Multiresistance in Staphylococcus spp. blood isolates in Finland with special reference to the distribution of the mecA gene among the Staphylococcus epidermidis isolates. The Finnish Study Group for Antimicrobial Resistance.

A total of 570 Staphylococcus spp. blood isolates collected in Finland in 1991 were tested for susceptiblity to oxacillin and 19 additional antimicrobial agents. The Staphylococcus epidermidis isolates were also analyzed for the presence of the mecA gene by the polymerase chain reaction (PCR). Of the 238 S. epidermidis, 137 (58%) were in vitro identified as methicillin-resistant and 5 (2%) exhibited oxacillin MICs between 1 and 3 micrograms/ml. All these isolates were positive for the mecA gene in PCR as an indication of genetic resistance to methicillin, while none of the remaining 96 S. epidermidis isolates (oxacillin MICs < or = 0.25 microgram/ml) was positive. Multiresistance was observed in 123 (87%) of the 142 mecA-positive S. epidermidis. Of the 332 Staphylococcus aureus isolates, only one (0.3%) was phenotypically resistant to methicillin; the strain was also resistant to three other unrelated classes of antimicrobials. True methicillin resistance of this strain was manifested by the presence of the mecA gene in PCR. Based on these results, multiresistance was still extremely rate among the S. aureus in our country, whereas among the S. epidermidis as many as half of the blood isolates in central hospitals were multiresistant.

Testing of methicillin resistance by in vitro susceptibility and the presence of the mecA gene in clinical Staphylococcus aureus isolates in Finland.

A total of 140 epidemiologically unrelated Staphylococcus aureus strains collected in Finland between 1983 and 1994 were sent to the reference laboratory with verified or suspected methicillin resistance. These strains and 37 S. aureus strains previously identified as methicillin-susceptible were retested using 5 different susceptibility test methods including agar screening, disc diffusion, growth around methicillin (25 micrograms) test strips and minimal inhibitory concentration (MIC) determinations by an agar dilution method and E-test. The isolates were also analyzed for the presence of the mecA gene by the polymerase chain reaction (PCR). Based on in vitro susceptibility, 69 strains were identified as methicillin-resistant and were positive for the mecA gene in PCR, while 84 strains were methicillin-susceptible and negative for this gene. Susceptibility testing gave conflicting results for 24 (14%) strains. When the tests were repeated in triplicate for each isolate, discrepant results were still achieved with 18 of the 24 strains in at least 2 different tests. Thus, based on in vitro susceptibility, these strains could not be definitely classified as resistant or susceptible to methicillin. Yet 7 of them were positive for the mecA gene as an indication of genetic resistance to methicillin. Corroborating earlier studies, these results illustrate the difficulty of detecting methicillin resistance/susceptibility based only on susceptibility testing and underscore the importance of confirming methicillin resistance in S. aureus in specialized laboratories.

Saccade and blinking evoked by microstimulation of the posterior parietal association cortex of the monkey.

Electrical stimulation with microelectrodes of the posterior parietal association cortex in alert behaving monkeys elicited saccadic eye movements and blinking. The sites in which saccades were elicited by electrical stimulation were concentrated in the anteromedial part of area 7a, especially in the posterior bank of the intraparietal sulcus, in a region which sends efferent projections to the frontal eye field and the superior colliculus, but they were also found in the posterolateral part of area 7a. Compared with the frontal eye fields and the superior colliculus, the threshold current for eliciting saccades was relatively high, on the average 86 microA. Moreover, the elicitation of saccade was inconsistent even with suprathreshold stimulation and suppressed during visual fixation. Latencies of the saccades were relatively long, on the average 50ms; they were longer in the posterolateral part than in the anteromedial part. Direction and amplitude of evoked saccades depended on the site of stimulation, but was independent of eye position in most cases. However, "goal-directed" saccades which depended on initial eye position were elicited in three penetrations in the posterolateral part of area 7a. The threshold of mainly in the lateral part of area 7a. The threshold of blinking was 70 microA and the latency was 50 ms on the average. In contrast to saccades, blinking was elicited constantly with each stimulus even during attentive fixation. We occasionally recorded single unit activity at the site of stimulation with the same electrodes. More than half of the units recorded at the site of blinking responded to approaching visual stimulus.(ABSTRACT TRUNCATED AT 250 WORDS)

Higher functions and plasticity in visual pathways.

A summary of the visual pathways in the brain is presented as a basis for considering abnormalities in this system. The role of the cortical associative regions in visual function is briefly delineated. A short summary of experiments describing plastic properties of the visual pathways at early age is also presented, and experiments describing neural and behavioural changes after binocular deprivation are reviewed. It is concluded that early visual deprivation leads to a profound alteration of the associative systems of the brain and that in monkeys and humans these changes are difficult to remedy later. Therefore early detection and correction of visual abnormalities is very important as well as early compensation using other forms of sensory communication.

Early visual deprivation alters modality of neuronal responses in area 19 of monkey cortex.

Monkeys deprived on vision during the first year of life by lid suture appear functionally blind after the opening of the eyes, but move actively in familiar surroundings using somesthetic cues. Microelectrode recordings of multiple unit activity in the associative visual cortical area 19 of deprived monkeys indicated that 20% of the neuron groups studies responded only during active somatic exploration. In normal animals all neuron groups studied responses exclusively to visual stimuli, but in the deprived animals only 40% of them did. Visual deprivation alters the synaptic pathways to visual associative cortex enhancing the efficiency of those inputs that can mediate somatic information to this region.

Determinants of sexual behavior of Macaca arctoides in a laboratory colony.

Copulatory behavior of wild-born individually caged laboratory stumptail monkeys (Macaca arctoides) was investigated. The monkeys were paired daily for 20 min, and altogether 536 pairings were observed. The influence of the female's menstrual cycle and social factors of male sexual activity was determined. The reactions of the other monkeys during a pairing, and masturbation behavior of the males were observed and described. It was found that when a male and female were paired daily their sexual activity remained on a rather constant and high level for months provided the pair could not see, touch, or smell each other between pairings. In these conditions the most common copulatory behavior consisted of 3-4 ejaculations. When the couple lived continuously in adjacent cages, which allowed them visual, tactual, and olfactory communication between pairings, the male ejaculated, on the average, only once during five successive pairings. Thus separation and reunion was potent in triggering sexual activity. When the couple was visually separated between sessions the male's sexual activity did not depend on the menstrual cycle of the female. The males initiated copulation and the females were always willing, except in later stages of pregnancy, to cooperate. All males masturbated to ejaculation and it was often triggered by copulation, masturbation, or any happening causing arousal in the colony. The females were never seen to masturbate outside of the heterosexual context.

Regional distribution of functions in parietal association area 7 of the monkey.

The functions of cells in different parts of area 7 were studied in 5 hemispheres of three stumptail macaques (Macaca speciosa). Activity of groups of cells was recorded in non-anesthetized animals using course microelectrodes. Functional maps covering the exposed part of area 7 showed that purely visual and oculomotor responses occurred in area 7a (PG) whereas the skin was dominantly represented in area 7b (PF). Vision was also represented in 7b but here together with somatic mechanisms. Oculomotor discharges were concentrated in the medial part of area 7a, whereas motor action of the arm and hand extended across the medial part of area 7. Motor actions of the mouth were represented most laterally. A statistically significant somatotopic arrangement of the body surface was also observed: the face was represented most laterally and the body and legs most medially with large overlapping regions. In the posterior part of 7a a kinesthetic region was found with representation of joints and muscles. The combination of visual and cutaneous activation was common more laterally than the combination of visual and somatomotor activation. Laterally the visual representation ended at the border between area 7 and area 2 of S I at a locus in front of which the S I receptive fields were located inside the mouth. These results indicate that different functions are represented in different degrees in different parts of area 7. Therefore, one important determinant of the results obtained by various research groups is the area of recording within area 7.

Functional properties of neurons in the temporo-parietal association cortex of awake monkey.

The temporo-parietal association cortex around the caudal end of the Sylvian fissure was studied with the single cell recording technique in three awake behaving Macaca speciosa-monkeys. Of the 197 cells isolated, 5% were active only during the monkey's own movements, mostly during head rotation, and 95% were responsive to sensory stimulation: 54% to auditory stimuli, 24% to somatosensory stimuli, 13% to both of these and 4% to visual stimuli. Some cells, classified as responsive to somatosensory stimuli, were activated only by passive rotation of the head on the cervical axis; it is possible that they were driven by vestibular stimuli. Half of the cells were activated by stimuli on both sides of the monkey, and almost all the rest, only by stimuli on the side contralateral to the hemisphere recorded. Of the acoustically drivable cells, 95% responded to natural sounds, such as, rubbing hands together, rustle of clothes, clicks or jingles (sounds with noise spectrum and rapid intensity transitions). Most of these neurons were also examined with pure tones of 0.2-20 kHz: various inhibitory or excitatory responses were elicited in half of them, usually over a wide range of frequencies. The responses of most acoustically drivable cells (62%) depended on the location of the sound source with reference to the monkey's head so that the maximal response was elicited by sounds with a certain angle of incidence, usually on the contralateral side. The present results suggest that the area studied participates in the analysis of the temporal pattern of a sound, the location of the sound source and in spatial control of head movements.

Comparison of effects of pentobarbital and ethanol on the neuronal activity in the posterior parietal association cortex.

The problem of this study was whether the effects produced by alcohol in the posterior parietal association cortex are specific to this drug or shared by other centrally acting depressant drugs such as barbiturates. The effect of graded doses of pentobarbital on multineuronal impulse activity was recorded with transdural microelectrode technique in 30 expts. in Brodmann's area 7 of five stump-tailed monkeys (Macaca speciosa). The results were compared with those from 32 expts. performed with alcohol and published separately. The dosage of the two drugs was determined on the basis of the monkeys' sensori-motor coordination which was assessed with a rating scale of reaching accuracy for food rewards. There were several recording sites where the actions of the two drugs were similar at similar behavioural levels of intoxication. However, in the distribution of effects among various functional types of recording sites a significant difference was found between pentobarbital and alcohol. Alcohol commonly diminished cellular activity related to motor behaviour (reaching, grasping) and only rarely responses to somesthetic stimuli, whereas the effects of pentobarbital were the opposite being most common on somatosensory responses and least common on activity related to motor behaviour. Also responses to visual stimuli were more sensitive to pentobarbital than to alcohol. The actions of pentobarbital and alcohol on responses evoked by sensory stimulation differed significantly (P less than 0.01). We conclude that significant differences exist in the mechanisms of action of alcohol and barbiturate on the associative systems of the brain.

Blindness and modification of association cortex by early binocular deprivation in monkeys.

Cells in the parietal association area of stumptail monkeys did not respond to visual stimuli after binocular early deprivation. Although the monkeys responded to stimuli in the visual cortex, behaviourally they were blind. The importance of encouraging babies and infants to use all residual vision is stressed, so that the representation of visual input in the brain does not become permanently overtaken by other modalities.

Effect of air ionization on heart rate and perceived exertion during a bicycle exercise test. A double-blind cross-over study.

The influence of ionization of air on heart rate (HR) and ratings of perceived exertion (RPE) during bicycle exercise was studied in nine healthy medical students selected according to a randomized schedule from the class of 90 students. The exercise tests were performed both under negative and positive ionization. The study was made with a double-blind, cross-over design. The body surface exposed to ionic current was made large by reducing the clothing of the subject. A significant overall tendency to lower HR and RPE values under negative ionization was observed (p less than 0.01, sign tests). The RPE values were significantly lower (p less than 0.01, paired t-test and the Wilcoxon test) under negative than under positive ionization at the maximal work load level but not at other relative load levels. However, when separately tested at each relative load level HR values did not differ significantly in negative and positive ionization. The results of this pilot study indicate that ionic composition of the air can modify the RPE and possibly also HR during exercise; negative air ionization seems to be beneficial compared with positive ionization. The mechanisms involved are obscure, but we suggest that negative ionization of air may increase oxidative metabolism through generation of a superoxide radical (O2-) that is reduced to H2O2 by superoxide dismutases.