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Biomedical subjects

S A Harris

Publications and source records attributed to S A Harris.

At least 55 records · Page 3Linked to original sources
PubMed1992

Human exposure to 2,4-D following controlled activities on recently sprayed turf.

Total body dose of 2,4-D was determined in 10 volunteers following exposure to sprayed turf 1 hour following application and in 10 volunteers exposed 24 hours following application. Each group of 10 volunteers was divided in half and five wore long pants, a short-sleeved shirt, socks and closed footwear. The other five wore shorts and a short-sleeved shirt and were barefoot. All volunteers were exposed to a 2 by 15 m area of turf for 1 hour during which they alternated between walking and sitting or lying on the turf surface for intervals of 5 minutes. Dislodgeable residues of 2,4-D taken during the exposure sessions showed a rapid decline from 1 hour following application (8%) to 24 hours following application (1%). No detectable residues were found in 4-day urine samples supplied by volunteers except for 3 people who were barefoot and wearing shorts and contacted the turf 1 hour following 2,4-D application. The highest dose was measured in a volunteer who removed his shirt for 30 minutes of the exposure session (426 micrograms). Exposure levels of the other two volunteers who wore the prescribed clothing were lower (153 and 103 micrograms). No detectable residues were found in urine samples supplied by volunteers exposed to sprayed turf 24 hours following application. These results indicate that at the doses measured, exposure to sprayed turf should present little risk in humans. However, people can reduce exposure to non-detectable levels by remaining off treated turf for a period of 24 hours or until after rainfall or irrigation so that dislodgeable residues and therefore potential exposure are essentially zero.

2,4-Dichlorophenoxyacetic Acid↗
PubMed1992

Exposure of homeowners and bystanders to 2,4-dichlorophenoxyacetic acid (2,4-D).

Total body dose received in home gardeners applying 2,4-D and bystanders living within the household, but not applying the pesticide was measured. Levels of 2,4-D were monitored in air samples both inside the home and downwind of the application site. Homeowners were divided into protective and non-protective apparel groups and applied both a granular and liquid formulation of 2,4-D on two separate dates. Analyses of urine collected from homeowners for 96 hours following applications found total body doses ranging from non-detectable to 0.0071 mg/kg of body weight. The highest exposures occurred in the non-protected group and were consistently associated with spills of the liquid concentrate or excessive contact with the dilute mixture on the hands or forearms. Residues of 2,4-D were not detected in urine samples supplied by bystanders to home applicators. Residues of 2,4-D were detected in five of the 76 air samples taken during the home applications. Two of these air samples coincided with measurable applicator exposure but it is unlikely that this was a major route of exposure.

2,4-Dichlorophenoxyacetic Acid↗
PubMed1992

Percutaneous penetration of 2,4-dichlorophenoxyacetic acid and 2,4-D dimethylamine salt in human volunteers.

The percutaneous penetration of 2,4-dichlorophenoxyacetic acid (2,4-D) and 2,4-D dimethylamine salt (DMA) was evaluated separately in five male volunteers who participated in both experiments. Urine samples collected for 144 h following dermal applications of 10 mg to the dorsum of the hand (9 cm2) were analyzed for 2,4-D. Following the acid application, an average of 4.46 +/- 0.849% was recovered in the urine and a significantly lower amount of 1.76 +/- 0.568% following the DMA application. Significantly higher amounts of 2,4-D DMA (7.68 +/- 0.493 mg) were washed off the hand 6 h following application as compared with 2,4-D acid (5.35 +/- 0.384 mg). These results indicate that, in addition to the differences in physical and chemical properties of the two compounds that will affect absorption, the amount of the chemical absorbed is related inversely to the amount of washed off. Urinary excretion of 2,4-D was not complete in all volunteers 144 h following either application, but in all cases it was approaching the limit of detection. An average of 84.8 +/- 2.55% and 76.8 +/- 8.05% of the total recovered in 144 h was recovered in the urine 96 h following 2,4-D acid and 2,4-D DMA application, respectively. Average, approximated half-lives for excretion were 39.5 +/- 8.1 h for the acid application and 58.5 +/- 13.2 h for the DMA application.

2,4-Dichlorophenoxyacetic Acid↗
PubMed1991

Evidence for interleukin-1 beta production by cultured normal human osteoblast-like cells.

To determine if bone cells produce interleukin-1 beta (IL-1 beta), a potent bone resorption-stimulating agent, we studied well-characterized, nearly homogeneous cultures of normal human osteoblast-like (hOB) cells. With four strains of such cells, vehicle-treated cultures produced minimal IL-1 beta (mean +/- SEM, 1.3 +/- 0.3 pg/ml per 10(6) cells per 24 h) and showed dose-dependent (r = 0.99) increases to 2.2 +/- 0.7, 5.0 +/- 0.9, or 17.8 +/- 6.7 pg/ml, respectively, after treatment with lipopolysaccharide (LPS) at 3, 10, or 30 micrograms/ml (for increases after 10 and 30 micrograms/ml treatments, P less than 0.05). After treatment with tumor necrosis factor alpha (TNF-alpha) at 10 U/ml, IL-1 beta increased to 16.2 +/- 3.7 pg/ml (P less than 0.05). Neither 17 beta-estradiol nor bovine parathyroid hormone(1-34) (each at 10 nM), alone or in combination with LPS or TNF-alpha, affected IL-1 beta release. Northern blot analysis of total cellular RNA preparation revealed a single hybridization band at 1.9 kb when probed with a partially deleted cDNA for human IL-1 beta. The steady-state IL-1 beta mRNA levels showed a significant increase with LPS treatment and a lesser increase with TNF-alpha treatment in hOB cells. Moreover, TNF-alpha produced an even greater increase in IL-1 mRNA in HOBIT cells, a well-differentiated clonal cell line derived from normal hOB cells transfected with the SV40 large T antigen. We conclude that human cells of the osteoblast lineage produce IL-1 beta in response to well-recognized stimuli for IL-1 release from responsive tissue.(ABSTRACT TRUNCATED AT 250 WORDS)

Antigens, Polyomavirus Transforming↗
PubMed1991

Night studies for primary diurnal and nocturnal enuresis and preliminary results of the "clam" ileocystoplasty.

Modified conventional urodynamic apparatus was used to provide overnight monitoring of bladder and rectal pressure. A group of 26 patients with primary diurnal and nocturnal enuresis underwent both daytime rapid fill cystometry and overnight natural fill cystometry. The overnight study was effective in detecting detrusor instability in 10 patients deemed normal on rapid fill cystometry; 6 of these have now undergone clam ileocystoplasty and 5 are dry; 3 are awaiting this procedure. The clam remains very effective in the management of patients with resistant nocturnal and diurnal enuresis if careful selection is adopted. Overnight cystometry has proved to be an invaluable adjunct to the investigation of patients with primary diurnal and nocturnal enuresis previously felt to be urodynamically normal.

Adolescent↗
PubMed1991

Ambulatory urodynamics.

Long-term ambulatory urodynamic monitoring has been employed in 20 patients in an attempt to detect detrusor abnormality not appreciated by conventional cystometry. In 9 female patients with the "urge syndrome" it detected 2 previously unrecognised cases of detrusor instability; in 4 enuretic patients, only 1 of whom was known to be unstable previously, unstable contractions were confirmed, and 2 of 7 cystoplasty patients had high amplitude contractions detected only on ambulatory assessment. The technique provides a more sensitive index of lower urinary tract function than conventional cystometry in such patients.

Adolescent↗
PubMed1991

Permanent urethral stents for detrusor sphincter dyssynergia.

A series of 22 patients, most of whom had spinal injuries with detrusor sphincter dyssynergia, have had Medinvent Wallstents placed across the distal mechanism. All but 8 patients had undergone outflow surgery and 11 had had repeated unsuccessful sphincterotomies. The proximal end of the stent was placed over the verumontanum unless fertility was contemplated, when it was placed immediately below the verumontanum. Fifteen patients achieved complete voiding after placement of the first stent; 3 developed bladder neck obstruction after stenting, but in 1 of these cases resolution occurred after bladder neck incision. The 3 patients with artificial urinary sphincters failed to improve after stenting. Use of the urethral stent for patients with detrusor sphincter dyssynergia and failed sphincterotomy is a major advance. It should probably be the primary treatment in selected cases. Its effect on fertility is currently under assessment.

Humans↗
PubMed1989

Management of pneumonia in India and Indonesia.

Although the death rates from neonatal tetanus have been lowered and the death rates from childhood diarrhoea are becoming lower in India and Indonesia, death rates from pneumonia have not yet begun to fall. Pneumonia has become the greatest killer of children and the most important cause of preventable death. The reason for this relative rise in significance may lie in the failure to realize that the majority of the most acute cases of respiratory illness are not viral but rather bacterial infections which rapidly respond to appropriate antibiotic therapy. This paper reviews recent research on the aetiology of pneumonia; it examines age distribution and regional variation in morbidity and mortality; and it concludes by suggesting appropriate pneumonia treatment and case management guidelines. The essential priority is to make procaine penicillin available to children presenting with cough and a respiratory rate over 50 breaths per minute. This alone would substantially reduce the number of child deaths in India and Indonesia.

Child↗
PubMed1988

Post-traumatic changes of the temporo-mandibular joint by bone scintigraphy.

13 patients who sustained mandibular trauma were investigated with radiographs and scintiscans. The scintiscans showed abnormal uptake of radiopharmaceutical in the temporomandibular joint (TMJ). In patients with a long history of traumatic arthrosis, there was more positive correlation between the scintiscans, and clinical symptoms and histology than between radiographs, and symptoms and histology. In patients with mandibular body fractures and no TMJ symptoms, the scans showed abnormal uptake in the TMJ in 7/8 joints, in the absence of radiographic abnormality. The significance of the abnormal uptake and the value of scintigraphy is discussed.

Adolescent↗
PubMed1984

Gorlin's syndrome with a cardiac lesion and jaw cysts with some unusual histological features. A case report and review of the literature.

A 25-year-old male with Gorlin's syndrome associated with an intracardiac lesion, presented with jaw cysts requiring surgical treatment. One of the cysts contained unusual histological components including fibrous tissue, myxomatous stroma and abnormal epithelial hyperplasia. Metabolic investigation showed normal parathyroid function and normal tissue responsiveness to parathyroid hormone, despite several clinical and radiological features suggestive of pseudo-hypoparathyroidism. The principal features of the syndrome are reviewed.

Adult↗
PubMed1984

Radionuclide bone scanning in the diagnosis and management of condylar hyperplasia.

Four patients with maxillo-mandibular facial dysharmony and four controls were evaluated by 99Tcm-MDP (methyl diphosphonate) scintiscanning. The scintiscans in all patients with dysharmony showed positive uptake of the tracer indicating the increased degree of activity in the condylar region of the mandible. The significance of this is discussed.

Adolescent↗
PubMedDate not supplied

An evaluation of 24-hour urinary creatinine excretion for use in identification of incomplete urine collections and adjustment of absorbed dose of pesticides.

The accurate quantification of the absorbed dose of pesticides following occupational exposures generally requires complete 24-hour urine collections, often over extended periods of time. Difficulty in obtaining volunteer cooperation may result in incomplete urine collections. Traditionally, 24-hour urinary creatinine has been used to identify incomplete urine samples and has been used to standardize pesticide and other chemical dose estimates. More recently, the use of creatinine to standardize dose estimates has been questioned, as has its utility in the identification of incomplete urine collections. This research evaluates the use of personal observation, statistical methods, and published models to predict creatinine excretion to identify and adjust for incomplete urine collections. Based on the use of published creatinine prediction models, an evaluation of the day-to-day creatinine excretion within subjects, and personal observation, a small number of suspected urine samples were identified. Although it is likely that these samples were incomplete, correction of these urine volumes based on the published models did little to improve pesticide dose prediction. Further, results indicate that subjects who report missed urine samples may be able to estimate the missing volumes with some accuracy. In future pesticide exposure studies, the use of self-reported missed volumes may help to increase the accuracy of dose prediction when there is strong cooperation with collection procedures. A statistical model to predict creatinine excretion in professional turf applicators was developed to provide a preliminary screening for urinary completeness for future studies in which compliance with urinary collection is thought to be insufficient.

Adult↗