Organization of hindbrain segments in the zebrafish embryo

To learn how neural segments are structured in a simple vertebrate, we have characterized the embryonic zebrafish hindbrain with a library of monoclonal antibodies. Two regions repeat in an alternating pattern along a series of seven segments. One, the neuromere centers, contains the first basal plate neurons to develop and the first neuropil. The other region, surrounding the segment boundaries, contains the first neurons to develop in the alar plate. The projection patterns of these neurons differ: those in the segment centers have descending axons, while those in the border regions form ventral commissures. A row of glial fiber bundles forms a curtain-like structure between each center and border region. Specific features of the individual hindbrain segments in the series arise within this general framework. We suggest that a cryptic simplicity underlies the eventual complex structure that develops from this region of the CNS.     

Tired,weak, or in need of rest: fatigue among general practice attenders.

OBJECTIVES--To determine the prevalence and associations of symptoms of fatigue. DESIGN--Questionnaire survey. SETTING--London general practice. PARTICIPANTS--611 General practice attenders. MAIN OUTCOME MEASURES--Scores on a fatigue questionnaire and reasons given for fatigue. RESULTS--10.2% Of men (17/167) and 10.6% of women (47/444) had substantial fatigue for one month or more. Age, occupation, and marital status exerted minor effects. Subjects attributed fatigue equally to physical and non-physical causes. Physical ill health, including viral infection, was associated with more severe fatigue. Women rather than men blamed family responsibilities for their fatigue. The profile of persistent fatigue did not differ from that of short duration. Only one person met criteria for the chronic fatigue syndrome. CONCLUSIONS--Fatigue is a common complaint among general practice attenders and can be severe. Patients may attribute this to physical, psychological, and social stress.     

A simple and sensitive method for detecting bacterial elastase production

A sensitive method for detecting bacterial elastase production in growing cultures is described. A variety of commonly isolated clinically relevant aerobic and anaerobic bacteria have been shown to produce the enzyme.     

Developmental expression of 44-kDa bone phosphoprotein (osteopontin) and bone γ-carboxyglutamic acid (Gla)-containing protein (osteocalcin) in calcifying tissues of rat

New aspects of the distribution and developmental appearance of the 44-kDa bone phosphoprotein (44K BPP, also called sialoprotein I or osteopontin) and bone gamma-carboxyglutamic acid (Gla)-containing protein (BGP, also called osteocalcin) during osteogenesis and dentinogenesis were investigated with immunocytochemical techniques using monospecific, affinity-purified polyclonal antibodies. Sections from newborn rat incisors and from various bone anlagen of newborn animals and fetuses were processed for detection of 44K BPP or BGP antigenicity. In addition, histochemical reactions for detection of alkaline phosphatase or calcium salts were performed on a number of the sections. The 44K BPP appears to be synthesized and secreted by chondrocytes only in the areas of cartilage-to-bone transition; these cells could participate indirectly in the process of bone formation by providing a suitable scaffold onto which primary marrow osteoblasts attach and spread. During osteogenesis, 44K BPP is found in bone-forming cells almost concomitantly with the appearance of alkaline phosphatase and before osteoid deposition, whereas BGP is still absent during early stages of mineralization. We hypothesize that this dramatic difference between the developmental appearance of 44K BPP and BGP reflects the delayed expression of the BGP gene relative to that of 44K BPP. In long-term cultures of bone marrow from adult mice, some fibroblastic cells expressed the 44K BPP phenotype; these cells could represent early osteogenic progenitor cells. Some experiments also suggested that, as with BGP, 44K BPP or an immunologically related protein is synthesized by some odontoblasts and secreted into predentin, prior to the onset of mineralization.     

Resonance Raman spectra of chlorophylls dissolved in liquid crystal matrices. II. Order parameters of chlorophyll a in an MBBA + EBBA liquid crystalline mixture

The molecular ordering of molecules embedded in a uniaxial liquid crystalline system has been considered. In particular, planar Chl a molecules in an MBBA + EBBA mixture have been studied by using polarized resonance Raman spectroscopy. The second- and fourth-rank order parameters and the orientational distribution function of Chl a in the nematic MBBA + EBBA liquid crystalline phase are discussed.