Surface roughness enhances upward migration of bacteria on polymer fibers above liquid cultures.

Monofilament polypropylene (PP) fibers, very similar to fibers that have been used as monofilament tailstrings of interuterine contraceptive devices, were suspended vertically in bacterial liquid monocultures so that a portion of a fiber extended above the liquid surface. In some cases these highly oriented, cold drawn fibers were abraded prior to insertion in the cultures in order to produce surface roughness characterized by axial channels and protruding microfibrils that partially peeled from the fiber surface thereby forming the channels. Extent of migration on a fiber was assessed by aseptically cutting it into small segments, followed by culturing each segment on agar containing growth medium. Such assessment of the PP fibers after 48 h of incubation in the cultures revealed upward migration of Eschericia coli, Pseudomonas aeruginosa, and Staphylococcus aureus over significantly longer distances on the pre-roughened fibers than on those not so pre-treated. Mean measured distances of migration during 48 h were: for E. coli 2.7+/-0.6 mm on roughened fibers (n = 16) and 0.4+/-0.7 mm on fibers not roughened (n = 17); for S. aureus 9.0+/-4.3 mm on roughened fibers (n = 13) and 0.2+/-0.3 mm on fibers not roughened (n = 14); for P. aeruginosa 8.5+/-3.7 mm on roughened fibers (n = 26) and 0.2+/-0.5 mm on fibers not roughened (n = 5). Although no statistically significant (95% confidence level) difference could be discerned between the migration distances of S. aureus and P. aeruginosa, each of these species migrated a greater distance on the PP than did E. coli. The migrations observed are attributed predominantly to wicking of the liquid cultures upward in the axial grooves developed on the surface of the PP by the eruption and peeling of microfibrils from the surface. Surface tension of the growth medium was significantly lower than that of water and its contact angle on PP was less than 90 deg, thereby indicating a tendency to wet the PP. Bacterial growth in the medium further reduced its contact angle on PP, thereby indicating an even greater tendency to wet PP after such growth.

Comparative behavior of E. coli and S. aureus regarding attachment to and removal from a polymeric surface.

Staphylococcus aureus was found to attach more readily on polypropylene fibers with greater resistance to subsequent washing off than Escherichia coli after immersion of the fibers up to 300 s in pure culture suspensions in mineral salts medium. Each of five different washing solutions were effective against E. coli, whereas only a solution that contained SDS was effective against S. aureus. Placement of inoculated fibers on nutrient agar for longer periods of time resulted in greater resistance to washing by both organisms, although S. aureus remained more resistant than E. coli.

Novel technology for the preparation of sterile alginate-poly-l-lysine microcapsules in a bioreactor.

The purpose of this study was to develop a method that may be suitable for the commercial manufacture of sterile alginate-polylysine-alginate microcapsules in a bioreactor. A Turbotak atomizing device in conjunction with a Bellco Bioreactor was used to prepare sterile microcapsules. Aseptic procedures were followed using sterilized equipment and materials. Sodium alginate solution was sprayed into calcium chloride solution using the Turbotak, with nitrogen as the atomizing gas. The resultant gelled alginate microcapsules were coated with polylysine and alginate to produce alginate-poly-l-lysine microcapsules. In-process contamination of the atomizing gas and microcapsules was investigated using modified USP sterility tests. Microcapsule size was determined using a light blockage technique (Accusizer) which measures both number and volume weighted mean diameters. The microcapsules prepared passed a modified USP sterility test, and the Bellco Bioreactor was found to minimize the possibilities of environmental contamination and therefore enhanced operator safety. The flow rate of the atomizing gas was determined to significantly alter number and volume weighted mean microcapsule diameters. Statistical analysis indicated that the number weighted mean diameters in conjunction with the volume weighted mean diameters can be used to detect batch-to-batch changes in microcapsule diameters. In conclusion, the modified Bellco Bioreactor offers a novel approach for producing sterile alginate-polylysine microcapsules on a laboratory scale.

Abnormal responses to cold stress in Charcot-Marie-Tooth I syndrome.

In Charcot-Marie-Tooth syndrome (CMT, Hereditary Motor Sensory Neuropathy), patient complaints of cold intolerance are common but their peripheral responses to cold have not been documented. Using digital plethysmography, a simple test of vascular reactivity with 1 minute cold stress, 20 unrelated adult CMT patients showed a significantly increased average heart rate and decreased average arterial oxygen saturation following cold when compared to 50 age-matched normal controls. There did not appear to be a unique or characteristic CMT vascular reaction to cold stress in CMT patients because their abnormal peripheral vascular responses were variable. Variability in CMT neuropathic responses to cold is consistent with the known irregular segmental demyelination of CMT peripheral nerves as well as abnormal CMT sweating patterns. Though understanding the precise patterns of CMT patient peripheral nerve disturbances remains difficult, awareness of CMT patient's abnormal responses to cold may facilitate CMT patient care and rehabilitation.

Migration of bacteria along synthetic polymeric fibers.

E. coli, S. epidermidis, and B. distasonis were observed to migrate readily along polymer fibers impressed upon the surface of nutrient agar. E. coli was also observed to migrate readily along polymer fibers embedded in brain-heart infusion agar. Within periods of about 24 h, migration distances of about several centimeters were observed. No migration was observed in control experiments conducted on or in the same media, but without fibers. Migration speed was greatest for E. coli and slowest for B. distasonis. Cell population density was found to decrease rapidly with distance from a source culture. Swimming motility or natural convection in liquid between fiber and gel appears to be improbable based on the expected dimensions of capillary-condensed liquid between fiber and gel.

Polypropylene IUCD retrieval fibers: surface morphology, material properties, microbial attachment, and migration.

Highly drawn and oriented polypropylene fibers used for the retrieval thread of the Cu-7 intrauterine contraceptive device (IUCD) are compared as to surface morphology and crystallinity with polypropylene fibers prepared under different conditions. A series of experiments also demonstrates the colonization of the surface of polyolefin fibers by pathogenic bacteria that are often found in the human vagina. Moreover, it is demonstrated that the retrieval threads appear to encourage pathogenic bacteria to migrate across the surface of agar. The results also indicate that control of drawing and annealing can avoid the surface fibrillation and tendency to fail by separation into a bundle of multifilaments that are observed with the IUCD retrieval threads.

Electrocorticographical observation of seizures induced by pentylenetetrazol (PTZ) injection in rats.

The various seizure responses observed behaviorally in freely moving rats after repeated pentylenetetrazol (PTZ) injections were compared with simultaneous electrocorticographical (ECoG) recordings. Seizures induced were divided into 7 behavioral categories (grade 0-6): grade 0, no behavioral seizures; grade 1, head nodding, head twitching; grade 2, myoclonic jerks; grade 3, head twisting, forelimb clonic convulsions; grade 4, kangaroo position; grade 5, falling down; grade 6, tonic convulsions. Specific behavioral seizure types were always associated with identifiable ECoG patterns. All rats which exhibited higher than grade 3 seizures developed decrease in spontaneous movements and decreased amplitude in ECoG activity after the end of their behavioral seizures, which suggests the existence of post-ictal inhibition. Both myoclonic jerks (grade 2) and tonic convulsions (grade 6) are important features of these seizure types which are not seen in electrical amygdaloid seizure models. This seizure classification will be useful for further rat PTZ seizure studies.

Cerebral electrical potentials evoked by balloon distention of the human esophagus.

UNLABELLED: Cerebral evoked potentials provide a technique for evaluation of central nervous processing of information derived from a variety of sensory modalities. Evoked potentials associated with balloon distention of the smooth muscle esophagus were studied in 14 adult volunteers. Stimulation was applied via repeated inflation and deflation of a balloon attached to a pressure pump that cycled at 0.2 Hz. Cortical electrical responses were recorded from scalp electrodes at Cz, Cz', and Pz of the international 10-20 System for electroencephalographic recording. The recording electrodes were referenced to Fpz and averaged over a 1-s period for 100 repetitions. Latencies, amplitudes, and waveforms of the evoked potentials were compared with controls consisting of pump on/balloon detached, auditory masking, and conventional somatosensory posterior tibial nerve stimulation. Polyphasic evoked potentials were obtained in all subjects, and maximum positive deflections occurring with latencies of 202-396 ms. Maximal amplitudes ranged from 2.5-8.3 microV. Latencies and amplitudes of the evoked responses were highly reproducible in each subject with considerable variation among subjects. CONCLUSIONS: (a) Reproducible evoked potentials with distinctive waveforms can be recorded in response to esophageal balloon distention in humans; (2) long latency of the evoked potentials suggests involvement of nonmyelinated visceral afferent pathways; (3) the evoked potentials are probably specific to mechanical stimulation rather than being nonspecific arousal responses; and (4) the results support this as a promising new method for investigation of the neurobiology of gastrointestinal sensation in humans that may help clarify pathological conditions of the irritable esophagus syndrome and esophagus-related chest pain.

Electromyography: its potential as an adjunct to other monitored parameters during conscious sedation in children receiving dental treatment.

The purpose of this study was to evaluate the effect of a combination of a low dose of chloral hydrate and hydroxyzine on the frontalis muscle electromyogram in addition to other physiologic parameters in pediatric dental patients. A double blind, two-appointment cross-over design was used. Either a placebo or a combination of chloral hydrate and hydroxyzine was given to children during the first visit with the sequence of placebo/drug conditions being randomly determined. During the second visit, the children received that agent not given during the first visit. Baseline physiologic data was obtained at the beginning of each visit and the physiologic measures were again recorded during topical and local anesthesia administration, high-speed tooth preparation, and at the end of the dental appointment. The results indicated that the frontalis muscle activity and cardiovascular parameters were significantly affected by the drug and dental procedures. Oxygen saturation was least affected. The frontalis muscle appears to be a sensitive physiologic parameter to monitor during conscious sedation as an index of the amount of patient relaxation.