Application of Polyacrylamide (PAM) through Lay-Flat Polyethylene Tubing: Effects on Infiltration, Erosion, N and P Transport, and Corn Yield.

Polyacrylamides (PAMs), when applied as a soil amendment, purportedly improve soil infiltration, decrease erosion, and reduce offsite agrochemical transport. The effect of PAM on infiltration, erosion, agrochemical transport, and crop yield when applied in furrow to mid-southern US production systems has not been evaluated. The objective of this study was to assess PAM effects on infiltration, erosion, corn ( L.) grain yield, and nitrogen (N) and phosphorus (P) transport when applied at 10 mg L through lay-flat polyethylene tubing. A 2-yr field study was conducted at the Mississippi State Delta Research and Extension Center in Stoneville, MS, on a Dundee silt loam and a Forestdale silty clay loam. The experimental design was a randomized complete block with four replications of each treatment: irrigated plus no PAM (control) and irrigated plus PAM at 10 mg L. Each irrigation event delivered 102 mm of water at 18.9 L m per furrow, and runoff was captured in a holding tank on the lower end of each plot. Pooled over year and soil texture, PAM increased infiltration and corn grain yield by 6% ( ≤ 0.0398). Polyacrylamide effects on the offsite transport of sediment and N and P were inconsistent, varying across year and soil texture. Results indicate that PAM improves infiltration and corn grain yield on silt loam and silty clay loam textured soils; however, further research is required before PAM can be recommended as a best management practice for mitigating erosion and offsite agrochemical transport in mid-southern production systems.

Rotavirus VP6 expressed by PVX vectors in Nicotiana benthamiana coats PVX rods and also assembles into viruslike particles.

The rotavirus major inner capsid protein (VP6) has been expressed in Nicotiana benthamiana plants using vectors based on potato virus X (PVX). VP6 was expressed either as a fusion with the PVX coat protein or from an additional subgenomic promoter inserted to enable both VP6 and PVX coat protein to be expressed independently. Both approaches yielded VP6, which retained the ability to form trimers. VP6 expressed from the subgenomic promoter assembled into paracrystalline sheets and tubes. Expression as a fusion protein yielded PVX rods that presented an external "overcoat" of VP6, but unexpectedly, some rotavirus protein also assembled into icosahedral viruslike particles (VLPs). The assembly of viral protein into VLPs suggests that prior display of VP6 on the flexuous PVX rod facilitates the subsequent assembly of VP6 into stable icosahedral particles.

A comparison of the early postoperative care required by patients treated with single and two stage surgical techniques for the provision of Brånemark implant supported mandibular overdentures.

Patients who underwent a single stage surgical procedure to place two Brånemark implants to stabilise complete mandibular overdentures with bar attachments, required no more postoperative follow-up visits before definitive prosthesis construction than patients who had their implants placed at two separate surgical stages. However, the visits of the single stage group, occurred over a shorter time-scale and more attention was required to tighten or replace their healing abutments.

Use of intra-articular morphine for postoperative analgesia following TMJ arthroscopy.

Recent studies have suggested that giving opioids locally into inflamed tissue may cause analgesia. This antinociceptive effect has been attributed to the interaction of the drug with opioid receptors upregulated by inflammation in the peripheral tissues. We have compared the analgesic effect of intra-articular morphine with that of normal saline and a combination of morphine and its antagonist naloxone after arthroscopy of the temporomandibular joint (TMJ). Twenty-one patients took part in a randomized controlled double-blind trial and received one of these three solutions at the end of operation. The pain scores, time to the first request for analgesia, and the analgesic consumption of the patients in the three groups did not differ significantly at any time during the study period.

Maxillofacial surgery and the role of the extended day case.

AIM: To determine the change in use of a day surgery unit over a 21-year period. DESIGN: Retrospective analysis. SETTING: The day surgery unit within a central London dental hospital. MATERIALS: The operating and anaesthetic records of surgical activity in 1973, 1983, 1993 and 1994. RESULTS: A six-fold increase in the total number of dentoalveolar procedures performed was demonstrated during the period studied. However, these procedures represented only 77.6% of surgical activity in 1994 compared with 98.9% in 1973. CONCLUSIONS: Day case surgery appears to be advantageous to patients, clinicians, hospital managers and purchasing authorities. The development of more specialist day case services and facilities within "dental centres' is proposed as a means of ensuring that the specialty is able to adapt to the changing patterns of health care in the future.

Dysmorphophobia: recent developments of interest to the maxillofacial surgeon.

Recent changes in the classification of psychiatric illnesses have resulted in the term dysmorphophobia being replaced by that of body dysmorphic disorder (BDD). This paper attempts to alert the clinician to the presenting features of the condition and discusses its management, with particular emphasis on the role of surgery and current concepts of pharmacological treatment. A number of case reports are included to illustrate the diversity of this interesting disorder and the difficulties involved in treatment.

Negotiating advance directives for persons with AIDS.

A focus group was conducted to determine the views of persons with AIDS about how to best conduct the process of establishing advance directives. (Advance directives are instructions regarding future medical care to be implemented should a patient be unable to communicate his/her treatment preferences.) Several hypotheses emerged from this focus group that were then formally tested with a questionnaire. The results of the questionnaire identified (a) predictors of attitudes toward advance directives and (b) predictors of the act of having established a directive. Based upon the findings from the focus group and the questionnaire, recommendations for social workers raising the issue of advance directives can be made. First, time for the client to adjust to seropositive notification should be allowed prior to raising the advance directive issue. Second, the advance directive issue should be raised in the context of empowerment rather than being embedded in other paper work. Third, people who are most likely to be disturbed by the process of establishing advance directives are those who have low health locus of control, low trait optimism, low reliance on active involvement as a coping mechanism, and low reliance on distraction as a coping mechanism. More time should be allotted for people with those characteristics.

Control of paint overspray in autobody repair shops.

Commercially available controls for reducing worker exposure to paint overspray were evaluated in six autobody shops and a spray-painting equipment manufacturer's test facility. Engineering control measures included spray-painting booths, vehicle preparation stations, and spray-painting guns. The controls were evaluated by measuring particulate overspray concentrations in the worker's breathing zone, visualizing the airflow in spray-painting booths and vehicle preparation stations, and measuring airflow volumes and velocities. In addition, respirator usage observations were collected at five of the autobody repair shops, and quantitative fit tests were conducted on existing respirators at three shops. Several conclusions were drawn from this study. Downdraft spray-painting booths provide lower particulate overspray concentrations measured on the worker than crossdraft and semidowndraft spray-painting booths. In the latter two booths, the spray-painting gun can disperse as much as half the paint overspray into the incoming fresh air, increasing worker overspray exposure. Vehicle preparation stations have no walls to contain the overspray and, commonly, a single exhaust fan removes air from the painting area. Airflow patterns suggest that these do not control the paint overspray. Switching from a conventional spray-painting gun to a high-volume low pressure spray-painting gun reduced the particulate overspray concentration by a factor of 2 at a manufacturer's test facility. However, this change did not significantly affect solvent concentrations. Finally, respirator usage in five of the six shops studied was inappropriate. Respirators were poorly maintained and/or did not fit the workers, perhaps due to the absence of a formal respirator program.

Possible interrelations among environmental toxicants, amphibian development, and decline of amphibian populations.

Many amphibian populations are declining in a number of geographical locations throughout the world. In most cases, the cause or causes are unknown, but are assumed to result from man-made alterations in the environment. We review existing evidence concerning how environmental xenobiotics could contribute to declines of amphibian populations by impacting growth and development of the young. This paper examines the potential roles of toxicants in: a) affecting the susceptibility of young to disease; b) retarding growth and development of amphibian young; c) affecting the ability of larvae to avoid predation; d) affecting the development of physiological, morphological, or behavioral processes in a manner that subsequently impairs the ability of the young for future reproduction; and e) directly causing mortality of young. These issues are not well studied, and more studies are needed before the roles of environmental xenobiotics in amphibian declines are fully understood.

The mutagenicity of electrocautery smoke.

Careful analysis of electrocautery smoke produced during breast surgery has found organic compounds that are unidentifiable with current analytical techniques. The purpose of this study was to determine the potential mutagenicity of the smoke produced by the electrocautery knife during reduction mammaplasty. Multiple air samples were collected in the operating room during two reduction mammaplasty procedures. Airborne smoke particles were tested for mutagenic potential in both tester strains of Salmonella typhimurium (TA98 and TA100) using the standard Salmonella microsomal test (Ames test). All testing was performed by the Hazard Evaluations and Technical Assistance Branch of the National Institute of Occupational Safety and Health. The smoke produced with the electrocautery knife during reduction mammaplasty was found to be mutagenic to the TA98 strain. The Ames test, an established technique for evaluating the mutagenicity of a substance, was convincingly positive for the smoke collected during the breast surgery. Whether the smoke represents a serious health risk to operating room personnel is not known. Development of techniques to limit electrocautery smoke exposure in the operating room appears to be needed, and surgeons should attempt to minimize their exposure.

Evaluation of a smoke evacuator used for laser surgery.

A preliminary study was conducted to determine the effectiveness of a smoke evacuation system used in laser surgery. A 30 W medical CO2 continuous wave (CW) laser was used to make cuts in a pork chop to simulate smoke production during laser surgery. A commercially available smoke evacuation system was used to control the smoke from the simulated surgery. The smoke concentration was measured at 6 in and at 3 and 4 ft from site of laser interaction. The nozzle of the smoke evacuator was located at distances of 2, 6, and 12 in from the surgical site to measure the relative effectiveness of the control. Complete control of smoke was achieved when the nozzle was located at 2 in, but significant amounts of smoke escaped when the nozzle was located at 6 and 12 in. Suggestions for the use of the smoke evacuation system and areas for further study are given.

Polymer-fume fever associated with smoking and use of a mold-release spray containing polytetrafluoroethylene.

An ephemeral and debilitating flu-like illness experienced by stamp-makers prompted them to solicit assistance from the National Institute for Occupational Safety and Health. It was determined that a combination of the use of a mold-release spray containing a fluorocarbon polymer (polytetrafluoroethylene), poor general hygiene, and smoking during and after use of the spray was responsible for the workers' symptoms, commonly referred to as "polymer-fume fever." Recommendations made, and which resulted in the abatement of illness included: ventilating the vulcanizing furnace, cessation of smoking in the workplace, or using a mold-release spray that does not contain fluorocarbon.