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B Baldwin

Publications and source records attributed to B Baldwin.

52 records · Page 3Linked to original sources
PubMed1989

Expression of infectious woodchuck hepatitis virus in murine and avian fibroblasts.

The liver is the primary site for replication of the hepadnavirus genome. We asked whether the posttranscriptional phase of the viral replication cycle would depend on hepatocyte-specific functions. For this purpose, we assayed a previously constructed chimera between sequences of the cytomegalovirus immediate-early promoter-enhancer region and woodchuck hepatitis virus (WHV) (C. Seeger and J. Maragos, J. Virol. 63:1907-1915, 1989) for its ability to direct the synthesis of infectious WHV in hepatoma cells and in murine and avian fibroblast cells. Viruslike particles containing WHV DNA were produced transiently in transfected hepatoma cells and in fibroblasts. Inoculation of woodchucks with culture medium from hepatoma cells or fibroblasts transfected with viral DNA led to productive WHV infection, as observed following infection of woodchucks with serum from WHV-infected animals. These results demonstrate that posttranscriptional events of the hepadnavirus replication cycle are not dependent on hepatocyte-specific functions.

Animals↗
PubMed1989

Natural history of woodchuck hepatitis virus infections during the course of experimental viral infection: molecular virologic features of the liver and lymphoid tissues.

In this study, the kinetic patterns of woodchuck hepatitis virus (WHV) infection were monitored in the liver and the five primary components of the lymphoid system (peripheral blood lymphocytes, lymph nodes, bone marrow, spleen, and thymus). Groups of woodchucks experimentally infected with a standardized inoculum of WHV were sacrificed at different times over a 65-week period beginning in the preacute phase of viral infection and continuing to the period of serologic recovery or the establishment of chronic infections and subsequent hepatocellular carcinoma. Infection by WHV was not limited to the liver but involved the major components of the lymphoid system during all stages of virus infection. A complex series of kinetic patterns was observed for the appearance of WHV DNA in the different lymphoid compartments and the liver during the entire course of viral infection. A progressive evolution of different WHV genomic forms related to the replicative state of WHV was also observed. Lymphoid cells of the bone marrow were the first cells in which WHV DNA was detected, followed in order by the liver, the spleen, peripheral blood lymphocytes, lymph nodes, and finally the thymus. Several differences were observed in the cellular WHV DNA patterns between woodchucks that developed chronic WHV infections and those that serologically recovered from acute WHV infections. The observations compiled in this study indicate that the host lymphoid system is intimately involved in the natural history of hepadnavirus infections from the earliest stages of virus entry.

Animals↗
PubMed1989

Report from the American Nurses' Association council on psychiatric and mental health nursing.

Society has demonstrated a major need for expanded gerontological and geropsychiatric nursing services. Current needs have not yet been met and the call for service will increase throughout the balance of this century and beyond. Social responsiveness demands that nurses: (1) formally establish their clinical authority in care of the aged; (2) lobby for public policy which enables the provider professional to control the practice environment, rather than be controlled by it; (3) improve the educational preparation of nurses to care for the aged; and (4) expand the professions' scientific and research base in this area. The national professional organization of registered nurses, the American Nurses' Association, provides leadership to influence the course of nursing as it continues to provide vital services in a dramatically changing environment.

Aged↗
PubMed1984

Serum progesterone profiles and corpora lutea of pregnant, postpartum, barren and isolated females in a laboratory colony of woodchucks (Marmota monax).

Female woodchucks, greater than or equal to 1 year old (n = 10) or recently weaned locally in the wild at 42 degrees N (n = 10), were maintained indoors in standard laboratory animal facilities from one summer solstice to the next except for those killed after 11 months of study. Available ambient light was supplemented with a 12L: 12D incandescent light schedule. Food and water were provided ad libitum, except for a 63-day period when feeding and supplemental lighting were discontinued, starting at the winter solstice . Temperatures fluctuated with outdoor temperatures greater than or equal to 4 degrees C. During the winter, females within each age class (adult vs. subadult ) were housed with (n = 5) or without (n = 5) a male cagemate , and scored for hibernation at variable intervals. Blood samples for serum progesterone assay were collected at intervals of 1-4 weeks. Birth of litters occurred in 2 of 5 adults (March 19, April 2) and in 0 of 5 subadults . Neither the incidence nor frequency of hibernation were correlated to the occurrence of pregnancy or to the extent or timing of elevations in progesterone in barren or isolated females. Serum progesterone was elevated during the 31-day gestation and for 1-2 months postpartum in the 2 fertile colonized animals and in 7 others captured pregnant during the same breeding season and which gave birth April 12-24. Postpartum animals had progesterone levels equal or above those near midgestation and had 3.1 +/- 0.2-mm diameter corpora lutea which numbered 2.5 +/- 0.3 per ovary.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1983

Corpora lutea of pregnancy and elevated serum progesterone during pregnancy and postpartum anestrus in woodchucks (Marmota monax).

Serum samples (n = 62) were collected from wild-caught woodchucks (n = 45) that were nonpregnant (n = 3), pregnant (n = 25) or postpartum (n = 34) when bled at the time of capture and/or necropsy, or following maintenance and observation for variable periods of time. Progesterone concentrations were determined by radioimmunoassay and related to the actual or estimated time from parturition which occurs at 31 days postcoitum in this species. Mean serum progesterone levels during the initial, middle and last third of pregnancy were 6.5 +/- 1.7, 22.5 +/- 3.7 and 16.8 +/- 3.2 ng/ml, respectively. Postpartum progesterone levels were elevated above basal values (less than or equal to 0.3 ng/ml) in both lactating and nonlactating animals for 2-3 months postpartum and were not consistently basal until more than 90 days postpartum. Mean progesterone levels at less than 30, 30-60, 61-90, and greater than 90 days postpartum were 25.1 +/- 6.2, 60.6 +/- 18.5, 22.8 +/- 8.7 and 0.4 +/- 0.2 ng/ml, respectively, and those at 30-60 days postpartum were greater than those at midpregnancy (P less than 0.05). Mean corpus luteum diameters were also greater (P less than 0.05) postpartum (2.9 +/- 0.3 mm) than during pregnancy (1.5 +/- 0.3 mm). The correlation between placental scars and ipsilateral corpora lutea indicated that the corpora lutea observed postpartum were the corpora lutea of the recent pregnancy. The termination of each uterine horn in a separate external cervical os precluded the occurrence of transcornual migration.(ABSTRACT TRUNCATED AT 250 WORDS)

Amenorrhea↗
PubMedDate not supplied

Evaluating the appropriateness of a nurse expert system's patient assessment.

The Urological Nursing Information System (UNIS) is an expert-system prototype designed to help nurses perform patient assessments on elderly nursing home residents known to be incontinent of urine. A study was conducted to evaluate the appropriateness of the patient-assessment parameters stored in the knowledge base of UNIS. These parameters were stored as objects--a kind of template for holding related clusters of data, facts, rules, hypotheses, or any knowledge in a single conceptual unit. Each object was rated for its appropriateness by 14 nurse experts. Resulting scores ranged from +14 to -14. The effect of the nurse experts' educational backgrounds and work settings on their ratings were also analyzed. The results indicated that 95.6% of the objects received favorable ratings from the nurse experts. Educational background was not a significant factor chi 2 = 5.2, but work settings did have a significant affect chi 2 = 21.07, p = 0.01.

Aged↗
PubMedDate not supplied

Clinically relevant optimization of 3-D conformal treatments.

In this paper a method of computer-aided optimization of 3-D conformal treatment plans is presented which incorporates models to predict the clinical consequences of resulting dose distributions. Even though these models are simplistic, it is submitted that their intelligent use leads to treatment plans which indicate lower normal tissue complications and higher tumor control. Dose distribution data, biological models, and observed normal tissue and tumor response data are used to compute tumor control and normal tissue complication probabilities for each of the critical normal structures encountered in a treatment plan. These quantities are combined into a single score using an objective function which incorporates the importance of each end point as assessed by the physician. Using the "simulated annealing" method of optimization, the beam weights are adjusted to maximize the score. Additional constraints are applied to ensure consistency of the results of optimization with the judgment of the physician. These optimization methods have been applied to conformal treatment plans consisting of multiple fixed fields with conformal field shaping. The results indicate that the methods presented have considerable potential.

Aged↗