Post-parturient shedding of Listeria monocytogenes in breast milk of infected mice. [corrected].

The objectives of this study were to develop an animal model to study Listeria monocytogenes infection during the peri-parturient period and identify sources of maternal shedding of the pathogen. Peri-parturient mice were infected intragastrically with L. monocytogenes that expressed bacterial luciferase. Mice were then imaged in vivo over time. Secreted breast milk samples from mice infected after parturition were enriched and plated for culture and imaging. Bioluminescence imaging technology was able to detect luciferase emitting L. monocytogenes in vaginal secretions and maternal and fetal organs at 72 and 96 h post infection in mice infected prior to, or just after, parturition. The results from this study clearly show that L. monocytogenes is shed in vaginal secretions and disseminates to the mammary chain, from which it can be shed in the milk of peri-parturient mice.

Training needs for mid-level managers and immunisation coverage in Western Kenya.

OBJECTIVES: To determine the current status of immunisation coverage in Western Kenya before intervention, to identify strengths and weaknesses of the existing programme in order to design educational interventions that could improve the services provided and find out the training needs of the mid-level managers of Kenya Expanded Programme of Immunisation. DESIGN: Cross-sectional descriptive study. SETTING: All thirty nine districts in Rift Valley, Western and Nyanza provinces. SUBJECTS: Mid-level managers of Kenya Expanded Programme on Immunisation in the 39 districts and the provinces. These included Provincial Logisticians, Provincial Medical Officers of Health, District Medical Officers of Health, District Public Health Nurses, District Records and Health Information Officers, District Disease Surveillance Officers, and District Public Health Officers. MAIN OUTCOME MEASURES: Number of staff trained on EPI, coverage rates and perceived training needs of the mid-level managers. RESULTS: A total of eighty eight mid-level managers participated in the interviews. Most of these were District Public Health Nurses (40.9%) and District Health Information and Records Officers (23.9%). Only 49 (25%) of the District Health Management Team members had undergone training at the supervisory level. Eighteen districts (43.6%) had no member of the District Health Management Team that had ever been trained at the supervisory level. Using rates of Pentavalent 1 and measles coverage, Nyanza Province had the highest immunisation dropout rate (Pentavalent 1--measles) whereas Rift Valley Province had the lowest. The annual cumulative coverage for all the provinces by antigen was 80% for Pentavalent 1 and 2 and 60% for measles. The most requested need for inclusion in the training curriculum was maintenance of the cold chain equipment. CONCLUSIONS: Most of the members in the study area have not been trained on Expanded Programme on Immunisation and may be ill-equipped to manage the complicated programmes needed to maximise delivery of services. The immunisation coverage in this area is low while the dropout rates are high. We therefore recommend that all the mid-level managers of Expanded Programme on Immunisation in this area be trained comprehensively through the Merck Vaccine Network--Africa programme using the World Health Organisation approved mid-level managers course.

Packing, tiling, and covering with tetrahedra.

It is well known that three-dimensional Euclidean space cannot be tiled by regular tetrahedra. But how well can we do? In this work, we give several constructions that may answer the various senses of this question. In so doing, we provide some solutions to packing, tiling, and covering problems of tetrahedra. Our results suggest that the regular tetrahedron may not be able to pack as densely as the sphere, which would contradict a conjecture of Ulam. The regular tetrahedron might even be the convex body having the smallest possible packing density.

Inhaled synthetic surfactant abolishes the early allergen-induced response in asthma.

Allergen-induced inhibition of pulmonary surfactant in asthma may promote airway oedema and consequently potentiate the severity of the asthmatic response. A randomised, single-blind, cross-over study of an inhaled synthetic phospholipid dry-powder surfactant (Pumactant) was conducted in atopic, asthmatic subjects with previously documented early and late asthmatic responses (EAR and LAR) to an inhaled allergen. This was conducted to evaluate the role of exogenous surfactant administration on EAR and LAR. A total of seven subjects had complete evaluable data and received the full dose of Pumactant. Asthmatic subjects inhaled two separate doses of 400 mg Pumactant prior to an allergen exposure. The first dose was administered 8 h in advance and the second dose 30 min in advance. The dosage occurred through a purpose-built administration device. This was followed by a standard bronchial-provocation test, and forced expiratory volume in one second (FEV1) was measured at regular intervals over a 10-h period. Pumactant was well tolerated and, surprisingly, abolished the EAR but not the LAR in all seven subjects. The mean area under the curve between 0-2 h (EAR) following bronchial provocation test was 0.08 for the Pumactant treatment group (PT) and 13.29 for the no treatment (NT) group. The maximum drop in FEV1 for EAR was 4.19% and 23.98% in the PT and the NT group, respectively. The demonstration of inhibition of the early asthmatic response by exogenous surfactant, provides the first evidence that pulmonary surfactant dysfunction may also contribute to the very early asthmatic response to allergen. Exogenous surfactant administration could serve as a useful adjunct in controlling the early allergen-induced symptoms in patients with allergic asthma.

A comparison of planar scintigraphy and SPECT measurement of total lung deposition of inhaled aerosol.

Planar gamma camera imaging of inhaled aerosol deposition is extensively used to assess the total deposition in the lung. However, validation of the measurements is not straightforward, as gold standard measurements of lung activity against which to compare are not readily available. Quantitative SPECT imaging provides an alternative method for comparison. Four different methods for planar image quantification are compared. Two attenuation correction techniques, thickness measurement and transmission measurement, have been combined with two scatter correction techniques, reduced attenuation coefficient and line-source scatter function convolution subtraction. Each technique has been applied to 10 studies of aerosol deposition of a fine aerosol (mass median aerodynamic diameter 1.8 microm) and 10 studies using a coarse aerosol (mass median aerodynamic diameter 6.5 microm). The total activity in the right lung for each measurement has been compared to the value determined from SPECT imaging on the same subjects. When the thickness measurement and transmission techniques were applied with scatter compensation using a reduced attenuation coefficient, activity was systematically overestimated by 5% in both cases. The corresponding random errors (coefficient of variation) were 8.6% and 6.6%. Separate scatter correction reduced these systemic errors significantly to -1.5% and 2.7%, respectively. The random errors were not affected. All techniques provided assessment of total lung activity with an accuracy and precision that differed by less than 10% compared to the SPECT values. Planar gamma camera imaging provides a good method of assessing total lung deposition of inhaled aerosol.

Pulmonary clearance rate of two chemically different forms of inhaled pertechnetate.

Attempts to image the pulmonary deposition site of radiolabeled aerosols delivered by dry powder inhalers (DPIs) and pressurized metered-dose inhalers (pMDIs) using single photon emission computed tomography (SPECT) have been limited by the rapid pulmonary clearance of radiolabel. To determine whether aqueous solubility of the radiolabel is a significant factor, the pulmonary clearance rates of two chemically different forms of 99mTc were calculated. A dry powder formulation of terbutaline sulphate was radiolabeled for inhalation by Turbuhaler (AstraZeneca) using the water-soluble salt sodium pertechnetate and the water-insoluble salt tetraphenylarsonium pertechnetate. A pilot study was conducted during which two control subjects each inhaled the two radiolabeled aerosols on separate days. Intrasubject clearance rates for the two species were very similar. It was therefore concluded that water insolubility of the pertechnetate salt alone was not enough to extend the lung residency time of the radiolabel.

An advanced and detailed in vitro validation procedure for the radiolabeling of carrier-free terbutaline sulphate dry powder.

The aerodynamic properties of 99mTc radiolabeled carrier-free terbutaline sulphate (TBS) have been thoroughly investigated following delivery by Turbuhaler (AstraZeneca Lund, Sweden). A full and detailed radiolabeling procedure is also reported. The in vitro radiolabel validation was performed to determine whether TBS radiolabeled in this way would be representative of the commercially available product Bricanyl Turbuhaler during clinical trials. The results indicated that variations in aerodynamic properties had been introduced and that the radiolabel would slightly underestimate the fine particle fraction of Bricanyl, but would nonetheless act as a suitable marker in vivo. Assumptions regarding the aerodynamic properties of doses likely to be received by clinical trial subjects were also examined. This has been achieved by extending the validation procedures beyond those usually reported to include dose number, time, and homogeneity dependent studies. It was found that doses extracted for testing purposes and simulated patient doses extracted shortly afterward had similar properties. Doses extracted 2 h after initial testing also had similar properties to the test doses. These results suggested that data from the test doses could be used for quality control purposes, would be representative of the doses to be received by clinical trial subjects, and that a short delay between initial testing and trial subject inhalation would be acceptable.

Evaluation of the accuracy and precision of lung aerosol deposition measurements from single-photon emission computed tomography using simulation.

Single-photon emission computed tomography (SPECT) imaging is being increasingly used to assess inhaled aerosol deposition. This study uses simulation to evaluate the errors involved in such measurements and to compare them with those from conventional planar imaging. SPECT images of known theoretical distributions of radioaerosol in the lung have been simulated using lung models derived from magnetic resonance studies in human subjects. Total lung activity was evaluated from the simulated images. A spherical transform of the lung distributions was performed, and the absolute penetration index (PI) and a relative value expressed as a fraction of that in a simulated ventilation image were calculated. All parameters were compared with the true value used in the simulation, and the errors were assessed. An iterative method was used to correct for the partial volume effect, and its effectiveness in improving errors was evaluated. The errors were compared with those of planar imaging. The precision of measurements was significantly better for SPECT than planar imaging (2.8 vs 6.3% for total lung activity, 6 vs 20% for PI, and 3 vs 6% for relative PI). The method of correcting for the influence of the partial volume effect significantly improved the accuracy of PI evaluation without affecting precision. SPECT is capable of accurate and precise measurements of aerosol distribution in the lung, which are improved compared with those measured by conventional planar imaging. A technique for correcting the SPECT data for the influence of the partial volume effect has been described. Simulation is demonstrated as a valuable method of technique evaluation and comparison.

Human lung morphology models for particle deposition studies.

Knowledge of human lung morphology is of paramount importance in calculating deposition patterns of inhaled particulate matter (PM) to be used in the definition of ambient air quality standards. Due to the inherently complex nature of the branching structure of the airway network, practical assumptions must be made for modeling purposes. The most commonly used mathematical models reported in the literature that describe PM deposition use Weibel's model A morphology. This assumes the airways of the lung to be a symmetric, dichotomously branching system. However, computer simulations of this model, when compared to scintigraphy images, have shown it to lack physiological realism (Martonen et al., 1994a). Therefore, a more physiologically realistic model of the lung is needed to improve the current PM dosimetry models. Herein, a morphological model is presented that is based on laboratory data from planar gamma camera and single-photon emission computed tomography (SPECT) images. Key elements of this model include: The parenchymal wall of the lung is defined in mathematical terms, the whole lung is divided into distinct left and right components, a set of branching angles is derived from experimental measurements, and the branching network is confined within the discrete left and right components (i.e., there is no overlapping of airways). In future work, this new, more physiologically realistic morphological model can be used to calculate PM deposition patterns for risk assessment protocols.

Evaluation of the accuracy and precision of lung aerosol deposition measurements from planar radionuclide imaging using simulation.

Planar images of known, theoretical distributions of radioaerosol in the lung have been simulated using lung models derived from magnetic resonance studies on human subjects. Total lung activity was evaluated from the simulated images together with the absolute penetration index (PI) and a relative value expressed as a fraction of that in a simulated ventilation image. The accuracy and precision of these measurements were calculated by comparison with the true values used in the simulation. Total activity was assessed with systematic errors within 5% and precision within 6.5%. Measured PIs varied only slowly with true PI and inter-model variation masked changes between measurements on the different distributions. The relative PI reduced inter-model variation and provided significant differences between all the distributions. PI was significantly affected by misalignment of the lung region of interest. The conducting airways deposition fraction (CADF) used in the simulation correlated linearly with the fractional activity in a central lung region, allowing CADF to be estimated with a precision of 21%.

Assessment of deposition of inhaled aerosol in the respiratory tract of man using three-dimensional multimodality imaging and mathematical modeling.

Multimodality medical imaging enables measurement of the three-dimensional spatial distribution of a radiolabeled aerosol within the lung. Using a conceptual spatial morphological model these data may be transformed to provide information on deposition per airway generation. This methodology has been used to study the intrapulmonary deposition patterns of two formulations of a metered dose inhaler and two nebulizers in control subjects. The nebulizer study has also been stimulated using a computer model of deposition. The comparison between derived experimental results and those from computer modeling shows areas of agreement, although there are also areas of discrepancy. The new methodology has considerable potential value in the fields of inhalation therapy and deposition modeling, although more detailed validation is still required.

Initial presentations of pediatric hemophiliacs.

OBJECTIVE: To examine the manner of presentation and time elapsed before diagnosis in a current population of pediatric patients with coagulopathies compared with a historically similar group presented by Baehner and Strauss in 1966. DESIGN: Comparative retrospective patient series. SETTING: A large pediatric (hemophilia) referral center in New York, NY. POPULATION: Sixty-five male patients presented for evaluation of a presumed coagulopathy between 1974 and 1989. Nine patients were excluded for inadequate data or follow-up. Of the 56 patients included, 47 were were factor VIII deficient (32 severely affected, 15 not severely affected) and nine were factor IX deficient (six severely affected, three not severely affected). INTERVENTIONS: None. RESULTS: Severely affected neonates were diagnosed younger than 1 month significantly more often in this patient population compared with the 1966 population (68.4% vs < 10%, P < .001). Patients not severely affected were also diagnosed younger than 1 month significantly more often than in 1966 (50% vs 2.5%, P < .001). Workup in these groups was initiated because of either bleeding events or family history with similar frequency (48.6% vs 51.4%); historically, diagnosis had ensued primarily after bleeding events. By 1 year of age, all severely affected infants had been diagnosed in our population, a statistically significant improvement compared with the historical group (100% vs < 40%, P < .001); patients not severely affected were also diagnosed more frequently (72.2% vs 15%, P < .001). Eighty-five percent of diagnoses made after 1 month of age were based on bleeding events, despite a positive family history of 28.6%. Overall, 35.7% of diagnoses resulted after a positive family history was elicited. CONCLUSIONS: In this population, diagnoses were made earlier than in the comparison group. Attention to family history and early bleeding events continues to contribute to the early diagnosis of factor deficiencies.

Nasal intermittent positive pressure ventilation in acute exacerbations of chronic obstructive pulmonary disease--a preliminary study.

Ten patients (two male) suffering from acute exacerbations of long-standing chronic obstructive pulmonary disease and admitted in hypoxic, hypercapnic respiratory failure were treated with Nasal Intermittent Positive Pressure Ventilation (NIPPV) plus supplemental oxygen, on a general medical ward. The median (range) pH on admission was 7.30 (7.20-7.35), the median age was 67 years (47-77) with an FEV1 (percent of predicted) of 30 (17-39). On admission the median arterial oxygen tension (PaO2) was 4.71 kPa (3.45-6.26) on air, and the carbon dioxide tension (PaCO2) was 7.68 kPa (6.85-9.83). With controlled oxygen therapy there was no significant improvement in PaO2, but the median PaCO2 increased significantly to 9.75 kPa (7.04-11.70) (P < 0.05). By using NIPPV with supplemental oxygen it was possible to significantly improve the median PaO2 to 11.25 kPa (6.70-26.90) (P < 0.01) without worsening PaCO2 levels (8.96 kPa; 6.85-13.10). NIPPV was applied by a senior, respiratory physiotherapist and used intermittently depending on patient tolerance and clinical response. The median total time on NIPPV was 27 h, delivered over 1-5 days. One patient found the mask difficult to tolerate beyond a short period of time. NIPPV was well accepted on a general ward by nursing staff. Three patients later died with progressive hypercapnia, despite an initial response; with one of these patients also receiving intubation and mechanical ventilation. A further patient also received intubation and mechanical ventilation and was eventually discharged. NIPPV plus supplemental oxygen offers a method to correct hypoxaemia on a general medical ward without worsening hypercapnia for acute on chronic, hypoxic, hypercapnic respiratory failure, and warrants further investigation.

Randomised controlled trial of nasal ventilation in acute ventilatory failure due to chronic obstructive airways disease.

Acute exacerbations of chronic obstructive airways disease (COAD) are a common cause of admission to hospital, and have a high mortality. Nasal intermittent positive pressure ventilation (NIPPV) has been used successfully in patients with respiratory failure due to neuromuscular and skeletal disorders, but the outcome of treatment in patients with COAD is less well known. We carried out a prospective randomised controlled trial of conventional treatment versus conventional treatment plus NIPPV, in 60 patients with acute ventilatory failure due to exacerbations of COAD. For the NIPPV group there was a rise in pH, compared with a fall in the controls (mean difference of change between the groups 0.046 [95% CI 0.06-0.02, p < 0.001]), and a larger fall in PaCO2 (mean difference in change between the groups 1.2 kPa [95% CI 0.45 to 2.03, p < 0.01]). Median visual analogue scores over the first 3 days of admission showed less breathlessness in the NIPPV group (2.3 cm [range 0.1-5.5]) than in the control group (4.5 cm [range 0.9-8.8]) (p < 0.025). Survival rates at 30 days were compared for intention-to-treat and efficacy populations. In the efficacy mortality comparison, mortality in the NIPPV group was reduced: 1/26 vs 9/30 (relative risk = 0.13, CI = 0.02-0.95, p = 0.014). This effect was less in the intention-to-treat analysis: 3/30 vs 9/30 (relative risk = 0.33, CI = 0.10-1.11, p = 0.106). In patients with acute ventilatory failure due to COAD who received NIPPV there was a significant rise in pH, a reduction in PaCO2 and breathlessness, and reduced mortality.

Humidification as an adjunct to chest physiotherapy in aiding tracheo-bronchial clearance in patients with bronchiectasis.

Humidification of inspired air or oxygen is frequently utilized by respiratory physiotherapists to relieve sputum retention. Cold water, jet nebulizing humidifiers are in widespread use but there has been no previous attempt to investigate the efficacy of this treatment. We have performed a single-blind, cross-over study to quantify the effect of humidification as an adjunct to chest physiotherapy. Seven patients with bronchiectasis completed the trial, with a mean (range) age of 51 years (41-64 years) and mean (range) percent of predicted FEV1 of 46% (29-76%). On 2 days, separated by 1 week, subjects were randomly allocated to humidification or no humidification as a precursor to an optimal chest physiotherapy regimen. A radio-aerosol of human serum albumin millimicrospheres labelled with 99mTechnetium was used to measure sputum clearance by serial gamma camera images. Serial measurements of sputum weight and FEV1 were also recorded. Humidification (30 min) was followed by postural drainage (20 min) with the subject using the forced expiration technique to assist clearance. When humidification was combined with physiotherapy there was a significant increase in total wet weight of sputum (P less than 0.05) with a median (range) increase of 6 g (-9-15.5 g); and a significant increase in total radiolabel clearance (P less than 0.05) with a median (range) increase of 8.7% (1-13%), compared to physiotherapy alone. This study demonstrates that the use of cold water, jet nebulizing humidifiers significantly increases tracheo-bronchial clearance above that of an optimal physiotherapy regimen alone in bronchiectasis.(ABSTRACT TRUNCATED AT 250 WORDS)

Humoral immune responses to gag and env proteins from human immunodeficiency virus type 1 in hemophiliac patients.

Solid-phase enzyme immunoassays using recombinant gag and env proteins were developed to study humoral immune responses to HIV infection in a cohort of 105 hemophiliac patients. Thirteen patients with ARC or AIDS and 92 asymptomatic patients were studied. A cross-sectional study showed a wide range of antibody responses to gag and env proteins; however, the differences between the ARC/AIDS and asymptomatic patients were statistically significant for both antigens (P less than .0004). In a longitudinal study, antibody levels in sera from 11 asymptomatic patients with gag antibody log units less than or equal to 1.5 were compared to levels in sera from 10 ARC/AIDS patients and 8 asymptomatic patients with gag antibody greater than 1.5. These patient groups were followed for comparable periods of time (67.1-71.7 mo). The asymptomatic patients with low gag antibody and the ARC/AIDS patients showed a similar pattern of antibody response to gag protein overtime. In hemophiliac patients with HIV-1 infection a low titer of antibody to gag protein is not invariably associated with clinical deterioration and is not a useful serologic marker of impending progression to AIDS.