form. Not only can all types of lymphangioma occur in one lesion, but lymphatic and vascular malformations may also coexist.

Humans↗
PubMed1992

Production of interleukin-6 by human retinal pigment epithelium in vitro and its regulation by other cytokines.

Interleukin-6 (IL-6) is a pleiotropic cytokine which produces uveitis if administered intraocularly. It has been demonstrated in the aqueous of patients with various uveitis entities. We have investigated the ability of human retinal pigment epithelium (RPE) to produce IL-6 in vitro, both unstimulated, and in the presence of interleukin-1 (IL-1), tumor necrosis factor alpha (TNF), interferon (IFN) gamma, and lipopolysaccharide (LPS). Five human RPE cell lines were cultured over a 6-day period, both unstimulated and in the presence of these cyokines. IL-6 in the supernatants was measured using an ELISA assay. Unstimulated RPE produced small amounts of IL-6. IL-1 at 100 or 10 U/ml markedly upregulated IL-6 production, and TNF at 1000, 100 or 10 U/ml did so to a lesser extent. Neither IFN gamma or LPS alone increased IL-6 expression, but together gave significant upregulation. Thus human RPE can produce IL-6 and may be the source of this cytokine in ocular inflammatory states.

Cell Line↗
PubMed1992

Mucinous sweat-gland adenocarcinoma of the eyelid.

A case of mucinous sweat-gland adenocarcinoma of the eyelid, clinically diagnosed as a cyst, is presented. This lesion, although accounting for a small proportion of all sweat gland tumors, has a predilection for the eyelid. It is locally aggressive, has metastatic potential, and wide local excision is recommended as the primary procedure. This case illustrates the clinical, macroscopic, and histopathological features of a rare primary malignancy of the eyelid.

Adenocarcinoma↗
PubMed1991

A novel approach to the assessment of afferent pupillary defects.

The pupil response to a flashing light stimulus was observed for a group of 26 healthy volunteer controls, and 15 patients with relative afferent pupillary defects (RAPDs). For the control group, the mean interval between flashes which would just produce a perceptible pupil response was 295 milliseconds (ms). The mean difference between right and left eyes was 8.84 ms. The mean difference between normal and abnormal eyes of the APD group was 78.6 ms. The difference between these results and those of the control group are highly significant statistically (p less than 0.001), and we conclude that this test may be of use in the assessment of defects of the afferent light pathways.

Adult↗
PubMed1990

Cyclocryotherapy: a review of cases over a 10-year period.

There are conflicting reports on the value of cyclocryotherapy in the management of glaucoma. This retrospective study was carried out to assess the efficacy and complication rate of this procedure. The case notes of all patients undergoing cyclocryotherapy at a single centre over a 10-year period were reviewed. Case records were available for 68 eyes of 64 people. Thirty-eight eyes had neovascular glaucoma, nine had aphakic glaucoma, nine had angle closure glaucoma, three had primary open angle glaucoma, and nine had secondary open angle glaucoma. The mean follow-up periods for these groups varied from 2.0-6.3 years. The mean reduction in intraocular pressure following treatment varied from 7.9 mm Hg in the secondary open angle glaucoma group to 24.3 mm Hg in those with angle closure glaucoma. Pressure was controlled in 29.4% overall, ranging from 66.7% in the angle closure and primary open angle groups to 0% in the secondary open angle group. Of the painful eyes 71% were rendered comfortable, indicating that pain relief from cyclocryotherapy is not due solely to pressure control. 30% of the patients lost their vision following the procedure, phthisis occurred in 11.8% and four eyes (5.9%) went on to enucleation. Our results indicate that cyclocryotherapy affords good pain relief, without good pressure control, in various types of glaucoma. While there is an apparent high complication rate, visual loss and phthisis cannot be ascribed directly to the procedure, since these are eyes with a poor prognosis.

Adolescent↗
PubMed1990

External ocular pigmentation secondary to perforating eye injury.

The dispersal of pigment centrifugally through the conjunctiva from the site of a repaired traumatic perforation was observed. Iris tissue had been incarcerated in the wound for three days prior to surgical repair. Conjunctival biopsies were examined by light and electron microscopy. Light microscopy revealed a normal, non-pigmented conjunctival epithelium and numerous pigment-laden cells in the substantia propria. Electron microscopy showed these cells to contain melanosomes closely resembling those found in normal iris posterior pigment epithelium. The causes of abnormal external ocular pigmentation are discussed.

Conjunctival Diseases↗
PubMed1990

Silastic foam dressing for healing exenteration cavities.

Dressing the exenterated orbital cavity is difficult and time consuming for staff, traumatic to the healing wound, and painful for the patient, particularly when the wound is being left to granulate. We report the use of a silastic foam dressing which offers a number of advantages in this clinical situation.

Bandages↗
PubMed1989

Formed hallucination in the hemianopic field.

We present a case in which formed hallucinations were the sole presenting feature of an occipital infarct. The hallucinations occurred in the resulting hemianopic field. The localizing value of such phenomena is discussed.

Cerebral Infarction↗
PubMed1988

Factors affecting the acceptance of deoxyguanosine-treated thymus allografts.

dGuo-treated mouse embryo thymus lobes depleted of lymphoid and dendritic cells are not rejected by normal allogeneic mice despite expression of class I and class II major histocompatibility (MHC) antigens on thymic epithelial cells. Our results suggest that host mice are not tolerant to donor antigens, but treated lobes survive because thymic epithelial cells are not immunogenic. Multiple grafts of dGuo-treated lobes are rejected perhaps because numbers of residual dendritic cells reach a threshold necessary for priming. Mice previously primed by injection of spleen cells reject dGuo-treated thymus lobes, and crossreactions between major and minor histocompatibility antigens can be demonstrated. The acceptance of dGuo-treated thymus allografts by normal mice provides a system for investigating the requirements for priming.

Animals↗
PubMed1987

Survival of deoxyguanosine-treated fetal thymus allografts is prevented by priming with dendritic cells.

Allogeneic thymus lobes rendered alymphoid by treatment with deoxyguanosine are not rejected in normal mice despite expression of class I and class II MHC antigens on donor cells. The results presented here show that the injection of as few as 10,000 cells from dendritic cell-enriched populations is followed by the rejection of deoxyguanosine-treated grafts. These findings support the notion that treated thymus grafts do not provoke rejection because they lack dendritic cells, which are destroyed by deoxyguanosine.

Animals↗
PubMed1984

Unusual exercise-related stress fractures. Two case reports.

We describe two unusual exercise-related stress fractures, one in the sacroiliac joint of a long distance runner, the other in the body of the scapulae of an above-knee amputee. Each were detected on a 2-hour delay bone scan. To our knowledge, neither have been described scintigraphically. The bilateral scapular fracture is an unreported entity, and the fractured SI joint is a very uncommon site for an overuse injury.

Adolescent↗