Oxidation of dichlorvos with hydrogen peroxide using ferrous ion as catalyst

This study examines how Fenton's reagent (Fe2+ and H2O2) decomposed dichlorvos insecticide. Results showed that dichlorvos decomposed in a two-stage reaction. The first stage is a Fe2+/H2O2 reaction in which dichlorvos swiftly decomposed. In the second stage, dichlorvos decomposed somewhat less rapidly, and it is a Fe3+/H2O2 reaction. The detection of ferrous ions also supports the theory of the two-stage reaction for the dichlorvos oxidation with Fenton's reagent. The dissolved oxygen of the solution decreased rapidly in the first stage reaction, but it slowly increased in the second stage with a zero-order kinetics. The Fenton system decomposed dichlorvos most rapidly when the initial pH in the solution is 3-4. In addition, increasing the concentration of hydrogen peroxide or ferrous ions can enhance the decomposition of dichlorvos. Consequently, the relationship of rate constant (kobs), [H2O2] and [Fe2+] at initial pH 3 is determined as kobs = 2.67 x 10(4)[H2O2]0.7[Fe2+]1.2.

Effect of adsorbents coated with titanium dioxide on the photocatalytic degradation of propoxur

Photocatalytic oxidation of pesticides in aqueous media irradiated by UV light is a rapidly growing field of research. Therefore, the treatment technology for degradation of propoxur (an insecticide) using titanium dioxide coated on the supports such as activated carbon, zeolite, brick, quartz and glass beads, was performed in this research. Results show that GAC/TiO2 is the best complexing agent for oxidizing propoxur because of its adsorption properities. The others follow the sequence: plain TiO2 > glass beads > zeolite > brick > quartz. The degradation rate of propoxur with plain TiO2 is higher than that with TiO2/GAC complexing agent. But the mineralization rate of propoxur with plain TiO2 is lower than that with TiO2/GAC complexing agent. However, it can be concluded that using GAC as the support can improve the photocatalytic efficiency.

Effects of Jen-San-Yaung-Jung-Tang on scopolamine-induced amnesia in rats

The effect of Jen-San-Yaung-Jung-Tang (YJT) on scopolamine (SCOP)-induced amnesia was investigated in a step-through passive avoidance task in rats. It was observed that YJT (0.5 and 1.0 g/kg) significantly improved SCOP-induced amnesia and did not change the horizontal activity and pain threshold. YJT at 0.5 and 1.0 g/kg also did not change SCOP-treated horizontal activity and pain threshold. Furthermore, the antiamnesic effect of YJT at 1.0 g/kg on the SCOP-induced amnesia was augmented by physostigmine, but was not altered by neostigmine or scopolamine N-methylbromide. These results suggest that the antiamnesic effect of YJT could only be related to the memory-related process, and to an increase in central cholinergic neuronal activity.

Clinical and histologic trends of melanoma

BACKGROUND

Several changing clinical and histopathologic melanoma trends occurred from the 1950s to the 1980s.

OBJECTIVE

The purpose of this study was to evaluate melanoma trends during the past decade and to compare present trends to those documented during the past four decades.

METHODS

Sex, age at diagnosis, location, tumor thickness, stage, and histologic subtypes were evaluated from 1984 to 1995 and compared with trends during the past four decades.

RESULTS

Most changing trends from the past four decades have slowed or stabilized during the past decade.

CONCLUSION

Complete reporting of all melanomas to central tumor registries is necessary to accurately analyze present and future melanoma trends. Ongoing and new prevention and control strategies beginning at birth may be necessary to continue the positive efforts to curtail the melanoma epidemic.

Studies on the sedative effect of Cistanche deserticola

In this study, we investigated the sedative effect of Cistanche deserticola Ma. (CD) on hexobarbital-induced sleeping time in mice and spontaneous motor activity by using automated activity meter in rats. It was found that crude extract of CD could prolong the hexobarbital-induced sleeping time and reduce spontaneous motor activity, including horizontal activity, ambulatory time and total distance. Then the water fraction of CD extract could prolong the hexobarbital-induced sleeping time and reduce the spontaneous motor activity more than that of the other fraction of CD extract in rats. These results suggest that CD ethanol extract and its water fraction possessed the sedative effect.

Age-related enhancement of 5-lipoxygenase metabolic capacity in cattle alveolar macrophages

Arachidonic acid (AA) metabolism was assessed in cultured alveolar macrophages (AM) obtained from newborn (9- and 23-day-old) and adult (2- and 6-yr-old) cattle. The AM were prelabeled in [3H]AA-containing medium and, thereafter, stimulated with either A-23187 or zymosan. The released radiolabeled AA metabolites were measured by high-performance liquid chromatography with on-line radiodetection. The results showed that, among different-aged cattle, the synthesis of total 5-lipoxygenase (5-LO) metabolites [leukotrienes (LT) B4, LTC4, LTD4, and 5-hydroxyeicosatetraenoic acid (5-HETE)] increased with age in spite of similar levels of phospholipase-catalyzed AA release. In response to A-23187 and zymosan, 5-LO metabolic capacity of adult cattle AM was approximately 4- and approximately 10-fold that of 9-day-old cattle AM, respectively. As 5-LO metabolic capacity increased, the release of prostaglandins and thromboxane tended to decrease. Immunoblot analysis showed that the steady-state expression of 5-LO and 5-lipoxygenase-activating protein (FLAP) also increased in an age-dependent manner. In newborn calves, AM do not produce great amounts of LTB4; this factor might contribute to insufficient polymorphonuclear leukocyte recruitment into the alveolar space and the high susceptibility to neonatal lung infection.

Production of chitinase by Pseudomonas aeruginosa K-187 using shrimp and crab shell powder as a carbon source

Shrimp and crab shell powder prepared by treating shrimp and crab processing waste with boiling and crashing was used as a substrate for isolating alkali-tolerant chitinolytic microorganisms. Strain K-187 appeared to be the chitinase-producing strain with the most potential. The organism was identified as a strain of Pseudomonas aeruginosa. Maximum chitinase activity was obtained when the strain was grown aerobically in a medium consisting of 3.0% shrimp and crab shell powder, 0.1% CMC, 0.1% (NH4)2SO4, 0.1% K2HPO4, 0.1% MgSO4.D7H2O and 0.1% ZnSO4 (pH 9), at 45 degrees C after 3 days. The optimum pH and temperature of the enzyme reaction were 7 and 40 degrees C, respectively. The chitinase was stable at pH from 5 to 10 and was stable under 60 degrees C.

Catecholamine affects acetylcholine release in trachea: alpha 2-mediated inhibition and beta 2-mediated augmentation

We investigated the effects of catecholamines on acetylcholine (ACh) release from equine airway parasympathetic nerves. Trachealis strips were suspended in 2-ml tissue baths with Krebs-Henseleit solution containing atropine (10(-7) M), neostigmine (10(-6) M), and guanethidine (10(-5) M). Electrical field stimulation (20 V, 0.5 ms, 0.5 Hz, for 15 min) was applied, and ACh was measured by high-performance liquid chromatography with electrochemical detection. Epinephrine (Epi) and norepinephrine (NE) inhibited ACh release in a concentration-dependent manner. Inhibition was attenuated by the alpha 2-adrenoceptor antagonist idazoxan (10(-6) M) but not by the alpha 1-antagonist prazosin (10(-6) M). After alpha 2-blockade with idazoxan (10(-5) to 10(-4) M), Epi but not NE augmented ACh release. Isoproterenol (10(-7) to 10(-5) M) increased ACh release, an effect that was reversed by the beta 2-adrenoceptor antagonist ICI-118,551 (10(-5) M) but not by the beta 1-adrenoceptor antagonist atenolol (10(-5) M). Our results indicate that horse airway cholinergic nerves are modulated by both alpha 2-inhibitory and beta 2-excitatory adrenoceptors, with the former being predominant.

Why it was hard for me to learn compassion as a third-year medical student

Ms. B. was a 70-year-old woman who presented with a chief complaint of “my belly got puffy.” She noted that her waistband got progressively tighter as her abdomen swelled up on the month prior to her admission. Although not painful, the swelling caused considerable discomfort and anorexia.

Ms. B. had come to the university hospital by referral from her primary care doctor. She was my first patient on my junior clerkship in internal medicine, a specialty I was particularly interested in going into. It is a rare opportunity for a medical student to pick up a mystery case. Ms. B. had come to us without a diagnosis.

Measurement of circulating blood volume in vivo after trauma-hemorrhage and hemodilution

Although cardiac output (CO) and other hemodynamic variables are used to assess the adequacy of fluid resuscitation after hemorrhage, it is not known whether there is any correlation between restoration of CO and circulating blood volume (CBV). To determine this, rats underwent a midline laparotomy (i.e., trauma induced) and were bled to and maintained at a mean arterial pressure of 40 mmHg until 40% of maximum bleedout volume was returned in the form of Ringer lactate (RL). The animals were then resuscitated with four or five times the volume of maximum bleedout in the form of RL. CO and hepatocellular function were measured using an in vivo hemoreflectometer. CBV was monitored by using in vivo indocyanine green clearance. A good correlation between the values of blood volume obtained by this method and the 125I-albumin method indicates that the indocyanine green method is also a reliable technique for measuring CBV. Results indicate that resuscitation after hemorrhage improved the decreased CBV but did not restore it to control levels despite the fact that CO was restored and central venous pressure was more than doubled. A good correlation between depressed CBV and hepatocellular dysfunction was also observed under such conditions. Thus measurement of CBV appears to be useful for evaluating the adequacy of fluid resuscitation after trauma-hemorrhage and hemodilution.

Pharmacological evaluation of 2-amino-6(7)- and 9-amino-6-trifluoromethylbenzonorbornenes, the conformationally rigid analogues of norfenfluramine in mice

1. The possible role of conformational requirements which fenfluramine and norfenfluramine must satisfy to elicit its observed pharmacological activities was investigated in mice with the use of four conformationally-rigid norfenfluramine analogues. 2. In this study, both the syn-9-amino and endo-2-amino isomers, which structurally resemble the gauche conformation of norfenfluramine, were found to have little or no effect on spontaneous locomotor activity. 3. On the other hand, the isomers (i.e. the anti-9-amino and exo-2-amino isomers) that mimic the anti conformation of norfenfluramine were capable of causing a decrease in spontaneous motor activity similar to that of norfenfluramine. 4. The analgesic activities of these rigid analogues were also assessed and all of the isomers were found to be weakly analgesic. 5. Only the exo-2-amino isomer exhibited analgesic potency similar to that of fenfluramine. Furthermore all of these compounds were capable of enhancing the analgesic activity of morphine.

Structure modification and biological activity of some griseofulvin derivatives

Griseofulvin is an orally acting anti-fungal antibiotic with very limited water solubility. Five chemical modifications were made on the griseofulvin structure in order to evaluate these changes on the antifungal and water solubility properties. Antifungal activity was measured against Tricophyton mentagrophytes, T. rubrum, T. terrestre, and Microsporum canis. The oxime of griseofulvin was the most potent of the five compounds tested, but it was only of equal or less potency than griseofulvin. The somewhat increased water solubility of some of these compounds was offset by the lower anti-fungal potency of the structural modification.

The use of the polymerase chain reaction to identify porcine isolates of Trichinella

A method was developed to identify domestic isolates of Trichinella using the polymerase chain reaction. Oligonucleotide primers, based on the repetitive DNA sequence (pPRA) from the P1 isolate of Trichinella, were used to amplify genomic DNA from 13 domestic isolates and tested against sylvatic isolates of Trichinella. Pattern differences were observed among domestic isolates, indicating divergence of this repetitive sequence. The primers were specific for domestic Trichinella as no amplification was detected for sylvatic isolates or Trichinella pseudospiralis. It was possible to identify an isolate from a single larva following digestion or in situ in muscle tissue.

Inhibition of cholesterol side-chain cleavage. Part 5. Synthesis of 22-(p-chlorophenyl) cholesterol analogues

Three 22-(p-chloroaryl) analogues of cholesterol (6a-c) were synthesized and evaluated as potential inhibitors of the adrenal cholesterol side-chain cleavage enzyme, in comparison with the known 20-aryl analogue, 20-(p-chlorophenyl)-5-prenen-3 beta,20-diol (2b). All were potent inhibitors. An oxygen at C-22 (analogues 6a and 6b) enhanced the strong binding to the enzyme. Two compounds (6b and 6c) are potential substrates of the enzyme. Possible pharmaceutical uses for these compounds and their derivatives are discussed.

Preparation and use of double-labelled enterobactin

Double-labelled 3H/14C-enterobactin was isolated from bacterial cultures, and evaluated as a potential tool for studying the mammalian metabolism of this iron chelator. Microbial yields were low, but adequate, with a final 3H/14C ratio of 2.95 to 1. Studies conducted with mice indicated that considerable metabolism and rapid elimination of an intraperitoneally injected sample had occurred in 24 hours.

Genes for immunodominant protein antigens are highly homologous in Mycobacterium tuberculosis, Mycobacterium africanum, and the vaccine strain Mycobacterium bovis BCG

The relatedness of immunodominant protein antigens in Mycobacterium tuberculosis, M. africanum, and M. bovis BCG was investigated by comparing the genes that encode major protein antigens in M. tuberculosis with their counterparts in the other two mycobacteria. Genes encoding homologs of M. tuberculosis major protein antigens were isolated from M. africanum and M. bovis BCG by constructing lambda gt11 recombinant DNA expression libraries and screening them with murine monoclonal antibodies and DNA probes. The antibodies were directed against four major protein antigens of M. tuberculosis with molecular masses of 71, 65, 19, and 14 kilodaltons. The isolated M. africanum and M. bovis BCG DNA clones were mapped with restriction endonucleases, and the maps of the mycobacterial genes were confirmed by Southern analysis of mycobacterial genomic DNA. The restriction maps of DNA containing the four genes in M. tuberculosis, M. africanum, and M. bovis BCG are identical, indicating that the immunodominant proteins that they encode are highly homologous in the three mycobacteria. Thus, the immunity against tuberculosis engendered by M. bovis BCG vaccination could be provided, at least in part, by the immune response to these homologous antigens.

Molecular modification of anticholinergics as probes for muscarinic receptors. 3. Conformationally restricted analogues of benactyzine

The synthesis and pharmacological evaluation of conformationally restricted analogues of certain anticholinergic agents is a powerful method for probing the topography of the muscarinic receptor. In the present study, clues as to the binding conformation of structurally flexible anticholinergics are provided by approximating certain conformations of benactyzine by synthetic analogues 1-6, which are structurally locked into desired conformations. The pharmacological activity of each analogue is an indication of how well particular conformational models are accommodated by the receptor. The conformation of benactyzine in which an intramolecular hydrogen bond may exist between the hydroxyl group and the carbonyl oxygen of the ester group (conformation I) is approximated by the synthetic analogue 2,2-diphenyl-3-tetrahydrofuranyl (diethylamino)ethyl ether (1) and related analogues. Pharmacological evaluation using dose-response experiments on isolated rat ileum tissue demonstrated that these compounds noncompetitively inhibited acetylcholine-induced ileum contractions. Restriction of the conformational freedom of the amino side chain of 1 by synthesis of the hexahydro[3,4-b]furan derivative 3 provided a weak but competitive inhibitor at low concentration. The conformation of benactyzine in which an intramolecular hydrogen bond may exist between the hydroxyl group and the ether oxygen of the ester group (conformation II) is approximated by 2,2-diphenyl-4-[2-(diethylamino)ethyl]-3-tetrahydrofuranone (4). Pharmacological studies showed that this compound competitively inhibited acetylcholine-induced ileum contractions. These experiments provide evidence that receptor-bound conformation II for benactyzine is preferred over conformation I in providing competitive binding with the muscarinic receptor.

Molecular modification of anticholinergics as probes for muscarinic receptors. 1. Amino esters of alpha-substituted phenylacetic acid and related analogues

Two series of compounds having the general structure of C6H5CRR'COOCH2CH2NEt2 were synthesized and examined for their antispasmodic activities. These compounds were selected as structural probes for exploring the nature of muscarinic cholinergic receptor binding sites that interact with atropine-like anticholinergics. These studies indicate a rather strict size limitation for the hydrophobic region of the receptor and suggest intramolecular hydrogen bonding as a possible means to explain the observed stereoselectivity.

Molecular modification of anticholinergics as probes for muscarinic receptors. 2. Amino esters of alpha-methyltropic acid

As a continuation of our goals to study molecular probes for muscarinic cholinergic receptors, a series of 3-substituted 2-methyl-2-phenylpropanoates with the general structure of C6H5C(CH2X)(CH3)COOCH2CH2NEt2 where X = OH, OTs, F, Cl, Br, I, and OAc were prepared and their antispasmodic activities examined on isolated rat ileum preparations. Structure-activity relationship studies with these compounds provide further evidence suggesting that binding of an aromatic moiety in a specific location within the hydrophobic region of the receptor is important for anticholinergic potency. A nucleophilic displacement of chloride by "naked" fluoride under mild conditions is also reported.

Pharmacological properties of two amino esters of diphenylpropanoic acid

N, N-Diethylaminoethyl ester and 3-quinuclidinyl ester of 2, 2-diphenylpropanoic acid (compound 1 and 2, respectively) were prepared and pharmacologically evaluated in vitro and in the intact animal. Both compounds attenuated the effects of increasing doses of ACh in the isolated rat ileum (pA2 = 8.40 and 8.55, respectively). These effects were comparable to that of atropine (pA2 = 8.73). The duration of methacholine-induced salivation in male Swiss-Webster mice was significantly decreased by compound 2 but not by compound 1. Cardiorespiratory studies in adult male Sprague-Dawley rats revealed that both compounds shifted the dose-response curves to methacholine in terms of arterial blood pressure, heart rate and respiration upwards; indicative of cholinergic blockade. The observed pharmacological differences between the two compounds may be attributed to apparent in vivo hydrolysis of compound 1 by esterases.

The effects of stereoisomers of 2-amino-6(7)- and 9-amino-6-trifluoromethylbenzonorbornenes on food intake, brain serotonin concentration, and monoamine oxidase activity

To evaluate the importance of the conformation of fenfluramine in eliciting its various central nervous system effects, the isomers of 2-amino-6(7)- and 9-amino-6-trifluoromethylbenzonorbornene were employed as conformationally defined analogs of norfenfluramine. In this series of isomeric amines, the exo-2 and anti-9 isomers resemble the fully extended conformation of fenfluramine, whereas the endo-2 and syn-9 isomers resemble the folded conformation. The exo-2 and anti-9 isomers were equi-effective in reducing food intake in the rat, but were approximately seven times less potent than fenfluramine. The endo-2 and syn-9 isomers had no effect on food intake up to a dose of 40 mg/kg. All of the isomers were as effective as amphetamine in inhibiting brain monamine oxidase type B. These isomers also inhibited monoamine oxidase type A to the same extent as type B, but were significantly less potent than amphetamine in inhibiting this form of the enzyme. The effects at anorectic doses on brain serotonin (5-HT) concentration were also studied. Although fenfluramine decreased brain 5-HT concentration, the exo-2, syn-9 and anti-9 isomers had no significant effect. The endo-2 isomers caused an 11% decrease in 5-HT concentration, but this effect was observed at higher doses of the compound. The data suggest that the fully extended conformation of fenfluramine is preferred over the folded conformation for eliciting its anorectic activity. However, no conclusion can be made for the conformational requirements for the other biological responses investigated in this study.

The effects of stereoisomers of 2- and 9- aminobenzonorbornenes on food intake, brain serotonin concentration and monoamine oxidase activity in the rat

To evaluate the importance of the conformation of amphetamine in eliciting its various central nervous system effects, the conformationally defined analogs of amphetamine. In this series of isomeric amines, the exo-2 and anti-9 isomers resemble the fully extended conformation of amphetamine, whereas the endo-2 and syn-9 isomers resemble the folded conformation. The exo-2 and anti-9 isomers were equally as effective in reducing food intake in the rat, but were much less potent than amphetamine. The endo-2 and syn-9 isomers had no effect on food intake up to a dose of 40 mg/kg. These latter two isomers also caused very little inhibition of monoamine oxidase in vitro. The exo-2 and anti-9 isomers, however, were nearly as effective as amphetamine in inhibiting monoamine oxidase type A, but only amphetamine and the anti-9 isomer inhibited monoamine oxidase type B. The effects at anorectic doses on brain serotonin (5-HT) concentration were also studied. Although amphetamine had no effect on the 5-HT concentration and fenfluramine decreased its concentration, the exo-2 and anti-9 isomers caused a significant increase in brain 5-HT. The anti-9 isomer caused a 14% increase in 5-HT, whereas the exo-2 isomer gave a 49% increase over controls. The data suggest that the fully extended conformation of amphetamine is preferred over the folded conformation for eliciting its biological responses, although the rigid analogs were less potent than amphetamine.

Inhibition of cholesterol side-chain cleavage. 3. 22-azacholesterol analogues bearing aryl-substituted side chains

The potent inhibitory activity of 22-azacholesterol analogue 2a, in which the (3-methylbutyl)amino side chain had been replaced by the (phenylethyl)amino side chain, on the conversion of cholesterol to pregnenolone prompted the synthesis and enzymatic studies of two series of 22-azacholesterol analogues bearing (arylalkyl)amino and (arylalkyl)amino side chains. The potent inhibitory activity of both the amines (2) and the amides (3) indicated that a basic nitrogen was not a requirement for inhibitory activity. However, the amide analogue (4) in which the positions of the carbonyl and the nitrogen were interchanged was a much poorer inhibitor. The inhibitory activities in the phenylacetamido series were decreased by electron-withdrawing groups on the aromatic ring, while an electron-donating group effected a small increase.

Inhibition of cholesterol side-chain cleavage. 4. Synthesis of A or B ring modified azacholesterols

A number of A or B ring modified 20- and 22-azacholesterol analogues (1 and 2, respectively) were synthesized in an attempt to ascertain the structural requirements for inhibition of the cholesterol side-chain cleavage reaction in bovine adrenocortical mitochondrial acetone powder preparations. The inhibition studies of these analogues revealed that (1) the 3-methyl ethers were as active as the parent compounds and that (2) reduction of the delta 5 double bond greatly lessened the inhibitory activity. These studies demonstrated a crucial role of the delta 5 double bond for inhibitory activity, while a free hydroxyl group at C-3 is not essential for this action. Furthermore, as in the parent compounds, 22-azacholesterol analogues were more potent than their 20-azacholesterol counterparts.

Some pharmacological properties of a novel series of 2-substituted 2-phenylcyclohexyl N,N-diethylaminoethyl ethers. II

The second of a series of 2-phenylcyclohexyl N,N-diethylaminoethyl ethers, (trans-compound), was investigated for its pharmacological actions in mice and rats. The trans-compound shortened the duration of methacholine (20 mg/kg)-induced salivation in mice, which was observed to be inversely proportional to the intraperitoneally administered dose of the compound. In anesthetized rats, a time-course study revealed the effects of the compound to be brief (5-15 minutes). When administered alone, it decreased heart rate, systolic, diastolic and mean arterial pressures and increased pulse-pressure. It produced transient apnea followed by slight increase in respiration. In other anesthetized rats, pretreatment with 5 mg/kg trans-compound reversed the depression response and bradycardia induced by injection of increasing doses of methacholine. Respiratory rate was similarly decreased due to initial transient apnea followed by a slight increase. There was a non-significant decrease in rectal temperature when methacholine was injected before or after the compound. These experiments suggest that the trans-compound possesses a weaker anticholinergic activity compared to the cis-compound.