Comparative in vitro activity of first, second and third generation cephalosporins

Minimum inhibitory concentrations (MIC) were determined against 662 recent clinical isolates for eight cephalosporins representing first, second and third generation compounds. All four third-generation cephalosporins tested (cefoperaxone, cefotaxime, ceftazidime and moxalactam) were significantly more active against aerobic gram-negative bacteria than the older compounds (cephalothin, cefamandole, cefoxitin, and cefuroxime). Cefotaxime and moxalactam were most active against Enterobacteriaceae with extremely low MIC-values. Ceftazidime was definitely most active against Pseudomonas aeruginosa with more than 90% of strains inhibited at 4 micro g/ml. MIC-values for cefotaxime against Staphylococcus aureus were for all strains 1-2 micro g/ml, slightly higher for cefoperazone, while the effect of ceftazidime and moxalactam was more limited. All third generation cephalosporins demonstrated efficiency against Streptococcus pyogenes, cefotaxime being most active and moxalactam least active, but were essentially ineffective against Streptococcus faecalis. Moxalactam demonstrated higher activity against Bacteroides fragilis than other second and third generation cephalosporins including cefoxitin. Previous studies have demonstrated a very high activity of all third generation cephalosporins against Haemophilus influenzae and Neisseria gonorrhoeae, including beta-lactamase producing strains.     

Public opinion toward the first,second, and third generations of plant biotechnology

Summary This paper considers public attitudes toward genetically modified plants in the fields or those soon to be planted. Analyzing a regional public opinion survey of 680 respondents in Arkansas, Texas, Louisiana, New Mexico, and Oklahoma carried out in the Spring—Summer of 2004, we look at the importance of public attitudes toward the three generations of agricultural biotechnology in light of the changing regulatory environment. Specifically, we ask questions concerning the first generation of plants with agronomic qualities, comparing our findings with previous studies, then look at perceptions of the second generation of crops with product quality characteristics, and the third generation, which expresses industrial products and pharmaceutical drugs. We look at perceived benefits, the likelihood, that these plants might accidentally enter the food supply, the likelihood that these plants might be eaten by the respondent, as well as how worried and angry the respondent would be as a result. Findings suggest that the public is still largely unaware of food biotechnology and genetically modified food products in their life. When compared with the first and second generation agricultural biotechnology products, survey respondents indicated that third generation products are not only likely to provide greater benefits, but are also potentially the source of more worry and anger if accidentally eaten.     

Diagnosis of abnormalities of the human fetus during the first, second, and third trimesters.

Clinical teratologists will have new challenges during the 1990s as birth defects are diagnosed more frequently than in previous decades. Malformations and genetic disorders will be diagnosed in utero during all three trimesters of pregnancy. The teratologist may participate in or lead a multispecialty group to give the involved family optimal interpretation of test results, counseling, and recommendations regarding subsequent clinical management.     

Backbone dynamics of the first, second, and third immunoglobulin modules of the neural cell adhesion molecule (NCAM)

The neural cell adhesion molecule (NCAM) is a cell surface multimodular protein, which plays an important role in cell-cell adhesion by homophilic (NCAM-NCAM) and heterophilic (NCAM-non-NCAM molecules) binding. In the present study, the backbone dynamics of the first three immunoglobulin-like (Ig) modules of NCAM have been investigated by NMR spectroscopy. Ig1, Ig2, and Ig3 share low sequence identity but possess the same fold and have very similar three-dimensional structures. (15)N longitudinal and transverse relaxation rates and heteronuclear NOEs have been measured and subsequently analyzed by the axial symmetric Lipari-Szabo modelfree formalism to characterize fast (pico- to nanosecond) and slow (micro- to millisecond) motions in the three protein modules. We found that backbone motions of residues located in the beta-strand regions are generally restricted, while increased flexibility is observed in turns and loops. In all three modules, residues located in the segments connecting the C- and D-strand plus residues located in the segment connecting the E- and F-strand show significant chemical exchange on the micro- to millisecond time scale. In addition, a number of residues with small chemical exchange contribution seem to form contiguous regions in the beta sheets, suggesting that these motions might be correlated. Only few residues in the homophilic binding sites in the NCAM Ig1 and Ig2 modules show increased flexibility, indicating that the Ig1-Ig2-mediated NCAM homophilic binding does not depend on the local backbone mobility of the interacting modules.     

Occurrence of HLA-A, B, C antibodies in first, second, and third pregnancies (follow-up studies of 161 pregnancies

In the course of their gravidity 161 women, among them 71 pregnant for the first time, 64 for the second time and 26 for the third time, were examined five times for the presence of cytotoxic HLA-A, B, C antibodies in NIH-LCT. This resulted in a total frequency of 23% of cytotoxic antibodies. Among those women pregnant for the first time there was an antibody rate of 18.3% (12.7% specifically), in those being in their second or third pregnancy the antibody rate amounted to 26%. In women with the second pregnancy the frequency of specific antibodies amounted to 17%, in those with the third pregnancy to 7.7%. HLA-antibodies were identified in the first gravida at the earliest between the 33rd and 40th week of pregnancy, in the second gravidas from the 12th to 16th or 33rd to 40th week of pregnancy and in the third gravidas from the 6th to 12th week. The results are discussed in comparison with HLA-mass screening of gravids carried out in the GDR in selected pregnant women and with other data taken from literature. They obtain a practical significance for performing a programme of HLA-antibody screening in a selected number of pregnant women with the aim of providing a possibility for gaining test sera from pregnant women for the purpose of improving the yield of test sera in comparison with the HLA-antibody screening test commonly used for pregnant women in the GDR.     

Administration of D-glucosamine into the third cerebroventricle induced feeding accompanied by hyperglycemia in rats

D-glucosamine, 2-amino-2-deoxy-D-glucose, is known to be an endogenous glucose analogue and to antagonize glucose uptake and metabolism. The present experiments were aimed to clarify effects of glucosamine and related chemical substances on ingestive behavior, as well as its direct effects on hypothalamic neurons. Infusion of 24 mumole glucosamine into the third cerebroventricle induced feeding within 30 min in 5 rats out of 7 tested, accompanied by increased ambulatory activity. No periprandial drinking was observed. Plasma glucose level increased, peaking at 30 min after the injection. Plasma insulin level tended to increase, but not significantly. Electrophoretic application of glucosamine activated glucose-sensitive neurons in the lateral hypothalamus and suppressed glucoreceptors in the ventromedial hypothalamus. These facts, together with other reported results, suggest that glucosamine can modulate physiological feeding and that carbon 2 of the glucose molecule is important in feeding modulation by glucose analogues.     

On the mapping of chains of first order chemical reactions on random walks

We present the transient solution to a random walk problem which characterizes chemical kinetic processes in which a particular state may have a finite number of internal states. While there are many chemical and physical examples, we introduce the solution through models of biophysical interest.     

Intra-accumbens baclofen, but not muscimol, increases second order instrumental responding for food reward in rats

Stimulation of either GABA(A) or GABA(B) receptors within the nucleus accumbens shell strongly enhances food intake in rats. However the effects of subtype-selective stimulation of GABA receptors on instrumental responses for food reward are less well characterized. Here we contrast the effects of the GABA(A) receptor agonist muscimol and GABA(B) receptor agonist baclofen on instrumental responding for food using a second order reinforcement schedule. Bilateral intra-accumbens administration of baclofen (220-440 pmol) stimulated responding but a higher dose (660 pmol) induced stereotyped oral behaviour that interfered with responding. Baclofen (220-660 pmol) also stimulated intake of freely available chow. Muscimol (220-660 pmol) was without effect on responding for food on this schedule but did stimulate intake of freely available chow. Unilateral administration of either baclofen or muscimol (220 pmol) induced similar patterns of c-fos immunoreactivity in several hypothalamic sites but differed in its induction in the central nucleus of the amygdala. We conclude that stimulation of GABA(A) or GABA(B) receptors in the nucleus accumbens shell of rats produces clearly distinguishable effects on operant responding for food.     

Sterol methyltransferase from Uromyces phaseoli: An investigation of the first and the second transmethylation reactions

The two-carbon unit at C-24 of many plant, algal and fungal sterols is known to be synthesized by two successive transmethylations with S-adenosylm     

P50 values in hypoxic albino rats of first and second generation.

We determined the "in vivo" (arterial pH and PCO2) and standard (pH = 7.4, PCO2 = 40 mm Hg) PO2 at 50% O2 saturation of hemoglobin (P50, vv and P50, st) in Wistar albino rats when living in a normobaric hypoxic environment. Two generations of hypoxic rats were observed for changes in their P50, vv, P50, st, (n50) 2,3-diphosphoglycerate (2,3-DPG), hemoglobin (Hb) and DPG-Hb ratio: the first generation (H1) and the second generation (H2). A few hours after birth, the H1 rats were placed and raised in a normobaric hypoxic environment (10% O2 in N2). The H2 rats were born from hypoxic parents of first generation and were raised in the same hypoxic environment. The control group had a normoxic environment. The P50, st was significantly higher in H1 rats than both H2 and controls. P50, st was similar in H2 and control rats. The P50, vv was significantly higher in H1 rats than both H2 and controls but it was significantly lower in H2 when compared with both controls and H1. Hb and 2,3-DPG had values significantly greater for both H1 and H2 when compared with their controls. However, the values of H2 were significantly lower than H1. The effectiveness of an increase in Hb-O2 affinity as an adaptive mechanism in H2 rats is discussed.     

The solid state physical theory of cytochrome oxidase kinetics. Inhibition of second order rate constant,and second to first order kinetic shift with increasing oxygen,predicted from electron injection and trapping

Conduction of electrons through the solid protein cytochrome oxidase particle in accord with Ohm's law, driven by the difference in electrode potentials of two substrates which exchange electrons with the two sides of the enzyme particle, was previously shown to explain the inhibitory effect of cytochromec on the first order rate constant, and to predict the low semiconduction activation energy of dried cytochrome oxidase. If the solid conduction path in the cytochrome oxidase particle shows electron injection from sites of electron exchange with substrate, and shows trapping of conduction electrons by reversible O₂ complexes, then one may also predict that the first order kinetics observed as high O₂ concentrations will change to second order kinetics at lower O₂ concentrations, as observed by Gibson and Wharton. One may also predict quantitatively the inhibitory effect of increasing O₂ concentrations on the second order rate constant as observed by Gibson and Wharton. The same concept of electron trapping by O₂ complexes provides a possible reason for the unusually low semiconduction activation energy of cytochrome oxidase.