Biomedical subjects

J L Creech

Publications and source records attributed to J L Creech.

14 recordsLinked to original sources

PubMed1998

In vivo tear-film thickness determination and implications for tear-film stability.

PURPOSE: Previous measurements of tear-film thickness in vivo are limited and cannot be easily applied in a clinical setting. A novel technique to measure tear-film thickness indirectly is introduced here, requiring only a slit lamp, video camera, and computer. A recent fluid mechanical theory relates tear-film thickness h, to the tear meniscus radius R, tear surface tension or, tear viscosity mu, and upper lid velocity U. This theory yields the result that h/R = 2.12 (microU/sigma)2/3. All parameters except h/R are taken as known physical constants, and R was measured for each subject, allowing the above equation to establish h. Tear-film breakup was also evaluated and correlated with tear-film thickness. METHODS: A clinical study was performed in which aqueous tear-film thickness was determined for 45 subjects, including 24 non-lens subjects, 15 hydrogel contact lens wearers, and 6 RGP lens wearers. R was measured by instilling fluorescein dye in the form of an eyedrop and videotaping the tear meniscus in profile. Tear-film breakup was videotaped through the ocular port of the slit lamp and evaluated based on a severity scale. RESULTS: Aqueous tear-film measurements are in the same range as literature values, with most measured values falling between 6 and 12 microm. Average tear-film thicknesses for non-lens, hydrogel, and RGP subjects are 10.4, 6.5, and 5.8 microm, respectively. Tear-film breakup is most severe in subjects with thin tear films, especially in contact-lens wearers. CONCLUSIONS: Tear-film thickness is an important parameter that varies among individuals. These variations correlate with differences in tear-film stability.

Adult↗

PubMed1984

Effect of occlusal relief on endodontic pain.

It has been suggested that removal of occlusion contacts will prevent or reduce postoperative endodontic pain during treatment. However, this theory has not been tested in clinical experiments. In this study, after endodontic instrumentation, the treated posterior tooth randomly received occlusal relief or mock-occlusal relief. Mean pain levels and the incidence of pain to occlusal pressure at various time intervals were recorded on questionnaire postcards by all patients, as was the duration of discomfort. Comparison of pain experienced by the occlusal treatment groups through statistical analysis gave the following conclusions: Spontaneous pain levels in the mock-occlusal relief and occlusal relief groups were not significantly different; Spontaneous pain levels in the mock-occlusal relief and occlusal relief groups did significantly relate to preoperative pain; Pain incidence from occlusal pressure in the mock-occlusal relief and occlusal relief groups did not significantly differ; Pain from occlusal pressure in both occlusal treatment groups did not significantly relate to preoperative pain; Duration of discomfort was not related to the occlusal treatment provided. The theory may be invalid that prophylactic removal of occlusal contacts is a pain preventive measure.

Dental Occlusion, Balanced↗

PubMed1983

The identification of hepatic injury and hepatic angiosarcoma among vinyl chloride workers--the epidemiological approach.

The Occupational Health Surveillance System described herein has provided the experience and data to clearly demonstrate that prospective, epidemiological application to the problem of health surveillance in the occupational environment is feasible and economical. It has demonstrated that the approach is implementable in industries of any size or type, can be operated without interference with industrial productivity, is extremely cost-effective at the epidemiological surveillance program level, provides the best means to identify and characterize agents which may produce occupationally-related disease in the human population, provides an ongoing means of assessing the effectiveness of intervention or preventive measures and be provided through the expertise of health sciences centers with economic benefit to the universities and industry and a significant social benefit to the community.

Health Promotion↗

PubMed1980

Herniation of the gallbladder through the foramen of Winslow.

A rare case of herniation of the gallbladder through the foramen of Winslow is presented. There are only six surgically proven previously reported cases. This condition should be suspected where symptoms suggest gallbladder disease in the presence of normal functioning gallbladder. A simultaneous cholecystogram and an upper gastrointestinal study is necessary to confirm the diagnosis. A cholecystectomy with plication of the foramen of Winslow is the suggested treatment.

Adult↗

PubMed1976

Clinical and morphologic features of hepatic angiosarcoma in vinyl chloride workers.

Fifteen male workers exposed to vinyl chloride developed angiosarcoma of the liver. Thirteen died of disease and two are currently living for short periods after diagnosis. Their ages ranged from 36 to 58 years (average 47.5 years). Their exposure time ranged from 4 to 27.8 years (average 16.9 years). The most common presenting symptoms were fatigue, weight loss, and abdominal pain. Hepatomegaly followed by splenomegaly were the most common physical findings. Biochemical profiles yielded variable results and proved to be of little value in the detection or diagnosis. Of eight patients autopsied, distant organ involvement was present in two cases, duodenal involvement in one, and direct extension of tumor to adjacent organs or tissues in four additional ones. The remainder, diagnosed by open liver biopsy, revealed no tumor extension. The gross features of the tumors were hemorrhagic necrosis, cystic degeneration, fibrosis, and apparent multicentricity. The histologic features were those of the typical angiosarcoma found in a variety of sites with a wide range of cellular differentiation. The histologic diagnosis was often impaired by the extensive tumor necrosis. Elsewhere in the liver subcapsular fibrosis, a distinct type of portal fibrosis, and endothelial cell hyperplasia with or without sinusoidal dilatation were noted. The reduction of industrial chemical exposure has already been achieved and will hopefully eliminate this chemically related tumor in the future. There is, however, a significant group of previously exposed workers who will require careful monitoring to detect functional abnormalities of the liver and possible early neoplastic changes.

Adult↗

PubMed1976

Angiographic and radionuclide characteristics of hepatic angiosarcoma found in vinyl chloride workers.

Hepatic angiosarcoma, recently discovered in a large series of vinyl chloride workers, demonstrates characteristic angiographic and radionuclide changes. Tumors exhibiting central hypovascularity with puddling are usually surrounded by a peripheral stain. A negative peripheral defect is demonstrated on hepatic scan. Healing hepatic infarction secondary to wedged hepatic venography creates a false-positive lesion on angiography similar to angiosarcoma. Splenomegaly and systemic venous hypertension develop in a number of these patients.

Adult↗

PubMed1975

Liver disease among polyvinyl chloride production workers.

A protocol for systematic testing of all employees of a chemical plant is presented. This factory manufactures polyvinyl chloride compounds and resins, ABS compounds and resins, and synthetic rubber. The results were reviewed, which led to the discovery of 2 additional cases of angiosarcoma and 11 cases of portal fibrosis. Two of the 11 cases were found to have developed in employees other than polyvinyl chloride production workers.

Chemical and Drug Induced Liver Injury↗

PubMed1975

Characteristics of cases of angiosarcoma of the liver among vinyl chloride workers in the United States.

A total of 13 cases of ASL have been documented to date among VC workers in four different plants in the United States. In this particular industrial population, this number of cases represents at least a 400-fold increase over expected incidence for this extremely rare tumor. The first case occurred in 1961. Average age at diagnosis is 48.2 years. Average length of time between initial VC work and diagnosis has been 20.3 years. A detailed review of 7 cases associated with one plant revealed that clinical features varied from little or no overt illness prior to diagnosis to advanced liver disease with portal hypertension and marked splenomegaly. Portal fibrosis was present in all 7 of these ASL cases as well as in 4 additional cases with non-malignant liver disease among VC workers at the same plant. These findings suggest that exposure to VCM in industrial settings can produce hepatic fibrosis with angiosarcoma as a late manifestation. Conventional liver function tests may not be sensitive indicators of such liver impairment, at least in its early stages.

Adult↗

PubMed1975