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Biomedical subjects

G H Cassel

Publications and source records attributed to G H Cassel.

12 recordsLinked to original sources
PubMed1989

Lens changes and the incidence of cardiovascular events among persons with diabetes.

Previous analysis of data from the Framingham Heart Study and the Framingham Eye Study showed that the "all-cause" death rate for diabetic persons with lens opacities was more than twice that of diabetic persons without lens opacities. Additional follow-up information was used to investigate whether these lens changes were associated with cardiovascular morbidity and mortality in particular. At the eye examination (1973 to 1975) there were 133 diabetic persons with no cardiovascular disease, of whom 41% had lens changes. Of these 133 persons, 57 had at least one cardiovascular event by the time of the most recent follow-up examination (1981 to 1983). Regression analyses suggested an increased risk of cardiovascular events among diabetic persons with lens changes (incidence rate ratio = 1.8; p = 0.07). Specifically there were associations of lens changes with the development of congestive heart failure (incidence rate ratio = 3.6; p = 0.01) and coronary heart disease (incidence rate ratio = 2.4; p = 0.08). Thus lens changes, in addition to being early prognostic signs of mortality, appear to be predictors of cardiovascular disease in adult-onset diabetes.

Age Factors↗
PubMed1985

Lens changes and survival in a population-based study.

The Framingham Heart Study was begun in 1948 to study factors associated with cardiovascular disease. Participants have been reexamined approximately every two years. From 1973 to 1975, the Framingham Eye Study examined the eyes of available Heart Study participants. We used information about nearly 2000 persons from these population-based studies to investigate the relation of lens changes to survival. Follow-up ranged from five to eight years; 312 persons (16 per cent) died. Proportional-hazards regression analyses indicated an overall association of lens changes and decreased survival (P = 0.01), but detailed investigation showed (1) no association of lens changes and decreased survival among persons without diabetes (P = 0.29) and (2) a significant association of lens changes and decreased survival among persons with diabetes (P = 0.001). Diabetic persons with lens changes had an estimated death rate more than twice that of diabetics without lens changes. The duration of diabetes and degree of retinopathy were not associated with survival in this group, most of whom had adult-onset diabetes of short duration. We conclude that lens changes are earlier predictors of death in diabetics than these more traditional variables.

Age Factors↗
PubMed1985

Wills Eye Hospital Traumatic Hyphema Study.

Hyphema associated with nonpenetrating ocular trauma is a common cause for emergency hospitalization. The complications which result from this form of eye injury can cause permanent impairment of vision. Complications within the study population were reviewed. Analysis found a 16% rate of rebleeding, with the majority of these occurring within three to four days following the traumatic event. Unfortunately, no risk factors could be identified to help predict which patients were more at risk of complications. However, management of the complications which did develop in the study population was effective.

Adult↗
PubMed1984

Central corneal endothelial cell density after argon laser trabeculoplasty.

We report our experience using specular microscopy to perform endothelial cell counts in a series of 16 patients with bilateral, uncontrolled, primary open-angle glaucoma undergoing argon laser trabeculoplasty (ALT). Trabeculoplasty was performed in 20 eyes of these 16 patients. Untreated fellow eyes in 11 patients were used as controls for this series. Endothelial specular microphotographs and pachymetry were done using a Pocklington specular microscope (Keeler-Konan) before ALT and again approximately one and four months later. The endothelial cell densities were normal in all of the affected eyes before treatment and in the control eyes. No statistically significant differences between the pretreatment and posttreatment cell densities and pachymetry values relative to the controls were observed during the course of this study.

Cell Count↗
PubMed1984

Site visits in a multicenter ophthalmic clinical trial.

Site visits were conducted to 19 clinical centers in a large multicenter ophthalmologic clinical trial, the Early Treatment Diabetic Retinopathy Study (ETDRS). The purpose of these site visits was to ensure the consistency of study procedures among clinics and to verify that these procedures were being carried out in accordance with the ETDRS Manual of Operations. The five major aspects of this quality control program are as follows: To monitor and review each clinical center's organization and procedures; To promote comparability of participating centers in all important aspects of the clinical trial; To gain more understanding about special problems facing individual clinical centers; To establish good rapport between the site visitor and clinic staff to aid future clinic monitoring; To promote and maintain enthusiasm for the study. The ETDRS clinical center site visits were conducted by using an observational approach. Presite visit preparations included the formation of a site visit agenda and the design of a site visit form, providing a guide for the site visitor, and a list of the topics that were to be reviewed at each center. Important concerns common to all site visits proved beneficial in the ETDRS.

Attitude of Health Personnel↗
PubMed1984

Central serous chorioretinopathy: a seasonal variation?

A review of 345 consecutive cases of patients under the age of 40 years with central serous chorioretinopathy seen between 1969 and 1979 was performed in order to define temporal patterns of occurrence. The monthly distribution of cases significantly differed (p less than 0.01) from an expected random distribution. Although a statistical trend analysis failed to confirm a definite seasonal variation (p less than 0.01), an increased number of cases were seen in March and April.

Adult↗
PubMed1984

New thoughts on ocular neovascularization: a neurally controlled regenerative process?

Although the final common pathway of ocular neovascularization has been produced by a variety of stimuli in various locations in the eye, a specific unifying mechanism has not been generally accepted. Regeneration in lower vertebrates is a phenomenon that closely parallels new vessel growth in the eye, especially in its ontogenic potential and may give clues to its pathogenesis. The importance of a neural factor in regeneration has been demonstrated using several models. Interestingly, ocular tissues such as the iris, lens, and neural retina exhibits some of the most remarkable evidence for this regenerative mechanism. This article explores, through various developmental associations and clinical observations, the concept of ocular neovascularization as a neurally mediated regenerative process. Recent research utilizing a model of corneal denervation has added further support to this association.

Animals↗
PubMed1984

Anterior nongranulomatous uveitis: a seasonal variation.

A review of 348 consecutive cases of nontraumatic uveitis seen in the Wills Eye Hospital emergency room between Jan 1, 1981, and Dec 31, 1981, was conducted. Patients who presented with an initial episode of anterior nongranulomatous uveitis, without obvious etiology by history or clinical examination, were further evaluated for epidemiologic clues suggestive of a pathogenesis. This group consisted of 121 patients. A statistical analysis for seasonal variation suggested an increased occurrence during the summer months (p .01).

Female↗
PubMed1983

The effect of corneal trephination on neovascularization.

In order to investigate a neural influence on corneal neovascularization, we attempted to induce new vessel growth within a denervated zone produced by trephination. The stimulus for vascularization was cauterization central to the trephined margin. We demonstrated that in corneas denervated and stimulated in this manner neovascularization did not occur. This finding supports our hypothesis of a neural influence on neovascularization.

Angiogenesis Inducing Agents↗
PubMed1982

A clinical perspective on retinal neovascularization research.

Past research on retinal neovascularization forms the basis for our current primary and secondary preventive approaches toward its treatment. Several obstacles will probably delay the clinical application of angiogenic or antiangiogenic factors once these factors are satisfactorily identified. In the near future, however, the Early Treatment Diabetic Retinopathy Study should at least provide further insight into primary preventive efforts against the diabetic neovascular process. Overall, it appears that clinicians in the future must continue to rely on current modalities for the treatment of retinal neovascularization. Although new laser protocols or medications may be recommended, specific therapy targeted at the basic underlying mechanism of angiogenesis still seems to be in the distant future.

Angiogenesis Inducing Agents↗
PubMed1976

Enhancement of natural and experimental respiratory mycoplasmosis in rats by hexamethylphosphoramide.

Hexamethylphosphoramide (HMPA) was given orally (100 mg/kg/day) to: a) conventional rats of Sprague-Dawley and Long-Evans substrains known to have indigenous Mycoplasma pulmonis infection, b) uninfected pathogen-free (PF) Fischer rats, and c) PF and axenic Fischer rats inoculated intranasally with M. pulmonis strains having a wide range of virulence. Treated rats infected with virulent M. pulmonis, either naturally or experimentally, developed severe clinical signs of murine respiratory mycoplasmosis (MRM) with mortalities of 25 to 60% compared to relatively mild MRM and no deaths in untreated, infected controls. Deaths were attributed to unusually severe lung lesions of MRM (extreme neutrophilic exudation into major bronchi and bronchiectasis) with ulceration of respiratory mucosa and hemorrhage. Rhinitis also was increased in severity by HMPA in conventional rats, but not in experimentally infected PF or axenic rats. Severity of otitis media and tracheitis was not affected by HMPA. Incidence of lesions of MRM was unchanged except for increased frequency of gross lung lesions. In the absence of M. pulmonis infection, HMPA treatment of rats caused thinning and microulceration of respiratory epithelium in major bronchi without inflammatory lung disease. Other effects induced by HMPA, with or without the infection, were destruction and fibrous replacement of olfactory epithelium, atrophy of testes, and reduced weight gains. It was concluded that HMPA markedly enhances both rate of progression and severity of the pneumonia while inconsistently potentiating the rhinitis of MRM in rats. Previous studies of HMPA are emphasized as an additional example in which the synergistic effects of an experimental chemical and an indigenous pathogen of laboratory rats have given misleading experimental results.

Animals↗