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J H Bates

Publications and source records attributed to J H Bates.

At least 73 records · Page 4Linked to original sources
PubMed1996

Evaluation of method for secondary DNA typing of Mycobacterium tuberculosis with pTBN12 in epidemiologic study of tuberculosis.

Secondary fingerprinting of Mycobacterium tuberculosis DNA with a probe containing the polymorphic GC-rich repetitive sequence present in pTBN12 has been found to have greater discriminating power than does fingerprinting with the insertion sequence IS6110 for strains carrying few copies of IS6110. To validate the use of pTBN12 fingerprinting in the molecular epidemiology of tuberculosis, M. tuberculosis isolates from 67 patients in five states in the United States and in Spain were fingerprinted with both IS6110 and pTBN12. Epidemiologic links among the 67 patients were evaluated by patient interview and/or review of medical records. The 67 isolates had 5 IS6110 fingerprint patterns with two to five copies of IS6110 and 18 pTBN12 patterns, of which 10 were shared by more than 1 isolate. Epidemiologic links are consistently found among patients whose isolates had identical pTBN12 patterns, whereas no links were found among patients whose isolates had unique pTBN12 patterns. This suggests that pTBN12 fingerprinting is a useful tool to identify epidemiologically linked tuberculosis patients whose isolates have identical IS6110 fingerprints containing fewer than six fragments.

Bacterial Typing Techniques↗
PubMed1996

Usefulness of the secondary probe pTBN12 in DNA fingerprinting of Mycobacterium tuberculosis.

A comparison was made between DNA fingerprints of Mycobacterium tuberculosis produced with the insertion sequence IS6110 and those produced with the polymorphic GC-rich repetitive sequence contained in the plasmid pTBN12. A total of 302 M. tuberculosis isolates from the prison system in Madrid, Spain, and the Denver Public Health Department (Denver, Colo.) were analyzed with the two probes. Both probes identified the same isolates in the same clusters when the fingerprints had six or more copies of IS6110. Analysis of isolates with unique IS6110 fingerprints demonstrated that they were unique with pTBN12. The pTBN12 probe had greater discriminating power in isolates having five or fewer copies of IS6110. Forty-seven isolates from Denver having fewer than five copies of IS6110 which were grouped in 11 clusters with identical fingerprint patterns were subdivided into 35 different patterns by pTBN12. Isolates with IS6110 fingerprints with more than six copies of IS6110 that differed from one another by only one or two hybridizing bands were analyzed with pTBN12. Most of these sets of isolates demonstrated identical patterns with pTBN12. However, some exceptions were observed, suggesting that those having nearly identical IS6110 patterns should not necessarily be included in the same cluster. Since IS6110 provides more polymorphism in the fingerprint, it is most useful in identifying isolates with unique fingerprint patterns and those in clusters in which the isolates contain six or more copies of the insertion. However, it is necessary to employ a secondary probe, such as pTBN12, to discriminate isolates with five or fewer copies of IS6110 and those with similar but not identical IS6110 patterns.

DNA Fingerprinting↗
PubMed1996

Assessment of local lung impedance by the alveolar capsule oscillator in dogs: a model analysis.

The alveolar capsule oscillator technique has shown that the response of the lung periphery to intravenous histamine injection in dogs is extremely inhomogeneous both in terms of local peripheral airway resistance (RA) and local peripheral elastance (EA) (M. Mishima, Z Balassy, and J. H. T. Bates. J. Appl. Physiol. 77: 2140-2148, 1994). To assess the physical extent of the local lung region identified by this technique, we performed computer simulations using an asymmetrical branching model of the canine lung proposed by K. Horsfield, W. Kemp, and S. Philips (J. Appl. Physiol. 52: 21-26, 1982). The acoustic impedance of the model from 26 to 200 Hz as seen from the alveolar capsule oscillator was calculated. RA and EA were estimated from the simulated acoustic impedance between 26 and 200 Hz and were found to be 492 hPa.s.l-1 and 156,300 hPa/l, respectively. These values are similar to those found experimentally in previous studies. By simulating data using the model in various stages of completeness, we determined that approximately 50% of RA is determined by the acinus to which the alveolar capsule is attached, whereas the remainder is determined by airways < or = 1 mm diameter that converge on this acinus. By contrast, EA was determined almost entirely (95%) by the acinus directly under the capsule. Inhomogeneous peripheral airway constriction altered RA severalfold but did not affect EA by >5%. This suggests that the previously observed changes induced in EA by bronchial challenge reflect real changes in intrinsic tissue elastance rather than merely regional mechanical inhomogeneities.

Airway Resistance↗
PubMed1996

Polymerase chain reaction detection of Mycobacterium tuberculosis in formalin-fixed tissue.

Use of the polymerase chain reaction (PCR) to detect Mycobacterium tuberculosis in formalin-fixed, paraffin-embedded tissue would be of great diagnostic value. However, formaldehyde has been reported to decrease the efficiency of amplification by structurally altering the polynucleotide chain. We sought to determine the ability of the PCR assay to detect M. tuberculosis in formalin-fixed, paraffin-embedded tissue in a mouse experimentally infected with the H37Rv strain of M. tuberculosis. Lung tissue from the infected mouse was cultured to determine the number of organisms per gram of tissue. The remaining lung tissue was divided into eight portions, seven of which were fixed in 10% neutral buffered formalin for 24-h intervals over periods lasting from 1 to 7 d, and a control portion was placed in isotonic saline. The tissue samples were then paraffin-embedded, and sections were obtained from each tissue block for PCR analysis. We show that the PCR assay can detect as few as nine organisms in a 5-micron section of tissue, and that up to 7 d of fixation in 10% neutral buffered formalin has a negligible effect on the assay. The PCR assay can detect low numbers of M. tuberculosis organisms in formalin-fixed, paraffin-embedded tissue.

Animals↗
PubMed1996

The multilevel mechanical behaviour of the lung during induced bronchoconstriction.

The standard way of simulating obstructive lung disease in animals is by induced bronchoconstriction, where a bronchoactive agent is applied to the lungs either by inhaled aerosol or i.v. injection. This paper reviews some of the recent advances in our understanding of how lung mechanics in animals are affected by bronchoconstriction at both the microscopic and macroscopic levels. At the microscopic level, the alveolar capsule oscillator technique provides mechanical information at the level of a single acinus, and has shown that bronchoconstriction causes both spatial and temporal inhomogeneities throughout the lung. These inhomogeneities become more profound as lung volume is reduced, presumably because of reduced mechanical interdependence between adjacent lung regions. At the macroscopic level, studies of the time-evolution of lung impedance following a sudden application of bronchial agonist have provided evidence that regional mechanical inhomogeneities are the major contributor to impedance changes. Thus, an important general problem is to find out how the distributed regional (microscopic) mechanical properties of the lung determine its macroscopic properties. Computer models of the lung, such as those based on branching airway trees terminating in complex tissue impedances, are beginning to make this link.

Animals↗
PubMed1995

Ventilatory response to cholecystokinin tetrapeptide in anaesthetized dogs.

Cholecystokinin (CCK) has been implicated in the genesis of panic disorder. In this study we measured the ventilatory response to i.v. injection of CCK-tetrapeptide (CCK-4) in anaesthetized dogs. We found an immediate and transient increase in minute ventilation. The response was large (more than 100% of baseline) and lasted 1-2 min. Repeated CCK-4 injection produced a somewhat reduced response, suggestive of a slight degree of tachyphylaxis. Blood pressure and heart rate changed only slightly (<10%), while respiratory mechanical parameters remained unchanged following CCK-4 administration. We conclude that CCK-4 has a significant effect on ventilation in the anaesthetized dog, which suggests that this species may provide a useful quantitative assay for the anxiogenic effects of CCK.

Animals↗
PubMed1995

The risk for transmission of Mycobacterium tuberculosis at the bedside and during autopsy.

OBJECTIVE: To emphasize the differing infectious potentials of a patient with tuberculosis. SETTING: Hospital ward and autopsy room. DESIGN: An epidemiologic investigation of tuberculin skin test conversions in a clinical setting and during autopsy when results of tuberculin tests done before exposure were available for all participants. MEASUREMENTS: Tuberculin skin test results after the discovery of tuberculosis exposure from a patient with unsuspected tuberculosis for comparison with the test results before exposure; culture of sputum and autopsy material for Mycobacterium tuberculosis; and DNA fingerprinting of organisms. INTERVENTION: Preventive therapy for persons with skin test conversion. RESULTS: None of the 40 skin test-negative health care workers caring for the patient for 3 weeks on an open medical ward showed a skin test conversion, even though they had not used respiratory precautions. By contrast, among personnel present during the 3-hour autopsy, the test results of all five nonreactors converted from negative to positive (mean reaction, 24 mm). Two of these persons had a positive sputum culture 8 weeks later. The DNA fingerprints of all three isolates were identical. CONCLUSIONS: A patient who did not transmit tuberculosis before death released a prodigious number of tubercle bacilli during autopsy.

Air Microbiology↗
PubMed1995

Ventilatory depression by halothane in infants and children.

The purpose of this study was to extend previous observations of a greater decrease in tidal volume in infants than in children during halothane anaesthesia. We analyzed the inspiratory flow waveform recorded during spontaneous ventilation in: infants, two to six months of age, and children, one to five years of age. In addition we analyzed the CO2 signal and the pressure waveform during an occluded inspiration. The pressure generated during the initial 100 msec of inspiratory occlusion, an index of respiratory drive, was analyzed to give some insight into the aetiology of the age-related differences. In 15 infants and 15 children, Flow (V), pressure (Pao) and PCO2 were recorded at three concentrations of inspired halothane (FIH): 0%, 1% and 2% which correspond to an endtidal halothane concentration of about 0.3%, 0.9% and 1.3% respectively. Data were analyzed for minute ventilation (Vi) and parameters of timing (Total time (Ttot), Inspiratory time (Ti)), the amplitude of the neural output (mean inspiratory flow (VT/Ti), tidal volume (VT)) and the shape of the inspiratory breath profile (the inspiratory centroid flow (Ci/Ti), the inspiratory duty cycle (Ti/Ttot)). In some, the airway was occluded at end expiration and the slope of the initial 100 msec of occlusion (dP/dt) together with the maximal negative pressure (PMAX) were measured. Estimates of respiratory mechanics E'rs (PMAX/VT) and (VT/Ti)/(dP/dt) were obtained. The VT and Ttot decreased with increasing FIH in both infants and children (P < 0.05). The PETCO2 increased in both groups and the % increase was greater in infants.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗
PubMed1995

Time course of histamine-induced bronchoconstriction and its adrenergic and H2 modulation.

We characterized the complete time course of histamine-induced bronchoconstriction and its modulation via the release of endogenous catecholamines and by its actions on H2-receptors in anesthetized, tracheostomized, paralyzed, and artificially ventilated mongrel dogs. Respiratory resistance (R) and elastance (E) were estimated continuously with a recursive least squares estimator. Three protocols were followed in which multiple histamine bolus injections were given 1 h apart. We found that the time courses of E and R had consistent patterns (transient peak that returned to baseline within 1000 sec) even in cases of low mean arterial pressure (MAP). Indomethacin pre-treatments prevented tachyphylaxis to repeated i.v. challenges. beta-blockade produced a mild increase in baseline and a potentiation of the histamine-induced response in E and these effects were not altered with further alpha-or H2-blockade. Blockade of alpha-receptors increased the time to recovery in both E and MAP presumably by decreasing blood flow. Finally, we suggest that preventing the H2-receptor induced increase in bronchial blood flow may have increased the time to maximal E without affecting the recovery time.

Animals↗
PubMed1995

On the use of the alveolar capsule technique to study bronchoconstriction.

Using the alveolar capsule technique, we studied the time courses of respiratory mechanical parameters at various sites on the lung surface during bronchoconstriction. Six mongrel dogs were anesthetized, tracheostomized, paralyzed and artificially ventilated (12-25 ml/kg, 19-22 breaths/min). Sternotomy was performed and alveolar capsules were glued to various parts of the lungs. Tracheal pressure and flow and alveolar pressure were measured continuously for 25 min after i.v. bolus injections of histamine (0, 0.05, 0.5, 5.0, 50.0 mg). The challenges were spaced 1 h apart. Estimates of lung tissue resistance and elastance were obtained with our recursive least-squares estimator (Lauzon and Bates, J. Appl. Physiol., 1159-1165, 1991). We found that the time courses of the parameters of most capsules were initially uniform but quickly diverged as bronchoconstriction developed. Also, we found that the differences in time course of mechanics between alveolar regions either developed randomly with step-like features presumably reflecting intermittent opening and closing of the airways leading to the various alveolar capsules, or in a progressive dose-dependent manner, possibly reflecting a gradual but structurally pre-set pattern of bronchoconstriction, or with a combination of these two patterns. We explain our results in terms of inhomogeneous mechanical properties of the lungs and examine some artifacts introduced by the alveolar pressure measurement technique.

Animals↗
PubMed1995

Measuring the mechanical properties of the lung in vivo with spatial resolution at the acinar level.

The alveolar capsule technique involves measuring subpleural alveolar pressure in the chamber of a plastic capsule glued to the perforated lung surface. However, measurements of alveolar pressure alone do not permit one to say whether the inhomogeneities that develop are due to changes in local lung resistance, elastance, or both. We have developed an extension of the alveolar capsule technique in which small broad-band oscillations in flow are applied through the capsule. At low oscillation frequencies the imposed flows travel all the way through the airway system, so the associated alveolar pressures then reflect the resistance of the pathway from a small local alveolar region out to the tracheal opening. At high frequencies flows propagate only a very short distance into the lung whereupon the dynamic relationship between flow and alveolar pressure gives a measure of local lung elastance. In this paper we show that considerations of canine lung anatomy suggest that the elastic and resistive quantities provided by the capsule oscillator technique pertain to a lung region of the order of a single acinus with its associated terminal bronchioles. This represents a greatly improved spatial resolution of lung mechanics over that which was possible before the development of the alveolar capsule oscillator technique.

Air Pressure↗
PubMed1995

The effect of changing end-expiratory pressure on respiratory system mechanics in open- and closed-chest anesthetized, paralyzed patients.

The decrease in functional residual capacity (FRC) with anesthesia may cause lung volume to decrease below closing volume, thereby impairing oxygenation. Increasing end-expiratory pressure (EEP) reexpands atelectatic areas in anesthetized, ventilated patients, but its effect on pulmonary mechanics is less well understood. We studied the effect of varying EEP on the mechanical behavior of the respiratory system in patients undergoing either closed (Group 1) or open-chest (Group 2) surgical procedures. We measured airway opening pressure (PaO), flow (V), and esophageal pressure (Pes) (in Group 1 only) at EEPs of 0, 2.5, 5, and 10 cm H2O. Dynamic elastance (E) and resistance (R) for the respiratory system (RS), the lung (L), and the chest wall (CW) were estimated by fitting the equation P = RV + EV + K to the measured data by multiple linear regression where P was either Pao, Pes, or Pao-Pes. Group 1 EL decreased with increases in EEP to 5 cm H2O and then began to increase with EEP above this level. The same occurred in Group 2 before opening the chest. After opening the chest in Group 2, EL increased as EEP increased at all values above 0 cm H2O. The magnitudes of RRS and RL were similar in both groups of subjects and in each group these quantities decreased with increases in EEP. Dynamic EL responded differently to changes in EEP in subjects with open-chest and closed-chest procedures. We attribute this difference to overdistension of the remaining ventilable lung tissue at all levels of EEP in open-chest patients.

Adult↗
PubMed1995

A computer-controlled research ventilator for small animals: design and evaluation.

The understanding of the mechanical properties of the mammalian respiratory system and how they change under the influence of drugs and in disease are frequently pursued in small animals, since they can be easily obtained in large numbers as pure-bred strains. However, conventional experimental set-ups for studying small animals are generally limited in their ability to measure gas flow into the lungs. In this paper, we present a computer-controlled research ventilator for small animals which can provide conventional mechanical ventilation as well as arbitrary flow perturbations with a bandwidth from 0-55 Hz. Respiratory impedance is estimated from the displacement of the piston and the pressure it generates, thereby obviating the need for a direct flow measurement. The performance of the device was tested on mechanical loads whose impedances were calculated theoretically. The measured and predicted loads agreed within less than 5% up to 30 Hz. Furthermore, the measured impedance of two mechanical loads in series precisely matched the sum of their individual impedances.

Animals↗
PubMed1995

Changes in regional lung impedance after intravenous histamine bolus in dogs: effects of lung volume.

We measured the effect of lung volume on the time course of regional lung input impedance (ZA) after bolus intravenous administration of 2 mg of histamine in seven open-chest dogs using alveolar capsule oscillators. ZA (24-200 Hz) was obtained during apnea at constant lung volume every 2 s for 80 s at lung inflation pressures of 0.1, 0.2, 0.3, 0.5, 0.7, and 1.0 kPa. Local airway resistance (RA) and elastance of the local lung region were calculated by fitting a four-parameter model to the measured ZA. Total lung resistance and lung elastance were also calculated from tracheal pressure and flow measured during mechanical ventilation (0.3 Hz) just before and after each set of ZA measurements. We found the histamine-induced changes in both lung resistance and lung elastance to decrease with increasing lung volume. RA also showed a large negative dependency on lung volume, and the variation between different RA measurements became markedly increased as lung volume decreased. In contrast, local airway elastance was essentially unaffected by lung volume. These results support the idea that parenchymal tethering of the very distal airways impedes their narrowing during bronchoconstriction. They also indicate that reduced parenchymal tethering causes airway narrowing to become markedly more inhomogeneous.

Airway Resistance↗
PubMed1995

Dynamic viscoelastic nonlinearity of lung parenchymal tissue.

To investigate the contribution of nonlinear tissue viscoelasticity to the dynamic behavior of lung, time and frequency responses of isolated parenchymal strips of degassed dog lungs were investigated. The strips were subjected to loading and unloading stretch steps for 60 s and to sinusoidal oscillations (0.03-3 Hz) of different stretch amplitudes (delta lambda = 0.05, 0.1, and 0.2) and at different operating stresses (T(o) = 0.5, 1, and 2 kPa). Elastance (E) increased linearly with the logarithm of frequency (approximately 10% per frequency decade), and resistance (R) decreased hyperbolically with frequency. Both E and R varied little with delta lambda but they increased proportionally with T(o). Hysteresivity (eta = R x 2 pi x frequency/E) ranged from 0.07 to 0.10. In agreement with the frequency response, the magnitude of the unit step response increased with T(o) and was higher when loading than when unloading, and the stress relaxation ratio (approximately 0.10) did not vary greatly with T(o) or with delta lambda. The time and frequency behavior of the strips were interpreted in terms of the quasilinear viscoelastic model of Navajas et al. (J. Appl. Physiol. 73:2681-2692, 1992). The model explains most of the dependencies of step and oscillatory responses on the measurement conditions, in particular the proportional dependence of E and R on T(o). According to the model, about two-thirds of energy dissipated during oscillation arises from tissue viscoelasticity. The remaining dissipated energy could be accounted for by plasticity. Thus the effect of nonlinear elasticity on the dynamic behavior of lung tissue can be empirically described by a simple quasilinear model characterized by only two parameters.

Animals↗