Variations of bacterial populations in human feces measured by fluorescent in situ hybridization with group-specific 16S rRNA-targeted oligonucleotide probes

Six 16S rRNA-targeted oligonucleotide probes were designed, validated, and used to quantify predominant groups of anaerobic bacteria in human fecal samples. A set of two probes was specific for species of the Bacteroides fragilis group and the species Bacteroides distasonis. Two others were designed to detect species of the Clostridium histolyticum and the Clostridium lituseburense groups. Another probe was designed for the genera Streptococcus and Lactococcus, and the final probe was designed for the species of the Clostridium coccoides-Eubacterium rectale group. The temperature of dissociation of each of the probes was determined. The specificities of the probes for a collection of target and reference organisms were tested by dot blot hybridization and fluorescent in situ hybridization (FISH). The new probes were used in initial FISH experiments to enumerate human fecal bacteria. The combination of the two Bacteroides-specific probes detected a mean of 5.4 x 10(10) cells per g (dry weight) of feces; the Clostridium coccoides-Eubacterium rectale group-specific probe detected a mean of 7.2 x 10(10) cells per g (dry weight) of feces. The Clostridium histolyticum, Clostridium lituseburense, and Streptococcus-Lactococcus group-specific probes detected only numbers of cells ranging from 1 x 10(7) to 7 x 10(8) per g (dry weight) of feces. Three of the newly designed probes and three additional probes were used in further FISH experiments to study the fecal flora composition of nine volunteers over a period of 8 months. The combination of probes was able to detect at least two-thirds of the fecal flora. The normal biological variations within the fecal populations of the volunteers were determined and indicated that these variations should be considered when evaluating the effects of agents modulating the flora.     

Atrophy and degeneration of peptidergic neurons and cessation of egg laying in the aging pond snail Lymnaea stagnalis

The morphology of the neuroendocrine caudodorsal cells (CDCs), which are involved in the regulation of female reproduction in the pond snail Lymnaea stagnalis, was studied in young (200 to 234 days of age) and old (400 to 500 days) animals. Lucifer Yellow fills of ventral CDCs showed that in young animals ventral CDCs branch ipsilaterally as well as contralaterally in the cerebral commissure. In old animals these branches were reduced at different degrees and in some cases even lacking completely, leaving only an axon crossing the commissure. Immunocytochemical stainings with antibodies against CDC peptides (CDCH-I and alpha CDCP) corroborated the finding that ventral CDCs degenerate. Among the other types of CDCs (dorsal, lateral), degeneration was found as well. The immunocytochemical findings showed that in old animals the axon terminals of the CDCs were strongly stained, indicating that they are packed with secretory vesicles containing peptides. It was also found that these darkly stained, peptide-containing axon terminals protruded into the perineurium. These findings suggest that accumulation of peptides in the terminals of the CDCs of old animals may be due to the impaired release. The relationship between atrophy and degeneration of CDCs and cessation of egg-laying activity in Lymnaea is discussed.     

Forgetting in primed fragment completion.

Seven experiments examined the time course of primed fragment-completion performance. A pilot experiment and Experiment 1 showed that rapid forgetting occurs immediately after study for a period of approximately 5 min. The rate of this immediate forgetting is independent of the length of the list. Experiment 2 showed that priming effects were still present after 16 months. Experiments 3 and 4 provided further evidence of forgetting over 1 week. Experiment 5 showed that retention performance after 20 min is unaffected by the interpolated study and recall of other lists of words. Experiment 6 showed that 10-min retention performance was substantially reduced as list length was increased from 10 to 100 words; but it showed no evidence of intralist proactive interference. The combined results of the seven experiments illustrate some similarities and differences between forgetting in primed fragment completion and in episodic memory tasks such as recall and recognition. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

1310-nm DBR-type MQW gain-clamped semiconductor optical amplifiers with AM-CATV-grade linearity

A 1310-nm gain clamped semiconductor optical amplifier with amplitude modulation CATV-grade linearity at an output power of 8 mW is demonstrated for the first time. The InGaAsP multiquantum-well laser amplifier is equipped with distributed Bragg reflectors at each end to supply the feedback necessary for gain clamping. The TE optical gain of 21.3 dB is measured to be constant within 0.1 dB up to 25-mW signal output power. Electrical signal distortion experiments are presented to demonstrate the linearity of the device.     

Foreword to the special issue on program evaluation.

Introduces the special issue of Rehabilitation Psychology, which focuses on program evaluation. It is hoped that these paper will stimulate further productive work in this area. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

National rehabilitation policy and rehabilitation psychology.

This article presents a summary of legislation that has influenced psychology’s role in the rehabilitation process since 1918, when the Soldier Rehabilitation Act was passed. The increasingly important role that psychologists have played in the rehabilitation process is detailed and implications for the role that psychologists must now play in the public policy arena are noted. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Operating system redundancy on an active,a stand-by or a passive basis

When applying redundancy, the system designer may find himself facing the dilemma of weighing the better life prospects of passive redundant hardware against the lower system complexity in the case of active redundant hardware. This dilemma is analyzed here by comparing the MTTF and the reliability obtained with active, stand-by and passive redundancy. The analysis makes use of Markov diagrams and a generalized reliability model that embraces all three types of redundancy and covers all types of failure which can occur in practice.     

Quality control of equipment used in digital and interventional radiology

Digital and interventional radiology are increasingly important areas of radiology. Quality control (QC) of such equipment is of particular importance to avoid unnecessary high doses and to help to achieve good image quality. Within the DIMOND III project, equipment requirements and specifications for digital and interventional radiology have been formulated. A protocol for QC tests has been drafted based on various national and international recommendations. Tests are included for various parts of the imaging chain, i.e. X-ray tube and generator, X-ray tube control system, laser printer and display station, and image quality and patient dose. Preliminary tolerance levels have been set for the various tests, after initial measurements. To check the suitability of QC tests and stated tolerance levels, measurements were made at the University Hospital Gasthuisberg in Leuven for equipment used for paediatric radiology and a unit used for chest examinations. The results of the various tests are reported.