Changes in serum trace element levels following local irradiation of a solid tumor.

The changes in concentrations of a number of trace elements have been determined by neutron activation analysis in tumor, liver, and blood serum of host animals, following local irradiation of a solid tumor (3924A Morris hepatoma). These trace element changes are compared to the changes observed in a parallel study of the effects of the chemotherapeutic agent 5-fluorouracil on the same tumor. Since the changes in some of the trace elements parallel the changes in pathological and biochemical factors resulting from the insult of radiation on the tumor, these trace elements may be valuable markers in the clinical evaluation of therapeutic response and as monitors of the long term effects of cancer therapy.     

Theory of nucleus breeding schemes with overlapping generations

Summary Explicit methods are derived for estimating steady-state genetic responses and genetic differences between nucleus and base progeny crops in open nucleus breeding schemes which utilize genetic differences between progeny groups with parents of different ages or between age groups. Explicit methods are also given for estimating proportions which should be selected from the different nucleus and base selection groups so as to maximise genetic responses under each of a range of selection methods. Some basic differences between selection programmes utilizing genetic differences between progeny groups with parents of different ages and those utilizing genetic differences between age groups in nucleus breeding schemes are summarized.     

Goiter in Tibetan Medicine

The visit of two Tibetan physicians provided a unique opportunity to gain insight into a practice of medicine very different from that of Western civilization. Initial discussions indicated that the practice of medicine and mysticism were inextricably interwoven in the Tibetan culture. Accordingly, the focus of the study was directed to goiter, which is both common in the Himalayas and easy to define.In Tibetan medical practice, illness is considered to be derived from both proximate and distant causes. Three humors, “wind,” “bile,” and “phlegm” are thought to be responsible for normal mental and physical functions when in balance, but disease when out of balance. Goiter was thought to be due to an imbalance of these humors. The Western discovery that endemic goiter in the Himalayas was due to iodine deficiency explained the proximate cause but did not explain why some individuals have goiter and others do not in the same iodine deficient village.     

Inactivation kinetics and pharmacology distinguish two calcium currents in mouse pancreatic B-cells

Summary Voltage-dependent calcium currents were studied in cultured adult mouse pancreatic B-cells using the whole-cell voltage-clamp technique. When calcium currents were elicited with 10-sec depolarizing command pulses, the time course of inactivation was well fit by the sum of two exponentials. The more rapidlyinactivating component had a time constant of 75±5 msec at 0 mV and displayed both calcium influx- and voltage-dependent inactivation, while the more slowly-inanctivating component had a time constant of 2750±280 msec at 0 mV and inactivated primarily via voltage. The fast component was subject to greater steady-state inactivation at holding potentials between –100 and –40 mV and activated at a lower voltage threshold. This component was also significantly reduced by nimodipine (0.5 m) when a holding potential of –100 mV was used, whereas the slow component was unaffected. In contrast, the slow component was greatly increased by replacing external calcium with barium, while the fast component was unchanged. Cadmium (1–10 m) displayed a voltage-dependent block of calcium currents consistent with a greater effect on the high-threshold, more-slowly inactivating component. Taken together, the data suggest that cultured mouse B-cells, as with other insulin-secreting cells we have studied, possess at least two distinct calcium currents. The physiological significance of two calcium currents having distinct kinetic and steady-state inactivation characteristics for B-cell burst firing and insulin secretion is discussed.     

A Specific Transduction Mechanism for the Glutamate Action on Phosphoinositide Metabolism via the Quisqualate Metabotropic Receptor in Rat Brain Synaptoneurosomes: II. Calcium Dependency, Cadmium Inhibition

In this article, we demonstrate that an increase in intracellular Ca2+ concentration may represent a specific common step(s) in the mechanism(s) of action of glutamate (Glu) and depolarizing agents on formation of inositol phosphates (IPs) in 8-day-old rat forebrain synaptoneurosomes. In fact, A23187, a Ca2+ ionophore, induces a dose-dependent accumulation of IPs, which is not additive with that evoked by Glu and K+ but is slightly synergistic with that induced by carbachol. In addition, Glu and K+ augment the intracellular Ca2+ concentration in synaptoneurosome preparations as measured by the fura-2 assay. The absence of external Ca2+ decreases basal and Glu-, and K(+)-stimulated formation of IPs. Cd2+ (100 microM) fully inhibits both Glu- and K(+)-evoked formation of IPs without affecting the carbachol-elicited response of IPs. Zn2+ inhibits Glu- and K(+)-stimulated accumulation of IPs (IC50 approximately 0.4 mM) but with a lower affinity than Cd2+ (IC50 approximately 0.035 mM). The organic Ca2+ channel blockers verapamil (10 microM), nifedipine (10 microM), omega-conotoxin (2 microM), and amiloride (10 microM) as well as the inorganic blockers Co2+ (100 microM) and La3+ (100 microM) block neither Glu- nor K(+)-evoked formation of IPs, a result suggesting that the opening of the L-, T-, N-, or P-type Ca2+ channels does not participate in these responses. All these data suggest that an increase in intracellular Ca2+ concentration resulting from an influx of Ca2+, sensitive to Cd2+ but not to other classical Ca2+ antagonists, may play a key role in the transduction mechanism activated by Glu or depolarizing agents.     

Cognitive and behavioural impairment among elderly people in institutions providing different levels of care.

OBJECTIVE: To compare the prevalence and degree of cognitive and behavioural impairment in elderly patients in institutions providing different levels of care. DESIGN: Prevalence study. SETTING: A nursing home, a home for the aged and psychogeriatric wards in a provincial psychiatric hospital. PATIENTS: Only subjects 65 years of age or older were eligible for inclusion. A random sample was selected comprising 25% of the residents in the nursing home and the home for the aged; of the 119 asked to participate 95 agreed (44 in the nursing home and 51 in the home for the aged). All 50 on the psychogeriatric wards agreed to participate. MAIN OUTCOME MEASURES: The Mini-Mental State Examination (MMSE) and the Kingston Dementia Rating Scale (KDRS). RESULTS: An MMSE score of less than 24 (cognitive impairment) was given to 37 (84%) of the residents in the nursing home, 43 (84%) of those in the home for the aged and 48 (96%) of the patients in the psychiatric hospital; the corresponding numbers for a KDRS score of more than 0 (cognitive impairment) were 41 (93%), 48 (94%) and 50 (100%). The seven patients receiving the highest level of care at the home for the aged (special care) had more behavioural problems than those in the psychiatric hospital did (p less than 0.001). CONCLUSIONS: Cognitive and behavioural impairment was widespread in the three institutions regardless of the level of care. When planning services and allocating resources government funding agencies should consider the degree and prevalence of such impairment among elderly people in institutions.     

Gly-238-Ser substitution changes the substrate specificity of the SHV class A beta-lactamases

The SHV-type beta-lactamase SHV-2A is related to SHV-1 by a Gly-238-Ser replacement. Strains carrying SHV-2A are resistant to the third generation cephems cefotaxime and ceftizoxime, whereas those that carry SHV-1 are sensitive to these drugs. We present a kinetic analysis of a SHV-1 and SHV-2A enzymes, with the goal of gaining insight into the role of residue 238 in hydrolyzing cefotaxime and ceftizoxime. SHV-2A shows altered kinetic properties for a number of other cephems that also have heterocyclic side chains at the amino position of the 7-aminocephalosporanic acid nucleus (R1 side chain), including a significantly higher kcat/Km than does SHV-1 for cephaloridine, cephalothin, and cefotiam. Two cephems with straight chain R1 substitutions, cephalosporin C and cephacetrile, are not hydrolyzed more efficiently by SHV-2A. These results indicate that the Ser-238-Gly substitution increases the affinity toward cephems with a heterocyclic ring in the R1 side chain. In addition, the data for ampicillin and benzylpenicillin show that addition of a nitrogen to the second carbon of the R1 side chain of a penem results in a lower kcat/Km for SHV-2A relative to SHV-1. These data strongly suggest that the previously proposed hydrogen bond formation between Ser-238 and the second carbon nitrogen of cefotaxime is not an important factor in hydrolysis by SHV-2A. We propose that the Gly-238 to Ser-238 replacement in SHV-2A has altered the hydrophobic pocket so that it can better accommodate cephems with bulky R1 side chains.     

Stage-specific cuticular proteins of Ostertagia circumcincta and Ostertagia ostertagi

In this study we have shown that NHS-biotin and I¹²⁵-streptavidin can detect cuticular polypeptides of Ostertagia spp. The labelled polypeptide profile of intact nematodes is simple compared to the profile obtained by labelling homogenates. None of the major internal polypeptides are labelled and the subset of proteins labelled in intact nematodes appears to be mainly surface associated. The results presented here demonstrate that NHS-biotin may be used as a reagent for the analysis of surface polypeptides. The surface polypeptide profiles of the five major developmental stages (L1, L2, L3, L4 and adult) of Ostertagia circumcincta show a series of stage-specific molecules with no polypeptides common to all stages, indicating that the cuticle is a dynamic structure which changes throughout the life cycle. Similarity comparison of Ostertagia ostertagi L3 and L4 stage surface profiles showed that each stage is clearly distinct; comparison of these stages between the two species shows an overall similarity.     

Attraction of the grasshopper, Melanoplus sanguinipes, to host plant odors and volatile components

The attraction of the polyphagous grasshopper, Melanoplus sanguinipes (F.), to odors from plant foliage or to chemical components of these odors was tested in a glass Y-tube olfactometer. Humidified air was passed at equal flow rates through a sample chamber containing plant material and an empty control chamber and then through the Y-tube to the holding chamber containing the test insect. Solutions of volatile chemicals in water were metered at a constant rate into the sample air stream with a syringe pump. Insects moving upwind were recorded after entering either the sample or control arm of the Y-tube. Both nymphs and adults were strongly attracted to the odor of chopped and intact seedling foliage of perennial ryegrass and wheat. Chopped leaves but not intact leaves of sorghum and alfalfa also were significantly attractive. The major components of ryegrass odor from both chopped and stem-cut leaves were Z-hex-3-en-1-yl acetate, Z-hex-3-en-1-ol, and pent-1-en-3-ol, in that order, with lesser amounts of E-hex-2-enal. Chopped leaves released many more minor components. The major components when tested individually or in binary and ternary mixtures were significantly attractive to grasshoppers compared to humidified air but not to the degree of whole plant odor. However, a quartenary mixture simulating the odor blend had levels of attractancy equal to that of chopped grass odor. Blends of these 5- and 6-carbon unsaturated alcohols, esters, and aldehydes volatilizing from green plants probably play an important role as olfactory cues for orientation of grasshoppers to food plants.

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Résumé L'attraction de M. sanguinipes (F.) par l'odeur du feuillage et des composés chimiques de ces odeurs a été examinée dans un olfactomètre en tube de verre en Y. Des flux identiques d'air humidifié étaient introduits dans une enceinte contenant le matériel végétal et dans une enceinte témoin, et, via le tube en Y, dans l'enceinte contenant l'insecte à étudier. Des solutions aqueuses de substances volatiles étaient introduites à un taux constant dans le courant d'air grâce à une seringue. Les insectes se déplaçant contre le vent étaient enregistrés après pénétration dans une branche déterminée du tube en Y. Larves et adultes étaient fortement attirés par l'odeur de feuillage intact ou coupé de semis de Lolium perenne et de blé (Triticum aestivum). Les feuilles coupées, mais non les feuilles intactes de sorgho (Sorghum bicolor) et de luzerne (Medicago sativa) étaient, elles aussi, significativement attractives. Les principales substances constituant de l'odeur de feuilles de Lolium perenne, tant coupées qu'intactes, étaient dans l'ordre de Z-hex-3-en-1-yl acétate, le Z-hex-3-en-1-ol et le pent-1-en-3-ol, et dans une moindre mesure, E-hex-2-enal. Les feuilles coupées libéraient beaucoup plus de composés secondaires. Les principaux constituants testés, seuls ou en mélanges binaires ou ternaires, étaient significativement attractifs, mais moins que l'odeur totale de la plante. Toutefois, un mélange quaternaire, simulant le mélange odorant, avait le même pouvoir attractif que l'odeur de la plante entière. L'union de ces alcools, esters et aldéhydes à 5- et 6-carbones non saturés, volatilisés à partir des plantes vertes, jouent probablement un grand rôle comme signaux orientateurs lors de l'attraction des criquets par leur plantes alimentaires.