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Biomedical subjects

D M Robertson

Publications and source records attributed to D M Robertson.

At least 289 records · Page 16Linked to original sources
PubMed1980

Rhegmatogenous retinal detachment without macular involvement treated with scleral buckling.

Among 173 patients who had rhegmatogenous retinal detachment with spared maculas, high percentage achieved anatomic and functional success. We reattached 171 (99%) of the retinas; 150 (76%) of the eyes had final visual acuities of 6/15 (20/50) or better. Eighteen eyes (10%) had final postoperative visual acuities reduced more than two lines from the preoperative level. This reduced visual acuity was primarily related to postoperative changes occurring in the macula. The prognosis both for anatomic reattachment and visual acuity after scleral buckling for rhegmatogenous retinal detachment is significantly better when the macula is spared than when it is not. Large numbers of cryoapplications were not associated with macular complications.

Adult↗
PubMed1980

Massive vitreous hemorrhage and senile macular choroidal degeneration.

In the elderly patient with a massive vitreous hemorrhage in one eye and senile macular choroidal degenerative changes in the fellow eye, a hemorrhagic disciform detachment causing this massive vitreous hemorrhage must be considered in the differential diagnosis. Ultrasonography selectively combined with radioactive phosphorus (32P) testing differentiates between a hemorrhagic disciform detachment or disciform scar and a malignant melanoma of the choroid. The ultrasonographic findings of a hemorrhagic disciform detachment may vary, but usually the posterior pole lesion is relatively flat and broad-based with a fairly homogeneous pattern without choroidal excavation. Posterior polar lesions secondary to senile macular choroidal degeneration do not grow. The vitreous hemorrhage clears in about three fourths of the patients, eventually allowing visualization of the posterior pole and ophthalmoscopic confirmation of a disciform scar. Almost one half of the eyes may be expected to lose all light perception because of the development of an initially hemorrhagic retinal detachment.

Age Factors↗
PubMed1980

7. Pseudometastatic lesions of the choroid.

A 64-year-old man with a six-month history of visual loss was found to have multiple darkly pigmented lesions scattered throughout the choroid of both eyes. Some lesions, up to several disc diameters in size, were flat, but others were elevated one to two millimeters. The right eye also contained a darkly pigmented ciliary body mass. Impairment of light transmission was striking. Ultrasonography of the elevated lesions demonstrated solid masses with high internal reflectivity. The initial diagnostic differential included the possibility of pigmented metastases from a primary tumor elsewhere, as well as multiple primary nevi. A general medical examination demonstrated arteriosclerotic heart disease, hypertension, diabetes mellitus, areas of patchy pigmentation of the oral mucosa, and a hilar prominence. A mediastinal lymph node biopsy specimen showed a grade 3 undifferentiated carcinoma compatible with a lung primary carcinoma. Enlargement of the choroidal lesions was observed until the patient's death 15 months later. Autopsy showed an undifferentiated carcinoma of the lung with widespread metastases. Each eye showed multiple discrete benign melanocytomas within a diffuse nevus involving the entire uveal tract. The nature of the relationship between multiple uveal melanocytomas and the systemic carcinoma is uncertain, but recognition of multiple uveal melanocytomas warrants a general medical examination to exclude primary malignancy elsewhere.

Carcinoma↗
PubMed1980

Diabetic neuropathy in the mutant mouse [C57BL/ks(db/db)]: a morphometric study.

Detailed studies of peripheral nerves were undertaken in the mutant diabetic mouse of the [C57BL/ks(db/db)] strain using electrophysiologic and morphometric techniques. Electrophysiologic studies showed severely impaired motor nerve conduction velocity (MNCV), which developed promptly during the early phase of the diabetic syndrome. Morphometric changes occurred first after 20 wk of diabetes in both myelinated and unmyelinated fibers. There were both loss and shrinkage of myelinated fibers, most pronounced in the sural nerve and the ventral root. Changes appeared late in the dorsal root and in the peroneal and vagus nerves. Unmyelinated fibers showed both shrinkage and loss of axons, presumably involving sympathetic and afferent somatic fibers. Teased fiber studies and calculations of axon-myelin ratios confirmed our earlier suggestion that the neuropathy is primarily axonal in nature. The temporal discrepancy between functional and structural impairments in the present model strongly suggests a metabolic cause of the early neuropathy. This was further supported by the positive effect of insulin treatment on MNCV during the early phase of diabetes, whereas, during the late phase, treatment failed to show any effect.

Age Factors↗
PubMed1980

Microdensitometry as a clinical tool for diagnosing the progress of fracture healing.

By use of a scanning microdensitometer, a simple quantitative method of radiograph evaluation is made available for assessing the extent of bone healing after treatment of fractures or surgery. The surgeon is thus able to quantitatively determine the degree of healing and to choose a clinically desirable value of X at which he feels confident immobilization may be terminated.

Absorptiometry, Photon↗
PubMed1979

Quantitative estimate of pinocytosis in experimental acute hypertension.

Cerebral cortical arterioles in focal neocortical areas develop increased permeability to plasma proteins and protein tracers in experimental hypertensive encephalopathy. The mechanism underlying this increased permeability has been the subject of several studies. In our previous studies of angiotensin-induced acute hypertension, pinocytosis appeared to be the principal mechanism for the increased blood-brain barrier (BBB) permeability observed. In the present study pinocytotic activity was assessed quantitatively to determine whether enhanced pinocytosis was confined to the permeable arteriolar segments of hypertensive animals. In addition, the effect of horseradish peroxidase (HRP) itself on the pinocytotic activity of normal cerebral cortical arteriolar endothelium was determined. In 12 rats following administration of HRP, hypertension was induced by an infusion of angiotensin. The animals were perfusion-fixed 90 s after the onset of the infusion. Control animals received saline only or HRP only. The area of arteriolar endothelium in cross section was determined by a planimeter from overlapping electron micrographs taken at a constant magnification around the circumference of the vessel wall. Results indicate a significant (P less than 0.001) increase in the number of pinocytotic vesicles in the permeable arteriolar segments of hypertensive animals as compared with nonpermeable arteriolar segments of the same animals and comparable segments of normotensive rats. In addition, eight times as many vesicles appear to be transporting tracer in the permeable arteriolar segments of hypertensive animals as compared to the nonpermeable segments of the same animals and normotensive animals. HRP alone did not affect the pinocytotic index, there being no difference (P greater than 0.05) in the number of vesicles in normotensive animals receiving saline only and those receiving HRP only. Our previous observation that disruption of endothelial cells or their tight junctions did not occur was confirmed.

Animals↗
PubMed1979

360 degrees prophylactic cryoretinopexy. A clinical and experimental study.

Complications occurred after 360 degrees prophylactic cryoretinopexy in three of six eyes in which fellow eyes had previously developed aphakic retinal detachment. Two of the six prophylactically treated eyes developed retinal detachment in advance of anticipated cataract surgery, and a third developed vitreitis and progressive preretinal membrane formation after uncomplicated cataract extraction. In an experiment study with rhesus monkeys, preretinal membrane formation was produced by administering heavy freezes with 360 degrees cryoretinopexy. Although the quantities of cold were considered excessive for clinical use, the cryoretinopexy used clinically in this series must also be considered excessive. The use of 360 degrees cryoretinopexy in the management of eyes at high risk for retinal detachment must be considered judiciously. Particular caution must be exercised in administering cryoretinopexy to nondetached retinas so as to avoid heavy freezes, which destroy the linear retinal layers.

Aged↗
PubMed1979

Errors in the diagnosis of malignant melanoma of the choroid.

We reviewed our consultations and enucleations for suspected choroidal melanomas from 1954 through 1977. Among 876 eyes enucleated here during that period, 203 contained malignant melanomas; among these were 172 with melanomas of the choroid. Eighteen additional eyes contained melanomas of the anterior uvea. Six melanomas were clinically unsuspected. These unsuspected cases represented 2.6% of the 233 eyes in this series of enucleated eyes that were removed because of painful glaucoma, and 3.2% of the 190 uveal melanomas. Our study included eyes enucleated elsewhere after a clinical diagnosis of malignant melanoma was made here. Six of 224 eyes enucleated for clinically suspected melanoma were found to have mimicking lesions, a misdiagnosis rate of 2.7%. Two additional eyes were misdiagnosed as having simulating lesions before histologic confirmation of malignant melanoma after enucleation elsewhere.

Adult↗
PubMed1979

Immune responsiveness in patients with choroidal malignant melanoma.

We studied selective in vivo and in vitro immunologic factors of 25 patients with choroidal malignant melanoma. Immune profile factors did not show consistent differences between patients with melanoma and an age-matched control population. The studies were also non-contributory in delineating variations in immunocompetence with respect to melanoma cell types. Serial immune profiles failed to identify a change when clinical evidence of metastasis developed. When tested as a group, patients with melanoma in whom metastatic disease developed during the study showed significant depression of initial mitogen-induced lymphocyte blastogenesis. This depression was noted in advance of clinically recognized metastatic disease. This group had a wide range of responses that overlapped those of control patients, thus making the usefulness of these testing factors questionable for individual prognosis or for clinical monitoring.

Adult↗
PubMed1979

Delayed absorption of subretinal fluid after scleral buckling procedures.

Delayed absorption of subretinal fluid beyond six weeks after surgical repair for rhegmatogenous retinal detachment was recognized in 39 of 575 consecutive cases of scleral buckling. The most common preoperative condition was large clumps of cells on the undersurface of the detached retina (subretinal precipitates). Approximately one in four patients in whom precipitates are seen preoperatively will have fluid persisting beyond six weeks from surgical repair to complete absorption. A second relatively common condition associated with delayed fluid absorption that could be recognized before operation was long-standing peripheral (usually inferior) retinal detachment, which typically spared the macula, was associated with demarcation lines, and was caused by round atrophic holes with or without associated lattice degeneration. An analysis of subretinal fluid protein concentrations in 39 cases showed a positive relationship between protein concentration and duration of detachment. Pigment-laden macrophages in the subretinal space, possibly originating from the retinal epithelium, were common.

Absorption↗
PubMed1979

What patients recall of the preoperative discussion after retinal detachment surgery.

We conducted a prospective study to determine the percentage of preoperative information that was retained by 100 patients undergoing a scleral buckling procedure. Each patient received a standardized preoperative discussion regarding the nature of retinal detachment and its management. During the immediate postoperative period, each patient was questioned about the informed consent discussion. Although 97% of the patients acknowledged a thorough preoperative discussion there was a definite disparity between the patients' concept of adequate physician disclosure and the actual retention of the preoperative explanation. Overall retention of preoperative disclosure based on correct answers to 12 questions was only 57%. Few patients, 23%, retained knowledge of surgical risks, and only 61% remembered that a foreign material would be permanently sutured to the eye. When a patient failed to remember the correct answer to a question, more than half of the time he or she denied that information relevant to the question had been discussed. The results of this study indicate that patients retain primarily information that seems to be in favor of their decision to have surgery.

Adolescent↗
PubMed1979

Incidence of uveal malignant melanoma in the resident population of Rochester and Olmsted County, Minnesota.

Uveal malignant melanomas were diagnosed in 15 patients in the resident population of Rochester and Olmsted County, Minnesota, from 1935 through 1974. There were five males and ten females. In this well-defined community, the annual incidence of uveal malignant melanoma for the 40-year period was calculated to be seven per million per year. The incidence in the resident population under age 50 years was three per million, whereas for those age 50 years or older, it increased to 21 per million per year.

Adolescent↗
PubMed1979

The effect of prolonged indirect ophthalmoscopy on the human eye.

In an experiment designed to simulate an excessively prolonged clinical examination, seven human eyes were exposed to light focused through a 20-diopter, aspheric condensing lens for 30 to 45 minutes. Three eyes contained primary malignant tumors of the choroid and were enucleated 1 1/2 to 4 1/2 days after light exposure. Follow-up data on four blind eyes with clear media were evaluated 15 to 36 months after light exposure. Concentrated prolonged light exposure used in this experiment caused grossly visible progressive corneal edema, along with significant discomfort to the patient. Even with light exposures sufficient to cause these complications of the anterior segment, retinal injury was recognizable only with electron microscopy and was characterized by irregular bending and twisting of the outer segments of the photoreceptors, changes that are considered reversible in nonhuman primate studies. Intermediate to long-term follow-up of 15 to 36 months after light exposure to blind eyes failed to reveal lens changes or delayed light-induced degenerative changes in the retina recognizable by ophthalmoscopy, fundus biomicroscopy, or color and fluorescein fundus photography.

Adult↗
PubMed1979

Melanin containing neurofibroma: case report with evidence of Schwann cell origin of melanin.

This case report describes a melanin-containing neurofibroma involving a spinal nerve root. Electron microscopy of the tumor shows that neoplastic Schwann cells are capable of melanogenesis. Although this capability is suggested in the literature, few reports provide ultrastructural confirmation. The likely identity between reported "cellular blue nevi of spinal nerve roots" and nerve sheath tumors is discussed. It is possible that pigmented nerve sheath tumors behave more aggressively than nonpigmented ones, although it is debatable.

Adult↗
PubMed1979

A sensitive and specific in vitro bioassay method for the measurement of follicle-stimulating hormone activity.

An in vitro bioassay method for hFSH is presented. The method is based on the principles previously described by Dorrington et al. (1976b) and involves the assay of oestradiol produced from 19-hydroxyandrostenedione by dispersed Sertoli cells of 10-day old rats when cultured in the presence of graded doses of FSH. Using the 1st International Reference Preparation for human pituitary gonadotrophins (FSH and LH/ICSH) for bioassay (code no. 69/104) as standard, the useful range of the method is from 0.5 to 32 mIU/chamber (2 to 128 mIU/ml). The sensitivity of the method is 0.5 mIU/chamger. The mean index of precision (lambda) obtained from 16 multiple assays over 2 or 3 dose levels was 0.084. Parallelism was obtained between the 69/104 preparation and all preparations under study. The practicability of the proposed assay method is such that 15 preparations at 3 dose levels can be assayed by one person in 3 days. The specificity of the assay was investigated by determining the FSH activity in the following preparations: hFSH alpha- and beta-subunits, hLH, hCG, hTSH, ACTH, human growth hormone (hGH) human prolactin (hPRL) and luteinizing hormone-releasing hormone (LH-RH). The ACTH, hGH, hPRL and LH-RH preparations studied showed no detectable FSH activity in the assay. In the remaining preparations very low levels of FSH activity were found, corresponding to 0.004 to 0.6% of the weight of these preparations when compared with a highly purified hFSH preparation, suggesting that the method is specific for FSH. The possible synergistic or antagonistic influence of the above preparations when assayed in the presence of the 69/104 preparation was also assessed. No evidence of a synergistic or antogonistic effect was found. The assay of the hFSH potencies of a limited number of hFSH preparations of varying purity by the proposed in vitro bioassay, an hFSH radioreceptor method and an hFSH specific radioimmunoassay technique revealed that - although the relationship of the various potencies obtained with each method showed a close agreement - the bioassays yielded the highest potency estimates, and the radioimmunoassays the lowest ones. Since the proposed bioassay method is sensitive and considered to be specific for hFSH activity, it provides a suitable basis for the assessment of the specificity of other in vitro methods (radioreceptor and radioimmunoassay) currently used for detecting low levels of FSH activity.

Age Factors↗