Showing papers by "United States Department of the Army published in 1991"

Botanical derivatives in mosquito control: a review.

Abstract: A review on the reported uses of chemicals derived from botanical sources is presented, along with the part of the plant used for extraction, the mosquito species studied and the bioactivity observed for 344 plant species. Examples of phytochemicals evaluated against mosquitoes as general toxicants, growth and reproduction inhibitors, repellents and ovipositional deterrents are given. The effects of mosquito species and life stage specificity, solvents used for extraction, phototoxic activity and the geographical source from where the plant compounds are derived are discussed.

Prospective, Double-Blind, Concurrent, Placebo-Controlled Clinical Trial of Intravenous Ribavirin Therapy of Hemorrhagic Fever with Renal Syndrome

Abstract: A prospective, randomized, double-blind, concurrent, placebo-controlled clinical trial of intravenous ribavirin (loading dose of 33 mg/kg, 16 mg/kg every 6 h for 4 days, and 8 mg/kg every 8 h for 3 days) was conducted in 242 patients with serologically confirmed hemorrhagic fever with renal syndrome (HFRS) in the People's Republic of China. Mortality was significantly reduced (sevenfold decrease in risk) among ribavirin-treated patients, when comparisons were adjusted for baseline risk estimators of mortality (P = .01; two-tailed). HFRS typically consists of five consecutive but frequently overlapping clinical phases. Only occurrence of oliguric phase and hemorrhage was associated with severity of clinical disease in the placebo group. Ribavirin therapy also resulted in a significant reduction in the risk of entering the oliguric phase and experiencing hemorrhage. The only ribavirin-related side effect was a well-recognized, fully reversible anemia after completion of therapy.

Two-Dimensional Cure Simulation of Thick Thermosetting Composites

Abstract: An investigation into the two-dimensional cure simulation of thick thermosetting composites is presented. Temperature and degree of cure distributions within arbitrary cross-sectional geometries are predicted as a function of the autoclave temperature history. The heat conduction equation for two-dimensional, transient anisotropic heat transfer is coupled to the cure kinetics of the thermosetting composite material. A heat generation term, expressed as a function of cure rate and the total heat of reaction, is introduced to account for the heat liberated during the curing process. A generalized boundary condition formulation is employed, enabling arbitrary temperature boundary conditions to be enforced straightforwardly. An incremental, transient finite difference solution scheme is implemented to solve the pertinent governing equations and boundary conditions. The boundary-fitted coordinate system (BFCS) transformation technique is combined with the Alternating Direction Explicit (ADE) finite difference ...

Diarrheal disease during Operation Desert Shield.

Abstract: Background. Under combat conditions infectious disease can become a major threat to military forces. During Operation Desert Shield, there were numerous outbreaks of diarrhea among the U.S. forces. To evaluate the causes of and risk factors for diarrheal disease, we collected clinical and epidemiologic data from U.S. troops stationed in northeastern Saudi Arabia. Methods. 432 military personnel who presented with diarrhea, cramps, vomiting, or hematochezia. In addition, a questionnaire was administered to 2022 soldiers in U.S. military units located in various regions of Saudi Arabia. Results. A bacterial enteric pathogen was identified in 49.5 percent of the troops with gastroenteritis. Enterotoxigenic Escherichia coli and Shigella sonnei were the most common bacterial pathogens. Of 125 E. coli infections, 39 percent were resistant to trimethoprim–sulfamethoxazole, 63 percent to tetracycline, and 48 percent to ampicillin. Of 113 shigella infections, 85 percent were resistant to trimethoprim–sulf...

Synthesis and characterization of polymers produced by horseradish peroxidase in dioxane

Abstract: Polymers were synthesized from substituted phenolic and aromatic amine compounds with hydrogen peroxide as the source of an oxidizing agent and horseradish peroxidase enzyme as the catalyst. The polymerization reaction was carried out in a monophasic organic solvent with small amounts of water at room temperature. Conditions for the synthesis of polymers with respect to reaction time and yield were studied with a number of monomers at different concentrations and in solvents with different buffers with pH range of 5.0–7.5. Physical and chemical properties of these homo-and copolymers were determined with respect to melting point, solubility, elemental analysis, molecular weight distribution, infrared absorption (including FTIR), solid-state 13C nuclear magnetic resonance, thermal gravimetric analysis, and differential scanning calorimetry. The enzyme catalyzed reactions produced polymers of molecular weight greater than 400,000 which were further fractionated by differential solubility in solvent mixtures and the molecular weight distribution of the polymer fractions were determined. In general, the polymers synthesized have low solubilities, high melting points, and some degree of branching.

Nonlinear Modeling of Time Series Using Multivariate Adaptive Regression Splines (MARS)

Abstract: Multivariate Adaptive Regression Splines (MARS) is a new methodology, due to Friedman, for nonlinear regression modeling. MARS can be conceptualized as a generalization of recursive partitioning that uses spline fitting in lieu of other simple fitting functions. Given a set of predictor variables, MARS fits a model in the form of an expansion in product spline basis functions of predictors chosen during a forward and backward recursive partitioning strategy. MARS produces continuous models for high-dimensional data that can have multiple partitions and predictor variable interactions. Predictor variable contributions and interactions in a MARS model may be analyzed using an ANOVA style decomposition. By letting the predictor variables in MARS be lagged values of a time series, one obtains a new method for nonlinear autoregressive threshold modeling of time series. A significant feature of this extension of MARS is its ability to produce models with limit cycles when modeling time series data that...

Liquid crystallinity of natural silk secretions

Abstract: NATURAL silk exhibits a strength and stiffness similar to, and a toughness up to ten times greater than, that of artificial high-performance fibres1–5. These exceptional tensile properties, the optical birefringence of some silk secretions6–9 and the molecular order exhibited by some synthetic polypeptides in solution10 all suggest that natural silk secretions might form liquid-crystalline phases. We have now used polarized-light microscopy to study the secretions from major ampullae of spiders (Nephila clavipes) and from silk glands of silkworms (Bombyx mori). As the concentration is increased by evaporation of water, nematic liquid-crystalline microstructures develop. We deduce that natural silk secretions become liquid crystalline after leaving the gland but before solidifying into a fibre, thus promoting global molecular alignment in the fibre. Our hand-drawn fibres from droplets of secretion, as well as sheared thin films, show a banded microstructure which is indicative of a periodic variation in the direction of molecular alignment11. Both B. mori and N. clavipes, on the other hand, have apparently developed processing routes that ensure uniform molecular alignment: the threads and draglines, respectively, of these species do not show banded microstructures.

Protection by butyrylcholinesterase against organophosphorus poisoning in nonhuman primates.

Abstract: Butyrylcholinesterase (BuChE) was examined as an in vivo exogenous scavenger for highly toxic organophosphorus (OP) poisons. Protection studies with equine BuChE were carried out in rhesus monkeys trained to perform a Serial Probe Recognition task. The pharmacokinetics of equine BuChE administered i.v. in rhesus monkeys revealed an elimination T1/2 of approximately 620 hr. Animals given 503 nmol of BuChE i.v. and then challenged with 220 to 260 nmol of soman (two LD50; a lethal dose in untreated animals) all survived with no clinical signs of OP poisoning. Serial Probe Recognition performance was depressed after enzyme administration and at 1 hr postsoman. However, all monkeys performed the task at base-line levels at 8 hr after soman and throughout the remainder of the experimental period. Two different monkeys each were given two doses of sarin, 183 nmol/dose (one LD50) after 460 nmol of BuChE. No signs were observed. A third group of monkeys given 253 or 340 nmol (three and four LD50, respectively) of soman after 460 nmol of BuChE required 1 mg/kg of atropine i.v. 10 min postsoman, but recovered completely within 24 hr. Our results indicate that BuChE has the required properties to function as a biological scavenger to protect against the pharmacological and behavioral toxicity of OP poisons.

Pyridostigmine Used as a Nerve Agent Pretreatment Under Wartime Conditions

Abstract: Objective. —To determine the adverse effects of pretreatment with pyridostigmine bromide for nerve agent exposure during wartime. Design. —A retrospective study. Setting. —Southwest Asia. Participants. —Personnel who provided medical support to the XVIII Airborne Corps. These medical officers supplied information pertaining to symptoms and disposition of 41 650 soldiers who received pyridostigmine at the onset of hostilities of Operation Desert Storm. Intervention. —Pyridostigmine bromide, 30 mg orally, was self-administered every 8 hours while under the threat of nerve agent attack (for 1 to 7 days). Main Outcome Measure. —Physiologic changes attributable to pyridostigmine that resulted in need for medical attention, discontinuation of the drug, hospitalization, and/or evacuation from Southwest Asia. Results. —About half of the population noted physiologic changes that were not incapacitating, such as increased flatus, abdominal cramps, soft stools, and urinary urgency. Approximately 1% of the soldiers believed they had effects that warranted medical attention, but fewer than 0.1% had effects sufficient to discontinue the drug. Nonincapacitating symptoms often occurred; however, military mission performance was not impaired. Conclusion. —While under the threat of nerve agent attack, pyridostigmine can be administered to virtually all soldiers. ( JAMA . 1991;266:693-695)

Dentinal Tubule Occlusion and Root Hypersensitivity

Abstract: Previous studies have established that root sensitivity is due in part to open dentinal tubules at the root surface. The purpose of this study was to longitudinally evaluate the occlusion of dentinal tubules by various clinical procedures including scaling and root planing and the application of potassium Oxalate. A model was developed to evaluate dentinal surfaces in vivo. Six 2 mm x 3 mm sections were taken from the roots of extracted teeth immediately below the CEJ. One half of the treated dentin samples from each donor was incorporated into the removable denture worn by the donor and the other half served as baseline. The dentin samples were evaluated at 1 week by scanning electron microscopy. At day zero no open tubules were observed in any of the samples due to the presence of a smear layer or Oxalate crystals. Evaluation of root planed samples revealed that by 7 days the tubules had re-opened. The samples which had been treated with potassium Oxalate showed few Oxalate crystals by 7 days revealing ...

Operation Everest II: structural adaptations in skeletal muscle in response to extreme simulated altitude.

Abstract: Alterations in skeletal muscle structure were investigated in 6 male subjects who underwent 40 days of progressive decompression in a hypobaric chamber simulating an ascent to the summit of Mount Everest. Needle biopsies were obtained from vastus lateralis of 5 subjects before and immediately after confinement in the chamber, and were examined for various structural and ultrastructural parameters. In addition, total muscle area was calculated in 6 subjects from CT scans of the thighs and upper arms. Muscle area at these sites was found to decrease significantly (by 13 and 15%) as a result of the hypobaric confinement. This was substantiated by significant (25%) decreases in cross sectional fibre areas of the Type I fibres and 26% decreases (non significant) in Type II fibre area. Capillary to fibre ratios remained unchanged following hypoxia as did capillary density although there was a trend (non significant) towards an increase in capillary density. There were no significant increases in mitochondrial volume density or other morphometric parameters. These data indicate that chronic, severe hypoxia on its own does not result in an increase in absolute muscle capillary number or a de novo synthesis of mitochondria. The trends toward an increase in capillary density and mitochondrial volume density were interpreted as being secondary occurrences in response to the pronounced muscle atrophy which occurred.

Abnormal battery cell voltage detection circuitry

Abstract: Defective battery cells are detected by individually monitoring the voltageutput therefrom, which characteristically becomes abnormal when the defective condition occurs. Each cell is independently referenced to a common ground by its voltage monitoring device which drives a level sensing comparator that generates a control signal when the output voltage from that cell becomes abnormal. This control signal drives at least one switch to indicate when the defective condition occurs.

Pilot Personality and Crew Coordination: Implications for Training and Selection

Abstract: It is contended that past failures to find linkages between performance and personality were due to a combination of premature performance evaluation, inadequate statistical modeling, and/or the reliance on data gathered in contrived as opposed to realistic situations. The goal of the research presented is to isolate subgroups of pilots along performance-related personality dimensions and to document limits on the impact of crew coordination training between the groups. Three different profiles were identified through cluster analysis of personality scales that replicated across samples and predicted attitude change following training in crew coordination.

Purification and properties of an organophosphorus acid anhydrase from a halophilic bacterial isolate.

Abstract: A moderately halophilic bacterial isolate has been found to possess high levels of enzymatic activity against several highly toxic organophosphorus compounds. The predominant enzyme, designated organophosphorus acid anhydrase 2, has been purified 1,000-fold to homogeneity and characterized. The enzyme is a single polypeptide with a molecular weight of 60,000. With diisopropylfluorophosphate as a substrate, the enzyme has optimum activity at pH 8.5 and 50 degrees C, and it is stimulated by manganese and cobalt.

Medical defense against blistering chemical warfare agents.

Abstract: • First used in World War I, chemical blistering agents present a serious medical threat that has stimulated renewed interest in the light of extensive use in recent conflicts. Current medical management cannot yet prevent or minimize injury from the principal agent of concern—sulfur mustard. Research directed at this goal depends on defining effective intervention in the metabolic alterations induced by exposure to sulfur mustard. ( Arch Dermatol. 1991;127:1207-1213)

Prophylactic use of high-frequency percussive ventilation in patients with inhalation injury.

Abstract: Death and the incidence of pneumonia are significantly increased in burn patients with inhalation injury, despite application of conventional ventilatory support techniques The effect of high-frequency percussive ventilation on mortality rate, incidence of pulmonary infection, and barotrauma were studied in 54 burn patients with documented inhalation injury admitted between March 1987 and September 1990 as compared to an historic cohort treated between 1980 and 1984 All patients satisfied clinical criteria for mechanical ventilation High-frequency percussive ventilation was initiated within 24 hours of intubation The patients' mean age and burn size were 322 years and 478%, respectively (ranges, 15 to 88 years; 0% to 90%) The mean number of ventilator days was 153 +/- 167 (range, 1 to 150 days), with 26% of patients ventilated for more than 2 weeks Fourteen patients (259%) developed pneumonia compared to an historic frequency of 458% (p less than 0005) Mortality rate was 185% (10 patients) with an expected historic number of deaths of 23 (95% confidence limits of 17 to 28 deaths) The documented improvement in survival rate and decrease in the incidence of pneumonia in patients treated with prophylactic high-frequency ventilation (HFV), as compared to a cohort of patients treated in the 7 years before the trial, indicates the importance of small airway patency in the pathogenesis of inhalation injury sequelae and supports further use and evaluation of HFV

Low temperature degradation of Y-TZP materials

Abstract: Seven yttria-tetragonal zirconia polycrystal (TZP) materials were examined to determine if they were susceptible to low temperature degradation. Flexure specimens were exposed to approximately 800 Pa of water vapour pressure for 50 h between 200 and 400 °C. Only one of the TZPs was unaffected by these low temperature treatments. Three underwent catastrophic degradation after all the low temperature treatments, while the final three had property losses of varying degrees, depending on the treatment temperature.

Comparative susceptibility of anopheline mosquitoes in Rondonia, Brazil to infection by Plasmodium vivax.

Abstract: Seven anopheline species from Costa Marques, Rondonia, Brazil were compared with Anopheles darlingi for susceptibility to infection by Plasmodium vivax. Laboratory-reared F1 progeny of field-collected An. darlingi and the test anopheline species were fed at the same time on the same patients, all of whom had gametocytes in peripheral blood before treatment. Mosquitoes were dissected on day 8 after infection for oocysts and on days 14-16 after infection for sporozoites. The mean numbers of P. vivax oocysts and the percent of salivary gland infections for An. darlingi and An. deaneorum were similar and far exceeded those found in the other anopheline species tested. Anopheles albitarsis and An. mediopunctatus were less susceptible to infection by oocyst measurements than An. darlingi. However, for oocyst-infected An. albitarsis and An. mediopunctatus, the percent of mosquitoes with salivary gland infections and the numbers of sporozoites in the salivary glands were similar to An. darlingi. Anopheles triannulatus and An. oswaldoi were both susceptible to P. vivax infection, but the sporozoite infection rates and the numbers of sporozoites observed in the salivary glands were very low. Anopheles braziliensis and An. benarrochi both developed oocysts, but were never observed to have sporozoites in the salivary glands. These studies implicate some anopheline species as potential malaria vectors, but also show that species previously incriminated by ELISA techniques are not vectors of malaria parasites in Costa Marques, Rondonia, Brazil.

Cantilevered air-gap type thin film piezoelectric resonator

Abstract: A method and apparatus directed to a thin film piezoelectric resonator deposited on a support layer of dielectric material and being configured in the form of a cantilever structure having a base portion formed on an integrated circuit substrate and having an overhanging beam portion joined at one end to the base portion, with the opposite end being unsupported with an air-gap intermediate the beam portion and the substrate. In the fabrication of the resonator, a thin film of dielectric material, e.g. zinc oxide (ZnO) is first deposited on the substrate, but is subsequently removed from beneath the beam portion resulting in the air-gap which is open on three sides and thus results in a greater ease of fabrication. A completely monolithic chemical detector is implemented utilizing a matched pair of these cantilevered air-gap thin film resonators, with one of the resonators further including a coating on one of its electrodes and which is responsive to a predetermined chemical to cause a frequency shift in the presence of the chemical to be detected. In one embodiment of the chemical detector, the frequency outputs of the two resonators are compared with the difference frequency providing an indication of the chemical being detected.

Fungal burn wound infection. A 10-year experience.

Abstract: • To evaluate our experience with fungal burn wound infection, we performed a 10-year review for comparison with our experience with bacterial burn wound infection. During the study period, a marked decline occurred in bacterial wound infection but not in fungal wound infection. Patients with either bacterial or fungal burn wound infection had massive injury, with burn size averaging greater than 50% of the total body surface area. Factors that appear to have markedly reduced bacterial burn wound infection, including patient isolation, topical chemotherapeutic agents, and burn wound excision, do not appear to have had a similar effect on fungal wound infection. The mechanism of spread and colonization of fungi, and the lack of effective topical chemotherapeutic antifungal agents, may explain in part our findings. ( Arch Surg. 1991;126:44-48)

Treatment of travelers' diarrhea: ciprofloxacin plus loperamide compared with ciprofloxacin alone. A placebo-controlled, randomized trial.

Abstract: Objective To compare the safety and efficacy of loperamide used in combination with ciprofloxacin or ciprofloxacin alone for the treatment of travelers' diarrhea. Design Double-blind, placebo-controlled, randomized clinical trial. Setting United States Army hospital in Egypt. Participants United States military personnel with travelers' diarrhea (n = 104) during a military exercise in November 1989. Persons who were noncompliant, had bloody diarrhea, or had received antidiarrheal medications before entry into the study were excluded. Interventions All participants with travelers' diarrhea were treated with ciprofloxacin, 500 mg twice daily for 3 days. Fifty of these patients were randomly assigned to receive loperamide, a 4-mg first dose and 2 mg for every loose stool (as much as 16 mg/d), and 54 were randomly assigned to receive placebo. Measurements Enterotoxigenic Escherichia coli was isolated from 57% of patients; Shigella and Salmonella, seen in 4% and 2% of patients, respectively, were not common. Main results After 24 hours, the symptoms of 82% of patients in the ciprofloxacin and loperamide group compared with 67% in the ciprofloxacin and placebo group had improved or fully recovered (odds ratio, 2.3; 95% CI, 0.8 to 6.3; P = 0.08). After 48 hours, the symptoms of 90% of both groups had improved or fully recovered. The mean number of stools for those receiving loperamide was not much lower than those who did not receive loperamide after 24 hours (1.9 +/- 0.2 [SE] compared with 2.6 +/- 0.2) or 48 hours (3.1 +/- 0.3 compared with 4.0 +/- 0.3) of treatment (P = 0.19). Conclusions In a region where enterotoxigenic E. coli was the predominant cause of travelers' diarrhea, loperamide combined with ciprofloxacin was not better than treatment with ciprofloxacin alone. Loperamide appeared to have some benefit in the first 24 hours of treatment in patients infected with enterotoxigenic E. coli. Both regimens were safe.

Fire Severity, Ash Deposition, and Clipping Effects on Soil Nutrients in Chaparral

Abstract: Fire may affect soil nutrient status by direct addition of nutrients and by indirectly altering the soil environment. The objective of this study was to examine how fire severity, ash deposition, and clipping affect posttreatment soil nutrient status. There were eight experimental treatments designed to examine increasing fire severity, ash (nutrient) addition independent of fire severity, clipping to study competition for nutrients per se, and untreated controls. Fire severity affected both the quality and quantity of ash. Increasing fire severity increased the concentrations of Mg and K and decreased the concentrations of NH₄-N and NO₃-N in the ash. As fire severity increased, there was an increasing recovery of ash relative to standing biomass (10–18 g kg⁻¹). Fire increased the availability of all nutrients (NH₄-N, NO₃-N, PO₄-P, Ca, Mg and K). This nutrient enhancement was largely restricted to the surface soil (0–5 cm); only soluble N appeared to increase in the subsurface soil (5–10 cm). The soil quantities of NH₄-N increased and NO₃-N decreased with increasing fire severity, suggesting either a direct addition of variable amounts of these N ions or an indirect effect on postfire nitrification rates. Clipping had no effect on enhancing soil nutrient availability. The apparent recovery of the basic cations in the water extracts of the ash samples was in the order: K » Mg > Ca; this was different from the subsequent recovery in the soil: Ca > K > Mg. It was hypothesized that the relative recovery of basic cations in the water extracts of the ash samples was controlled by the solubility of Ca, Mg, and K salts.

Protection against microcystin-LR-induced hepatotoxicity by silymarin : biochemistry, histopathology, and lethality

Abstract: Microcystin-LR, a cyclic heptapeptide synthesized by the blue-green algae, Microcystis aeruginosa, is a potent hepatotoxin. Pathological examination of livers from mice and rats that received microcystin-LR revealed severe, peracute, diffuse, centrilobular hepatocellular necrosis, and hemorrhage. These changes were correlated with increased serum activities of sorbitol dehydrogenase, alanine aminotransferase, and lactate dehydrogenase. Pretreatment of either rats or mice with a single dose of silymarin, a flavonolignane isolated from the wild artichoke (Silybum marianum L. Gaertn), completely abolished the lethal effects, pathological changes, and significantly decreased the levels of serum enzymes induced by microcystin-LR intoxication.