Opioid -and ␦-receptors are present on the central terminals of primary afferents, where they are thought to inhibit neurotransmitter release. This mechanism may mediate analgesia produced by spinal opiates; however, when they used neurokinin 1 receptor (NK1R) internalization as an indicator of substance P release, Trafton et al. (1999) noted that this evoked internalization was altered only modestly by morphine delivered intrathecally at spinal cord segment S1-S2. We reexamined this issue by studying the effect of opiates on NK1R internalization in spinal cord slices and in vivo. ]-enkephalin (DPDPE) (1 M). In vivo, hindpaw compression induced NK1R internalization in ipsilateral laminas I-II. This evoked internalization was significantly reduced by morphine (60 nmol), DAMGO (1 nmol), and DPDPE (100 nmol), but not by the agonist trans-(1S,2S)-3,4-dichloro-N-mathyl-N-[2-(1-pyrrolidinyl)cyclohexyl]-benzeneacetamide hydrochloride (200 nmol), deliveredat spinal cord segment L2 using intrathecal catheters. These doses of the and ␦ agonists were equi-analgesic as measured by a thermal escape test. Lower doses neither produced analgesia nor inhibited NK1R internalization. In contrast, morphine delivered by percutaneous injections at S1-S2 had only a modest effect on thermal escape, even at higher doses. Morphine decreased NK1R internalization after systemic delivery, but at a dose greater than that necessary to produce equivalent analgesia. All effects were reversed by naloxone. These results indicate that lumbar opiates inhibit noxious stimuli-induced neurotransmitter release from primary afferents at doses that are confirmed behaviorally as analgesic.

An effective method for the isolation and purification of exfoliatin which has been recently reported by Melish and others as the staphylococcal toxin responsible for the scalded skin syndrome and the physicochemical properties of the purified toxin were described. From an active crude toxin produced by one of the clinical isolates of phage group 2, four types of toxic proteins which were all capable of causing the typical Nikolsky sign in neonatal mice were obtained and designated A, B, C, and D toxins. They had a molecular weight of about 24,000 and showed the same serological features in neutralization and precipitation tests, but were different from each other in showing a different single band with their respective mobilities in polyacrylamide disk electrophoresis. They were precipitated between pH 4.0 and 4.5 and lost their exfoliative capabilities. The resulting precipitates, however, could be solubilized in acetate buffer containing 0.5% sodium dodecyl sulfate, restoring their toxicities to almost the same extent as before. They were all stable when heated at 60 C for 60 min and at 100 C for 20 min, but lost their toxicities when heated at 100 C for 40 min. Additionally, the present authors observed that some staphylococcal strains not belonging to the typical phage group 2, isolated from patients with the scalded skin syndrome, were also capable of producing a similar but serologically unrelated exfoliative toxin. Recently several groups of workers have pointed out the close association between Staphylococcus aureus of phage group 2 and the disease of infants known as toxic epidermal necrolysis of the Ritter's type (3, 4, 7-9, 12, 13). An experimental model with newborn mice for the study of the toxic epidermal necrolysis (TEN) has been reported by Melish and Glasgow (10). Subsequently, Arbuthnott et al. (1)

Four strains of Staphylococcus aureus of a phage type other than the second group, isolated from patients with impetigo and Ritter's disease, were found to produce an exotoxin similar to those reported by Melish et al. (1972), Kapral and Miller (1971), and Arbuthnott et al. (1973). This toxin could elicit a general exfoliation of the epidermis with the so-called Nikolsky sign when subcutaneously inoculated into neonatal mice within 4 days after birth. The new toxin was serologically different from exfoliatin produced by the phage group II staphylococci previously reported (Kondo et al., 1973) and showed an electrophoretic pattern corresponding to that of the B-type toxin of the latter in acrylamide disc electrophoresis. It had the same molecular weight as that of the latter, which was estimated to be about 24,000. It was thermolabile and lost its toxic activity by heating at 60 C for 30 min; in addition, most of the toxicity was lost within 1 month of storage even at-30 C. We propose to designate the old typical heat-stable exfoliatin as S. aureus exfoliatin A and the new heat-susceptible exfoliatin as S. aureus exfoliatin B.

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Spinal opiate analgesia is associated with presynaptic inhibition of release of excitatory neurotransmitters/neuromodulators, e.g., substance P (SP), from primary afferent terminals. Chronic intrathecal (i.t.) administration of opiates such as morphine results in an initial analgesia followed by tolerance and a state of dependence. In this study, we examined the resting and evoked neurokinin 1 receptor (NK1r) internalization, indicative of endogenous SP release, in dorsal horn neurons of the lumbar spinal cord by immunocytochemistry during chronic i.t. infusion of morphine in rats. Noxious mechanical stimulation (compression) applied to unilateral hind paw evoked a significant increase in NK1r internalization in lamina I neurons in the ipsilateral dorsal horn. Intrathecal morphine infusion (40 nmol/l/h) for 1 day possessed similar analgesic efficacy as acute morphine and blocked compression-induced spinal NK1r internalization. After 5 days of morphine infusion, thermal escape latencies were the same as in preinfusion animals or saline-infused controls, and compression-evoked NK1r internalization was no longer suppressed. Systemic administration of naloxone to rats on day 6 of morphine infusion resulted in prominent withdrawal behaviors and a concomitant increase in NK1r internalization in dorsal horn. The naloxone-induced internalization was blocked by NK1r antagonist L-703,606.2]octan-3-amine] or pretreatment with capsaicin, confirming that the internalization is due to the endogenous SP release from the primary afferents. We conclude that inability to suppress release of excitatory neurotransmitters/neuromodulators from primary afferents by morphine after chronic exposure is an important component in spinal morphine tolerance, and excessive release from these afferents contributes to the spinal morphine withdrawal syndrome.

Lactoferrin (LF) is a component of saliva and is suspected to be a defense factor against oral pathogens including Streptococcus mutans and Candida albicans. Periodontitis is a very common oral disease caused by periodontopathic bacteria. Antimicrobial activities and other biological effects of LF against representative periodontopathic bacteria, Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, and Prevotella intermedia, have been widely studied. Association of polymorphisms in LF with incidence of aggressive periodontitis and the role of LF in the gingival crevicular fluid as a marker of periodontitis severity have also been reported. Periodontopathic bacteria reside as a biofilm in supragingival and subgingival plaque. Our recent study indicated that LF exhibits antibacterial activity against planktonic forms of P. gingivalis and P. intermedia at higher concentrations, and furthermore, LF effectively inhibits biofilm formation and reduces the established biofilm of these bacteria at physiological concentrations. A small-scale clinical study indicated that oral administration of bovine LF reduces P. gingivalis and P. intermedia in the subgingival plaque of chronic periodontitis patients. LF seems to be a biofilm inhibitor of periodontopathic bacteria in vitro and in vivo.

Two serotypes of exfoliatin, A and B, previously reported by Kondo et al. (1974) were examined for their presence in 43 strains of Staphylococcus aureus, most of which were isolated from patients with Ritter's disease and impetigo. The tested strains consisted of 24 strains of phage group II and 19 strains not of phage group II. Twenty-four strains were found to produce an exfoliatin of either type A or type B, but 16 strains produced both types and 3 strains produced neither. No relationship was found between the serotype of an exfoliatin and the phage type of the exfoliative strain, although the single producers of exfoliatin A were all found to belong to phage group II and those of exfoliatin B to the other phage group.

Restriction fragments of DNA from bacteriophage S phi-C of Staphylococcus aureus which carries the gene for staphylokinase, one of the plasminogen activators, were cloned onto plasmid pBR322. Recombinant plasmids carrying the 2.5 kilobase pair segment of S phi-C DNA confer on Escherichia coli cells the capacity to synthesize staphylokinase. The enzyme is synthesized in amounts comparable to that found in S. aureus, and irrespective of the orientation of cloned fragments and their insertion site on pBR322. The active enzyme produced by E. coli cells is preferentially recovered from the periplasmic space and in part excreted into the culture medium. It is indistinguishable from the enzyme produced by S. aureus in molecular weight, as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and in antigenicity, as determined by the micro-Ouchterlony precipitation test.