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Biomedical subjects

R J Hunt

Publications and source records attributed to R J Hunt.

71 records · Page 4Linked to original sources
PubMed1980

An improved procedure for sampling and analysis of dinitrotoluene vapor concentrations in workplace air.

Allied Chemical Corporation, Specialty Chemicals Division industrial hygienists required an accurate, convenient method for the sampling and analysis of dinitrotoluene vapor concentrations in the workplace air. A method has been developed which combines collection of dinitrotoluene vapor onto silica gel sample tubes, desorption in chloroform, and gas chromatographic determination of the various isomers of dinitrotoluene. Concentrations of less than 10 percent of the TLV can be determined in a 50 liter air sample.

Air Pollutants↗
PubMedDate not supplied

Mid-metacarpal deep digital flexor tenotomy in the management of refractory laminitis in horses.

Deep digital flexor tendon transection at the mid-metacarpus was performed in 20 horses with severe acute or chronic laminitis that was not responsive to conventional treatment. Sixteen horses improved within 72 hours, one horse worsened, and two horses were unaffected by the surgery. Eleven horses survived less than 1 month after surgery and six horses survived longer than 6 months. Three horses surviving longer than 6 months have remained lame and no horse has returned to athletic performance. Transection of the deep digital flexor tendon at the mid-metacarpus may decrease the pain associated with the acute refractory stage of laminitis and may be useful as an immediate salvage procedure; however, despite the early clinical improvement observed after tenotomy, the survival rate of affected horses may not be altered.

Acute Disease↗
PubMedDate not supplied

Sutured end-to-end and stapled side-to-side jejunal anastomoses in the horse.

Hand sutured end-to-end (EE) and stapled side-to-side (SS) small intestinal anastomoses were performed in 10 healthy adult horses. In five SS anastomoses, staple lines on the blind ends of the jejunum were inverted (SSI) and in five they were not (SSNI). Five EE anastomoses were sutured with polydioxanone and five were sutured with polyglyconate. All horses were euthanatized on day 30. Intra-abdominal adhesions were graded (0-4), and stomal areas were calculated from contrast radiographs made with the bowel distended. Histopathology scores for the anastomoses were based on the degree of inflammation (0-3), fibrosis (0-3), and alignment and healing of intestinal layers (0-3). Mean surgery times +/- standard deviations for EE, SSI, and SSNI techniques were 33.9 +/- 5.4, 36.2 +/- 5.6, and 29.6 +/- 5.9 minutes, respectively. Mean and median stomal areas were 9.4 +/- 5.5 and 8.9 cm2 for EE anastomoses and 17.2 +/- 16.5 and 12.1 cm2 for SS anastomoses. Intra-abdominal adhesions developed in three horses, one of which had clinical signs of colic. Mean histopathology scores for EE and SS anastomoses were 4.8 +/- 2.0 (median = 5) and 4.4 +/- 1.8 (median = 4), respectively. There were no statistically significant differences in surgery times, intra-abdominal adhesion scores, stomal areas, or histopathology scores between small intestinal EE and SS anastomoses in these horses.

Abdominal Pain↗
PubMedDate not supplied

Repair of fractures of the distal aspect of the radius in two horses.

Fractures of the distal radius in two horses were repaired by open reduction and interfragmentary compression using screws placed in a lag fashion. One horse had a complete oblique fracture of the medial aspect of the epiphysis of the distal radius and was sound for riding 32 months after surgery. The other horse had an open spiral comminuted fracture with medial displacement of the distal radial fragment. Laminitis developed in the contralateral limb and this horse was euthanatized 5 weeks after surgery.

Animals↗
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Intraperitoneal use of sodium carboxymethylcellulose in horses undergoing exploratory celiotomy.

The effect of intraperitoneal sodium carboxymethylcellulose (SCMC) administration on clinical outcome and survival was evaluated in horses undergoing exploratory celiotomy for acute gastrointestinal disease. Comparison of variables was made retrospectively between 44 horses that had SCMC and 92 horses (controls) not treated with SCMC. Mean age, body weight, heart rate, packed cell volume and plasma total protein of horses at admission, and convalescent period were not significantly different between control and SCMC groups. No significant differences were noted between control horses and SCMC horses with respect to incisional infection, hernia formation, recurrent episodes of colic, clinical outcome, and long-term survival (> 6 months). Seventy-six (83%) control horses and 34 (77%) SCMC horses survived long-term. Seventy (76%) control horses and 30 (68%) SCMC horses survived without complications and returned to their previous use. These results suggest that intraperitoneal use of SCMC does not adversely affect abdominal incisional wound healing, clinical outcome or long-term survival, however, the efficacy of SCMC in prevention of postoperative intestinal adhesions in horses requires further investigation.

Abdomen↗
PubMedDate not supplied

Delineating a recharge area for a spring using numerical modeling, Monte Carlo techniques, and geochemical investigation.

Recharge areas of spring systems can be hard to identify, but they can be critically important for protection of a spring resource. A recharge area for a spring complex in southern Wisconsin was delineated using a variety of complementary techniques. A telescopic mesh refinement (TMR) model was constructed from an existing regional-scale ground water flow model. This TMR model was formally optimized using parameter estimation techniques; the optimized "best fit" to measured heads and fluxes was obtained by using a horizontal hydraulic conductivity 200% larger than the original regional model for the upper bedrock aquifer and 80% smaller for the lower bedrock aquifer. The uncertainty in hydraulic conductivity was formally considered using a stochastic Monte Carlo approach. Two-hundred model runs used uniformly distributed, randomly sampled, horizontal hydraulic conductivity values within the range given by the TMR optimized values and the previously constructed regional model. A probability distribution of particles captured by the spring, or a "probabilistic capture zone," was calculated from the realistic Monte Carlo results (136 runs of 200). In addition to portions of the local surface watershed, the capture zone encompassed areas outside of the watershed--demonstrating that the ground watershed and surface watershed do not coincide. Analysis of water collected from the site identified relatively large contrasts in chemistry, even for springs within 15 m of one another. The differences showed a distinct gradation from Ordovician-carbonate-dominated water in western spring vents to Cambrian-sandstone-influenced water in eastern spring vents. The difference in chemistry was attributed to distinctive bedrock geology as demonstrated by overlaying the capture zone derived from numerical modeling over a bedrock geology map for the area. This finding gives additional confidence to the capture zone calculated by modeling.

Geological Phenomena↗
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Estimating recharge rates with analytic element models and parameter estimation.

Quantifying the spatial and temporal distribution of recharge is usually a prerequisite for effective ground water flow modeling. In this study, an analytic element (AE) code (GFLOW) was used with a nonlinear parameter estimation code (UCODE) to quantify the spatial and temporal distribution of recharge using measured base flows as calibration targets. The ease and flexibility of AE model construction and evaluation make this approach well suited for recharge estimation. An AE flow model of an undeveloped watershed in northern Wisconsin was optimized to match median annual base flows at four stream gages for 1996 to 2000 to demonstrate the approach. Initial optimizations that assumed a constant distributed recharge rate provided good matches (within 5%) to most of the annual base flow estimates, but discrepancies of >12% at certain gages suggested that a single value of recharge for the entire watershed is inappropriate. Subsequent optimizations that allowed for spatially distributed recharge zones based on the distribution of vegetation types improved the fit and confirmed that vegetation can influence spatial recharge variability in this watershed. Temporally, the annual recharge values varied >2.5-fold between 1996 and 2000 during which there was an observed 1.7-fold difference in annual precipitation, underscoring the influence of nonclimatic factors on interannual recharge variability for regional flow modeling. The final recharge values compared favorably with more labor-intensive field measurements of recharge and results from studies, supporting the utility of using linked AE-parameter estimation codes for recharge estimation.

Ecosystem↗
PubMedDate not supplied

Streptococcus mutans, lactobacilli, and caries experience in older adults.

This study investigated salivary levels of Streptococcus mutans, lactobacilli, and caries experience in a random sample of 448 black and 362 white older dentate adults living in North Carolina. Significant proportions of the participants had stimulated salivary flow rates less than 1.0 mL/min, salivary buffering capacity less than 4.0, S. mutans levels of 10(5) cfu/mL or more in stimulated whole saliva, or lactobacilli levels of 10(5) cfu/mL or more. Each of these factor levels could be considered, on a clinical basis, to increase caries risk. In general, people with higher levels of S. mutans or lactobacilli had more untreated coronal and root caries, but not greater total caries experience.

Aged↗
PubMedDate not supplied

The use of pit and fissure sealants in private dental practices.

Ninety percent of a stratified sample of 240 general dentists and thirty-two pedodontists in fulltime private practice in Iowa responded to a questionnaire about the use of sealants, attitudes and knowledge about sealants, and reasons for not using sealants. Approximately a third of the generalists and a half of the pedodontists use sealants regularly. Many negative attitudes about sealants were found, as well as a large degree of misinformation about them. Most dentists not using sealants thought that they did not last long or that amalgam restorations were more economical.

Attitude of Health Personnel↗
PubMedDate not supplied

Distribution of primary tooth caries in first-grade children from two nonfluoridated US communities.

In a prospective longitudinal study, 1099 first grade children from Aiken, South Carolina, and 1086 children from Portland, Maine, were examined annually for 3 years. Caries prevalence and dmfs incidence were determined. The mean dmfs in Portland children was 2.9. In Aiken, white children had a mean dmfs of 8.4, and black children had a mean dmfs of 10.2. The mean 3-year primary tooth caries increment was 1.5 surfaces in the Portland cohort 3.3 surfaces in the Aiken white cohort and 2.8 surfaces in the Aiken black cohort. These increments were divided evenly between interproximal and fissure surfaces. Twenty percent of the children in Portland had 75% of the caries; in Aiken, 20% of the children had 60% of the caries. This distribution suggests a high-risk group that could be targeted for aggressive caries prevention efforts if risk factors can be identified.

Child↗