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Biomedical subjects

G A Williams

Publications and source records attributed to G A Williams.

At least 19 recordsLinked to original sources
PubMed1992

Aspirin effects on the development of cataracts in patients with diabetes mellitus. Early treatment diabetic retinopathy study report 16.

The Early Treatment Diabetic Retinopathy Study, a randomized clinical trial supported by the National Eye Institute, was designed to assess the effect of photocoagulation and aspirin in 3711 patients with mild to severe nonproliferative or early proliferative diabetic retinopathy. Although the primary goal of the study was to evaluate the effect of photocoagulation and aspirin on diabetic retinopathy, the study also provided an opportunity to evaluate the effects of aspirin on the development of cataract. No evidence showed that aspirin use reduced the risk of development of cataract requiring extraction (4.1% vs 4.3% in patients assigned to aspirin or placebo treatment, respectively; Mantel-Cox P = .77; relative risk, 1.05; 99% confidence interval, 0.73 to 1.51). Aspirin use also did not reduce the risk of less extensive but visually significant lens opacities developing (29.6% vs 28.3%; Mantel-Cox P = .76; relative risk, 0.99; 99% confidence interval, 0.85 to 1.15). Early Treatment Diabetic Retinopathy Study results do not support the hypothesis that aspirin (at a dose of 650 mg/d) reduces the risk of cataract development in this diabetic population.

Adult↗
PubMed1992

Inhalation doses for aboriginal people reoccupying former nuclear weapons testing ranges in South Australia.

The Australian Government plans to rehabilitate the former nuclear weapons testing ranges at Maralinga and Emu in South Australia and to allow access to the areas for the Pitjantjatjara (Aboriginal) people who are the traditional owners of the land. The major radiological hazard posed by reoccupation of the ranges arises from inhalation of residual plutonium. The committed effective dose that these people might receive from inhalation on reoccupation of the lands is computed for a range of sites. The estimated doses for permanent occupancy range up to 300 mSv y-1 indicating the need for substantial rehabilitation before these areas are suitable for unrestricted access.

Environmental Pollution↗
PubMed1992

Applications and limitations of vitreoretinal biopsy techniques in intraocular large cell lymphoma.

The cases of 4 patients with clinical signs of intraocular large cell lymphoma are described. Initial cytopathologic examination of vitrectomy specimens failed to establish the malignant character of the vitreous infiltrates. Three of the four patients eventually developed solid central nervous system tumors, intracranial biopsy samples of which revealed large cell lymphoma, 13 months to 42 months after initial examination. In one patient, transscleral retinochoroidal biopsy confirmed the diagnosis at the same time as negative vitreous cytologic examination. Results of cytopathologic examination alone of vitreous biopsy specimens may not be sufficient to make a diagnosis in certain cases of large cell lymphoma that are subsequently documented by CNS biopsy. Careful attention should be paid to the handling, processing, and interpretation of vitrectomy specimens from patients suspected of having intraocular large cell lymphoma. Consideration should be given to immunocytologic staining and interpretation by centers that are highly experienced in vitreous cytopathology.

Biopsy↗
PubMed1992

Prevalence of dental caries and enamel defects in the primary dentition of Antiguan pre-school children aged 3-4 years including an assessment of their habits.

In 1989 a national survey was carried out on children aged 3 to 4 years attending nursery schools, to investigate the prevalence of caries experience, nursing bottle caries and enamel defects in the primary dentition, and these children's dentally related habits. In the first part of the study, examination of 482 Antiguan children showed that the dmft and dmfs values were 0.80 and 1.26 respectively, and that 77 per cent of the children were caries free; 4.6 per cent of children had nursing bottle caries; and enamel defects occurred in 24 per cent of children. No significant difference was found in oral health between urban and rural samples. In the second part, which was an interview survey, habits such as thumb sucking (13 per cent), not brushing their teeth (3 per cent), and swallowing fluoride toothpaste (13 per cent) were found among 369 children. In the third (a questionnaire) survey, a response rate of 63 per cent was obtained. Significantly more of the children with nursing bottle caries (78.6 per cent) had the habit of sleeping with a feeding bottle than occurred in caries free children (25.6 per cent), but there was no difference in the infant feeding pattern. The children with enamel defects were breast fed for a shorter period and had an earlier introduction to bottle feeding, compared with children without enamel defects. In the final part of the survey, an assessment of snack eating habits at school, a 58 per cent response rate was achieved. The majority of children often brought healthier snacks, together with daily sugar-rich drinks. Significantly more caries free children brought sugary snacks less frequently than children with caries experience.

Age Factors↗
PubMed1992

Assessment of loneliness at school among children with mild mental retardation.

This study was designed to determine whether children with mild mental retardation understand the concept of loneliness, whether their feelings of loneliness at school can be reliably assessed, and whether there are differences in loneliness between children with and without mental retardation. Results from a sample of 62 students with mild mental retardation and 62 students without retardation, ages 8 through 13, indicated that (a) high percentages of both groups understood what loneliness means, (b) a loneliness questionnaire yielded satisfactory internal reliability with both groups, and (c) boys but not girls with mental retardation reported significantly more loneliness than did children without mental retardation. Suggestions were made for future research on loneliness in school settings.

Adolescent↗
PubMed1991

Atrial pacing with two-dimensional echocardiography for evaluation of chest pain: comparison with thallium 201 scintigraphy.

Atrial pacing was performed with two-dimensional (2-D) echocardiography and thallium 201 scintigraphy in 40 men with stable chest pain. Coronary angiography showed significant (one or more lesions greater than or equal to 50%) coronary artery disease (CAD) in 36 patients and no or insignificant CAD in 4. Two dimensional echocardiography showed a left ventricular wall motion abnormality (WMA) either at rest or with pacing in 28 (78%) patients with CAD, with 17 (47%) showing a new or worsened WMA with pacing. A thallium scan showing abnormality (reversible or fixed perfusion defect) was seen in 26 (72%) patients with CAD; 18 (50%) had a reversible defect. In all, 34 of the 36 patients with CAD (94%) had a WMA, a perfusion defect, or both (specificity 50%). Occurrence of both a WMA and a perfusion defect in individual segments ranged from 10 of 25 patients with septal abnormalities to 0 of 12 with abnormalities of the lateral segment. Sensitivity of 2-D echocardiography for identifying CAD in specific vessels was 81% for the left anterior descending (LAD) artery, 30% for the right coronary artery, and 20% for the circumflex artery (both p less than .001 compared with the LAD artery). Corresponding sensitivities for thallium 201 imaging were 54% (p less than .05 compared with 2-D echocardiography), 27%, and 8% (both p less than .05 compared with the LAD artery). When combined with atrial pacing, 2-D echocardiography and thallium 201 perfusion imaging are of similar value for diagnosing the presence of CAD in patients with stable chest pain. Two-dimensional echocardiography is superior to thallium 201 imaging for identifying the presence of significant CAD in the LAD artery, but both tests are limited in their ability to detect lesions of the right coronary or circumflex arteries.

Aged↗
PubMed1990

Clearance of experimental vitreous hemorrhage after panretinal cryotherapy is related to macrophage influx.

We investigated the effect of panretinal cryotherapy on blood clearance and on the inflammatory cellular response in rabbit eyes with experimental vitreous hemorrhage. Eyes treated with cryotherapy demonstrated less extensive vitreous opacity and more rapid clearance of blood than untreated eyes. The peak inflammatory cellular response measured by counts or radiolabeled cells in the optic nerve was 2.5 times greater in the cryotherapy-treated eyes. Panretinal cryotherapy may promote the clearance of vitreous hemorrhage by stimulating the influx of increased numbers of phagocytic inflammatory cells.

Animals↗
PubMed1990

Relaxing retinotomies and retinectomies. Surgical results and predictors of visual outcome.

Functional and anatomic success after relaxing retinotomy may be limited by recurrent retinal detachment or severe hypotony. Fifty-four consecutive eyes undergoing relaxing retinotomy for proliferative vitreoretinopathy (42 eyes) and trauma (12 eyes) were analyzed to determine whether perioperative factors, including size and location of the retinotomy, influenced visual or anatomic outcome. After 6 months' minimum follow-up, anatomic success (retina attached posterior to buckle and an intraocular pressure of 3 mm Hg or more) was achieved in 35 eyes (64%). Functional success (visual acuity of 5/200 or better) was achieved in 14 eyes (26%). Factors predicting functional success by stepwise logistic regression analysis included a preoperative visual acuity of hand motions or better and location of the retinotomy in the superior four clock hours of the fundus. Causes of anatomic failure included proliferative vitreoretinopathy (11 eyes) and severe hypotony or phthisis (8 eyes). Superior location of the retinotomy and visual acuity of hand motions or better favorably influenced visual outcome after relaxing retinotomy.

Adolescent↗
PubMed1990

Thallium-201 perfusion imaging with atrial pacing or dipyridamole stress testing for evaluation of cardiac risk prior to nonvascular surgery.

Preoperative assessment of cardiac risk using thallium-201 scintigraphy and atrial pacing (n = 42) or dipyridamole stress testing (n = 35) was performed in 77 patients (mean age 65 +/- 7 years), who subsequently underwent elective nonvascular surgery. All patients were at low cardiac risk by clinical criteria; none could perform exercise stress testing due to physical limitations. ST depression consistent with ischemia occurred in 11 patients during atrial pacing and in 1 patient during dipyridamole stress testing (p less than 0.01). Nine patients had reversible perfusion defects with atrial pacing, and 10 patients with dipyridamole stress testing; fixed defects were present in 15 and 8 patients, respectively. Only one patient (fixed perfusion defect with atrial pacing, left main disease on coronary angiography) underwent preoperative coronary revascularization. Two patients subsequently had postoperative cardiac events. One patient (reversible perfusion defect with dipyridamole stress testing) experienced sudden death after a nonvascular procedure, while a second patient (normal thallium images with dipyridamole testing) had a nonfatal myocardial infarction. In patients having atrial pacing or dipyridamole stress testing, thallium-201 scans that are normal or show only a fixed perfusion defect confirm a low risk of cardiac complications following nonvascular surgery. The presence of a reversible perfusion defect does not preclude a postoperative course free of cardiac complications in patients at low cardiac risk by clinical criteria.

Aged↗
PubMed1990

Tissue plasminogen activator for postvitrectomy fibrin formation.

The authors injected 25 micrograms of recombinant tissue plasminogen activator (tPA) into the anterior chamber or vitreous cavity of 23 eyes of 22 patients with severe intraocular fibrin formation that developed after vitrectomy surgery for complicated cases of proliferative vitreoretinopathy (PVR) (13 eyes), diabetic traction retinal detachment (TRD) (7 eyes), or endophthalmitis (3 eyes). Tissue plasminogen activator injected an average (+/- standard deviation) of 73 +/- 63 hours after vitrectomy surgery resulted in complete fibrinolysis in 21 of 23 eyes and partial fibrinolysis in one eye. The mean time to fibrin resolution was 3.0 +/- 1.0 hours. Four eyes required repeat tPA injection for recurrent fibrin formation; repeat injection resulted in complete fibrinolysis in each case. The mean follow-up duration after tPA administration was 6 months. At the final follow-up examination, the retina was totally attached in 18 of 23 eyes and was partially attached in 2. Visual acuity improved in 12 eyes (52%); it was at least 20/400 in 8. Complications of tPA injection included hyphema (2 patients) and corneal stromal thickening (2 patients). Mild, transient, periocular pain that was easily managed with non-narcotic analgesia developed in three patients.

Adolescent↗
PubMed1990

Posterior segment manifestations of ocular trauma.

Nonpenetrating or blunt ocular trauma, orbital trauma and systemic trauma may cause a variety of posterior segment abnormalities. Blunt ocular trauma may cause damage to the retina (commotio retinae), retinal pigment epithelium (retinal pigment epithelial edema), choroid (choroidal rupture) and optic nerve (optic nerve evulsion) alone or in combination. Traumatic macular holes and retinal detachment or dialysis may also occur after blunt ocular trauma. Trauma to the orbital tissues adjacent to the globe can cause concussive forces with damage to multiple structures within the eye (chorioretinitis sclopetaria). Systemic trauma may result in diffuse retinopathy (Purtscher's retinopathy, shaken baby syndrome) or localized retinal abnormalities (whiplash retinopathy, fat embolism syndrome). Alterations in intravascular (Valsalva retinopathy) or intracranial pressure (Terson's syndrome) due to a variety of causes may result in preretinal or vitreous hemorrhage and associated visual loss. The purpose of this report is to review each of these entities of traumatic posterior segment abnormalities.

Choroid Diseases↗
PubMed1990

Tissue plasminogen activator and penetrating keratoplasty.

We report a patient who developed severe intraocular fibrin formation following penetrating keratoplasty and vitrectomy surgery. The fibrin response worsened despite aggressive treatment with topical steroids. On the second postoperative day, 25 micrograms of intracameral tissue plasminogen activator was administered, resulting in rapid resolution of the fibrin response. The graft remained clear. We believe tissue plasminogen activator may be useful in selected cases of severe, recalcitrant postkeratoplasy fibrin formation.

Eye Diseases↗
PubMed1990

Myocarditis: a clinical perspective.

Myocarditis can have many diverse presentations ranging from ventricular arrhythmias to congestive heart failure, secondary to dilated cardiomyopathy. The recent resurgence of endomyocardial biopsy has greatly enhanced our ability to diagnose this intriguing entity. The biopsy has shown that unexplained arrhythmias have a 15% to 29% incidence of myocarditis, while those with an idiopathic congestive cardiomyopathy have a biopsy-proved range of 9% to 63%. The cause of this process has, at times, been blamed on viruses, but definite cause-and-effect relationships are mostly conjecture and anecdotal. The current role of immunosuppressive therapy in myocarditis is potentially promising, and may alter the subsequent course of the illness.

Adult↗
PubMed1989

Prognostic value of atrial pacing and thallium-201 scintigraphy in patients with stable chest pain.

The value of atrial pacing and thallium-201 scintigraphy for assessing risk of subsequent cardiac events was examined in 210 patients with stable chest pain. Follow-up information was complete in 195 patients (mean age 61 years). Over an average follow-up of 19 months, cardiac events occurred in 38 patients--unstable angina in 20, nonfatal acute myocardial infarction in 6 and death from cardiac causes in 12. A history of previous myocardial infarction, diabetes mellitus, systemic hypertension or peripheral vascular disease at the time of pacing was not associated with an increased frequency of subsequent cardiac events. Six of 38 patients with later cardiac events had a history of congestive heart failure, compared with 8 of 157 without cardiac events (p less than 0.05). Neither pacing-induced angina, ST depression, nor the presence of a fixed perfusion defect was significantly more frequent in patients with cardiac events as a whole compared with patients without such events. Reversible defects and abnormal scans (reversible or fixed defects) were present, respectively, in 19 and 31 of 38 patients with cardiac events, compared with 42 and 79 patients, respectively, of the 157 patients without cardiac events (both p less than 0.01). In patients who developed unstable angina, a reversible defect was seen in 13 and an abnormal scan in 16 (both p less than 0.01 compared with patients without cardiac events). In 12 patients who died from a primary cardiac event, fixed defects were present in 8 and an abnormal scan in 11 (p less than 0.05 and p less than 0.01, respectively, compared with patients without cardiac events).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Treatment of postvitrectomy fibrin pupillary block with tissue plasminogen activator.

We injected 25 micrograms of recombinant tissue plasminogen activator into the anterior chamber or the vitreous cavity in seven aphakic patients for pupillary block caused by a complete fibrin pupillary membrane that formed after vitrectomy with fluid-gas exchange. Progressive fibrin deposition resulted in pupillary block by three days after vitrectomy surgery in six patients, and seven days after vitrectomy in one patient. The pupillary block was associated with increased intraocular pressure in six patients. Tissue plasminogen activator was injected via the corneoscleral limbus in five patients and via the pars plana in two patients. In all patients, injection of tissue plasminogen activator resulted in complete fibrinolysis of the fibrin pupillary membrane within four hours, associated with a deepening of the anterior chamber. In the six patients with increased intraocular pressure at the time of tissue plasminogen activator injection, dissolution of the fibrin membrane was associated with a decrease in pressure. In all patients, intraocular pressure had returned to normal by three days after the injection. No complications were associated with the injection.

Adult↗