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PubMed1986

The bone marrow histological pattern has independent prognostic value in early stage chronic lymphocytic leukaemia.

The initial diagnostic bone marrow specimens from 90 consecutive, untreated patients with chronic lymphocytic leukaemia were examined for the pattern of lymphocytic infiltration in relation to clinical stage (International Workshop System) and survival. Three non-diffuse (interstitial, nodular, mixed nodular-interstitial) and one diffuse pattern were recognized. Generally, the bone marrow patterns correlated well with clinical stage: a non-diffuse pattern prevailed in early, and a diffuse pattern in later stages. However, with a Cox analysis of the covariate effect of clinical stage and bone marrow pattern on survival, the bone marrow pattern was shown to have independent prognostic significance in the early stage A in which a diffuse pattern carried a fourfold increase in death rate as compared to a non-diffuse pattern. These high risk patients could not be identified by the Rai substages of the International Workshop System.

Aged↗
PubMed1997

Interchangeable discharge patterns of neurons in caudal nucleus tractus solitarii in rat slices: role of GABA and NMDA.

1. We characterized in rat brain slices the discharge patterns of spontaneously active neurons in the caudal region of the nucleus tractus solitarii (cNTS) and the neuromodulatory role of GABA and glutamate, via GABAA and NMDA receptors. 2. Spontaneous action potentials recorded intracellularly from cNTS neurons manifested either a regular or an irregular discharge pattern, alongside characteristic waveforms of the action potentials. These discharge patterns were interchangeable, and were highly sensitive to fluctuations in membrane potentials. In addition, the repolarizing rate of the after-hyperpolarization (AHP) in cNTS neurons that exhibited a regular discharge pattern was significantly higher than that of neurons that displayed irregular discharges. 3. cNTS neurons that manifested a regular discharge pattern were converted to irregular discharges upon superfusion with GABA (200 microM). This was accompanied by a reduction in the repolarizing rate of the AHP of both spontaneous and evoked action potentials. Conversion of discharge patterns in the opposite direction was elicited by superfusion with NMDA (6.8 microM). 4. The irregular discharges of spontaneous or evoked cNTS neurons were converted to a regular discharge pattern by bicuculline (200 microM). Subsequent application of D(-)-2-amino-5-phosphonopentanoic acid (250 microM) essentially led the neuronal discharges to revert to an irregular pattern. 5. Our results support the presence of two interchangeable modes of electrophysiological manifestations from the same cNTS neuronal population. They also showed that GABA and glutamate, via GABAA and NMDA receptors, may provide a novel form of neuromodulation at the cNTS by switching the patterns of neuronal discharges.

Animals↗
PubMed2006

Visual stimuli are common triggers of migraine and are associated with pattern glare.

OBJECTIVE: To investigate the associations between interictal pattern glare, visual stress, and visual triggers of migraine. BACKGROUND: There has been relatively little research on the visual stimuli that can trigger migraine episodes. This is surprising, since if practitioners can obviate such triggers, then some attacks may be prevented. The existing literature suggests that patients who are prone to visually triggered migraines report more illusions on viewing striped patterns ("pattern glare") and that colored filters may be an effective intervention for these people. METHODS: Headache symptoms and headache triggers were investigated in migraine and control groups in 2 separate experiments. In one experiment, we also determined, for each participant, pattern glare, whether it was reduced by colored filters and, if so, what the optimum color of filter was. Color vision was also assessed with the D15 test. RESULTS: People with migraine saw significantly more illusions on viewing each striped pattern and experienced greater pattern glare. They were also more likely to select a colored filter to aid visual comfort, particularly colors in the blue-to-green sector of the spectrum. Color vision was impaired subtly but significantly in migraine. Principal component analyses grouped common headache triggers into 5 broadly equal components: food, visual triggers, alcohol, stress and tiredness, and the environment. In a second analysis, the overall number of illusions seen in striped patterns was associated with visual triggers while pattern glare, use of colored filters, and interictal light sensitivity together formed a sixth component interpreted as visual stress. CONCLUSIONS: It is suggested that clinicians should ask migraine patients whether visual stimuli trigger their migraine, about interictal visual symptoms, and use the pattern glare test to ensure that those who may benefit from optometric interventions are appropriately managed.

Acute Disease↗
PubMed1996

Accuracy of wax, autopolymerized, and light-polymerized resin pattern materials.

PURPOSE: The marginal fit of MOD inlay and full-crown patterns fabricated from wax, autopolymerized acrylic resin, and two light-polymerized, diacrylate resin pattern materials was compared on standardized dies. MATERIALS AND METHODS: Four pattern materials were studied-two light-polymerized, diacrylate resin materials (Palavit G LC and Triad VLC Burnout Paste), an inlay wax, and an autopolymerized resin (Duralay). Patterns were fabricated using incremental and bulk techniques on stone dies made from addition silicone impressions of American Dental Association MOD and full-crown master dies. Gaps were measured with a measuring microscope in four marginal areas on the master dies at 1 and 24 hours after fabrication. RESULTS: For the MOD inlay patterns, marginal gaps ranged from 7 to 23 microns, and the light-polymerized, diacrylate resins and autopolymerized acrylic resin material had statistically smaller gaps than the inlay wax. For the full-crown patterns, marginal gaps ranged from 10 to 23 microns, with the exception of the autopolymerized acrylic resin prepared by the bulk technique (40 to 46 microns). With the incremental technique, the light-polymerized, diacrylate resins and inlay wax had statistically smaller gaps than the autopolymerized acrylic resin material. Overall, the incremental technique produced equal or smaller marginal gaps than the bulk technique for full-crown patterns. Generally, the patterns measured at 1 hour had smaller marginal gaps than at 24 hours. CONCLUSIONS: When measured on intra- and extracoronal master dies, the light-polymerized, diacrylate resins had equal or better marginal fit, compared with wax or autopolymerized acrylic resin, and were less affected by placement technique and storage. The marginal gaps of all four pattern materials ranged from 7 to 46 microns and are within the range of clinical acceptability.

Acrylic Resins↗
PubMedDate not supplied

Comparison of two laparoscopic suture patterns for repair of experimentally ruptured urinary bladders in normal neonatal calves.

OBJECTIVE: To compare 2 laparoscopic suture patterns for repair of experimentally ruptured urinary bladders in normal neonatal calves. STUDY DESIGN: Experimental surgical study. ANIMALS: Thirty male Holstein calves. METHODS: A bladder defect was created in 24 anesthetized calves (day 0). They were randomly divided into 4 groups (n=6/group). In groups 1 and 3, the defect was closed laparoscopically using a one layer full thickness simple continuous (FTSC) suture pattern (pattern A). In groups 2 and 4, the defect was closed laparoscopically in 2 layers using a FTSC suture pattern followed by Lembert continuous suture pattern (pattern B). Groups 1 and 2 calves were euthanatized at the end of the surgery and groups 3 and 4 at day 10. Six healthy calves were also euthanatized and used as a control group. The bladders were harvested and tested for bursting strength (BS). The surgical time (ST) data from the two groups for each pattern were pooled. A Student t-test was used to compare ST data. For the BS data, a 2-factor ANOVA test with post-hoc Student t-test was used to determine if treatment, time, or treatment-time interaction was significant. A Dunnett's test was used to compare BS of the 4 treatment groups to the control group. P<.05 was considered significant. RESULTS: Mean ST was significantly shorter for pattern A than for pattern B. In all treatment groups, the mean bladder BS (MBBS) was significantly lower than the MBBS for the control group. The MBBS was significantly lower for group 1 than for group 2. There was no significant difference in the MBBS between groups 3 and 4. CONCLUSION: In this study, a 1-layer laparoscopic closure technique had advantages compared with 2-layer laparoscopic closure technique. Further work is required before a 1-layer laparoscopic closure technique can be recommended clinically. CLINICAL RELEVANCE: One-layer bladder closure is fast and safe in clinically normal calves and permits additional research to evaluate its safety in foals and clinical ruptures.

Animals↗
PubMed2006

Pullout strength for three suture patterns used for canine tracheal anastomosis.

OBJECTIVE: To compare pullout strength of 3 suture patterns used for canine tracheal anastomosis. STUDY DESIGN: Experimental study. SAMPLE POPULATION: Cadaveric canine tracheae (n = 20). METHOD: Tracheal segments were anastomosed with 1 of 3 suture patterns: simple continuous, simple interrupted, and simple interrupted reinforced with horizontal mattress, each encircling annular cartilage rings adjacent to the transection site. Horizontal mattress sutures encircled the annular rings proximal and distal to the rings closest to the anastomosis. Each construct was distracted (0.5 mm/s) in a materials testing machine to failure. Load-displacement curves were generated and failure load (pullout strength) determined and mode of failure recorded. RESULTS: Tracheal anastomosis with a simple interrupted pattern was significantly weaker (mean+/-SD pullout strength, 102.55+/-30.14 N) than simple continuous (135.53+/-15.47 N) or simple interrupted plus horizontal mattress (132.39+/-21.46 N), which were not different from each other. Mode of failure was consistently by suture tear out. CONCLUSIONS: Both simple continuous and simple interrupted reinforced with horizontal mattress suture patterns have significant biomechanical advantage over a simple interrupted pattern alone in canine cadaveric tracheal anastomosis. The simple continuous pattern had the least variability in pullout strength. CLINICAL RELEVANCE: A simple continuous technique should be considered when selecting a tension-relieving pattern for canine tracheal anastomosis. It offers the same biomechanical advantage as a simple interrupted pattern reinforced with a horizontal mattress pattern and its strength appears to be reliably maintained when tested in canine cadaver tracheae.

Anastomosis, Surgical↗
PubMed1986

Patterns of alcohol and drug abuse in drug treatment clients from different ethnic backgrounds.

In this paper we have sought to identify differences in alcohol consumption patterns and problems among young adult males from white, black, and Hispanic ethnic groups entering drug treatment programs. In overall consumption patterns we found results similar to those obtained in general population studies. However, about one-third of the clients in all ethnic groups could be classified as heavier drinkers (drinking at least once a week and 4 or more drinks per drinking occasion) in the period immediately prior to treatment. About one-fourth of the clients in each ethnic group consumed a daily average of 2.5 ounces of absolute alcohol. Compared with the other ethnic groups, blacks were the most likely to be abstainers and reported regular alcohol use and drunkenness at later ages. Regardless of the pattern of development, similar proportions of the clients in all ethnic groups reported heavier drinking levels by age 21-30. Consistent with the current hypotheses in the literature, whites reported much higher levels of alcohol-related problems and prior treatment. Despite having similar levels of drinking, black and Hispanic ethnic groups did not appear to recognize alcohol as a problem or to report alcohol-related problems to the extent that whites did. Examination of drug-use patterns showed great variation in the nature and extent of drug use among the three ethnic groups. Whites were distributed among the seven patterns of use. Heroin use with cocaine, marijuana, and alcohol was the predominant pattern for blacks and Hispanics. Although the patterns of drug use differed greatly, these patterns were not differentially related to alcohol consumption or alcohol-related problems within ethnic groups. On the contrary, the drug-use patterns appeared to be a stronger predictor than ethnicity of use and problems. Multiple-nonnarcotic-users reported the highest levels of alcohol consumption and the greatest numbers of alcohol-related problems. This group typically reported the highest number of alcohol-related problems. Expression of a current need for treatment and a history of prior alcohol treatment were highest for black multiple-nonnarcotic-users. Our examination of the influences of family and friends was based on a limited number of questions available in the data. Heavier drinking was reported by clients who lived with friends, had family or friends who drank regularly, or had extensive involvement in the drug-use network, including drug sales. No ethnic differences were found.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1995

Changes in breathing pattern in the normal horse at rest up to age one year.

Changes in pattern of airflow, sequence of respiratory muscle activation and generated pressures were measured serially in a group of foals during the first year post partum, in order to describe the maturation of the equine breathing pattern. In neonatal foals, inspiration and expiration were both primarily active and airflow pattern was essentially monophasic. By age 1 year, foals displayed essentially the same breathing pattern previously described in adult horses, utilising a combination of active and passive inspiration and expiration to breathe around, rather than from, the relaxation volume of the respiratory system (Vrx). A strong temporal relationship during growth was found between the timing of changes observed in airflow pattern and in the neuromuscular strategy of breathing. The transition to the adult breathing pattern appeared to involve a time delay in activation of both inspiratory and expiratory muscle groups, establishing a passive and active component to both inspiration and expiration. Throughout the study period, concurrent with the increase in delay of abdominal muscle activation, the expiratory flow pattern became progressively more biphasic in appearance. The time of appearance of a consistent biphasic inspiratory flow pattern was considerably later, at approximately age 1 year and coincided with the appearance of a delay in inspiratory muscle activation. From our results, we conclude that the transition from the neonatal to the adult breathing strategy in the horse appears not to be induced by the time course of chest wall stiffening during maturation. While changes in relative body proportions and size of abdominal contents during growth may influence the transition in breathing, our results also indicate that respiratory control mechanisms play an essential role in the expression of the polyphasic breathing pattern.

Aging↗
PubMed2004

Effect of time of day and rabbit strain on patterns of aortic wall permeability.

Lipid deposits occur more frequently downstream of branch points than upstream in immature rabbit and human aortas but the opposite pattern is seen in mature vessels. These distributions correlate spatially with age-related patterns of aortic permeability, observed in rabbits, and may be determined by them. The mature but not the immature pattern of permeability is dependent on endogenous nitric oxide synthesis. Although the transport patterns have hitherto seemed robust, recent studies have given the upstream pattern in some mature rabbits but the downstream pattern in others. Here we show that transport in mature rabbits is significantly skewed to the downstream pattern in the afternoon compared with the morning (P < 0.05), and switches from a downstream to an upstream pattern at around 21 months in rabbits of the Murex strain, but at twice this age in Highgate rabbits (P < 0.001). The effect of time of day was not explained by changes in nitric oxide production, assessed from plasma levels of nitrate and nitrate, nor did it correlate with conduit artery tone, assessed from the shape of the peripheral pulse wave. The effect of strain could not be explained by variation in nitric oxide production nor by differences in wall structure. The effects of time of day and rabbit strain on permeability patterns explain recent discrepancies, provide a useful tool for investigating underlying mechanisms and may have implications for human disease.

Age Factors↗
PubMed2001

Effects of consonant environment on vowel formant patterns.

A significant body of evidence has accumulated indicating that vowel identification is influenced by spectral change patterns. For example, a large-scale study of vowel formant patterns showed substantial improvements in category separability when a pattern classifier was trained on multiple samples of the formant pattern rather than a single sample at steady state [J. Hillenbrand et al., J. Acoust. Soc. Am. 97, 3099-3111 (1995)]. However, in the earlier study all utterances were recorded in a constant /hVd/ environment. The main purpose of the present study was to determine whether a close relationship between vowel identity and spectral change patterns is maintained when the consonant environment is allowed to vary. Recordings were made of six men and six women producing eight vowels (see text) in isolation and in CVC syllables. The CVC utterances consisted of all combinations of seven initial consonants (/h,b,d,g,p,t,k/) and six final consonants (/b,d,g,p,t,k/). Formant frequencies for F1-F3 were measured every 5 ms during the vowel using an interactive editing tool. Results showed highly significant effects of phonetic environment. As with an earlier study of this type, particularly large shifts in formant patterns were seen for rounded vowels in alveolar environments [K. Stevens and A. House, J. Speech Hear. Res. 6, 111-128 (1963)]. Despite these context effects, substantial improvements in category separability were observed when a pattern classifier incorporated spectral change information. Modeling work showed that many aspects of listener behavior could be accounted for by a fairly simple pattern classifier incorporating F0, duration, and two discrete samples of the formant pattern.

Adult↗
PubMed2003

The role of contrasting temporal amplitude patterns in the perception of speech.

Despite a lack of traditional speech features, novel sentences restricted to a narrow spectral slit can retain nearly perfect intelligibility [R. M. Warren et al., Percept. Psychophys. 57, 175-182 (1995)]. The current study employed 514 listeners to elucidate the cues allowing this high intelligibility, and to examine generally the use of narrow-band temporal speech patterns. When 1/3-octave sentences were processed to preserve the overall temporal pattern of amplitude fluctuation, but eliminate contrasting amplitude patterns within the band, sentence intelligibility dropped from values near 100% to values near zero (experiment 1). However, when a 1/3-octave speech band was partitioned to create a contrasting pair of independently amplitude-modulated 1/6-octave patterns, some intelligibility was restored (experiment 2). An additional experiment (3) showed that temporal patterns can also be integrated across wide frequency separations, or across the two ears. Despite the linguistic content of single temporal patterns, open-set intelligibility does not occur. Instead, a contrast between at least two temporal patterns is required for the comprehension of novel sentences and their component words. These contrasting patterns can reside together within a narrow range of frequencies, or they can be integrated across frequencies or ears. This view of speech perception, in which across-frequency changes in energy are seen as systematic changes in the temporal fluctuation patterns at two or more fixed loci, is more in line with the physiological encoding of complex signals.

Adolescent↗
PubMed1990

Neural responses to auditory temporal patterns.

Sets of regularly repeating auditory stimuli elicit unique perceptions; listeners are able to identify specific temporal patterns. Some temporal patterns are unambiguous (only one pattern can be perceived), while others are ambiguous (numerous patterns can be detected). While the psychophysical properties of such percepts have been well studied, little is known about the underlying neurological bases of temporal pattern perception. In this experiment, the role of adaptation in temporal pattern perception is examined by studying neural responses in four cats to a temporal pattern that is perceptually unambiguous and one that is perceptually ambiguous. Measurements were made of the whole-nerve action potential, the auditory brainstem response, and potentials from the surface of the primary auditory cortex. The adaptation patterns corresponded with the perceptual organization of temporal patterns in humans at all levels of the nervous system studied.

Animals↗
PubMed1993

A model of auditory pattern analysis based on component-relative-entropy.

Recently results from detection and information theory have been used to predict performance of human observers in experiments involving the discriminability of changes in individual components of unfamiliar or uncertain tone patterns [R. A. Lutfi, J. Acoust. Soc. Am. 91, 3391-3401 (1992)]. In this paper, the theoretical analysis is expanded to yield a general rule of pattern analysis that accounts for nearly all of the major results of such experiments conducted over the last 18 years. The rule can be stated as follows: Component discriminability in an unfamiliar tone pattern (profile or sequence) is a linearly increasing function of the component's relative entropy (CoRE) in the pattern. Ancillary: The threshold for detection of a change decreases by one order of magnitude (factor of 10) for each one bit increase in CoRE. This precise relation of threshold to CoRE is demonstrated repeatedly in a review of past studies, and is shown to account for the relative effects of a variety of important variables and their interactions. Such variables include the total duration of the pattern; the number of tones in the pattern; the number of tones subject to change; the relative level and duration of individual tones in the pattern; the relative variability and the physical dimension of the tones' parameters that are subject to change; the number and position of targets in the pattern; the psychophysical procedure used (method of adjustment versus same-different), the type of discrimination task (frequency versus intensity discrimination), and the manner of presentation of the tones (simultaneous or sequential). The CoRE rule seems to reflect a general property of auditory analysis wherein the perception of patterns in an ensemble is dominated by those features that dominate the variance of the ensemble.

Auditory Perception↗
PubMed1999

Spontaneous and intentional pattern switching in a multisegmental bimanual coordination task.

Two experiments required right-handed subjects to trace circular trajectories while complying with either a symmetric or asymmetric pattern. In symmetric patterns, circles were traced in a mirror image either inward or outward. In asymmetric patterns, circles were traced in the same direction either clockwise or counterclockwise. Subjects were instructed to trace with spatial accuracy while maintaining a strict temporal relationship to a metronome that scaled movement rates from 1.25 to 3 Hz. The symmetric patterns were more stable than asymmetric patterns; the circularity of trajectories was greater for the dominant side; and there were spontaneous reversals in the direction of circling in the nondominant limb when performing asymmetric patterns. The second experiment examined the same subjects under the instruction of intentionally changing the pattern by reversing the left or right limb circling direction when cued to do so. The degree of interlimb interference was highly asymmetric and contingent on the direction of pattern change. Intentional direction reversals were more expedient and with less disruption to the contralateral limb when asymmetric to symmetric pattern changes were effected through a reversal in the direction of nondominant side. The results are interpreted with reference to evidence that the supplementary motor area mediates descending input to the upper limbs during disparate bimanual actions, but not during symmetric actions.

Adult↗
PubMed1999

Stability of Mycobacterium tuberculosis IS6110 restriction fragment length polymorphism patterns and spoligotypes determined by analyzing serial isolates from patients with drug-resistant tuberculosis.

The stability of Mycobacterium tuberculosis IS6110 fingerprint patterns and spoligotypes has been assessed by analyzing serial isolates from patients with drug-resistant tuberculosis. Altogether, 165 M. tuberculosis isolates obtained from 56 patients have been analyzed. The time spans between the first and the last or a changed isolate from one patient ranged from 1 to 772 days. Among the 56 patients, 5 (9%) were infected with isolates with changes in their IS6110 fingerprint patterns. According to the total number of strains analyzed, 5% of the subsequent isolates showed variations in their IS6110 restriction fragment length polymorphism patterns compared to the pattern of the first isolates. Up to 10 isolates from one patient sampled at time intervals of up to 772 days with no changes in their IS6110 patterns have been analyzed. A statistically significant correlation could be found between changes in insertion sequence (IS) patterns and the increased time intervals over which the isolates were obtained, whereas changes in IS patterns are not correlated to changes in the drug resistance of the isolates. In contrast to the observed variations in IS6110 fingerprint patterns, no changes in the spoligotypes of the isolates analyzed could be found. In conclusion, our results confirm that the IS6110 fingerprint patterns of M. tuberculosis isolates have high degrees of stability. Compared to IS6110, the direct repeat (DR) region, which is the basis for spoligotyping, has a lower rate of change. Partial deletions, e.g., deletions induced by homologous recombination between the repetitive DR elements, could not be detected in this study.

Adult↗
PubMed1994

Staining pattern of type IV collagen and prognosis in early stage adenocarcinoma of the lung.

AIMS: To examine the prognostic value of basement membrane expression in early stage adenocarcinoma of the lung. METHODS: Using antibodies to type IV collagen, basement membrane expression at the tumour-stromal border was immunohistochemically analysed in 30 patients with early stage adenocarcinoma of the lung (pstage I and pstage II). Two patterns of staining for type IV collagen were observed: in the first one the staining line was conserved or partially fragmented; in the second the staining line was widely fragmented or absent in more than 10% of the tumour area. The first staining pattern was categorised as continuous and the second as discontinuous. RESULTS: Of the 24 patients with pstage I adenocarcinoma, 12 (50%) cases showed a continuous pattern. In only one (16.7%) of the six patients with pstage II adenocarcinoma was this pattern evident. Five year survival was greater in pstage I adenocarcinoma (65%) than in pstage II adenocarcinoma (17%), but the difference was not significant. When the analysis was restricted to the 24 patients with pstage I adenocarcinoma, five year survival was better in continuous pattern cases (88%) than in discontinuous pattern cases (20.5%) (p < 0.05). The survival curve of 12 patients with pstage I adenocarcinoma and a discontinuous pattern resembled that of the six patients with pstage II adenocarcinoma. CONCLUSION: These findings suggest that patients with pstage I adenocarcinoma and a discontinuous pattern have histopathologically unrecognised micrometastasis when they come to surgery. The staining pattern of type IV collagen could help in the prognosis of pstage I adenocarcinoma of the lung after surgery.

Adenocarcinoma↗
PubMed1987

Interdigestive contractile patterns of the ileum in dogs.

The aim of this study is to elucidate the nature of ileal interdigestive contractile patterns by the computerized analysis of the contraction spread and by videofluoroscopy. Conscious dogs equipped with closely spaced strain-gauge force transducers were used. Two patterns of repetitive, phasic contractions were recorded, migrating clusters and phase IIIs; both patterns consisted of repetitive, propagated contractions. Both patterns migrated aborad by sequential movement of contraction waves down the bowel. Consequently, the rate of migration of either of the entire patterns was slower than the propagation velocity of constituent, individual contraction waves. Both patterns differed in several parameters, especially the propagated contractions of the clusters spread over shorter distances (1.47 +/- 0.4 cm) than those of phase III (4.65 +/- 0.99 cm). Compared with these complex patterns, propagating power contractions represented single contractions that propagated aborad at the same velocity as the contraction waves of the complex patterns. All three patterns propelled luminal contents distally.

Animals↗
PubMed1992

Expiratory bulbospinal neurons of dogs. I. Control of discharge patterns by pulmonary stretch receptors.

To better understand expiratory bulbospinal (EBS) neuronal processing of afferent patterns from slowly adapting pulmonary stretch receptors (PSRs), the responses of these caudal medullary neurons to various inflation patterns were analyzed in thiopental sodium-anesthetized paralyzed dogs. Normocapnic ventilation was obtained from lung inflations delivered during the neural inspiratory phase of control respiratory cycles by a solenoid ventilator triggered by the onset of phrenic nerve activity. Test inflation patterns, delivered during the neural expiratory (E) phase of specific cycles, were separated by 6-10 control cycles and consisted of slow augmenting and decrementing ramps and steps. Transpulmonary pressure (Pt) was used as an index of PSR activity, and the discharge patterns of single EBS neurons were quantified using cycle-triggered histograms. Based on the time course of the discharge pattern during no-inflation cycles, two types of neurons were identified. Type D, the most common, exhibited a decrementing-like pattern, while type A exhibited an augmenting-plateau pattern. Plots of discharge frequency vs. Pt for type D neurons consisted of a linear excitatory phase (1 less than Pt less than 4.6 mmHg) and a linear inhibitory phase (4.6 less than Pt less than 12 mmHg). Type A neurons exhibited only a linear inhibitory phase for 3.3 less than Pt less than 12 mmHg. Because the responses to step inflations (4 s duration) exhibited only a small amount of time dependency, and the activation Pt of PSRs, but not of the other pulmonary receptors with vagal fibers, is in the proper range, it appears that PSRs may mediate both excitatory and inhibitory components of the neuronal response. These data suggest that discharge patterns of the caudal EBS neurons in dogs are highly dependent on the time course of Pt in a predictable manner, and implicate the importance of instantaneous lung volume in the control of the E musculature and the optimization of the breathing pattern.

Animals↗