The MBCs of nafcillin, vancomycin, gentamicin and daptomycin (LY146032) were determined for three clinical isolates of coagulase-negative staphylococci grown in suspension and adherent to biomaterials. Strains studied were the slime-producing strain Staphylococcus epidermidis RP-12 (ATCC 35983), S. hyicus SE-360, and the non-slime-producing strain S. hominis SP-2 (ATCC 35982). All three strains were allowed to colonize surgical-grade disks of stainless steel, polymethylmethacrylate, and ultrahigh-molecular-weight polyethylene for 24 h, and the disks were then exposed to various concentrations of antibiotics for 24 h. Surviving adherent bacteria were mechanically dislodged from the disks and quantitated by standard broth dilution plating techniques. Biomaterial-adherent RP-12 and SE-360 yielded approximately 10 times more CFU per disk than non-slime-producing SP-2 did. For all organisms, 10 times more bacteria bound to polymethylmethacrylate disks than to the other biomaterials. In general, bacteria adherent to biomaterials exhibited greater resistance to antibiotics than the same strains in suspension did. Resistance was independent of bacterial slime-producing characteristics and was related to the biomaterial colonized.Biomaterial-centered infections are characterized by the following features: (i) a biomaterial or damaged tissue substratum; (ii) adhesive, frequently polymicrobial bacterial colonization; (iii) persistence of infection until the substratum is removed; (iv) resistance to host defense mechanisms and antibiotic treatment; (v) specificity of materials, organisms, and location; and (vi) transformation of autochthonous or opportunistic organisms to virulent pathogens (18).Mechanisms of antibiotic resistance have not been well characterized. A biofilm barrier effect has been proposed (4,5,7,16,30). Studies have shown that when organisms are grown in suspension they are susceptible to lower concentrations of antibiotics than when they are in surface-adherent, biofilm-enclosed populations (4,5,16,20,24). The selection of therapeutic antibiotics is usually based on standard suspension culture MIC and MBC studies. In this study, antibiotic susceptibilities of organisms grown in suspension and on biomaterials were examined.The ability of antibiotics to kill coagulase-negative staphylococci is clinically important, since studies have shown that staphylococci are major colonizers of surgical biomaterials, including heart valves, intravascular catheters, and orthopedic appliances (la, 6). Prosthetic infections are generally resistant to antibiotic therapy and frequently require removal of the implant before eradication of the infection is possible (12-19).Both coagulase-positive and coagulase-negative staphylococci have been reported as causes of biomaterial-centered infections, with a tendency for coagulase-negative species to be associated with polymer-sited infections (2,12,15,26 (2,21). RP-12 is an adherent slime producer, whereas strain SP-2 has been reported to be nonadherent to smooth, inert surfaces a...

Patients with right hemisphere lesions may be impaired in mobilizing attention and in emotional behavior. If so, autonomic responses to the mobilization of attention should be blunted. This was found when we studied the anticipatory heart rate deceleration that is seen normally in the foreperiod of a warned reaction task.

No abstract

Serial measurements of estradiol (E2) and progesterone (P) were used to describe the ovarian cycle of the Bolivian squirrel monkey. Group-caged, sexually mature female squirrel monkeys, housed with males, were sampled daily between 0900 and 1100 hr. Sampling was carried out during the breeding and nonbreeding seasons, for periods of 19-20 days from September 1981 to May 1982. Seasonal differences in serum concentrations of E2 and P were found with low levels of E2 and P and an absence of preovulatory surges of E2 during the nonbreeding season. This pattern was also observed in some animals during the breeding season. An abrupt increase in serum P concentrations in December appeared to signal the onset of cycling.Cycling animals had well-defined peaks of E2 (450-9,500 pgiml) followed by increasing levels of P, which were > 200 ng/ml in some animals. After the breeding season, E2 and P levels returned to their initially lour levels.Levels of both steroids in cycling animals were higher than those reported for other primates and for previous measurements made in squirrel monkeys. Cycle length based on time interval between consecutive E2 peaks varied from 6-12 days.

No abstract

No abstract

No abstract

Sensory ratings, respiratory behavior and eye blink rate were recorded in 11 nonsmokers exposed to a no‐smoking (CONTROL) condition or to environmental tobacco smoke (ETS) from one of three kinds of cigarettes: a Kentucky reference (1R4F), an ultra‐low tar (ULT) and one that heats tobacco (TEST).For each two‐hour session in a controlled‐environment room, two smokers “puffed” unlit cigarettes, for the CONTROL condition, or smoked 16 cigarettes to generate ETS (sidestream plus exhaled mainstream smoke). Concentrations of nicotine and respirable suspended particles (RSP) observed with the 1R4F and ULT cigarettes were 10‐ to 20‐fold higher than those typically found in field sampling studies of office and restaurant smoking environments. The ULT and TEST cigarettes resulted in ETS analyte concentrations that were 77‐100% and O‐56%, respectively, of those observed with 1R4E Sensory ratings (odor, irritation, annoyance, acceptability) with the two tobacco‐burning cigarettes were similar and were much greater than those recorded for the TEST or CONTROL conditions which were, in turn, rated similarly. Respiratory parameters (respiratory rate, tidal volume, expiratory time), which generally failed to discriminate the TEST and CONTROL conditions, were altered during exposure to ETS from the 1R4F and, to a lesser extent, the ULT cigarette. Eye blink rate was not significantly altered by ETS from any of the cigarettes.