External ocular hyperemia: a quantifiable indicator of spacecraft air quality.

BACKGROUND: Eye irritation consistently ranks as a top astronaut complaint but is difficult to measure. Exposure to internal air pollution hypothetically disrupts the eye's tear film, thereby exposing the crewmembers' conjunctivae to the irritating effects of the recirculated, contaminant-laden atmosphere of the space vehicle. Causes elude engineers and toxicologists, who report that measured irritants remain below established Spacecraft Maximum Allowable Concentrations. Lack of objective ocular endpoints stymies efforts to identify etiologies. HYPOTHESIS: Computers offer a practical means of analyzing ocular hyperemia in space. METHODS: We use computer analysis to quantify redness and blood vessels of digitized images of bulbar conjunctivae in near real time. Custom software masks artifacts, lids and lashes for each photographic or telemedicine ocular image, Algorithms then generate semi-independent measurements of hyperemia. Computed difference scores between 34 pairs of images were compared with subjective difference scores as voted on by a panel of ophthalmology residents. RESULTS: Objective data were reliably extracted from ocular images and significantly correlated (r = 0.583, p < 0.05) with subjective scores. CONCLUSIONS: This ground-based methodology generates accurate and reliable ocular endpoint data without mass, volume, or power penalty. To assist in identifying and eliminating onboard ocular irritants, these objective data can be regressed against independent variables such as mission elapsed time, subjective astronaut complaints, levels of chemical and electromagnetic contaminants, nephthelometric and barothermal data. As missions lengthen, sensitive tools such as hyperemia quantification will become increasingly important for assessing and optimizing spacecraft environments.

Automatic quantitative measurement of ocular hyperemia.

Evaluation of ocular hyperemia has been an important assessment in research studies of effects of contact lenses, medications, and pollutants on the eye. Hyperemia has been difficult to quantitate objectively. The purpose of this study was to validate a computer based image analysis system to quantitate hyperemia automatically and objectively in pixelated images of the external eye using two measures, the percent of the red color, RR, and the fraction of pixels which are blood vessels, VA. Validation was against an established photographic reference scale of ocular hyperemia and against the clinical pharmacologic effects of 0.5% dapiprazole hydrochloride, known to increase hyperemia, and 2.5% phenylephrine hydrochloride, known to decrease hyperemia. Color transparencies from the reference scale were converted to digital images. Temporal and nasal regions of the external eye were imaged directly to magnetic disk before and after pharmacologic intervention. Custom software automatically excluded unwanted regions, and quantitative image analysis produced RR and VA. RR and VA were each correlated with the reference scale. For each region and for each pharmacologic intervention, the mean RR and the mean VA, respectively, were compared at time zero and at a mean elapsed time of 713 +/- 47 s. RR and VA consistently increased as the hyperemia in the reference scale increased. Pearson correlation coefficients were 0.98 and 0.99, respectively, (p < 0.01). At 713 +/- 47 s after each pharmacologic intervention, RR and VA increased and decreased as expected (p < 0.001). Thus, this study successfully validated the methodology against expert clinical judgment and was able to measure automatically and objectively clinical changes in ocular hyperemia.

Angular kyphosis as an indicator of the prevalence of Pott's disease in Transkei.

To understand better the prevalence, distribution and major causes of sagittal spinal deformity in a rural homeland, the authors conducted a study of angular kyphosis in the spines of 2,329 Transkei patients. Thirty-one (1.33%) had angular kyphosis. Lateral chest radiographs were obtained from 22 of these patients. Radiographic kyphotic angles ranged from 28 degrees to 130 degrees (mean: 70.3 +/- 7.6). The vast majority (81%) demonstrated classical clinical and/or radiographic findings of tuberculous aetiology. Less frequent aetiologies included fractures (2), osteoporosis (1), congenital malformation (1) and kyphosis of unknown origin (2). Eleven of the kyphotic patients were seeking care for unrelated problems and were asymptomatic in respect of their kyphoses. As a subset, the asymptomatic individuals demonstrated a similar aetiological distribution, with 73% strongly suggestive of tuberculous aetiology. The prevalence of asymptomatic angular kyphosis in this unselected Transkei patient population was 0.47% +/- 0.14%. In this hospital-based study, angular kyphosis proved a valuable marker for spinal tuberculosis. Because tuberculous spondylitis is more successfully treated when detected early, spinal palpation should be included in the routine physical examination of patients or populations at risk for tuberculosis.

Unsuspected varicella-zoster virus encephalitis in a child with acquired immunodeficiency syndrome.

We report a case of progressive encephalitis caused by varicella-zoster virus (VZV) in an adolescent with hemophilia and acquired immunodeficiency syndrome but without cutaneous signs of VZV infection. Magnetic resonance imaging of the brain demonstrated an abnormally increased periventricular signal in T2-weighted images. Infection with VZV was proved by in situ hybridization and immunofluorescence staining of brain tissue, which showed histologic evidence of herpesvirus infection. Encephalitis caused by infection with VZV is a potentially treatable complication of acquired immunodeficiency syndrome and requires a high index of suspicion for diagnosis.

Early bacteriologic, immunologic, and clinical courses of young infants with cystic fibrosis identified by neonatal screening.

To understand better the events associated with the initiation of lung disease in young children with cystic fibrosis (CF), we prospectively performed a longitudinal study examining the early bacteriologic, immunologic, and clinical courses of 42 children with CF diagnosed after identification by neonatal screening. Serial evaluations included history and physical examination, chest radiographs, throat cultures for bacteria, and determinations of serum immunoglobulin levels and circulating immune complexes. At a mean follow-up age of 27 months, 19% of the children had serial throat cultures positive for Pseudomonas aeruginosa; the first positive culture was found at a mean age of 21 months. In three infants the initial P. aeruginosa isolates were mucoid. As determined by typing with a DNA probe, serial P. aeruginosa isolates from each patient were identical over time but were genetically distinct from isolates recovered from other patients. Of 11 infants with P. aeruginosa, nine (82%) had previous isolates of Staphylococcus aureus or Haemophilus influenzae; all had received prior antibiotic therapy. In comparison with other infants with CF, children with P. aeruginosa grown on serial throat cultures more frequently had daily cough (p less than 0.01), lower chest radiograph scores (p less than 0.05), and elevated levels of circulating immune complexes (p less than 0.01). None of the study infants had persistent hypogammaglobulinemia or hypergammaglobulinemia. We conclude that (1) S. aureus and H. influenzae remain the isolates most frequently recovered from infants with CF; (2) initial recovery of P. aeruginosa by throat culture is often preceded by the onset of chronic respiratory signs; (3) elevations of circulating immune complexes can occur early, often after the initial recovery of P. aeruginosa; and (4) early P. aeruginosa isolates are genetically distinct, demonstrating the lack of cross-colonization in this newborn population.

Absence of interferon in sera of patients with Kawasaki syndrome.

We measured serum interferon concentrations in 42 patients with Kawasaki syndrome. The children ranged in age from 7 months to 6 years. All acute sera were obtained within 12 days of the onset of fever. Convalescent sera (illness day 19 to 56) were available from 25 of 42 patients. Sera were also obtained from 40 controls ranging in age from 2 months to 12 years. Control sera included healthy children (n = 14), children with bacterial infection (n = 10) and children with viral infection (n = 16). Sera were coded and interferon concentrations were measured blindly using human diploid fibroblast cell monolayers challenged with 10(4) plaque-forming units of vesicular stomatitis virus. Specimens from 10 of 16 patients with viral infection were positive for interferon. Three of 10 patients with bacterial infection had detectable serum interferon. No interferon was detected in specimens from the 14 healthy control children or the 42 children with Kawasaki syndrome. Despite the use of a sensitive assay we were unable to detect interferon in the sera of patients with Kawasaki syndrome.

Molecular analysis of hemolytic and phospholipase C activities of Pseudomonas cepacia.

By using a gene-specific fragment from the hemolytic phospholipase C (PLC) gene of Pseudomonas aeruginosa as a probe and data from Southern hybridizations under reduced stringency conditions, we cloned a 4.2-kb restriction fragment from a beta-hemolytic Pseudomonas cepacia strain which expressed hemolytic and PLC activities in Escherichia coli under the control of the lac promoter. It was found, by using a T7 phage promoter-directed expression system, that this DNA fragment carries at least two genes. One gene which shares significant DNA homology with both PLC genes from P. aeruginosa encodes a 72-kDa protein, while the other gene encodes a 22-kDa protein. When both genes on the 4.2-kb fragment were expressed from the T7 promoter in the same cell, hemolytic and PLC activities could be detected in the cell lysate. In contrast, when each individual gene was expressed in different cells or when lysates containing the translated products of each separate gene were mixed, neither hemolytic activity nor PLC activity could be detected. Clinical and environmental isolates of P. cepacia were examined for beta-hemolytic activity, PLC activity, sphingomyelinase activity, and reactivity in Southern hybridizations with a probe from P. cepacia which is specific for the larger gene which encodes the 72-kDa protein. There were considerable differences in the ability of the different strains to express hemolytic and PLC activities, and the results of Southern DNA-DNA hybridizations of the genomic DNAs of these strains revealed considerable differences in the probe-reactive fragments between high- and medium-stringency conditions as well as remarkable variation in size and number of probe-reactive fragments among different strains. Analysis of the genomic DNAs from hemolytic and nonhemolytic variants of an individual strain (PC-69) by agarose gel electrophoresis. Southern hybridization, and transverse alternating pulsed field gel electrophoresis suggests that the conversion of the hemolytic phenotype to the nonhemolytic phenotype is associated with either the loss of a large plasmid (greater than 200 kb) or a large deletion of the chromosome of P. cepacia PC-69.

Congenital cytomegalovirus infection as a preventable complication of maternal transfusion. A case report.

Transfusion-mediated cytomegalovirus (CMV) infection among neonates and nonpregnant, adult female surgical patients has been described thoroughly. A case of symptomatic congenital CMV infection developed after a maternal transfusion during pregnancy. It is estimated that 2.5-12.5% of individual blood units mediate CMV infection though inadvertent transfusion of CMV-infected leukocytes. The use of CMV-seronegative or deglycerolized blood may eliminate or considerably reduce the risk of transfusion-mediated primary CMV infection in pregnant women and their fetuses. CMV-seronegative or deglycerolized blood is used routinely in the case of CMV-susceptible neonates and immunocompromised individuals who require a transfusion. Whenever possible, CMV-seronegative or deglycerolized blood should be used for transfusions in pregnant women who are CMV seronegative or whose serologic status is unknown.

Molecular epidemiology of Pseudomonas aeruginosa--urinary tract infections in paraplegic patients.

84 Pseudomonas aeruginosa strains from 29 paraplegic patients with urinary tract infections (UTI) and from the water reservoirs of specialized wards in two German hospitals were typed using a P. aeruginosa-specific DNA probe. P. aeruginosa strains were present in 51% of all accessible water reservoirs, including sinks of wash-basins and toilets in the wards. 14 of the 29 patients with UTI (48%) were infected by P. aeruginosa strains which were also isolated from these sources. Groups of up to four patients were infected by single strains. Some of the strains persisted in the wards and were isolated from the water reservoirs five to eight months after causing UTI. 89.5% of the investigated water samples yielded P. aeruginosa strains which were identical with strains from up to nine other sites. The wide distribution of single P. aeruginosa genotypes in the ward, the isolation of strains causing UTI from rooms inaccessible to the patients, and the outbreak of UTI caused by single, identical P. aeruginosa strains in groups of patients within short time periods, suggest that the strains are distributed by the personnel rather than by the patients who for the most part are immobile.

Pseudomonas aeruginosa cross-colonization and persistence in patients with cystic fibrosis. Use of a DNA probe.

To investigate cross-colonization with and persistence of Pseudomonas aeruginosa in cystic fibrosis (CF), 181 isolates from 76 CF patients were typed using a P. aeruginosa-specific DNA probe. Whereas sibling pairs predominantly harboured genotypically identical P. aeruginosa strains, all of the other patients harboured different strains. Seventy-nine per cent (22/31) of the infected CF patients harboured the same strains at the beginning and the end of a summer camp. A change of strains was seen in 10% (3/31) of the patients at the end of the camp. Forty-six per cent (6/13) of the patients who were apparently initially uninfected, acquired P. aeruginosa by the end of the period. Genotyping proved that strain change or acquisition was due to cross-colonization in four of nine cases. Very little P. aeruginosa was isolated from the inanimate environment. Persistence of P. aeruginosa after a temporary loss due to antibiotic therapy was seen in 12/16 paired patient strains before and after antibiotic therapy. Thus, suppression followed a flare-up seemed to occur in these patients rather than eradication and a new infection. When 35 patients were followed over a period of 6 months, 7 (20%) changed the strain in their sputum. Only one of 43 patients harboured two different P. aeruginosa strains simultaneously over a long period.

Role of respiratory syncytial virus in early hospitalizations for respiratory distress of young infants with cystic fibrosis.

To determine the frequency of respiratory syncytial virus (RSV) as the cause of hospitalization for acute pulmonary exacerbations in young infants with cystic fibrosis (CF), and to assess the clinical effects of RSV infections, we prospectively followed 48 children with a diagnosis of CF after identification by newborn screening. At a mean follow-up age of 28.8 months (range 5 to 59), 18 infants (38%) had been hospitalized a total of 30 times for acute respiratory distress. At the time of admission, 18 infants (60%) were less than 12 months, 8 (27%) between 12 and 24 months, and 4 more than 2 years of age. The RSV was identified in seven hospitalized infants, as determined by fluorescent antibody, immunoassay, or culture. Before admission with RSV infection, one of the seven infants had chronic respiratory signs, none had Brasfield chest x-ray scores below 20, and a previous throat culture was positive for Staphylococcus aureus in one infant. Hospitalizations were prolonged (mean duration 22 days), and were characterized by significant morbidity, with three infants (43%) requiring mechanical ventilation and five infants (71%) requiring home oxygen therapy for persistent hypoxemia at discharge. At a mean follow-up age of 26 months, these infants more frequently have chronic respiratory signs (p less than 0.01) and lower chest radiograph scores (p less than 0.05) than other CF infants. These findings demonstrate that RSV is an important cause of early acute respiratory tract morbidity in young infants with CF, and suggest the need for studying new strategies to implement early and aggressive antiviral therapy in young infants with CF.

Development of resistance in Pseudomonas aeruginosa to imipenem, norfloxacin, and ciprofloxacin during therapy: proof provided by typing with a DNA probe.

Differentiating reinfection from the acquisition of resistance in strains of Pseudomonas aeruginosa after antimicrobial therapy is difficult because currently used epidemiological markers are not stable genetic markers. We previously established that a 741-base pair PstI-NruI restriction fragment upstream from the Exotoxin A structural gene is a sensitive, specific, and stable epidemiological marker for P. aeruginosa. Therefore, we used this fragment as a probe in Southern hybridization to compare pre- and post-therapy isolates of P. aeruginosa. The susceptible and resistant pairs were recovered from multiple sources (including sputum, blood, and urine) from patients treated with various doses of imipenem (n = 15), norfloxacin (n = 6), and ciprofloxacin (n = 4). Southern blot analysis showed identity between the pre- and post-therapy isolates in 23 of the 25 pairs. In the majority of pairs studied, failure to eradicate P. aeruginosa after therapy with imipenem, norfloxacin, and ciprofloxacin was due to the development of resistance rather than to reinfection.