Urinary excretion and bactericidal activities of gemifloxacin and ofloxacin after a single oral dose in healthy volunteers

In a randomized crossover study, 16 volunteers (8 men, 8 women) received single oral doses of 320 mg of gemifloxacin and 400 mg of ofloxacin on two separate occasions in the fasting state to assess the urinary excretion and urinary bactericidal titers (UBTs) at intervals for up to 144 h. Ofloxacin showed higher concentrations in urine compared with those of gemifloxacin. The median (range) cumulative excretion of gemifloxacin was 29.7% (8.4 to 48.7%) of the parent drug administered, and median (range) cumulative excretion of ofloxacin was 84.3% (46.5 to 95.2%) of the parent drug administered. The UBTs, i.e., the highest twofold dilutions (with antibiotic-free urine as the diluent) of urine that were still bactericidal, were determined for a reference strain and nine uropathogens for which the MICs of gemifloxacin and ofloxacin were as follows: Escherichia coli ATCC 25922, 0.016 and 0.06 microg/ml, respectively; Klebsiella pneumoniae, 0.03 and 0.06 microg/ml, respectively; Proteus mirabilis, 0.125 and 0.125 microg/ml, respectively; Escherichia coli, 0.06 and 0.5 microg/ml, respectively; Pseudomonas aeruginosa, 1 and 4 microg/ml, respectively; Staphylococcus aureus, 0.008 and 0.25 microg/ml, respectively; Enterococcus faecalis, 0.06 and 2 microg/ml, respectively; Staphylococcus aureus, 0.25 and 4 microg/ml, respectively; Enterococcus faecalis, 0.5 and 32 microg/ml, respectively; and Staphylococcus aureus, 2 and 32 microg/ml, respectively. Generally, the UBTs for gram-positive uropathogens were higher for gemifloxacin than for ofloxacin and the UBTs for gram-negative uropathogens were higher for ofloxacin than for gemifloxacin. According to the UBTs, ofloxacin-resistant uropathogens (MICs, >or=4 mg/liter) should also be considered gemifloxacin resistant. Although clinical trials have shown that gemifloxacin is effective for the treatment of uncomplicated urinary tract infections, whether an oral dosage of 320 mg of gemifloxacin once daily is also adequate for the treatment of complicated urinary tract infections has yet to be confirmed.

Chlamydia and Borrelia DNA in synovial fluid of patients with early undifferentiated oligoarthritis: results of a prospective study

OBJECTIVE

More than 50% of patients with synovitis involving 1-4 joints remain classified as having undifferentiated oligoarthritis (UOA) after 1 year of disease. The clinical presentation is often similar to that of reactive arthritis (ReA) and other spondylarthropathies or to Lyme arthritis. We therefore determined how often Chlamydia trachomatis (Ct) and Borrelia burgdorferi (Bb) can be identified in patients with UOA, by using an extensive laboratory approach.

METHODS

We prospectively studied 52 patients with UOA who presented at an early synovitis clinic in a region highly endemic for Lyme disease. Patients were examined by standardized clinical and immunoserologic procedures. Synovial fluid was screened for the presence of Ct and Bb DNA by polymerase chain reaction (PCR). Urine was tested for Ct DNA by ligase chain reaction, and serum was tested for Ct antibodies by enzyme-linked immunosorbent assay and Bb antibodies by hemagglutination test and Western blotting. PCR results in the UOA patients were compared with the results in cohorts of patients with definite rheumatoid arthritis (RA), Lyme arthritis, and Chlamydia-induced arthritis (CIA).

RESULTS

In the synovial fluid of 9 of 52 patients with UOA (17%), we found Ct DNA, and in 6 of the 52 patients (12%), Bb DNA was found. The frequency of bacteria-specific DNA was 50% (7 of 14) in CIA patients and 69% (11 of 16) in patients with Lyme arthritis. No Bb or Ct DNA was found in the synovial fluid of the 31 RA patients.

CONCLUSION

With optimized PCR protocols, it is possible to detect considerable levels of Bb and Ct DNA in the synovial fluid of patients with UOA. Although the presence of bacterial DNA does not unequivocally prove its etiologic significance, we suggest that at least one-third of patients with UOA may have a form of ReA that involves asymptomatic primary infection.

The superefficient company

Most companies do a great job promoting efficiency within their own walls, streamlining internal processes wherever possible. But they have less success coordinating cross-company business interactions. When data pass between companies, inconsistencies, errors, and misunderstandings routinely arise, leading to wasted work--for instance, the same sales, order entry, and customer data may be entered repeatedly into different systems. Typically, scores of employees at each company manage these cumbersome interactions. The costs of such inefficiencies are very real and very large. In this article, Michael Hammer outlines the activities and goals used in streamlining cross-company processes. He breaks down the approach into four stages: scoping--identifying the business process for redesign and selecting a partner; organizing--establishing a joint committee to oversee the redesign and convening a design team to implement it; redesigning--taking apart and reassembling the process, with performance goals in mind; and implementing--rolling out the new process and communicating it across the collaborating companies. The author describes how several companies have streamlined their supply-chain and product development processes. Plastics compounder Geon integrated its forecasting and fulfillment processes with those of its main supplier after watching inventories, working capital, and shipping times creep up. General Mills coordinated the delivery of its yogurt with Land O'Lakes; butter and yogurt travel cost effectively in the same trucks to the same stores. Hammer says this new kind of collaboration promises to change the traditional vocabulary of corporate relationships. What if you and I sell different products to the same customer? We're not competitors, but what are we? In the past, we didn't care. Now, we should, the author says.

[The optics of retinal blood vessels and their significance for scanning laser Doppler flowmetry]

Recently, the scanning laser Doppler flowmetry (SLDF) has been developed as a standard method for the quantification of retinal blood flow. However, the measured quantities flow, volume, and velocity depend on the angle between the direction of the blood flow and of the light. The underlying theory assumes isotropic illumination of the vessel. This assumption, however, is not valid for light back-scattered from retinal vessels. This paper investigates the contribution of different pathways of the light to the SLDF signal by a Monte Carlo simulation. It is shown that the light measured on a vessel having a thickness of 50 microns is predominantly back-scattered from the blood inside the vessel, whereas the measurement on vessels 20 microns in diameter or less also includes light transmitted through the vessel.

Formation of strong airway irritants in mixtures of isoprene/ozone and isoprene/ozone/nitrogen dioxide

We evaluated the airway irritation of isoprene, isoprene/ozone, and isoprene/ozone/nitrogen dioxide mixtures using a mouse bioassay, from which we calculated sensory irritation, bronchial constriction, and pulmonary irritation. We observed significant sensory irritation (approximately 50% reduction of mean respiratory rate) by dynamically exposing the mice, over 30 min, to mixtures of isoprene and O3 or isoprene, O3, and NO2. The starting concentrations were approximately 4 ppm O3 and 500 ppm isoprene (+ approximately 4 ppm NO2. The reaction mixtures after approximately 30 sec contained < 0.2 ppm O3. Addition of the effects of the residual reactants and the identified stable irritant products (formaldehyde, formic acid, acetic acid, methacrolein, and methylvinyl ketone) could explain only partially the observed sensory irritation. This suggests that one or more strong airway irritants were formed. It is thus possible that oxidation reactions of common unsaturated compounds may be relevant for indoor air quality.

Transforaminal ventral epidural adhesiolysis

Epidural fibrosis with chronic low back pain, nonresponsive to traditional measures of treatment including surgery, is a common entity in modern medicine. Traditionally, epidural steroid injections have been employed to treat chronic low back pain and radiculopathy associated with failed back surgery. Due to the poor effectiveness of epidural steroid injections in post lumbar laminectomy syndrome, epidural adhesiolysis was introduced in the early 1980s. Caudal epidural adhesiolysis with hypertonic saline neurolysis has been described extensively in the literature and has been proven to be relatively successful and safe. To improve the results and reach the target area with steroid, transforaminal ventral epidural adhesiolysis has been utilized. This retrospective case analysis included 14 patients. Transforaminal ventral epidural adhesiolysis was performed on an outpatient basis in all patients. The results showed 93% improvement initially, which decreased to 71% at 1 month, 57% at 3 months, 43% at 6 months and 21% at 1 year. The results of this case study show that ventral epidural lysis of adhesions with hypertonic saline neurolysis is safe and effective in managing chronic low back and lower extremity pain in patients who failed to respond to other conservative modalities of treatments, including fluoroscopically directed transforaminal epidural steroid injections.

Evidence of T cell clonality in the infectious tolerance pathway: implications toward identification of regulatory T cells

We have shown that a rare population of regulatory CD4+ T cells plays a key role in the acquisition of infectious tolerance in rat sensitized recipients of cardiac allografts pretreated with nondepleting anti-CD4 mAb. This study was designed to analyze the TCR Vbeta expression patterns in this transplantation model. First, we used Vbeta-specific RT-PCR to show that there was no differential usage of TCR Vbeta genes by T cells mediating rejection or tolerance. Indeed, graft-infiltrating lymphocytes expressed most of the 22 known rat TCR Vbeta genes in both recipient groups, suggesting unrestricted TCR Vbeta repertoire in alloreactive T cells. Then, we applied CDR3 spectrotyping of TCR beta-chain to assess the clonality of T cells at different anatomic sites. CDR3 size restriction, indicative of the presence of T cell clones, was observed in graft-infiltrating lymphocytes but not in draining lymph nodes or spleen of tolerant hosts. Consisent with the clonal expansion, T cells in tolerated grafts exhibited the memory phenotype at a much higher percentage as compared with peripheral lymphoid organs. Moreover, in tolerated graft-infiltrating lymphocytes, the CD3 size restriction occurred in limited Vbeta gene families, with Vbeta8.1 and Vbeta18 most frequently detected. Hence, T cells at the graft site of tolerant recipients contain T cell clones expressing selective Vbeta genes. This phenotypic characteristics of the tolerogenic GILs may potentially be used as a novel marker to identify operational regulatory T cells in organ allograft recipients.

Light paths in retinal vessel oxymetry

The oxygen utilization and, therefore, the metabolic state, of a distinctive area of the retina may be calculated from the diameter of the supplying artery and vein, the haemoglobin oxygenation, and the velocity of the blood. The first two parameters can be determined by imaging spectrometry at the patients ocular fundus. However, the reflected light emerging from a vessel followed different pathways through the ocular fundus layers and the vessel embedded in the retina. The contribution of the single pathways to the vessel reflection profile is investigated by a Monte Carlo simulation. Considering retinal vessels with diameters of 25-200 microm we found the reflection from a thin vessel to be determined by the single and double transmission of light at 560 nm. The backscattering from the blood column determines the reflectance in the case of a thick vessel. However, both components are in the same order of magnitude. This has to be considered in the calculation of the oxygen saturation of blood in retinal vessels from their reflection spectra.

A scattering phase function for blood with physiological haematocrit

Though the optics of red blood cells as well as whole blood has been studied extensively, an effective scattering phase function for whole blood is still needed. The interference of waves scattered by neighbouring cells cannot be neglected in highly concentrated suspensions such as whole blood. As a result, the phase function valid for single erythrocytes may fail to describe a single scattering process in whole blood with physiological haematocrit (Hct approximately 0.4). In this study we compared the results obtained in goniophotometric measurements of blood samples with the results of angle-resolved Monte Carlo simulations. The results show that a Henyey-Greenstein phase function with an anisotropy factor of 0.972 is an adequate approximation for the effective scattering phase function of whole blood with high haematocrit at a wavelength of 514 nm.

[Relationship between illness, rehabilitation and work (ZERA)--an training program for medical-vocational rehabilitation of the mentally ill]

A training programme for rehabilitation of people with mental illness is presented, designed particularly for schizophrenic patients who need occupational rehabilitation. The training goal is to connect aspects of the schizophrenic disorder with vocational issues. It is aimed at supporting the participants in developing a realistic and appropriate vocational perspective in line with their illness related restrictions and current vocational possibilities, seeking to find out the individual's optimal ability to take stress so as to avoid over- or understimulation in vocational respects. The ZERA training has been developed for implementation in different medical and vocational rehabilitation settings for persons with mental illness. An initial control-group study was carried out to evaluate the effectiveness of this group training approach, and preliminary results have revealed changes in the experimental group in accordance with the objectives of the training and encourage further research.

Effects of R-(+)- and S-(-)-limonene on the respiratory tract in mice

The effects of airborne R-(+)- and S-(-)- limonene were studied in conscious BALB/c mice by continuous monitoring respiratory rate (f), tidal volume (VT) and mid-expiratory flow rate (VD) during an exposure period of 30 min. Both enantiomers decreasedf from a trigeminal reflex, i.e., due to sensory irritation. The exposure concentration decreasing f by 50% (RD50) in the first 10 min of the exposure period was estimated to be 1,076 ppm for R-(+)-limonene and 1,467 ppm for S-(-)-limonene. Results for sensory irritation of R-(+)-limonene in BALB/c mice and humans are in close agreement. The reported sensory irritation threshold is above 80 ppm in humans while the no-observed-effect level was estimated to be 100 ppm in mice. The enantiomers were devoid of pulmonary irritation or general anesthetic effects with R-(+)-limonene < or =1,599 ppm and S-(-)-limonene < or =2,421 ppm. R-(+)-limonene did not influence VT below 629 ppm. S-(-)-limonene increased VT above 1,900 ppm. Both enantiomers induced a mild bronchoconstrictive effect above 1,000 ppm.

Bioluminescence as a classroom tool for scientist volunteers

There is a great need for practicing scientists to volunteer their time and expertise in the K-12th grade science classroom. We have found that bioluminescence is a fun and exciting way to teach basic science concepts and is an excellent tool for the volunteering scientist. We have had very positive reactions from both teachers and students. The excitement of the students when they first see bioluminescence is contagious. Bioluminescent dinoflagellates are one of the easiest ways to introduce students to this fascinating topic. Many activities and experiments can be done using the bioluminescent dinoflagellates and many students and teachers could benefit from your knowledge and expertise. See you in the classroom.

Cardiovascular evidence for an intermediate or higher metabolic rate in an ornithischian dinosaur

Computerized tomography scans of a ferruginous concretion within the chest region of an ornithischian dinosaur reveal structures that are suggestive of a four-chambered heart and a single systemic aorta. The apparently derived condition of the cardiovascular system in turn suggests the existence of intermediate-to-high metabolic rates among dinosaurs.

Sensory preconditioning in honeybees

Sensory preconditioning means that reinforcement of stimulus A after unreinforced exposure to a compound AB also leads to responses to stimulus B. Here, we describe and analyze sensory preconditioning in an insect, the honeybee Apis mellifera. Using two-element odorant compounds in classical conditioning of the proboscis extension reflex, we found (i) that sensory preconditioning is not due to stimulus generalization, (ii) that paired, but not unpaired, presentation of elements supports sensory preconditioning, (iii) that simultaneous, but not sequential, exposure to the elements of the compound supports sensory preconditioning and (iv) that a single presentation of the compound yields maximal sensory preconditioning. The results are discussed with respect to configural and chain-like associative explanations for sensory preconditioning. We suggest an experience-dependent step of compound processing, establishing configural units, as an additional explanation for sensory preconditioning.

[Age-related maculopathy. Comparative studies of patients, their children and healthy controls]

BACKGROUND

The aim of this study was to evaluate prospectively whether there are differences in spectrometrically measurable parameters of the fundus between patients with early and late age-related maculopathy (ARM), the children of the ARM patients (F1 generation) and normals.

METHOD

Using the "Jenaer Imaging Spectrometer", retinal oxygen saturation, xanthophyll, and intrinsic fluorescence were measured; the spatial distribution of xanthophyll was determined using the Rodenstock SLO 101 model.

RESULTS

Xanthophyll is reduced in late ARM as compared to the F1 generation and the control group (alpha < 0.01). The different fluorescence spectra, measured at shortwave and at longwave excitation, suggest the presence of more than one fluorophore. Furthermore, the components of the fluorophores seem to be different between patients with ARM and their F1 generation. The longwave autofluorescence is age-dependent only in late ARM (r2 = 0.81). For the first time, we found an alteration in oxygen saturation in retinal vessels in patients with ARM.

CONCLUSIONS

Xanthophyll is reduced only in late ARM. Autofluorescence and oxygen saturation are different between ARM patients, the F1 generation and normals, however, we were not able to identify a genetically based predisposition concerning the parameters studied.

In vivo measurement of the oxygen saturation of retinal vessels in healthy volunteers

A new method for the spatially resolved measurement of the oxygen saturation of retinal vessels is described. Imaging spectrometry was used for both measurements of transmission and reflectance spectra of whole blood in cuvettes as well as for fundus reflectance spectra. A model was developed for the calculation of the oxygen saturation, valid in the wavelength range between 510 nm and 586 nm, in that the internal reflectance is constant and only the transmitted light depends on layer thickness and hematocrit. Altogether 265 measurements were performed in different number at 30 eyes. In each measurement, the oxygen saturation was simultaneously determined for 193 locations along a line of 1.5 mm at the fundus. The mean oxygen saturation in retinal arteries was (92.2 +/- 4.1)% and (57.9 +/- 9.9)% in retinal veins. The mean retinal arterio-venous difference of the oxygen saturation was (35.1 +/- 9.5)%. The venous oxygen saturation depended on distance from the optic disc. The measured mean of the arterio-venous difference of the oxygen saturation corresponded well to the value of the brain (34%). The utilization of oxygen in the temporal quadrants (inferior: 39.4 +/- 10.4%) is significantly (p = 0.05) higher than in the nasal quadrants (inferior: 31.3 +/- 6.7%).

How process enterprises really work

Many companies have succeeded in reengineering their core processes, combining related activities from different departments and cutting out ones that don't add value. Few, though, have aligned their organizations with their processes. The result is a form of cognitive dissonance as the new, integrated processes pull people in one direction and the old, fragmented management structures pull them in another. That's not the way it has to be. In recent years, forward-thinking companies like IBM, Texas Instruments, and Duke Power have begun to make the leap from process redesign to process management. They've appointed some of their best managers to be process owners, giving them real authority over work and budgets. They've shifted the focus of their measurement and compensation systems from unit goals to process goals. They've changed the way they assign and train employees, emphasizing whole processes rather than narrow tasks. They've thought carefully about the strategic trade-offs between adopting uniform processes and allowing different units to do things their own way. And they've made subtle but fundamental cultural changes, stressing teamwork and customers over turf and hierarchy. These companies are emerging from all those changes as true process enterprises--businesses whose management structures are in harmony, rather than at war, with their core processes. And their organizations are becoming much more flexible, adaptive, and responsive as a result.

[Oxygen saturation of retinal vessels. Studies for measuring with polarized light]

The accuracy of the spectrometric measurement of the oxygen saturation in retinal vessels is limited by its signal-to-noise ratio. The aim of this study was to investigate the possibility of enhancement of the reflection signal by the use of polarized light.

MATERIALS AND METHODS

The Jena ophthalmospectrometer was equipped with two polarizing filters: one in the illumination and the other in front of the detector. Reflection spectra of erythrocytes streaming through a cuvette in the focus of an artificial eye were recorded. The influence of the polarization on the reflection spectra was investigated by rotating the polarizer in front of the detector. Furthermore, the degree of polarization of the light reflected from retinal vessels in vivo was determined.

RESULTS

The degree of polarization of the light reflected from the erythrocytes was 0.6-0.8, whereas the polarization of light reflected by a standard white reflectance target was virtually zero.

CONCLUSION

Polarized light can be used for the reduction of error in retinal vessel oximetry.

A case of sequential anti-stress medication in a patient with major depression resistant to amine-reuptake inhibitors

One of the predictive factors of treatment-resistant depression is the syndrome of relative insulin resistance, i.e. adipositas, mild hypertension and a family history of type-2 diabetes. Such a case is here reported with a good outcome to anti-stress medication, including ketoconazole and lithium.

Acute airway effects of formaldehyde and ozone in BALB/c mice

1. Concentration and time-effect relationships of formaldehyde and ozone on the airways were investigated in BALB/c mice. The effects were obtained by continuous monitoring of the respiratory rate, tidal volume, expiratory flow rate, time of inspiration, time of expiration, and respiratory patterns. 2. With concentrations up to 4 p.p.m., formaldehyde showed mainly sensory irritation effects of the upper airways that decrease the respiratory rate from a trigeminal reflex. The no-effect level (NOEL) was about 0.3 p.p.m. This value is close to the human NOEL, which is about 0.08 p.p.m. 3. Ozone caused rapid, shallow breathing in BALB/c mice. Later on, the respiratory rate decreased due to another vagal response that indicated an incipient lung oedema. The NOEL in mice was about 1 p.p.m. during 30 min of ozone exposure. No major effect occurs in resting humans at about 0.4 p.p.m. 4. Thus, the upper airway irritant, formaldehyde, and the deep lung irritant, ozone, showed the same types of respiratory effects in humans and in BALB/c mice. Also, the sensitivity was nearly identical. Continuous monitoring of respiratory effects in BALB/c mice, therefore, may be a valuable method for the study of effects of other environmental pollutants, which, however, should be confirmed in further studies.

IA in Kenyon cells of the mushroom body of honeybees resembles shaker currents: kinetics, modulation by K+, and simulation

Cultured Kenyon cells from the mushroom body of the honeybee, Apis mellifera, show a voltage-gated, fast transient K+ current that is sensitive to 4-aminopyridine, an A current. The kinetic properties of this A current and its modulation by extracellular K+ ions were investigated in vitro with the whole cell patch-clamp technique. The A current was isolated from other voltage-gated currents either pharmacologically or with suitable voltage-clamp protocols. Hodgkin- and Huxley-style mathematical equations were used for the description of this current and for the simulation of action potentials in a Kenyon cell model. Activation and inactivation of the A current are fast and voltage dependent with time constants of 0.4 +/- 0.1 ms (means +/- SE) at +45 mV and 3.0 +/- 1.6 ms at +45 mV, respectively. The pronounced voltage dependence of the inactivation kinetics indicates that at least a part of this current of the honeybee Kenyon cells is a shaker-like current. Deactivation and recovery from inactivation also show voltage dependency. The time constant of deactivation has a value of 0.4 +/- 0.1 ms at -75 mV. Recovery from inactivation needs a double-exponential function to be fitted adequately; the resulting time constants are 18 +/- 3.1 ms for the fast and 745 +/- 107 ms for the slow process at -75 mV. Half-maximal activation of the A current occurs at -0.7 +/- 2.9 mV, and half-maximal inactivation occurs at -54.7 +/- 2.4 mV. An increase in the extracellular K+ concentration increases the conductance and accelerates the recovery from inactivation of the A current, affecting the slow but not the fast time constant. With respect to these modulations the current under investigation resembles some of the shaker-like currents. The data of the A current were incorporated into a reduced computational model of the voltage-gated currents of Kenyon cells. In addition, the model contained a delayed rectifier K+ current, a Na+ current, and a leakage current. The model is able to generate an action potential on current injection. The model predicts that the A current causes repolarization of the action potential but not a delay in the initiation of the action potential. It further predicts that the activation of the delayed rectifier K+ current is too slow to contribute markedly to repolarization during a single action potential. Because of its fast activation, the A current reduces the amplitude of the net depolarizing current and thus reduces the peak amplitude and the duration of the action potential.

Optimised sample preparation of synovial fluid for detection of Chlamydia trachomatis DNA by polymerase chain reaction

OBJECTIVE

To optimise sample preparation of synovial fluid for Chlamydia trachomatis (CT) specific polymerase chain reaction (PCR).

METHODS

Serial dilutions of purified CT elementary bodies in synovial fluid were prepared. The synovial fluid pellet was processed by eight different methods of sample preparation. Then samples were analysed by CT specific PCR. The sensitivity of PCR was the basis of ranking of the eight different methods.

RESULTS

Highest sensitivity was achieved by methods including an additional step of DNA isolation. Additional extraction of protein and polysaccharides by cetyltrimethylammonium bromide (CTAB) increased sensitivity. Addition of hyaluronidase did not increase sensitivity of QIAEX-DNA extraction but was necessary, however, before phenol-chloroform-DNA extraction.

CONCLUSIONS

The method of synovial fluid sample preparation significantly influences the sensitivity of subsequent PCR. Additional DNA isolation and extraction of PCR inhibitors by CTAB led to higher sensitivity.

Pattern learning by honeybees: conditioning procedure and recognition strategy

In recognizing a pattern, honeybees Apis mellifera, may focus either on its ventral frontal part, or on the whole frontal image. We asked whether the conditioning procedure used to train the bees to a pattern determines the recognition strategy employed. Bees were trained with the same patterns presented vertically on the back walls of a Y maze. Conditioning was either absolute, that is, bees should learn to choose a rewarded pattern when there is no alternative, or differential, that is, bees should learn to choose a rewarded pattern that is paired with a different, nonrewarded one. Bees used different pattern recognition strategies depending on the conditioning procedure: absolute conditioning restricted recognition to the lower half whilst differential conditioning extended it to the whole pattern. Bees trained with absolute conditioning saw and learned the features of the upper part of the trained patterns, but assigned more weight to the lower part. Bees trained with differential conditioning learned not only the features of the reinforced stimulus in an excitatory way, but also those of the nonreinforced one in an inhibitory way. Thus, conditioning tasks that involve not only excitatory acquisition of the conditioned stimulus per se, but also discrimination of nonreinforced stimuli, result in an increase in the visual field assigned to the recognition task. Conditioning tasks that involve only excitatory acquisition of the rewarded stimulus result in a higher weighting of the lower pattern half and thus in a more reduced field assigned to the recognition task. This difference may reflect that existing between a conditioned and an incidental behavioural modification. Copyright 1999 The Association for the Study of Animal Behaviour.

Single scattering by red blood cells

A highly diluted suspension of red blood cells (hematocrit 0.01) was illuminated with an Ar or a dye laser in the wavelength range of 458-660 nm. The extinction and the angle-resolved intensity of scattered light were measured and compared with the predictions of Mie theory, the Rayleigh-Gans approximation, and the anomalous diffraction approximation. Furthermore, empirical phase functions were fitted to the measurements. The measurements were in satisfactory agreement with the predictions of Mie theory. However, better agreement was found with the anomalous diffraction model. In the Rayleigh-Gans approximation, only small-angle scattering is described appropriately. The scattering phase function of erythrocytes may be represented by the Gegenbauer kernel phase function.