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Biomedical subjects

R S Lane

Publications and source records attributed to R S Lane.

At least 19 recordsLinked to original sources
PubMed1992

Risk factors for Lyme disease in a small rural community in northern California.

A 1-year prospective study of risk factors for seropositivity to and contraction of Lyme disease among members of a small rural community (population, approximately 150) was conducted in northwestern California in 1988-1989. The initial rate of seropositivity for Borrelia burgdorferi for 119 current or former residents ranged from 15 to 20% among three laboratories, with statistically significant interlaboratory agreement. Questionnaires were completed by 93 current residents at entry and 80 residents a year later to evaluate the association of serologic status with 20 categorical and 47 continuous variables. Seropositive subjects had resided in the study area about 2 years longer, were bitten by unspecified biting flies more often, and were less likely to have engaged in hiking than seronegative subjects. One of 59 seronegative subjects seroconverted a year later (annual incidence = 1.7%). The cumulative frequency of seropositivity for Lyme disease in the study population was > or = 24%. Of 83 subjects examined physically, 13 were diagnosed as having definite and 18 as having probable Lyme disease. The seropositivity rate was significantly higher (38.7%) among individuals with definite/probable Lyme disease than in asymptomatic subjects (13.5%). Subjects who were seronegative or free of Lyme disease reported nearly as many tick bites as subjects who were seropositive or had a diagnosis of the disease. Age, time spent outdoors in the fall multiplied by a clothing index, and woodcutting were significantly associated with Lyme disease in logistic regression analyses.

Adult↗
PubMed1992

Blood donation.

Explore the source record for details and available documents.

Antibodies, Viral↗
PubMed1992

Lyme disease in California: a novel enzootic transmission cycle of Borrelia burgdorferi.

Knowledge of zoonotic transmission cycles is essential for the development of effective strategies for disease prevention. The enzootiology of Lyme disease in California differs fundamentally from that reported from the eastern United States. Woodrats, not mice, serve as reservoir hosts, and Ixodes neotomae, a nonhuman-biting tick, maintains the agent of Lyme disease, Borrelia burgdorferi, in enzootic cycles. The western black-legged tick, Ixodes pacificus, is the primary vector to humans, but it appears to be an inefficient maintenance vector. Isolates of B. burgdorferi from California exhibit considerable antigenic heterogeneity, and some isolates differ strikingly from isolates recovered from this and other geographic regions.

Animals↗
PubMed1992

Production and therapeutic use of a factor XI concentrate from plasma.

Factor XI deficiency is an uncommon bleeding disorder usually manifested by excessive bleeding after surgery or trauma. Until recently the only effective therapy has been fresh-frozen plasma (FFP) infusion. We describe the efficacy and safety of a new factor XI concentrate produced from human donor plasma by a modification of the method used for antithrombin III concentrate. The mean recovery of factor XI in the circulation measured on 62 occasions was approximately 91% of the injected dose, and the mean half-disappearance-time was 52 h. The concentrate was used for 31 invasive procedures in 30 patients, including 16 patients who had a definite bleeding tendency on previous occasions, with normal haemostasis being achieved in all but 1. Only 1 patient (previously experiencing allergy to FFP) experienced adverse effects during infusion. Monitoring of liver function tests and viral antibody status in suitable patients has shown no evidence of transmission of hepatitis viruses, HIV-1 or parvovirus B19. We conclude that this concentrate provides effective treatment for patients with factor XI deficiency. Preliminary results suggest safety from virus transmission, but this needs to be established in further studies of previously untreated patients.

Adolescent↗
PubMed1992

First isolation of Borrelia burgdorferi in southern California.

The Lyme disease spirochete, Borrelia burgdorferi Johnson, Schmid, Hyde, Steigerwalt & Brenner, was isolated from the blood of a dusky-footed wood rat, Neotoma fuscipes Baird, in the San Bernardino Mountains of southern California. Antigenic, protein, and molecular analyses demonstrated that the isolate varied slightly from most isolates of B. burgdorferi from northern California and was clearly distinct from other species of Borrelia that are endemic to the state. This is the first reported isolate of B. burgdorferi from southern California and demonstrates that the Lyme disease spirochete is enzootic in mountains near the major human population center of the state.

Animals↗
PubMed1992

The western fence lizard Sceloporus occidentalis: evidence of field exposure to Borrelia burgdorferi in relation to infestation by Ixodes pacificus (Acari: Ixodidae).

The role of the Western fence lizard Sceloporus occidentalis in the enzootiology of the Lyme disease spirochete Borrelia burgdorferi was evaluated in the Hopland and Ukiah areas of Mendocino County, California. In 1989, half of 74 lizards collected monthly from April to October at Hopland were infested by the immature western black-legged tick Ixodes pacificus at a mean intensity of 6.0 ticks per lizard. The prevalence of infestation of lizards by immature I. pacificus (36 of 73) at Ukiah was similar, but the mean intensity (12.9) was approximately twice as great. Overall, zero of 223 larvae and 2 (0.6%) of 330 nymphs from both sites were found to contain spirochetes by direct immunofluorescence. Larval and nymphal I. pacificus fit the negative binomial distribution in spring, and the prevalence and abundance of these stages were significantly greater in spring than in summer at both sites. Spirochetes were not visualized in thick blood films prepared from 133 lizards from both localities. Plasma antibodies against B. burgdorferi were detected in seven of 10 experimentally inoculated lizards, in five (8%) of 63 lizards from Hopland, and in 10 (14%) of 70 lizards from Ukiah. Adult lizards had a significantly greater tick burden and seropositivity rate than juvenile lizards only at Ukiah. In 1991, efforts to detect and culture spirochetes from the blood of 21 wild-caught lizards and from the tissues of 189 associated ticks that fed xenodiagnostically on them were unsuccessful.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗
PubMed1991

Wood rats and kangaroo rats: potential reservoirs of the Lyme disease spirochete in California.

The etiologic agent of Lyme disease, Borrelia burgdorferi Johnson, Schmid, Hyde, Steigerwalt & Brenner, was isolated repeatedly from dusky-footed wood rats, Neotoma fuscipes Baird, and California kangaroo rats, Dipodomys californicus Merriam, in northern California. All animals were collected in a region endemic for Lyme disease but for which the natural reservoir of B. burgdorferi was unknown. Similar attempts to isolate spirochetes from lizards, other species of rodents, jack rabbits, and deer between 1987 and 1991 were unsuccessful. Spirochetes isolated from wood rats and kangaroo rats were antigenically similar to strains of B. burgdorferi that had been isolated previously from the western black-legged tick, Ixodes pacificus Cooley & Kohls, in California. Similar enzootic cycles involving wood rats or kangaroo rats should be sought in other regions of the United States where the reservoirs of this spirochete are unknown.

Animals↗
PubMed1991

Lyme disease in California: interrelationship of ixodid ticks (Acari), rodents, and Borrelia burgdorferi.

The association of immature ixodid ticks, several species of rodents, and the Lyme disease spirochete, Borrelia burgdorferi Johnson, Schmid, Hyde, Steigerwalt & Brenner, was studied in two habitats in northern California in spring and summer 1985 and year-round in 1986. A total of 428 rodents were collected from ecotonal chaparral and a woodland-grass-rock outcrop; the former habitat yielded six species, the latter three species. The deer mouse, Peromyscus maniculatus (Wagner), and the piñon mouse, P. truei (Shufeldt), were the dominant species year-round and collectively comprised 78% of rodents captured within chaparral and 87% from the rock outcrop in 1986. In both habitats, rodents were trapped most frequently in winter and spring, and least often in summer and fall. A total of 306 rodent blood films from all six species were assayed for spirochetes by direct immunofluorescence; of these, only one film prepared from P. truei (n = 123 films from 53 individual mice) was found to contain spirochetes. Immature western black-legged ticks, Ixodes pacificus Cooley & Kohls, and Pacific Coast ticks, Dermacentor occidentalis Marx, were collected from each species of rodent. Larvae of I. pacificus infested P. maniculatus and P. truei in low numbers year-round, but nymphs of this tick rarely parasitized these rodents. D. occidentalis larvae infested P. maniculatus and P. truei in spring and particularly in summer; nymphal ticks infested these mice primarily in summer. The efficiency of visual inspection for collecting immatures of these ticks from P. maniculatus ranged from 45 to 69% in spring and summer, whereas the efficiency of a drop-off technique appeared to be 100%. Spirochetes were detected in <1% of D. occidentalis larvae (n = 310) and nymphs (n = 120), and in approximately 4% of I. pacificus larvae (n = 75) derived from these hosts. The potential significance od these findings in the enzootiology of B. burgdorferi is discussed.

Animals↗
PubMed1991

Relationship of Borrelia burgdorferi to its arthropod vectors.

At the IV International Conference on Lyme Borreliosis, a workshop was held to identify the unique development of the Lyme disease spirochete, Borrelia burgdorferi, in its established and suspected arthropod vectors. The following is a summary of the panel's discussions of research aspects concerning relationship(s) of this borrelia to its vectors, and the mode(s) of its transmission to animal hosts.

Animals↗
PubMed1990

Clearance of Rh D-positive red cells with monoclonal anti-D.

Two human monoclonal antibodies, one IgG3 and one IgG1, with anti-Rh D specificity, were tested for their ability to clear red cells. Samples of red cells from 12 D-positive subjects were sensitised in vitro with various amounts of antibody, the number of antibody molecules bound to the cells was estimated, and the cells were reinjected into the donor's circulation. Both antibodies mediated clearance but substantially fewer IgG3 than IgG1 antibody molecules were required to produce a given rate of clearance. The IgG3 antibody was slightly more effective than polyclonal anti-D, as judged by comparison with previously published results. Since there is believed to be an association between the rate of red cell clearance by anti-D and the ability of the antibody to suppress D immunisation, the IgG3 monoclonal antibody may prove suitable for the immunoprophylaxis of Rh D haemolytic disease.

Antibodies, Monoclonal↗
PubMed1990

Host-seeking behavior of adult Ixodes pacificus (Acari: Ixodidae) as determined by flagging vegetation.

Diurnal host-seeking by adults of the western black-legged tick, Ixodes pacificus Cooley & Kohls in relation to vegetative habitat type and meterological factors was investigated at a coastal and an inland site in northern California. Host-seeking behavior and relative tick abundance were determined with a tick drag method from late fall to midwinter 1987-1988. At the inland site, tick abundance usually was significantly greater in chaparral-grassland ecotones than in adjoining dense chaparral on the south-facing slope of a mountaintop, whereas both of these vegetative types produced significantly fewer ticks on a north slope compared with a contiguous south-facing slope. There was no evidence for an association between tick abundance and plant species within ecotonal chaparral. Multiple regression analyses revealed that tick abundance in ecotonal chaparral at the inland site and in grassland at the coastal site was not associated consistently with either ambient temperature or relative humidity. Compared with the inland site, ticks were considerably more abundant at the coastal site where sampling occasionally yielded more than 100 ticks per 100 drag samples. The incidence of infection with Borrelia burgdorferi Johnson, Schmid, Hyde, Steigerwalt & Brenner, the etiologic agent of Lyme borreliosis, in adult ticks collected in the morning (1.5%) versus afternoon (2.2%), and in male (1.3%) versus female ticks (2.5%), at the coastal site in winter was similar.

Animals↗
PubMed1990

Survey of birds and lizards for ixodid ticks (Acari) and spirochetal infection in northern California.

A total of 138 birds (24 species) was captured in an oak woodland between December 1988 and June 1989 at the University of California, Sierra Foothill Range Field Station, Yuba County, Calif. Ticks were not found on 71 birds captured between December 1988 and March 1989. Five subadult Ixodes pacificus Cooley & Kohls were removed from 3 of 67 birds caught between April and June 1989. These three birds, an orange-crowned warbler (Vermivora celata (Say], a lazuli bunting (Passerina amoena (Say], and a chipping sparrow (Spizella passerina (Bechstein], represent new host records for I. pacificus in California. Tissues from two ticks and thick blood films prepared from 126 birds tested negative for spirochetes by direct immunofluorescence (DI). A total of 172 larval and 197 nymphal I. pacificus was removed from 15 of 16 western fence lizards (Sceloporus occidentalis Baird & Girard) caught between April and June 1989 in the same location as were birds. Thick blood films prepared from all 16 lizards and tissue smears from 334 of the ticks (143 larvae and 191 nymphs) were DI test-negative for spirochetes. One (1.1%) of 93 adult I. pacificus collected at the bird-lizard capture site in February 1989 was infected with spirochetes that resembled B. burgdorferi.

Animals↗
PubMed1990

A simple plasma anticoagulant-exchange method to increase the recovery of factor VIII in therapeutic concentrates.

Donor blood, primarily anticoagulated by acid citrate dextrose formula A (ACD-A), was separated by means of the HemaScience Autopheresis C plasmapheresis device. The citrated plasma was collected directly into a solution of heparin and calcium chloride to achieve a final plasma-ionised calcium concentration of approximately 2 mM, and a heparin concentration of 1.0 IU/ml. Heparin at this concentration provided adequate anticoagulation, and did not result in insoluble cryoprecipitates. Three pairs of donor-matched 4-kg plasma pools (anticoagulant-exchanged variant and ACD-A-anticoagulated control) were constructed and subsequently fractionated to an intermediate stage. The mean recovery of factor VIII from 3 anticoagulant-exchanged pools (394 IU/kg) was 23% greater than the mean recovery from the matched control pools (319 IU/kg). This increased recovery was not achieved at the expense of specific activity.

Anticoagulants↗
PubMed1990

DNA and protein analyses of tick-derived isolates of Borrelia burgdorferi from California.

Nine isolates of Borrelia burgdorferi from ixodid ticks collected in northern California were characterized. Restriction endonuclease analysis, pulsed-field gel electrophoresis, and Western blot (immunoblot) analysis were used in this study. Four isolates were very similar to each other. The others shared some similarities but were classified as having unique genotypes. A strain from an Ixodes neotomae tick displayed the greatest genetic and antigenic diversity when compared to the isolates collected from Ixodes pacificus ticks. A computerized library based on DNA banding patterns of the isolates by restriction enzyme analysis is also reported. This library was created by using a scanning laser densitometer.

Animals↗
PubMed1990

Interlaboratory and intralaboratory comparisons of indirect immunofluorescence assays for serodiagnosis of Lyme disease.

A conventional indirect immunofluorescence assay (IFA) and an anticomplement indirect immunofluorescence assay (ACIF) for detecting serum antibodies to Borrelia burgdorferi in humans were evaluated during a prevalence survey in northern California. Sera obtained from 119 current or former residents of an area in which Lyme disease is endemic were split and tested by the IFA in two laboratories and the ACIF in a third. The seropositivity rate ranged from 15 to 20% with 88 to 93% agreement among laboratories. Interlaboratory agreement was statistically highly significant in each of the three pairwise comparisons and was positively associated with clinical manifestations of Lyme disease. Intralaboratory agreement ranged from 93 to 96% in two laboratories and was also statistically highly significant. Immunoblotting confirmed 100 of 101 of the nondiscrepant immunofluorescence test results and likewise was positively correlated with the degree of interlaboratory agreement. The ACIF was found to be a highly specific test (100% specificity) with a much lower cutoff titer (1:8) than the conventional IFA (determined to be 1:128 or 1:256 in two laboratories) for detecting antibodies to B. burgdorferi. It also appeared to be more sensitive (80 versus 68%) than the IFA as determined by comparative immunoblotting, though the absolute sensitivity of the ACIF for serodiagnosis of early Lyme disease has yet to be determined. Significant serologic cross-reactivity was demonstrated between B. burgdorferi, Borrelia coriaceae, and Borrelia hermsii by the IFA, which may confound spirochetal serosurveys in California where all three spirochetes are known to coexist.

Antibodies, Bacterial↗