Ascending unmyelinated primary afferent fibers in the dorsal funiculus

The primary purpose of the present study is to obtain evidence as to the destination of the recently discovered unmyelinated primary afferent fibers in the mammalian dorsal funiculus. To do this rat dorsal roots were transected unilaterally from segments T8 or T9 caudally, and the numbers of axons were determined in the C3 fasciculus gracilis in normal animals and from both sides of the rhizotomied animals. In addition, C3 fasciculus gracilis counts were done in animals that had complete T6 or T10 spinal transections. The data indicate that there is an 80% loss of unmyelinated axons ipsilaterally and a 60% loss contralaterally in the fasciculus gracilis of the rhizotomied animals. These findings are interpreted as indicating that a significant fraction of the unmyelinated fibers in the fasciculus gracilis ascend, presumably to the nucleus gracilis in the brain stem, and also that a significant number of these fibers branch. We also provide evidence for contralateral myelinated primary afferent fiber projection in the fasciculus gracilis and show that the myelinated primary afferent fibers seem to be a more diverse population than the unmyelinated primary afferent fibers in the C3 fasciculus gracilis.

Aspartate immunoreactive axons in normal rat L4 dorsal roots

The present study demonstrates that approximately 15% of the unmyelinated axons and 4% of the myelinated axons in the rat L4 dorsal root are immunostained for the excitatory amino acid aspartate. Thus these primary afferent axons contain enough of the antigen to be labeled. This is the first report that high concentrations of aspartate characterize a subpopulation of dorsal root axons. This allows the suggestion that aspartate is a candidate transmitter for primary afferent neurons. We emphasize that these axons are demonstrated in otherwise normal animals so that changes in percentages of labeled axons in response to various stimuli are not complicated by manipulations usually necessary to demonstrate immunoreactive compounds in the cell body.

Staphylococcus aureus in commercial laying flocks: incidence and characteristics of strains isolated from chicks, pullets and hens in an integrated commercial enterprise

1. Staphylococcus aureus was able to colonise the surface of chicks as young as 1 d old. 2. The organism was detected in a hatchery particularly in the debris from the hatchers and on the working surfaces at the sexing and vaccination areas. 3. The degree of surface colonisation of chicks and pullets was low during rearing but rose to a maximum at mid-lay (50 weeks) when the organism was readily detectable on almost all hens. 4. Strains of Staphylococcus aureus were characterised by phage-typing and cultural characteristics and found to belong predominantly to poultry phage group B2 of Gibbs et al. (1978a). 5. A detailed description of poultry phage group B2 strains is presented; strains of this type can be considered as a second "live-bird" ecovar when compared with Staph. aureus var. gallinae of Witte et al. (1977).

The use of a new phage set for typing poultry strains of Staphylococcus aureus obtained from seven countries

1. Eighty per cent of poultry strains of Staphylococcus aureus tested from French, Belgian, English, West German, Japanese and Argentinian sources were typable using a set of typing phages isolated in this laboratory. Strains from Bulgaria, however, with few exceptions were not typable with this phage set. 2. Strains isolated from lesions generally resembled those from apparently healthy poultry. 3. The existence of two distinct Staph. aureus biotypes on poultry was confirmed by isolates from six of the countries; one of these biotypes closely resembled Staph. aureus variety gallinae as described by Witte et al. (1977).

Detection of volatile sulfide-producing bacteria isolated from poultry-processing plants

A technique using filter paper strips impregnated with 5-5'-dithiobis-nitrobenzoic acid was developed to allow the detection of bacteria (isolated from poultry-processing environs) which produced volatile sulfides (H2S, CH3SH, [CH3]2S). The technique is preferred to conventional methods in that it allows the detection of volatile organic sulfides in addition to hydrogen sulfide.

The effects of various treatments on the microbial flora of whole poultry carcasses with particular reference to Staphylococcus aureus contamination

Experiments are described in which the effects of dipping defrosted eviscerated poultry carcasses, for various periods, in acetic, lactic, succinic and citric acids, hypochlorite solution containing 200 ppm free Cl2 and in water at temperatures from 70 degrees C to 100 degrees C on the microbial flora were determined. 2. Hot (70 degrees C) water dipping for 2 min appeared to be the treatment most likely to succeed in reducing Staph. aureus, giving reductions of staphylococci of from 63 to greater than 99%, without completely eliminating other organisms. 3. A storage experiment showed this method to be relatively safe, provided the carcasses were refrigerated to less than 3 degrees C as soon as possible after treatment and held at this temperature until adequately cooked.

Characterization of hydrogen sulfide-producing bacteria isolated from meat and poultry plants

A survey of the types of aerobic organisms able to produce H2S on peptone iron agar (Levin, 1968), and commonly occurring in meat and poultry plants, revealed that these could be divided into four distinct groups. The ability of representative strains of each type to grow at low temperatures and cause off-odors on chicken muscle was examined. The results are discussed in relation to the role of these organisms in the psychrophilic spoilage of meat and meat products.