Comparison of the profiles of non-glycosylated triterpenoids from leaves of plants of selected species of genus Dioscorea

Remarkable qualitative and quantitative differences in non-glycosylated triterpenoid profiles of twelve Dioscorea spp. leaves were demonstrated with the use of GC–MS/FID analysis. The total content of tetracyclic triterpenoids and their esters ranged from 397 μg/g of dry leaf weight in D. bulbifera to 762 μg/g d.w. in D. discolor and 777 μg/g d.w. in D. alata. Three main phytosterols, i.e. campesterol (1), sitosterol (2) and stigmasterol (3) were found in extracts from all analyzed species in total amount ranging from 316 μg/g in D. bulbifera to 676 μg/g of dry leaf weight in D. hispida, with either sitosterol (2) or stigmasterol (3) as predominant in the profile. Extracts from D. hispida and D. purpurea leaves were distinguished from the others by particularly high amount of campesterol (1). In the majority of the species, except for D. caucasica, other tetracyclic triterpenoids were found: cycloartanol (4), 24-methylenecycloartanol (5) and cycloeucalenol (6). Less common steroids, stigmastan-3-en-6β-ol (7) and ergosta-7,22-dien-3β-ol (8) were detected in D. japonica. The significant content (992 μg/g) of pentacyclic triterpenoids of ursane, oleanane, taraxastane and taraxerene (friedooleanane)-type carbon skeletons, i.e. α-amyrin (9), β-amyrin (10), taraxasterol (11) and taraxerol (12), respectively, was found in D. caucasica. The obtained results supplement the knowledge of biochemical diversity of Dioscorea genus.     

Seasonal study of the fungal biota of the fur of dogs

During a one year period, 944 dogs from the Municipal kennel of Barcelona were examined to detect animals with suspected dermatophytosis. Only a few animals (1.8%) presented skin lesions but none of them had dermatophytosis. A representative number of dogs without visible skin lesions (n=172), selected at random, were used to carry out a seasonal study of the mycobiota of their fur. Fifteen isolates belonging to the genera Microsporum and Trichophyton were isolated from 14 of the 172 (8.1%) dogs without lesions. The identity of these fungi was Microsporum gypseum (6/15), Trichophyton terrestre (4/15), M. canis (2/15), M. cookei (2/15) and Trichophyton ajelloi (1/15) (one strain each of M. gypseum and T. ajelloi were isolated from one dog). Species of Penicillium (% prevalence=89.5%), Alternaria (86.6%), Cladosporium (84.9%), Aspergillus (77.3%), Scopulariopsis (65.7%) and Chrysosporium (64.5%) were the most prevalent. No significant differences in the fungal biota were observed with respect to age, gender, hair length or between mixed and pure breed dogs. A large number of isolates, including species belonging to the genera Beauveria, Chrysosporium, Malbranchea and Scopulariopsis, that macroscopically and/or microscopically resemble dermatophytes and may be mistaken for them, produced a red color change in Dermatophyte Test Medium. No significant seasonal difference was detected among the isolates belonging to the the most frequently encountered genera, with the exception of Scopulariopsis (higher in summer and autumn) and Chrysosporium (higher in summer). Species from other genera, with lower occurrence also presented significant differences in their seasonal distribution. Arthrinium, Aureobasidium, Chaetomium and Phoma spp. presented maximum prevalence peaks in spring, Fusarium, Paecilomyces, Phoma and Rhizopus spp. in summer and Geotrichum and Mucor spp. in autumn. The Microsporum and Trichophyton species were more frequently isolated in summer.     

Screening of antioxidant potential of Arctic lichens

Antioxidants are compounds that scavenge the free radicals produced in living organisms. The antioxidant potential of eight Arctic lichen species was evaluated in vitro using free radical scavenging activity (FRS), inhibition of lipid peroxidation (ILP), and Trolox equivalent antioxidant capacity assay (TEAC). FRS activities of lichen species in various organic solvents such as methanol, ethanol, acetone, and dimethyl sulphoxide (DMSO) were in the range 9.6–51.77%, while ILP activities in these solvents ranged from 32.5 to 82.43%. Pseudophebe pubescens showed the highest ILP (82.43%) and FRS (51.77%) activities as compared to other lichen species and the standard antioxidants butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT). The TEAC value was also found to be higher in all species compared to the standard water soluble vitamin E analog Trolox (3.9 mM). The order of antioxidative activities in lichen species was Pseudophebe pubescens > Cladonia amaurocraea > Cladonia mediterranea > Physcia caesia > Flavocetraria nivalis > Cetraria fastigata > Xanthoria elegans > Umbilicaria hyperborea. This is the first report of the measurement of antioxidant potential in Arctic lichens.     

Monthly Occurrence of Vectors and Reservoir Rodents of Scrub Typhus in an Endemic Area of Jeollanam-do, Korea

Monthly surveys were conducted to investigate the occurrence of chigger mites and seroprevalence of scrub typhus among small mammals in Jeollanam-do, the southwestern part of Korea, from November 2006 through October 2007. Fifty-eight small mammals, including 57 Apodemus agrarius (98.3%) and 1 Crocidura lasiura (1.7%), were captured, and a total of 4,675 chigger mites representing 4 genera and 8 species were collected from them. The chigger infestation rate among small mammals was 69.0%. The most predominant species in A. agrarius was Leptotrombidium scutellare (54.0%), followed by Leptotrombidium pallidum (39.4%), Leptotrombidium orientale (4.4%), Leptotrombidium palpale (1.1%), Neotrombicula tamiyai (0.6%), Eushoengastia koreaensis (0.3%), Neotrombicula gardellai (0.3%), and Cheladonta ikaoensis (<0.1%). The chigger index of A. agrarius was the highest in October (740.0), followed by November (242.0), September (134.6), March (98.3), February (38.2), January (35.3), December (34.5), April (30.8), and May (1.7). The average antibody positive rate of scrub typhus in wild rodents was 50.0%. The seropositive rates were high in October (100.0%) and November (83.3%), whereas those in other months were relatively low (28.6-57.1%). The chigger index of L. scutellare rapidly increased in September to form an acuminate peak in October, followed by a gradual decline. These results suggest that the outbreak of scrub typhus in the southwestern part of Korean peninsula is mostly due to L. scutellare.     

Reversal of Osteoporotic Changes of Mineral Composition in Femurs of Diabetic Rats by Insulin

Insulin plays an important role in bone prevention of diabetic osteoporosis, but little is known about the relation between the bone mineral density (BMD) increase and the change of mineral element content after treated with insulin. To address this problem, male Wistar rats were randomly divided into three groups: normal group (n = 6), streptozotocin-induced diabetic group (n = 5), and streptozotocin-induced diabetic group with insulin treatment (n = 5). The femoral BMD was measured by dual energy X-ray absorptiometry, and the element content was determined by inductively coupled plasma atomic emission spectrometry (ICP-AES). The results showed that the femoral BMD in diabetic group was significantly lower than that in normal group (P < 0.01) but restored by insulin treatment (P < 0.01 vs diabetic group). ICP-AES analysis revealed that the element content of calcium (Ca), phosphorous (P), magnesium (Mg), strontium (Sr), and potassium (K) in diabetic group were remarkably lower than those in normal group (P < 0.01) but only Ca, P, and Mg content were significantly increased compared with diabetic group (P < 0.05) after insulin treatment. However, no significant differences were observed in element zinc (Zn) content among three groups. Our findings suggested that the loss of Ca, P, Mg, Sr, and K content accounted for the lower BMD in streptozotocin-induced diabetes rats, insulin treatment could restore BMD by increasing the content of Ca, P, and Mg.     

Derivatives of phosphonate and vinyl phosphate analogs of D-ribose 5-phosphate

Propanal thiosemicarbazone (1a) showed activity in preventing anaphylactic shock in a mouse test-system; it also had some activity in stunting the growth of Botrytis allii. Hexanal thiosemicarbazone (1b) was active in the Botrytis allii test-system, and citral thiosemicarbazone (2) and citral guanylhydrazone nitrate (3) showed some activity in the same test-system. Heptanal guanylhydrazone nitrate (4) had some antibacterial activity against Staphylococcus aureus, and D-threo-pentosulose bis(thiosemicarbazone) (5) prevented anaphylactic shock in the mouse test-system. D-glycero-Tetrosulose bis(thiosemicarbazone) (6), D-lyxo-hexosulose bis-(guanylhydrazone) nitrate (7), D-galacto-heptosulose bis(thiosemicarbazone) (8), and D-galacto-heptosulose bis(guanylhydrazone) sulfate (9) showed some activity in stunting the growth of Botrytis allii. The copper chelate (10a) of D-arabino-hexosulose bis(thiosemicarbazone), and the copper (11a) and palladium (11b) chelates of 6-deoxy-L-arabino-hexosulose bis(thiosemicarbazone) showed antitumor activity in the KB cell-culture test-system. The palladium chelate 11b also showed some activity in the leukemia p-388 mouse test-system.     

Modulation of Adherence and Chemotaxis of Macrophages by Norepinephrine. Influence of Ageing

We evaluated thein vitro effect of norepinephrine (NE), over the range of concentrations between 10^-12 M and 10^-3 M, on adherence (to plastic surfaces) and chemotaxis (in a Boyden chamber) of peritoneal macrophages from BALB/c mice of different ages: young (12 weeks), adult (22 weeks), mature (48 weeks) and old (72 weeks). Increased adherence was induced by 10^-12 M of NE in macrophages from young, adult, mature and old mice. Also, 10^-9 M stimulated adherence in old animals, 10^-5 M in mature mice, and 10^-3 M in both young and old mices. With respect to chemotaxis, the low concentration of NE (10^-12 M) was stimulatory only in young and adult animals, higher concentrations (10^-5 M and 10^-7 M) were inhibitory for macrophages from mature and old animals, and the highest concentration of NE (10^-3M) stimulated this capacity of macrophages only in young and mature animals. The conclusion is that while the mobility of macrophages to the focus of infection (i.e. chemotaxis) is stimulated by low concentrations of NE (10^-12, M) only in young-adult animals, this neurotransmitter induces a decline in this capacity in mature and old mice at high concentrations (10^-5 M - 10^-7 M). Also, macrophages from old animals have lost the capacity to respond to pharmacological (10^-3 M) concentrations of NE. The lower capacity of response to NE by macrophages from old animals possibly contributes to immunosenescence.     

Synthesis and preliminary evaluation of pharmacological properties of some piperazine derivatives of xanthone

A series of 9 piperazine derivatives of xanthone were synthesized and evaluated for cardiovascular activity. The following pharmacological experiments were conducted: the binding affinity for adrenoceptors, the influence on the normal electrocardiogram, the effect on the arterial blood pressure and prophylactic antiarrhythmic activity in adrenaline induced model of arrhythmia (rats, iv). Three compounds revealed nanomolar affinity for α₁-adrenoceptor which was correlated with the strongest cardiovascular (antiarrhythmic and hypotensive) activity in animals’ models. The most promising compound was 4-(3-(4-(2-methoxyphenyl)piperazine-1-yl)propoxy)-9H-xanthen-9-one hydrochloride (12) which revealed antiarrhythmic activity with ED₅₀ value of 0.69 mg/kg in adrenaline induced arrhythmia (rats, iv). Other synthesized xanthone derivatives, that is, (R,S)-4-(2-hydroxy-3-(4-(2-methoxyphenyl)piperazine-1-yl)propoxy)-9H-xanthen-9-one hydrochloride (10) and (R,S)-4-(2-acetoxy-3-(4-(2-methoxyphenyl)piperazine-1-yl)propoxy)-9H-xanthen-9-one hydrochloride (11) also acted as potential antiarrhythmics in adrenaline induced model of arrhythmia in rats after intravenous injection (ED₅₀ = 0.88 mg/kg and 0.89 mg/kg, respectively). These values were lower than values obtained for reference drugs such as propranolol and urapidil, but not carvedilol.Results were quite promising and suggested that in the group of xanthone derivatives new potential antiarrhythmics and hypotensives might be found.     

The effects of ammonia on the fermentation of chopped sugarcane

Chopped sugarcane was ensiled with and without the addition of aqueous ammonia (28% NH₃) in laboratory silos (4.5 kg NH₃/t sugarcane). The effect of the NH₃ on the pattern of fermentation was studied over a period of 42 days. Addition of NH₃ resulted in: (a) an initial decrease in the population of yeasts and moulds, and Lactobacillus organisms; (b) a reduction (47.9%) in weight loss; (c) a reduction (46.4%) in the loss of water-soluble carbohydrates (WSC); (d) increased levels of lactic acid; and (e) lower levels of acid detergent fibre (ADF) when compared with untreated canelage (fermented, whole-plant sugarcane).In another experiment in which 205-litre drums were used as silos, addition of NH₃ (1.25 kg NH₃/t sugarcane) to chopped sugarcane also produced canelage with higher levels of lactic acid, more WSC, lower levels of ADF and a reduction in weight loss when compared with the control canelage.     

Use of mutagens in the improvement of production strains of microorganisms

Physical and chemical agents were employed in our laboratories to induce mutation in a variety of microorganisms used for production of antibioties or enzymes. Improved production strains ofPenicillium chrysogenum (penicillin-producer),Streptomyces griseus (streptomycin-producer),Streptomyces nodosus. (amphotericin B-producer),Streptomyces noursei (nystatin-producer),Streptomyces umbrinus (diumycin-producer),Streptomyces prasinus (prasinomycin-producer),Streptomyces roseochromogenes (steroid-16α-hydroxylase-producer), andArthrobacter simplex (steroid-1-dehydrogenase-producer) were developed by use of mutation selection techniques. The methods found to be most successful with each species are described. The genealogical relationships within species of a number of strains ofPenicillium chrysogenum, Streptomyces prasinus, andStreptomyces roseochromogenes are presented.     

Evaluation of insecticidal properties of botanicals for sustainable management of sucking pests of horticultural crops

Aphids, thrips, whiteflies, mealy bugs and mites could cause significant yield losses in horticultural crops. Many synthetic chemicals highly hazardous to non-target organisms and the environment are in use in their management. Botanicals are ideal for safe sustainable pest management by keeping synthetic chemical use at a minimum. We studied the insecticidal properties of three botanicals viz., Annona squamosa, Ricinus communis and Sapindus mukorossi seed extracts against sucking pests viz., aphids (Aphis gossypii and Aphis craccivora) on okra (Abelmoschus esculentus) and bittergourd (Momordica charantia), thrips (Scirtothrips dorsalis) on chilli (Capsicum frutescens), whiteflies (Bemisia tabaci) on eggplant (Solanum melongena), mealy bugs (Maconellicoccus hirsutus) on betel vine (Piper betle) and mites (Tetranychus urticae) on eggplant (Solanum melongena) under laboratory conditions. The bioassay showed that A. squamosa seed extract has potent insecticidal properties on all sucking pests, except T. urticae. Though S. mukorossi seed extract exhibited no insecticidal property, had a significant acaricidal property. A. squamosa and S. mukorossi seed extracts will therefore be additional botanicals for use in organic farming for managing the sucking pests effectively.     

pH Dependence of the Efficiency of Binding of Iron Cations to the Donor Side of Photosystem II

Light-induced interaction of Fe(II) cations with the donor side of Mn-depleted photosystem II (PS II(–Mn)) results in the binding of iron cations and blocking of the high-affinity (HA_Z) Mn-binding site. The pH dependence of the blocking was measured using the diphenylcarbazide/2,6-dichlorophenolindophenol test. The curve of the pH dependence is bell-shaped with pK ₁ = 5.8 and pK ₂ = 8.0. The pH dependence of the O₂-evolution mediated by PS II membranes is also bellshaped (pK ₂ = 7.6). The pH dependence of the process of electron donation from exogenous donors in PS II(–Mn) was studied to determine the location of the alkaline pH sensitive site of the electron transport chain. The data of the study showed that the decrease in the iron cation binding efficiency at pH > 7.0 during blocking was determined by the donor side of the PS II(–Mn). Mössbauer spectroscopy revealed that incubation of PS II(–Mn) membranes in a buffer solution containing ⁵⁷Fe(II) + ⁵⁷Fe(III) was accompanied by binding only Fe(III) cations. The pH dependence of the nonspecific Fe(III) cation binding is also described by the same bell-shaped curve with pK ₂ = 8.1. The treatment of the PS II(–Mn) membranes with the histidine modifier diethylpyrocarbonate resulted in an increase in the iron binding strength at alkaline pH. It is suggested that blocking efficiency at alkaline pH is determined by competition between OH^– and histidine ligand for Fe(III). Because the high-affinity Mn-binding site contains no histidine residue, this fact can be regarded as evidence that histidine is located at another (other than high-affinity) Fe(III) binding site. In other words, this means that the blockage of the high-affinity Mn-binding site is determined by at least two iron cations. We assume that inactivation of oxygen-evolving complex and inhibition of photoactivation in the alkaline pH region are also determined by competition between OH^– and a histidine residue involved in coordination of manganese cation outside the high-affinity site.     

Prediction of Nondiagnostic Results in Fine-Needle Aspiration of Thyroid Nodules: utility of On-Site Gross Visual Assessment of Specimens for Liquid-Based Cytology

Objective: To explore a comprehensive approach for on-site gross visual assessments of liquid-based cytology (LBC) specimens of thyroid nodules and determine morphologic criteria that help predict nondiagnostic rates.Methods: Two-hundred nodules from 165 patients who underwent fine-needle aspiration (FNA) at our hospital were included in this prospectively designed, retrospective analysis. Specimens were visually assessed on-site for three morphologic categories (specimen color, specimen volume, and particle count) using a 5-point grading.Results: Twenty-two nodules (11%) showed nondiagnostic results. Regarding specimen color, nondiagnostic rates tended to be higher in grades 1 (75%) and 5 (100%) than in grades 2 (18%), 3 (8%), or 4 (17%), with a significant difference between grade 1 and grade 3 (P = .003). For specimen volume, nondiagnostic results were significantly more common in grade 1 (33%) and 5 (33%) than in grades 3 (5%) or 4 (1%) (P<.005). There was a significant negative correlation between the grading of the particle count and the nondiagnostic rate (Spearman ρ = -1.000; P<.001). The sensitivity and specificity in the prediction of nondiagnostic results were 77% and 76%, respectively, at the optimal cutoff value of 2 (grade 2 or lower).Conclusion: Particle count was an important morphologic criterion that helped predict nondiagnostic rates in LBC specimens of thyroid nodules, and the specimen color and volume were also useful adjuncts. In routine practice, on-site gross visual assessment followed by resampling (if necessary) may potentially help reduce the rates of nondiagnostic results, repeat FNAs, and the number of unnecessary needle passes.Abbreviations: FNA = fine-needle aspiration; LBC = liquid-based cytology; ROC = receiver operating characteristic; US = ultrasonography     

Geographical Distribution and Relative Abundance of Vectors of Scrub Typhus in the Republic of Korea

A survey to determine the geographical distribution and relative abundance of potential vectors of scrub typhus was conducted from October to November 2006 at 13 localities throughout the Republic of Korea. Apodemus agrarius accounted for 97.6% (80/82) of all rodents, while only 2 Myodes regulus (2/82) were collected. A total of 10,860 chiggers were collected from A. agrarius belonging to 4 genera and 8 species, while only Walchia fragilis (40) was collected from Myodes regulus. Leptotrombidium pallidum (8,137; 74.9%), a vector of scrub typhus, was the predominant species collected from A. agrarius followed by Leptotrombidium scutellare (2,057, 18.9%), Leptotrombidium palpale (279; 2.7%), Leptotrombidium orientale (232; 2.1%), and Leptotrombidium zetum (79; 0.7%), Neotrombicula tamiyai (58; 0.5%), Euschoengastica koreaensis (16; 0.1%), and Cheladonta ikaoensis (2; < 0.1%). L. pallidum was the predominant chigger collected at collection sites in Gangwon (100%), Gyeonggi (87.2%), Chungnam (100%), Chungbuk (100%), Jeonbuk (73.9%), Jeonnam (77.0%), and Gyeongbuk (66.1%) provinces, whereas L. scutellare was the predominant chigger collected in Gyeongnam province (77.9%) and Jeju Island (62.3%). Data suggest a correlation between chigger population abundance and human cases of scrub typhus in Korea.     

Correlation of Dispersibility of Proteins with that of Selenium in Teas

Selenium-enriched tea was suggested as a possible source of supplemental Se. The result of this study indicates that it is not practicable to make selenium-enriched tea as a beverage like traditional green tea or black tea for the supplementation of selenium in human diet. The selenium dispersibilities of fresh tea leaves, green tea, and black tea highly correlated with those of protein (r ² = 0.998). The high protein dispersibility (85.0%) of fresh tea leaves in water solution was accompanied by that of selenium (93.8%). Decreases in protein dispersibility of green tea and black tea to 2.5% and 4.2 % coincided with those of selenium to only 8.3% and 10.1%, respectively. The amount (14.90 μg) of selenium in saturated ammonium sulphate (a protein precipitating reagent) precipitate was 83.8% of that (17.79 μg) in fresh tea leaf extract, and after the saturated ammonium sulphate precipitate was dialyzed against distilled water overnight, the amount (14.37 μg) of selenium remaining in the dialyzed precipitate (protein) was still 80.8% of that in the fresh tea leaf extract. However, there were no significant differences (p > 0.05) between the amount of selenium in the saturated ammonium sulphate precipitate and that in the saturated ammonium sulphate precipitate that was dialyzed.     

Mineral content of water and food in fluorotic villages and prevalence of dental fluorosis

The fluoride (F), calcium (Ca), magnesium (Mg), zinc (Zn), copper (Cu), and phosphorus (P) content in potable water and food samples (cereals, pulses, and vegetables) from endemic and nonendemic villages for fluorosis were analyzed. It was found that the F content in water was significantly higher (p<0.01) in endemic villages (4.20±1.6 ppm) than control villages (0.63±0.15 ppm), whereas the Ca, Cu, and Mg contents were found to be significantly lower (p<0.05) in endemic villages compared to control villages. However, there was no significant difference in Zn and P contents between the villages. Foods (cereals, pulses, and vegetables) grown in endemic villages contained significantly higher (p<0.01) fluoride content as compared to control villages. There was no significant difference in Ca, Mg, P, and Zn contents in food grown in endemic and control villages. Copper content in cereals (p<0.05), pulses (p<0.01), and vegetables (p<0.01) in endemic villages was found significantly higher as compared to control villages. The overall prevalence of dental fluorosis in six endemic villages was 97.4% in boys and 96% in girls, which was significantly higher (p<0.01) than that of control villages, where it was 10.5% in boys and 8.3% in girls. The prevalence of dental fluorosis was positively correlated (r=0.125, p<0.01) to fluoride and negatively correlated to Ca and Cu content in drinking water in endemic villages.     

Variability of light-induced circular dichroism spectra of photosystem I complexes of cyanobacteria

Circular dichroism (CD) spectra of photosystem I (PSI) complexes of the cyanobacteria Thermosynechococcus elongatus, Arthrospira platensis and Synechocystis sp. PCC 6803 were studied. CD spectra of dark-adapted PSI trimers and monomers, measured at 77 K, show common bands at 669–670(+), 673(+), 680(−), 683–685(−), 696–697(−), 702(−) and 711(−) nm. The intensities of these bands are species specific. In addition, bands at 683–685(−) and 673(+) nm differ in intensity for trimeric and monomeric PSI complexes. CD difference spectra (P700⁺–P700) of PSI complexes at 283 K exhibit conservative bands at 701(−) and 691(+) nm due to changes in resonance interaction of chlorophylls in the reaction center upon oxidation of P700. Additional bands are observed at 671(−), 678(+), 685(−), 693(−) nm and in the region 720–725 nm those intensities correlate with intensities of analogous bands of antenna chlorophylls in dark-adapted CD spectra. It is suggested that the variability of CD difference spectra of PSI complexes is determined by changes in resonance interaction of reaction center chlorophylls with closely located antenna chlorophylls.     

Chemical composition and mosquito repellency of essential oil of Conyza newii propagated in different geographical locations of Kenya

Previously, essential oil of Conyza newii (Asterale: Asteracea, Oliv. & Hiern) growing in the northern part of West Pokot (35°E, 1°N) of Kenya was shown to be highly repellent [RD₅₀ = 8.9 × 10^?5 mg/cm², 95% confidence interval (CL)] to Anopheles gambiae s.s. Fumigant toxicity of the oil to the mosquito was also demonstrated. The major constituents of the oil were found to be monoterpenoids, including (S)‐(‐)‐perillyl alcohol, (S)‐(‐)‐perillaldehyde, geraniol, (R)‐(+)‐limonene, trans‐β‐ocimene and 1,8‐cineol. In this study, the chemical composition and repellency of essential oils of the plant seedlings collected from West Pokot (35°E, 1°N) and propagated in seven different geographical regions of Kenya [West Pokot (35°E, 1°N), Kilome (37°E, 1°S), Naivasha (36°E, 0°), Webuye (34°E, 1°N), Nyakach (34°E, 0°), Kericho (35°E, 0°) and Nairobi (36°E, 1°S)] were compared. There were significant variations (P < 0.01, 95% CL) in the relative proportions of the six constituents and this was reflected in the repellency of the essential oils (P < 0.01, 95% CL). Higher repellency of the oil was associated with greater proportions of (S)‐(‐) perillyl alcohol, (S)‐(‐)‐perillaldehyde and geraniol, and lower repellency was associated with an increased proportion of (R)‐(+)‐limonene. The results suggest significant epigenetic (chemotypic) variations in the repellency and composition of C. newii essential oils growing in different regions of Kenya.     

Mechanisms of genetic control of immune responses

We examined multiple genetically regulated Immoral and cell-mediated immune (CMI) responses to poly(glu⁶⁰ala³⁰tyr¹⁰) (GAT) using a panel of mouse strains. We show that assignment of responder/nonresponder status depends upon the assay method. In addition, two distinct categories of nonresponder mice were found: (1) those which are unresponsive by all parameters tested (H-2 ^q and H-2 ^s haplotypes) and (2) those which are partially nonresponsive [H-2 ^bm12 mutant strain—a low/nonresponder by splenic plaque-forming cell (PFC) and delayed-type hypersensitivity (DTH) responses, but exhibits B6 parental levels of high GAT-specific T-cell proliferation (Tprlf) and interleukin-2 production]. The distinction between these two nonresponder types was confirmed by complementation tests in which significant GAT-specific PFC and DTH responses were seen in (H-2 ^q × H-2 ^bm12)F₁ hybrids, but not in (H-2 ^q × H-2 ^s )F₁ hybrids. Suppressor T cells (Ts) also play a selective role in nonresponsiveness to GAT. Cyclophosphamide treatment of nonresponders (to eliminate Ts activity) as well as immunization with GAT coupled to the immunogenic carrier MBSA result in the development of GAT-specific humoral, but not CMI responses. Our results indicate that the T cell is the cellular site of Ir gene expression and that Tprlf responses do not correlate with functional helper T-cell activity and suggest distinct, multi-step Th/Ts regulatory pathways in the development of humoral and CMI effector functions.     

Characterization of nickel tetrahydroxy phthalocyanine complexes and the electrocatalytic oxidation of 4-chlorophenol: Correlation of theory with experiments

This work reports on the use of nickel(II) tetrahydroxy (NiPc(OH)₄) and (poly-Ni(OH)Pc(OH)₄) phthalocyanine complexes as films on ordinary poly graphite electrode (OPGE) for the electrochemical oxidation of 4-chlorophenol (4-CP). The NiPc(OH)₄ film was electrotransformed to Ni(OH)Pc(OH)₄ film in aqueous 0.1 M NaOH solution to the ‘O-Ni-O oxo’ bridge form. The result showed that the Ni(OH)Pc(OH)₄ film on OPGE was more electroactive in terms of increase in current and less catalytic in terms of potential compared to the adsorbed NiPc(OH)₄ on OPGE. The reactivity of the two molecules was explained by theoretical calculations. The energies of the frontier orbitals of NiPc(OH)₄, Ni(OH)Pc(OH)₄ and 4-chlorophenol were calculated using density functional theory (DFT) method. The inter molecular hardness (η) and donor-acceptor hardness (η_DA) of Ni(OH)Pc(OH)₄, NiPc(OH)₄, Ni(OH)Pc(OH)₄/4-chlorophenol and NiPc(OH)₄/4-chlorophenol were estimated. The Ni(OH)Pc(OH)₄, showed stronger interaction with 4-chlorophenol than NiPc(OH)₄. DFT method was also used to model IR and Raman spectrum of H₂Pc(OH)₄ and NiPc(OH)₄.