Persistence of a strain of Mycobacterium tuberculosis in a prison system.

SETTING: A prison system with an average year-end census of 9084 inmates. OBJECTIVE: To determine transmission dynamics of tuberculosis over a long period; to establish whether Mycobacterium tuberculosis strains responsible for disease in a prison system persist; and to determine whether patients in a community whose isolates cluster with those in a prison system are linked. DESIGN: Retrospective epidemiologic analysis was performed on tuberculosis cases reported in a prison system over a 9-year period. In addition, IS6110 RFLP patterns of M. tuberculosis isolates obtained from prisoners were compared with those of other cases from the state at large. The results of the RFLP analysis and the epidemiologic investigation were compared. RESULTS: Approximately 80% of tuberculosis cases in the prison system were clustered. Over 9 years, a single strain of M. tuberculosis accounted for more than 50% of cases. Patients from the community at large who were infected with the same strain were linked to the prison system. CONCLUSION: In spite of intensive tuberculosis control efforts, a single strain of M. tuberculosis has persisted in the prison system. Its persistence is accounted for by activation of latent infection in patients who, prior to being diagnosed and treated, infected other patients, who then sustained the transmission chain.

Three-dimensional remote sensing by optical scanning holography.

A technique is presented by which holograms can be recorded when an object or scene is scanned with an optically heterodyned Fresnel zone pattern. The experimental setup, based on optical scanning holography, is described and experimental results are presented. We apply the scanning holography technique to three-dimensional reflective objects for the first time to our knowledge and address the unique requirements for such a system. We discuss holographic recording and numerical image reconstruction using a system point-spread function (PSF) approach. We demonstrate numerical image reconstruction of experimentally recorded holograms by two techniques: deconvolution with a simulated PSF and an experimentally acquired PSF.

An overview of behaviour difficulties found in long-term elderly care settings.

STUDY OBJECTIVE: To provide an understanding of the nature and prevalence of behaviour difficulties in long-term care facilities, to compare care settings and comment on the appropriateness of the need for specialist care. DESIGN: Nurses or carers implemented two rating scales in randomly selected settings. SETTING: Nursing homes, residential homes and NHS elderly long-stay wards. SUBJECTS: Elderly long-stay patients. MAIN RESULTS: NHS and nursing home long-term care facilities show similar behaviour difficulties, with nursing homes experiencing more behaviour manifestations in most cases. Residential facilities have behaviour difficulties to a lesser extent. CONCLUSIONS: Nursing homes have limited formal psychiatric intervention compared to NHS settings. Behaviour difficulties result in increased work for general practitioners and increased hospital referrals. More prospective research is required into the antecedents, effects and treatments of patients with behaviour difficulties in nursing homes. For example, it may be appropriate that specialist input is provided for nursing homes in order to implement behaviour intentions and contribute to the reduction of GP callouts and pharmacological interventions.

Interpretation of restriction fragment length polymorphism analysis of Mycobacterium tuberculosis isolates from a state with a large rural population.

Epidemiologic relatedness of Mycobacterium tuberculosis isolates from Arkansas residents diagnosed with tuberculosis in 1992-1993 was assessed using IS6110- and pTBN12-based restriction fragment length polymorphism (RFLP) and epidemiologic investigation. Patients with isolates having similar IS6110 patterns had medical records reviewed and were interviewed to identify epidemiologic links. Complete RFLP analyses were obtained for isolates of 235 patients; 78 (33%) matched the pattern of > or = 1 other isolate, forming 24 clusters. Epidemiologic connections were found for 33 (42%) of 78 patients in 11 clusters. Transmission of M. tuberculosis likely occurred many years in the past for 5 patients in 2 clusters. Of clusters based only on IS6110 analyses, those with > or = 6 IS6110 copies had both a significantly greater proportion of isolates that matched by pTBN12 analysis and patients with epidemiologic connections, indicating IS6110 patterns with few bands lack strain specificity. Secondary RFLP analysis increased specificity, but most clustered patients still did not appear to be epidemiologically related. RFLP clustering in rural areas may not represent recent transmission.

Retrospective detection of laboratory cross-contamination of Mycobacterium tuberculosis cultures with use of DNA fingerprint analysis.

In 1992-1993, we investigated possible cross-contamination of Mycobacterium tuberculosis cultures as part of a study of tuberculosis in Arkansas by using DNA fingerprint analysis. Of patients whose isolates were matched, those for whom smears were negative and only one culture was positive were identified from laboratory records. Clinical, laboratory, DNA fingerprint, and epidemiological data were reviewed. Of 259 patients, nine (3.5%) were judged to be due to cross-contamination. None of these patients had a clinical course consistent with tuberculosis. All nine specimens were processed with another isolate with a matching DNA fingerprint, and epidemiological connections were not identified among any of the patients. To avoid erroneous diagnoses and unnecessary therapy and public health investigations, specimens from patients with tuberculosis whose smears are negative and only one culture is positive should be investigated for cross-contamination. An inconsistent clinical course and a DNA fingerprint that matches those of other culture-positive specimens processed concurrently, coupled with the lack of an epidemiological connection, suggest cross-contamination.

Differences in the prevalence of IS6110 insertion sites in Mycobacterium tuberculosis strains: low and high copy number of IS6110.

SETTING: Mycobacterium tuberculosis (M. tuberculosis) isolates from various parts of the USA which have few copies of the insertion sequence IS6110. OBJECTIVES: To characterize the sites of insertion of IS6110 among M. tuberculosis isolates that have one to six copies of the insertion sequence. DESIGN: The mixed-linker polymerase chain reaction (ML-PCR) procedure was used to amplify the terminal repeats on the ends of IS6110 and adjacent flanking sequences. From the ML-PCR products, sequences flanking 14 copies of IS6110 in strains containing less than seven copies of the insertion were determined. Sequence information from the flanking deoxyribonucleic acid was used to construct flanking primers that can be used to indicate the presence of IS6110 at a particular site when paired with outbound IS6110 primers in a PCR. Over 200 strains of diverse origin were screened for the insertion of IS6110 at several distinct sites using this procedure. RESULTS: The direct repeat (DR) locus has been described as a highly preferred site for insertion of IS6110 in strains of M. tuberculosis. Another highly preferred site of insertion of IS6100, DK1, is herein described. Insertions at DK1 are highly prevalent in M. tuberculosis strains harboring two to six copies of IS6110. The prevalence of insertions at this site decreases in strains with more than six copies of IS6110, even though the sequence itself is present in strains lacking a copy of IS6110 at this site. CONCLUSION: In addition to the DR locus there are other conserved sites of insertion among M. tuberculosis strains. The data further suggest a separate lineage for the high copy and the low copy strains, and a possible sequential insertion of IS6110 in strains of M. tuberculosis with less than seven copies.

Strand displacement amplification and the polymerase chain reaction for monitoring response to treatment in patients with pulmonary tuberculosis.

Specific amplification of Mycobacterium tuberculosis DNA was investigated as an alternative to conventional microbiologic follow-up in 31 cases of smear- and culture-positive pulmonary tuberculosis. Strand displacement amplification (SDA) and the polymerase chain reaction (PCR) were applied to 438 sequential sputum specimens: 67 (15%) were positive by culture, 248 (57%) by SDA, and 231 (53%) by PCR (chi2=3.94, P=.05). Of 200 specimens collected >180 days after treatment started, none yielded positive cultures, while 50 (25%), representing 16 patients, were positive by both DNA assays. A weak correlation was demonstrated between DNA persistence in sputum and duration of culture positivity (r=0.45, P=.01), although no correlation was found with the radiographic extent of disease. The inability to distinguish live and dead organisms precludes DNA amplification from use in therapeutic monitoring. For this purpose, quantitative RNA assays are needed if such techniques are to supplant conventional microbiology.

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.

Stability of DNA fingerprint pattern produced with IS6110 in strains of Mycobacterium tuberculosis.

To assess the stability of IS6110 restriction fragment length polymorphism patterns, DNA fingerprints of 6 Mycobacterium bovis isolates from 1 patient and of 41 Mycobacterium tuberculosis isolates from 18 patients were compared. The fingerprint pattern for a given patient remained identical or nearly identical despite recovery of the isolates during intervals which ranged from 8 months to 4.5 years. Changes in drug resistance profile did not alter a strain's fingerprint pattern.

In vivo 3-D reconstruction and geometric characterization of the right ventricular free wall.

A prerequisite to biomedical analyses of the right ventricular free wall (RVFW) is the characterization of its in vivo geometry and instantaneous wall thickness (WT). We present a method to reconstruct and mathematically model the in vivo RVFW surface geometry using ECG-gated magnetic resonance imaging (MRI). From digitized contours we reconstructed the endo- and epicardial surfaces of the entire heart, and approximated the RVFW surface geometry by local biquadric surface patches. An insurface coordinate system was developed, with respect to which the metric tensor, curvature tensor, major (k2), and minor (k1) principal curvatures were computed. The method was evaluated using MRI data from one dog, which showed that k2 was about 10 times k1, with k2 and k1 approximately perpendicular and parallel to the RV long axis, respectively. During systole, k1 and both principal curvature directions remained essentially unchanged, while k2 revealed only a 7% decrease (rho < 0.05) in the sinus region. These results suggest that while the RVFW undergoes small changes in surface geometry during systole, its overall curvature remained constant. The WT/mean radius of curvature ratio was less than 0.1 during systole throughout the RVFW, indicating it can be idealized as a thin shell.

Regional deformation and contractile function in canine right ventricular free wall.

We used biplane cinefluorgraphy to study the regional deformation and local contractile function of the canine right ventricular free wall (RVFW) among the inflow, midventricular, and outflow regions. For a region delimited by three neighboring markers, under the assumption of homogeneous deformation, we identified the magnitudes and directions of principal shortening or elongation and changes in area every 16.7 ms. Furthermore, we extended this approach to study the alterations of these parameters during RV afterload increase by applying pulmonary artery (PA) occlusion. Results show that, at both control and PA occlusion states, the outflow region was subjected to maximal fractional area reduction (AR) and maximal time rate of fractional area reduction (ARR) during systole, with no differences between inflow and midventricular regions (P less than 0.05). At the control state, the percent AR and the corresponding value for ARR were 27% and 179%/s at the outflow, 19% and 112%/s at the midventricular, and 15% and 107%/s at the inflow region, respectively. During PA occlusion, they became 21% and 115%/s at the outflow, 14% and 97%/s at the midventricular, and 15% and 102%/s at the inflow region, respectively. Statistically, only the outflow region deformation was affected by PA occlusion (P less than 0.05). For the control state, we also compared the direction of regional principal shortening at end systole to the local transmural myocardial fiber orientations. The directions were found to correspond closely to the mean of all local transmural fiber orientations. This suggests that the regional RVFW deformation we measured is the combined deformation behavior from all the local participating myofibers.

Left ventricular coordinate systems.

Three-dimensional kinematics of radiopaque markers in anterior, posterior, septal, and lateral regions of a major equatorial plane were evaluated in anesthetized dogs by biplane fluoroscopy. Stationary coordinate systems measured marker locations recorded during diastole and systole from a contractile origin at the center of contraction at end systole and from a geometric origin at the intersection with the equatorial plane of the ventricular long axis at end diastole. A time-indexed system measured marker locations at end diastole and at end systole, respectively, from the locations of the geometric origin at end diastole and end systole. Compared to the stationary system with the geometric origin, both the stationary system with the contractile origin and the time-indexed system reduced the variability of the radial components of the contractile displacements between ventricular regions. In contrast to the other two systems, the system with the contractile origin reduced circumferential components to values not significantly different from zero. These results indicate that 1) abnormally contracting regions of the ventricle may be located and their size measured by determining the region where the radial component differs from that in the rest of the equatorial plane and 2) rotation in a major equatorial plane of the ventricle is significant, but the influence of rotation can be minimized by referencing ventricular dimensions to a coordinate system with an origin at the center of contraction.

Quantification of three-dimensional left ventricular segmental wall motion and volumes from gated tomographic radionuclide ventriculograms.

Tomographic radionuclide ventriculograms may be used for three-dimensional wall motion analysis. We propose that automatic quantification of these images is possible, and here we describe the implementation and validation of a method to perform this task. Automatic computer methods were developed to locate the left ventricular (LV) endocardial surfaces in all time frames of the cardiac cycle. Global, regional, and local motion and volume were computed. Results were displayed using three-dimensional graphics. The methods were validated using phantom, canine, and human studies. Actual phantom values correlated well with experimentally determined volumes, y = 1.01x + 1.29ml, r = 0.99. In the canine model, the LV endocardial surfaces were located to within an average of 1.9 mm and 3.7 mm at end-diastole and end-systole, respectively. Areas of obvious wall motion abnormalities in automatically processed patient studies corresponded well with angiographically documented coronary artery disease. End-diastolic and end-systolic volumes computed automatically from single photon emission computed tomography averaged errors of 9% and 38%, respectively, when compared with contrast ventriculographic volumes. These results indicate that it is possible to automatically identify the left ventricular endocardial surface in gated tomographic radionuclide ventriculograms. The location of these surfaces corresponds well with the location of implanted endocardial markers, and global volume computed from these surfaces corresponds well with known volumes.

Changes in fiber composition of soleus muscle during rat hindlimb suspension.

Chronic reduction of gravitational load in the rear limbs of rats to simulate the influence of near-zero gravity in skeletal muscles has been shown previously to elicit atrophy in the soleus muscle. Use of this model by the present investigation indicates that soleus atrophy was characterized by a decline in the number of fibers in groups that contained the slow isoenzyme of myosin and which were classified as type I from intensity of staining to myofibrillar actomyosin adenosinetriphosphatase (ATPase) and to NADH tetrazolium reductase. Furthermore total fiber number was not changed, whereas fibers containing the intermediate isoenzyme and those classified as type IIa increased. There results could be explained by either a change in the composition within existing fibers or a simultaneous loss of slow fibers and de novo synthesis of intermediate and fast fibers. Evidence for transformation included an absence of embryonic or neonatal myosin in muscles from suspended rats and the constant fiber number that was unchanged by 4 wk of suspension. Furthermore although fiber areas of both groups of type I and IIa fibers declined during suspension, variability of the fiber areas within each group did not increase.

Ventricular ejection fractions of linear transformation and ellipsoid models.

Eigenvolumes calculated from a linear transformation model were found previously to be linearly related to balloon volumes in excised hearts. The present study analyzed endocardial marker kinematics in intact, contracting left ventricles by biplane cinefluorography. Ejection fractions of the linear transformation model were compared by linear regression analysis with those of an ellipsoidal model, whose ejection fractions had been documented previously in closed and open-chest dog preparations. Data from 10 dogs indicated a correlation coefficient of 0.98 and a regression equation with close similarity to the line of identity. Ejection fractions calculated from the linear transformation model are concluded to be proportional to actual ejection fractions in intact, beating left ventricles.

In vivo and in vitro blocking of human lymphocyte Fc gamma-receptors by intravenous gammaglobulin.

Lymphocyte subpopulations were measured in patients with idiopathic thrombocytopenic purpura before and immediately after high dose intravenous gammaglobulin (IV-IgG) therapy. A significant relative and absolute reduction in the Fc gamma-receptor bearing lymphocyte subpopulation was observed in 5 out of 7 patients tested. In vivo modulation of lymphocyte Fc gamma-receptors therefore probably occurs: an effect which may be attributable to the Fc gamma R-blocking anti-lymphocytic antibodies found in IV-IgG preparations. In vitro studies showed that IV-IgG preparations also contain antibodies with the capacity to block Fc gamma-receptors on human monocytes and polymorphs and that these antibodies can inhibit the T cell response to phytohaemagglutinin. These anti-lymphocyte antibodies may be important in the mode of action of high dose IV-IgG therapy.

Lymphocyte Fc gamma-receptor blocking antibodies in intravenous gammaglobulin preparations.

Various batches of intravenous gammaglobulin (IV-IgG) were found to contain antibodies with the capacity to block human peripheral blood lymphocyte receptors for the Fc region of IgG i.e., Fc gamma-receptors (Fc gamma Rs). The level of Fc gamma R-blocking produced was found to vary considerably from batch to batch and from lymphocyte donor to donor. IgG purified from normal human serum pooled from only 20 donors was also found to produce significant Fc gamma R-blockade. Analysis of the individual contributors to this normal IgG pool indicated that Fc gamma R-blocking antibodies may in fact be auto-antibodies.

Influences of inactivity and indomethacin on soleus phosphatidylethanolamine and size.

Results of previous investigations indicate that muscular prostaglandins (PG) E2 and F2 alpha are biosynthesized during changes in muscular activity and stimulate protein degradation and synthesis, respectively. The results of the present investigation demonstrates a reduction by indomethacin of soleus hypertrophy, which occurred during a one week recovery period following rat hindlimb suspension. While this hypertrophic model evoked significant, rapid increases in soleus myosin and weight in control groups, continuous systemic release of indomethacin (3.5 mg/Kg/day) reduced the gain in soleus weight, Type I and II hypertrophy. Body weights of all groups were not significantly different. Additional analysis found a selective reduction in phosphatidylethanolamine (PE) during soleus atrophy and hypertrophy which were elicited by hindlimb suspension and recovery from suspension, respectively. Indomethacin enhanced PE recovery. Data from previous and present studies support a hypothesis that a change in soleus activity elicits PE catabolism, changes in cytosolic and muscular calcium, in calcium-dependent phospholipase activity, in PG biosynthesis, and in soleus size.