A Simplified Microscopy Technique to Rapidly Characterize Individual Fiber Traits in Cotton.

Recent advances in phenotyping techniques have substantially improved the ability to mitigate type-II errors typically associated with high variance in phenotyping data sets. In particular, the implementation of automated techniques such as the High-Volume Instrument (HVI) and the Advanced Fiber Information System (AFIS) have significantly enhanced the reproducibility and standardization of various fiber quality measurements in cotton. However, micronaire is not a direct measure of either maturity or fineness, lending to limitations. AFIS only provides a calculated form of fiber diameter, not a direct measure, justifying the need for a visual-based reference method. Obtaining direct measurements of individual fibers through cross-sectional analysis and electron microscopy is a widely accepted standard but is time-consuming and requires the use of hazardous chemicals and specialized equipment. In this study, we present a simplified fiber histology and image acquisition technique that is both rapid and reproducible. We also introduce an automated image analysis program that utilizes machine learning to differentiate good fibers from bad and to subsequently collect critical phenotypic measurements. These methods have the potential to improve the efficiency of cotton fiber phenotyping, allowing for greater precision in unravelling the genetic architecture of critical traits such as fiber diameter, shape, areas of the secondary cell wall/lumen, and others, ultimately leading to larger genetic gains in fiber quality and improvements in cotton.

Acute effects of an insect repellent, N,N-diethyl-m-toluamide, on cholinesterase inhibition induced by pyridostigmine bromide in rats.

Acute lethal interactions have been previously described between a cholinesterase (ChE) inhibitor, pyridostigmine bromide (PB), and the insect repellent, N,N-diethyl-m-toluamide (DEET). The mechanism of toxic interaction between these agents is unknown. Alterations in membrane permeability caused by DEET could facilitate or enhance absorption, or alter the distribution of peripherally restricted PB, causing increased inhibition of ChE at a given dose. Studies were conducted to investigate PB-induced ChE inhibition in the presence of DEET. Rats received ip injections of PB (1, 2, or 3 mg/kg), DEET (200 mg/kg), or PB + DEET at doses that potentiated acute lethality. ChE activity was measured in heart, diaphragm, blood, whole brain, or specific brain areas using a modified spectrophotometric assay. DEET did not alter PB-induced inhibition of ChE activity in rat diaphragm, heart, or blood. Administration of DEET alone had no effect on ChE activity. PB alone did not inhibit ChE in whole brain, but PB (3 mg/kg) + DEET (200 mg/kg) caused significant inhibition of whole brain ChE activity to approximately 60% of controls. In specific brain areas, (cortex, cerebellum, medulla, hypothalamus, hippocampus, midbrain, and striatum) PB alone did not inhibit ChE activity. PB (3 mg/kg) + DEET (200 mg/kg) reduced ChE activity to approximately 65-75% of controls in each brain area, but those results were not statistically significant. In conclusion, DEET did not alter PB-induced inhibition of ChE activity in the periphery. While DEET may have facilitated the access of PB into the CNS at high doses, it is doubtful that the resulting minor reduction in ChE activity would have resulted in death. It is unlikely that the lethal interaction between PB and DEET is mediated through a cholinergic effect resulting from increased inhibition of ChE.

Anticonvulsant-resistant seizures following pyridostigmine bromide (PB) and N,N-diethyl-m-toluamide (DEET).

An acute toxic interaction has been described, in which sublethal doses of pyridostigmine bromide (PB) and the insect repellent N,N-diethyl-m-toluamide (DEET), when administered concomitantly, resulted in seizures and lethality. To investigate the possible relationships between seizures and lethality and the role of the cholinergic system in this interaction, PB (5 mg/kg), DEET (200 mg/kg) or PB (3 mg/kg) + DEET (200 mg/kg) were administered i.p. to male ICR mice, alone or following i.p. pretreatment, with one of several anticonvulsant agents: diazepam, 10 mg/kg; fosphenytoin, 40 mg/kg; phenobarbital, 45 mg/kg; or dextrophan, 25 mg/kg), or the anticholinergic agents, atropine (5 mg/kg), atropine methyl nitrate (2.7 mg/kg), or mecamylamine (2.5 mg/kg). The anticonvulsants selected for this study act through different mechanisms to reduce seizures. None of the anticonvulsants was able to reduce the incidence of seizures following treatment with PB, DEET or PB + DEET. Only diazepam delayed the onset of seizures. Fosphenytoin or diazepam significantly prolonged the time to lethality following PB, but only fosphenytoin reduced the incidence of PB-induced lethality. Diazepam or phenobarbital significantly prolonged the time to lethality following PB + DEET. Both atropine and atropine methyl nitrate protected against PB and PB + DEET-induced lethality and PB-induced seizures. Neither agent blocked seizures resulting from DEET or PB + DEET. Mecamylamine reduced seizures and lethality in PB-treated mice, but not in mice treated with DEET or PB + DEET. The results indicate that seizure activity is not a causative factor in the toxic interaction between PB and DEET. Furthermore, PB, DEET and PB + DEET induce seizures that are resistant to standard anticonvulsants, and each appears to operate through different mechanisms to produce seizures. Peripheral muscarinic receptors may play a specific role in lethality caused by PB + DEET.

Event-related brain potentials during an extended visual recognition memory task depict delayed development of cerebral inhibitory processes among 6-month-old infants with Down syndrome.

Development of cerebral inhibitory processes among individuals with Down syndrome (DS) may be delayed at an early age. In support of this hypothesis, sensory-evoked potentials (EPs) and event-related brain potentials (ERPs) have previously delineated altered habituation to stimuli among infants with DS. The purpose of the current study was to provide extended experience with visual stimuli among 6-month-old infants with and without DS (nDS) to determine if altered ERP and behavioral response decrements would be evident even after repeated presentations of stimuli. An 80/20% oddball paradigm was employed. Infants with DS and nDS were matched according to age and gender. Infants with DS demonstrated significantly larger Nc areas, Nc peak amplitudes, Nc2 areas and, inversely, significantly smaller peak Pb amplitudes when compared to infants nDS. Contrasts of the two study groups were most robust within ERP measures from frontal (Fz) and parietal (Pz) recording sites. Infants with DS also demonstrated a significantly slower decrement of most ERP components with repetitive stimulus experience. Most noteworthy was the observation of little or no decrement of ERP components at Fz among infants with DS. Both infants with DS and nDS demonstrated significantly larger Nc peak amplitudes, Nc areas, Nc2 areas, Pb peak amplitudes and NSW areas to rare stimuli. While significant probability and experiential trends were observed in visual fixation measures across both study groups, there were no significant differences of visual attention between infants with DS or nDS. These data demonstrate the value of ERPs within the study of atypical cognitive development during infancy and support the concept of altered inhibitory processes in the brain of infants with DS.

Potentiation of pyridostigmine bromide toxicity in mice by selected adrenergic agents and caffeine.

Pyridostigmine bromide (PB) is a reversible cholinesterase inhibitor used routinely in the treatment of myasthenia gravis and recently by the US Army as a prophylactic agent against potential nerve gas attack in the Persian Gulf War. Pyridostigmine has been implicated as one of several possible causative factors associated with Persian Gulf illnesses. To investigate toxic interactions between PB and other drugs, male ICR mice received contralateral ip injections of either a selected adrenergic drug or caffeine, followed 15 min later by PB. Representative isobolograms plotted for each drug interaction illustrate that a beta-adrenoceptor agonist (isoproterenol), selective beta 2-adrenoceptor agonists (salbutamol, terbutaline), alpha 1- and alpha 2-adrenoceptor antagonists (yohimbine, phentolamine, prazosin), as well as the stimulant caffeine, strongly potentiate the lethal effect of PB. Agents with agonist activity at both alpha- and beta-adrenoceptors (epinephrine, norepinephrine) additively increase PB-induced lethality. The potentiation of toxicity between PB and these agents was counteracted by pretreatment with atropine and atropine methyl nitrate. An alpha 2-adrenoceptor agonist (clonidine) and beta-adrenoceptor antagonists (propranolol, nadolol, acebutolol) did not increase PB-induced lethalities. These data demonstrate a toxic synergism between PB, several commonly used classes of adrenergic agents and caffeine when exposure occurs in different combinations. Future studies into the mechanism(s) of these interactions may bring into question the usage of PB as a protective agent in combat conditions as well as delineate any possible contributions of the drug to Persian Gulf illnesses.

Coating cells with colloidal silica for high yield isolation of plasma membrane sheets and identification of transmembrane proteins.

Plasma membrane (PM) can be isolated by binding to a positively charged solid support. Using this concept, we have developed a novel method of PM isolation using cationic colloidal silica. The method is designed for the comparative study of various physiological states of PM and for transbilayer protein mapping. The procedure consists of coating intact cells with a dense pellicle of silica particles and polyanion. Since cells remain intact during pellicle formation, the external face of the PM is selectively coated. The pellicle greatly enhances PM density and stabilizes it against vesiculation or lateral reorientation. Upon cell lysis, large open sheets of PM are rapidly isolated by centrifugation. PM from Dictyostelium discoideum was prepared by this method. Marker enzymes, cell surface labeling and microscopy demonstrate that the PM was isolated in high yield (70-80%) with a 10-17-fold purification and only low levels of cytoplasmic contamination. The pellicle remains intact during cell lysis and membrane isolation, shielding the external surface of the membranes up to 92% from chemical or enzymatic attack. The PM can thus be labeled selectively from inside and/or outside. Transmembrane proteins were identified in Dictyostelium PM by means of lactoperoxidase iodination and autoradiography.

Long-path laser monitor of carbon monoxide: system improvements.

A system for measurement of long-path absorption of carbon monoxide has been redesigned for improved performance. The diode laser source is frequency stabilized by automatically correcting the laser current and is limited to a single-wavelength output by a tunable étalon. As a result, sensitivity variations of the system to CO are limited to +/-0.7%, and system response is linear with respect to CO concentrations.

Attributional and behavioral changes following two behavior management interventions with hyperactive boys: a follow-up study.

In a 6-month follow-up study of 2 interventions with hyperactive boys, different patterns of improvement were observed for an intervention which focused on self-control and 1 which employed contingent social reinforcement. Of the 2 manipulations, self-control methods produced significantly stronger long-term benefits in terms of the child's increased perception of personal control over academic outcomes; social reinforcement, on the other hand, produced significantly stronger long-term benefits in terms of teacher ratings of hyperactivity or impulsivity (Conners Teacher Rating Scale). Both interventions produced stable changes in terms of decreased behavioral impulsivity as measured by qualitative error scores on the Porteus Mazes.

Carbon monoxide automobile emissions measured from the interior of a traveling automobile.

During a procedure to monitor carbon monoxide (CO) concentrations inside a traveling car, it was discovered that CO emissions from individual passing vehicles produced accurately measurable increases in the CO concentration. The CO produced by individual vehicles varied by three orders of magnitude; this finding demonstrates that a relatively small number of cars can be responsible for a high percentage of total vehicle CO Emissions.

Multiplicity of cytochrome P-450 hemoproteins in rat liver microsomes. Preparation and specificity of an antibody to the hemoprotein induced by phenobarbital.

Rat liver microsomes have previously been shown to contain hemoproteins having molecular weights of 53,000, 50,000, and 45,000. The 45,000-dalton hemoprotein, which is induced in rat liver microsomes by pretreatment of animals with phenobarbital, is resistant to proteolysis by trypsin. This characteristic was used to purify it from the other microsomal hemoproteins. In the procedure used, a sodium cholate-solubilized microsomal fraction from phenobarbital-pretreated rats was treated with trypsin and chromatographed on Sephadex G-100 to separate the hemoprotein from preolytic degradation products. The hemoprotein thus isolated was homogenous on the basis of sodium dodecyl sulfate-polyacrylamide gel electrophoresis and was identified spectrally as a cytochrome P-420 hemoprotein. This hemoprotein was free of cytochrome b5 and NADPH-cytochrome c reductase activity. Antibody prepared against the protease-treated cytochrome P-420 hemoprotein will not cross-react with the 53,000- and 50,000-dalton hemoproteins. This was assessed by three criteria. First, immunoprecipitation studies were conducted with detergent-solubilized partially purified cytochrome P-450 preparations isolated from the liver microsomes of control and phenobarbital- and 3-methylcholathrene-retreated rats. The antibody immunoprecipitated only the 45,000-dalton hemoprotein from these partially purified cytochrome P-450 preparations, each of which contains all three hemoproteins. Second, the antibody demonstrated specificity with regard to the microsomal hydroxylation reactions it would inhibit in a reconstituted hydroxylation system containing partially purified cytochrome P-450 (448) fractions isolated from the liver microsomes from phenobarbital- or 3-methylcholathrene-pretreated rats. The antibody would inhibit benzphetamine-N-demethylation catalyzed by both cytochrome P-450 fractions but would not inhibit benzpyrene hydroxylation catalyzed by either. Third, agglutination and complement fixation assays were performed to assess the binding of the antibody to liver microsomes isolated from control and phenobarbital- or 3- methylcholanthrene-pretreated rats. These studies demonstrated that the antibody binds preferentially to the liver microsomes isolated from phenobarbital-pretreated rats, in which the 45,000-dalton hemoprotein has been shown to be induced. It is hypothesized that there are very significant structural and catalytic differences among the cytochrome P-450 hemoproteins.

The Nimbus III Michelson Interferometer.

The Michelson interferometer flown on Nimbus III in April 1969 has obtained infrared emission spectra of the earth and its atmosphere within 400 cm(-1) and 2000 cm(-1) (5 micro and 25 micro). Spectra of good quality have been recorded with a spectral resolution corresponding to 5 cm(-1). This paper discusses the design of the instrument including the optical layout, the phase locked loop operation of the Michelson motor, and the functioning of the reference interferometer. The methods of data reduction and in-flight calibration are demonstrated on sample spectra recorded while in orbit around the earth.