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Biomedical subjects

B R Keith

Publications and source records attributed to B R Keith.

At least 19 recordsLinked to original sources
PubMed2005

Effect of presynchronization using prostaglandin F2alpha and a milk-ejection test on pregnancy rate after the timed artificial insemination protocol, Ovsynch.

The objective of this research was to determine if PGF2alpha-induced milk letdown (ML) is an accurate indicator of luteolysis, allowing cows to be synchronized to begin the Ovsynch protocol (GnRH-7d-PGF2alpha-2d-GnRH-24h-AI) at the most beneficial time of the estrous cycle (days 5-9), and determine if this would improve pregnancy rate (PR). Lactating Holstein cows between 55 and 70 days in milk were used to evaluate the ML test and PR after the Ovsynch protocol, when initiated on the basis of the test result (PROSYNCH). PROSYNCH cows (n = 60) had one teat cannulated to test for ML and were treated with 500 microg cloprostenol, PGF2alpha analogue (PG). Cows with ML were started on Ovsynch 10 days later, and those without started 3 days later. Cows in the control group (OVSYNCH, n = 64) were injected with physiological saline and observed for ML. This group was started on Ovsynch 10 days after saline treatment. Milk samples were collected thrice weekly to determine progesterone concentrations. ML indicated luteolysis with a sensitivity of 98% and a specificity of 60%. The positive and negative predictive values were 83 and 92%, respectively. Pregnancy rates were 48% for PROSYNCH and 52% for OVSYNCH (P = 0.72). When data from both groups were combined, PR was greater in cows that started the Ovsynch protocol in stage 2 of the estrous cycle (days 5-9, 67%) than all other stages (stage 1: days 1-4, 35%; stage 3: days 10-16, 45%; stage 4: days 17-21, 42%; P < 0.01). The proportion of animals with ovulation after GnRH#1, luteolysis after PGF2alpha, and ovulation after GnRH#2 were all greater in the PROSYNCH group (77% versus 55%, P < 0.02; 83% versus 66%, P < 0.03; 97% versus 84%, P < 0.03, respectively). Therefore, the ML test indicated luteolysis with sufficient precision to time the initiation of the Ovsynch protocol between days 5 and 9 of the cycle, however, this did not alter PR compared to starting the protocol randomly throughout the cycle. Initiating the Ovsynch protocol between days 5 and 9 of the cycle increased PR, and improved the efficacy of each injection.

Animals↗
PubMed2001

The characterization of novel, dual ErbB-2/EGFR, tyrosine kinase inhibitors: potential therapy for cancer.

The type I receptor tyrosine kinases constitute a family of transmembrane proteins involved in various aspects of cell growth and survival and have been implicated in the initiation and progression of several types of human malignancies. The best characterized of these proteins are the epidermal growth factor receptor (EGFR) and ErbB-2 (HER-2/neu). We have developed potent quinazoline and pyrido-[3,4-d]-pyrimidine small molecules that are dual inhibitors of ErbB-2 and EGFR. The compounds demonstrate potent in vitro inhibition of the ErbB-2 and EGFR kinase domains with IC(50)s <80 nM. Growth of ErbB-2- and EGFR-expressing tumor cell lines is inhibited at concentrations <0.5 microM. Selectivity for tumor cell growth inhibition versus normal human fibroblast growth inhibition ranges from 10- to >75-fold. Tumor growth in mouse s.c. xenograft models of the BT474 and HN5 cell lines is inhibited in a dose-responsive manner using oral doses of 10 and 30 mg/kg twice per day. In addition, the tested compounds caused a reduction of ErbB-2 and EGFR autophosphorylation in tumor fragments from these xenograft models. These data indicate that these compounds have potential use as therapy in the broad population of cancer patients overexpressing ErbB-2 and/or EGFR.

Animals↗
PubMed2001

The effects of the novel, reversible epidermal growth factor receptor/ErbB-2 tyrosine kinase inhibitor, GW2016, on the growth of human normal and tumor-derived cell lines in vitro and in vivo.

The epidermal growth factor receptor (EGFR) and ErbB-2 transmembrane tyrosine kinases are currently being targeted by various mechanisms in the treatment of cancer. GW2016 is a potent inhibitor of the ErbB-2 and EGFR tyrosine kinase domains with IC50 values against purified EGFR and ErbB-2 of 10.2 and 9.8 nM, respectively. This report describes the efficacy in cell growth assays of GW2016 on human tumor cell lines overexpressing either EGFR or ErbB-2: HN5 (head and neck), A-431 (vulva), BT474 (breast), CaLu-3 (lung), and N87 (gastric). Normal human foreskin fibroblasts, nontumorigenic epithelial cells (HB4a), and nonoverexpressing tumor cells (MCF-7 and T47D) were tested as negative controls. After 3 days of compound exposure, average IC50 values for growth inhibition in the EGFR- and ErbB-2-overexpressing tumor cell lines were < 0.16 microM. The average selectivity for the tumor cells versus the human foreskin fibroblast cell line was 100-fold. Inhibition of EGFR and ErbB-2 receptor autophosphorylation and phosphorylation of the downstream modulator, AKT, was verified by Western blot analysis in the BT474 and HN5 cell lines. As a measure of cytotoxicity versus growth arrest, the HN5 and BT474 cells were assessed in an outgrowth assay after a transient exposure to GW2016. The cells were treated for 3 days in five concentrations of GW2016, and cell growth was monitored for an additional 12 days after removal of the compound. In each of these tumor cell lines, concentrations of GW2016 were reached where outgrowth did not occur. Furthermore, growth arrest and cell death were observed in parallel experiments, as determined by bromodeoxyuridine incorporation and propidium iodide staining. GW2016 treatment inhibited tumor xenograft growth of the HN5 and BT474 cells in a dose-responsive manner at 30 and 100 mg/kg orally, twice daily, with complete inhibition of tumor growth at the higher dose. Together, these results indicate that GW2016 achieves excellent potency on tumor cells with selectivity for tumor versus normal cells and suggest that GW2016 has value as a therapy for patients with tumors overexpressing either EGFR or ErbB-2.

Animals↗
PubMed1995

Screening for child-reported behavioral and emotional problems in primary care pediatrics.

In light of the findings that mother-completed checklists do not adequately reflect children's perceptions of their own adjustment, two child-completed questionnaires were assessed as screening measures for behavioral or emotional problems with 50 children seen for well-child examinations. Case criterion was child-reported DSM-III symptoms through a clinical interview. Support was provided for the Revised Children's Manifest Anxiety Scale but not the Children's Depression Inventory as a child-reported screening measure. Moreover, the findings indicated that both mother-completed and child-completed measures are needed to screen adequately for behavioral or emotional problems of children seen in a primary care pediatric clinic.

Child↗
PubMed1994

Psychological adjustment of children with sickle cell disease: stability and change over a 10-month period.

Rates of poor psychological adjustment of children with sickle cell disease remained relatively constant over initial and follow-up assessment points. However, there was relatively little stability in the classification of the adjustment of individuals, low congruence in specific behavior problem patterns and diagnoses in accordance with the Diagnostic and Statistical Manual of Mental Disorders (3rd ed.; American Psychiatric Association, 1980), and less stability in child adjustment by child report than by mother report. With initial levels of adjustment controlled, children's strategies for coping with pain accounted for a significant increment in child-reported symptoms (19%) and mother-reported internalizing behavior problems (8%) at follow-up beyond the contribution of illness and demographic parameters and follow-up interval. The findings suggest that children's coping strategies are a salient intervention target for enhancing adjustment.

Adaptation, Psychological↗
PubMed1994

Stability and change in the psychological adjustment of mothers of children and adolescents with cystic fibrosis and sickle cell disease.

Found moderate stability in the classification of maternal adjustment in two longitudinal studies of mothers of children and adolescents with cystic fibrosis and sickle cell disease. In terms of the transactional stress and coping model, stable poor maternal adjustment was associated with higher levels of appraisal of daily stress and palliative coping and low levels of family supportiveness. With initial levels of maternal adjustment, demographic parameters, and follow-up interval controlled, concurrent levels of daily stress accounted for significant portions of variance in maternal adjustment at follow-up for both illness groups. In addition, illness severity, child psychological adjustment, and family conflict added significant increments to maternal adjustment at follow-up in the cystic fibrosis group. Findings are discussed in terms of a basis for subsequent intervention studies to enhance the adjustment of mothers of children with chronic illness.

Adaptation, Psychological↗
PubMed1993

Role of child and maternal processes in the psychological adjustment of children with sickle cell disease.

In this study, 64% of children aged 7-12 years with sickle cell disease were found to have a parent-reported behavior problem, and 50% met the criteria for a Diagnostic and Statistical Manual of Mental Disorders (3rd ed.) diagnosis based on a structural clinical interview of the child. Internalizing types of behavior problems and diagnoses were the most frequent. Support was provided for a transactional stress and coping model in delineating the processes associated with child adjustment. In particular, maternal anxiety accounted for 16%-33% of the variance in mother-reported internalizing and externalizing behavior problems, respectively, and child pain-coping strategies accounted for 21% of the variance in child-reported adjustment problems.

Adaptation, Psychological↗
PubMed1993

Psychological adjustment of mothers of children and adolescents with sickle cell disease: the role of stress, coping methods, and family functioning.

Assessed the psychological adjustment of 78 mothers of children and adolescents (7-17 years of age) with sickle cell disease. Support was provided for a transactional stress and coping model in delineating the processes associated with maternal adjustment. In particular, poor maternal adjustment was associated with use of palliative coping methods and high levels of stress related to daily hassles. Variables of the model accounted for 55% of the variance in maternal psychological distress.

Adaptation, Psychological↗
PubMed1993

Sickle cell disease pain in children and adolescents: change in pain frequency and coping strategies over time.

Examined 9-month follow-up data obtained from children and adolescents with sickle cell disease (SCD) and their parents participating in a longitudinal study of pain coping strategies. Of 87 subjects completing the baseline assessment of pain coping strategies, 70 (80%) of their parents completed a structured pain interview assessing their child's health care use and activity reduction during painful episodes over the follow-up period. Regression analyses controlling for age and pain frequency revealed that baseline Coping Attempts were associated with higher levels of school, household, and social activity during painful episodes. Baseline Passive Adherence was associated with more frequent health care contacts during the subsequent 9 months. Increases in Negative Thinking over time were associated with further increases in health care contacts during the follow-up period. Comparing pain coping strategies assessed at baseline to pain coping strategies measured at follow-up revealed that pain coping strategies were relatively stable over time for younger children but changed more for adolescents.

Adaptation, Psychological↗
PubMed1993

Mother-child agreement on the child assessment schedule with nonreferred children: a research note.

This study replicated with nonreferred children the finding with psychiatrically referred children that mother-child concordance was a function of symptom type. Low mother-child concordance for internalizing problems and moderate concordance for externalizing problems characteristic of psychiatric samples was found to generalize to nonreferred children. Furthermore, mother-child concordance was also found to be a function of child gender and age. The implications of these findings for screening or assessment of nonreferred children were examined.

Adult↗
PubMed1993

Screening for behavioral and emotional problems in primary care pediatrics.

Case identification indexes based on the mother-completed Missouri Children's Behavior Checklist (MCBC) were compared with pediatrician identification of behavioral and emotional problems in 41 children seen for well-child examinations. Case identification indexes also were examined as a function of child gender and age and maternal education. The criterion was presence of DSM-III diagnoses determined through Child Assessment Schedule interviews of child or mother. The MCBC yielded better case identification indexes and improvements in both overidentification and underidentification rates. Pediatrician identification indexes were directly related to maternal education and MCBC identification indexes were inversely related to child age. The findings indicate the necessity for including child report, as well as mother report, in screening procedures that are incorporated into primary care pediatric practice.

Child↗
PubMed1992

In vivo antitumor activity and metabolism of a series of 5-deazaacyclotetrahydrofolate (5-DACTHF) analogues.

This study compares the antitumor activity and metabolism of the purine de novo biosynthesis inhibitor 5-deazaacyclotetrahydrofolate and a series of analogues. All compounds have similar IC50 values for inhibition of MCF-7 cell growth, activity of glycineamide ribonucleotide transformylase, and methotrexate uptake by MOLT-4 cells, the latter a measure of cellular uptake potential. Only 5-deazaacyclotetrahydrofolate and the 2'-fluoro and 3'-fluoro analogues demonstrated significant inhibition of colon 38 adenocarcinoma or HCT-116 colon carcinoma growth in vivo. This correlated with the Km of these compounds for folylpolyglutamate synthetase. 5-Deazaacyclotetrahydrofolate and 2'-fluoro-5-deazaacyclotetrahydrofolate which displayed the strongest antitumor activity were detectable in colon 38 tumor tissue 24 hr after dosing and were present nearly exclusively as the polyglutamated species. These results indicate that polyglutamation represents a critical step in the in vivo antitumor activity of these compounds.

Acyltransferases↗
PubMed1992

The Missouri Children's Behavior Checklist behavioral classification system: a construct validity study with nonreferred children.

This study provides validity information about the Missouri Children's Behavior Checklist (MCBC) classifications system with nonreferred children. MCBC behavior patterns of 41 children were related to DSM-III symptomatology ascertained through a structured clinical interview, the Child Assessment Schedule, conducted with the mother. The findings indicated that considering the Undifferentiated Disturbance pattern as an indicator of poor adjustment may be unwarranted with nonreferred children.

Child↗
PubMed1990

In vivo and in vitro metabolism of 5-deazaacyclotetrahydrofolate, an acyclic tetrahydrofolate analogue.

5-Deazaacyclotetrahydrofolate is a cytotoxic tetrahydrofolate analogue which inhibits glycinamide ribonucleotide transformylase (Kelley et al., J. Med. Chem., 33: 561-567, 1990). Cultured mouse L-cells and human MCF-7 and MOLT-4 cells concentrated the drug several hundred-fold after 24 h of continuous exposure to a cytotoxic level (100-200 nM) of radiolabeled drug. High performance liquid chromatography analysis revealed that each cell type metabolized greater than or equal to 80% of the internalized drug to polyglutamated forms, which are more potent glycinamide ribonucleotide transformylase inhibitors. In L-cells, 45% of the polyglutamated metabolites were also N-formylated. The pharmacokinetics and distribution of [14C]-deazaacyclotetrahydrofolate were studied in C57BL/6 male mice. Its plasma half-life was 2.15 h. Radiolabel was concentrated to well above plasma level in the kidney, pancreas, and liver. Metabolism was examined in tumor-bearing and in normal mice. Twenty-four h after a single i.p. injection (50 mg/kg), drug equivalents were 0.6 nmol/g (83% polyglutamated) in colon-38 adenocarcinoma carried s.c., 2.4 nmol/g (100% polyglutamated) in ascitic P388 cells, and 3.7 nmol/g (76% polyglutamated and approximately 20% formylated) in mouse liver. Elimination was mostly in the urine as unmetabolized drug. Feces contained 5-deazaacyclotetrahydropteroate (parent compound less glutamate). In conclusion, 5-deazaacyclotetrahydrofolate was shown to be concentrated to well above the extracellular level and metabolized to more active polyglutamated forms by transformed cells grown in culture and in mice.

Animals↗
PubMed1990

Effect of type 1 piliation on in vitro killing of Escherichia coli by mouse peritoneal macrophages.

Escherichia coli K-12 mutants possessing defined lesions affecting type 1 pilus production, receptor binding, or length were examined for their ability to resist killing by mouse peritoneal macrophages in vitro. Mutants were mixed pairwise at known ratios in wells containing macrophages, and after incubation, the ratio of the survivors was assayed. The difference in phagocytic killing between type 1 piliated cells and isogenic nonpiliated cells was significant, the piliated cells being approximately threefold more resistant. Pilus length had little effect upon survival, as the long-piliated mutants were no more resistant to killing than the normal-length parents. Interestingly, the receptor-binding function of type 1 pili was most important in effecting resistance, as mutants lacking the ability to bind receptor were killed as effectively as nonpiliated mutants. These data are consistent with the notion that pili actually impede killing by macrophages rather than serve as passive physical barriers to uptake.

Animals↗
PubMed1989

In vivo efficacy of zidovudine (3'-azido-3'-deoxythymidine) in experimental gram-negative-bacterial infections.

The therapeutic efficacy of orally administered zidovuldine (3'-azido-3'-deoxythymidine) was determined in animals infected with Escherichia coli and Salmonella dublin. The 50% effective dose (ED50) of zidovudine (9.6 to 11.8 mg/kg of body weight) compared favorably with that of trimethoprim (19.4 to 22.2 mg/kg) in mice with systemic E. coli infection. At 50 mg/kg, both zidovudine and ampicillin reduced the number of bacteria in the kidneys of mice and prevented lethal infection in mice with ascending pyelonephritis caused by E. coli. Zidovudine prevented a lethal S. dublin infection in calves over a wide dose range (8.0 to 31.0 mg/kg per day). Zidovudine levels in plasma of uninfected mice were 28.2 +/- 4.5 and 7.9 +/- 2.2 micrograms/ml at 30 and 60 min, respectively, exceeding the MICs for the bacteria used in the infections. Few zidovudine-resistant strains were observed. The in vivo data raise the possibility that zidovudine may have an antibacterial effect in patients receiving this therapy.

Ampicillin↗
PubMed1988

Comparison of response formats for Multidimensional Health Locus of Control Scales: six levels versus two levels.

Two formats of the Multidimensional Health Locus of Control (MHLC) Scales were administered to 54 college students. Each subject completed the MHLC Scales in the standard 6-level response format (ranging from strongly disagree to strongly agree) and in a revised 2-level format (ranging from disagree to agree). Comparisons of internal consistency measures, principal components, and classification of subjects into groups indicate that the 2-level response format yields comparable data to those obtained with the 6-level format, particularly when classification of subjects is the goal.

Adult↗