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At least 883 records · Page 49Linked to original sources
PubMed1992

Effects of permethrin on aquatic organisms in a freshwater stream in south-central Alaska.

Permethrin (0.5%) was applied to individual Lutz spruce, Picea x lutzii Little, to protect them from attack by spruce beetles, Dendroctonus rufipennis (Kirby). Residue levels were monitored in a freshwater stream above, adjacent to, and below the treatment site at intervals before, during, and after treatment. Maximum residue levels in the stream within the treatment site ranged from 0.05 +/- 0.01 ppb 5 h after treatment to 0.14 +/- 0.03 ppb 8-11 h after treatment, with a decrease to 0.02 +/- 0.01 ppb 14 h after treatment. Levels of permethrin in standing pools near the stream within the treatment site were 0.01 +/- 0.01 ppb. Numbers of drifting aquatic invertebrates increased 2-fold during treatment and 4-fold 3 h after treatment and declined to before spray numbers within 9 h. Terrestrial insects did not appear to respond to treatments because none was found in stream drift samples. Trout fry (Dolly Varden), aquatic insect larvae, and periphyton (attached algae) within and below the treatment site during and after treatment did not show signs of mortality compared with an upstream untreated control site.

Alaska↗
PubMed2002

Selection effect of needle exchange in Anchorage, Alaska.

Participation bias (selection bias) may be a problem in studies that attempt to evaluate the effects of needle-exchange programs (NEPs). The present study looked at only those injection drug users (IDUs) who were randomly placed in the needle-exchange condition in a two-arm randomized clinical trial of needle exchange. Time to follow-up between the experimental NEP condition (n = 296; median = 261 days) and pharmacy sales condition (n = 304; median = 256 days) was not statistically different [chi(2) (1, N = 600) = 0.42, P =.52]. Within the NEP condition, a similar analysis comparing time to follow-up between IDUs who used the NEP (n = 65; median = 199 days) and those who refrained from using the NEP (n = 231; median = 286 days) was highly significant, chi(2) (1, n = 296) = 17.3, P=.0001. The final logistic regression model predicting use of the NEP was the log 10 transformation of the number of times injected heroin in the last 30 days (odds ratio [OR ]=4.9, confidence interval [CI ]2.8, 8.9), ever injected amphetamine in the last 30 days (OR =4.9, CI 1.09, 22.5), and ever shared injection equipment in the last 30 days (OR =2.9, CI 1.5, 5.5). Within the NEP condition, follow-up rates differed between those who used the NEP and those who did not use it. Of drug users randomly assigned to an NEP, the ones who actually used the NEP had higher levels of drug use. Predictors of who used the NEP were consistent with the studies of Hagen et al. This study demonstrates that selection bias occurs among IDUs who use NEPs.

Alaska↗
PubMed1977

Epidemiology of hepatitis B in two Alaska communities.

In 1973, epidemiologic and serologic data related to hepatitis B infection were collected from the residents of two remote Alaskan Eskimo villages located in an area of high hepatitis incidence. A total of 418 sera were tested by solid-phase radioimmunoassay for heaptitis B surface antigen (HBsAg) and antibody to that antigen (anti-HBs). The overall infection prevalence of 54.8% in the two villages included a 13.9% prevalence of HBsAg and a 40.9% prevalence of anti-HBs. Families containing an individual with HBsAg had significantly higher infection prevalence than those without an antigen carrier. Larger households had higher proportions of infected members than smaller households. The data suggest that efficient transmission of hepatitis B virus occurs within the household setting in these villages by other than classically established parenteral routes.

Adolescent↗
PubMed1985

The descriptive epidemiology of sudden infant deaths among natives and whites in Alaska.

From 1976-1980, the incidence of sudden infant deaths among native Alaskans was 2.9 times higher than that for white Alaskans (6.28 per 1,000 live births among natives vs. 2.14 per 1,000 live births among whites). Linked birth and death vital records data were used to compare the age-at-death distributions and relative risks associated with demographic factors for natives and whites. The purpose of the comparisons was to seek clues to the etiology of sudden infant death in natives. The age-at-death distributions for natives and whites were virtually identical (mean age at death 90.4 +/- 7.0 days for natives; 87.8 +/- 6.5 days for whites). The associations between the risk of sudden death and birth weight, marital status, season of birth, and residence were similar for natives and whites. The risk associated with young maternal age (less than 20 years) was significantly higher for whites than for natives (3.20 vs. 1.38). The sex ratio for sudden deaths among whites significantly favored males (relative risk = 1.78; female = reference); a significant sex ratio was not apparent for natives. Vital records data were useful for confirming the native-white difference in sudden infant death incidence, but not for elucidating etiologic differences between natives and whites.

Age Factors↗
PubMed1987

Hepatitis B virus replication and tuberculin reactivity: studies in Alaska.

In a previous study in 1982-1984 of southeast Asian refugees in Philadelphia, the authors found that hepatitis B virus carriers who reacted to a tuberculin (purified protein derivative (PPD)) skin test were more likely to be negative for the hepatitis B e antigen (HBeAg) than carriers who did not react to PPD. Because it was not known whether the PPD reactivity was due to natural infection or vaccination with bacille Calmette-Guérin (BCG), the authors conducted a further study in 1985 in Alaskan Native hepatitis B carriers, a group not vaccinated with BCG. The inverse association of HBeAg and PPD reactivity was confirmed across all age groups and was similar in magnitude to that observed in the refugee population. The host response to tubercle bacilli may inhibit the replication of hepatitis B virus. If the host response to BCG is similar, BCG vaccination may be of therapeutic value in chronic hepatitis B infection.

Adolescent↗
PubMed1987

Pharyngeal carriage and acquisition of anticapsular antibody to Haemophilus influenzae type b in a high-risk population in southwestern Alaska.

Haemophilus influenzae type b disease in Alaskan Eskimos is characterized by greatly increased disease incidence at younger ages. This suggests that Eskimo infants have increased exposure to the disease. Exposure was studied in 1982-1983 in children less than age three years who lived in four Eskimo villages, as well as in a random sample of their family members (354 people from 132 households). During a 12-month period, up to four pharyngeal cultures and two serum specimens were obtained from each participant. Colonization with H. influenzae type b was relatively uncommon (overall 2.5% of cultures, 6.8% of individuals) and was not associated with age, sex, season, or prior incidence of disease in the village. Biotyping and outer-membrane-protein typing of H. influenzae type b isolates revealed homogeneity within villages, with differences between villages. Matched sera revealed a significant decline in H. influenzae type b capsular antibody in the course of the study year. However, pharyngeal carriage of H. influenzae type b was associated with increases in antibody for carriers and members of their households. Antibody levels were positively associated with age. Only one case of H. influenzae type b disease developed during the study. Low carriage of H. influenzae type b was coincident with low incidence of disease and declining levels of capsular antibody in these villages. Mechanisms for increased exposure which would not be reflected in high carriage rates may exist for these young children.

Adolescent↗