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Biomedical subjects

M L Davis

Publications and source records attributed to M L Davis.

At least 19 recordsLinked to original sources
PubMed2004

Ionophore taste preferences of dairy heifers.

Two taste preference studies were conducted using six Holstein heifers in each experiment to determine preferences for no ionophore, lasalocid, or monensin in the diet. In Exp. 1, individually penned (approx. 5 mo old; 220 +/- 14 kg BW) heifers were fed a basal total mixed ration containing 46% corn silage, 46% grass haylage, and 8% soybean meal (DM basis). There were five treatments (mg/kg BW(-1)*d(-1)): 0 ionophore (control), 1 lasalocid (1L), 2 lasalocid (2L), 1 monensin (1M), or 2 monensin (2M). Ionophores were provided as part of the mineral mix that had been added to the control diet and through an ionophore-grain by-product mix to make the 2L and 2M treatments. All five diets were offered for 7 d, with the first 2 d for adaptation and the last 5 d for measurement of feed intake. The most preferred diet was then removed and the study continued with the four remaining diets. The most preferred diets were again eliminated sequentially, so that only two diets remained on d 13 and 14. Each feeding segment ranking of treatment preferences was determined based on the weight of feed refused at the end of each feeding segment. In Exp. 2, six 6-wk-old heifers (75 +/- 5 kg of BW) were individually fed either 0, 1L, or 1M in a study similar to Exp. 1, except that the most preferred diet was removed after 4 d, with the first day for adaptation and the last 3 d for measurement of feed intake. In Exp. 1, orthogonal contrasts indicated that heifers preferred the 1L and 2L diets over the 1M and 2M diets. Preferences between diet concentrations of ionophores (1 and 2 mg/kg of BW; Exp. 1) and the control and ionophore treatments did not differ, nor was there an interaction between ionophores and their concentration. Dairy heifers previously fed lasalocid prefer lasalocid over monensin when given a choice; however, heifers without previous exposure to an ionophore did not indicate a preference (Exp. 2).

Animal Feed↗
PubMed2002

A randomized phase II study of two schedules of bryostatin-1 (NSC339555) in patients with advanced malignant melanoma: A National Cancer Institute of Canada Clinical Trials Group study.

PURPOSE: This study addressed the efficacy and toxicity of the novel compound Bryostatin-1 (NSC 339555), a novel agent with antineoplastic, hematopoietic and immunomodulatory activity in a variety of in vitro and in vivo systems. PATIENTS AND METHODS: This phase II study randomly assigned chemotherapy-naïve patients with untreated metastatic melanoma and measurable disease to two schedules of treatment: Arm A, 25 microg/m2 bryostatin-1 given as a 24 hour continuous infusion weekly or Arm B, 120 microg/m2 bryostatin-1 given as a 72 hour continuous infusion every 2 weeks. Although objective response was assessed using standard NCIC CTG criteria, antitumour activity was assessed using a multivariate endpoint incorporating both response (CR and PR) and early progression (PD at < or = 8 weeks). Seventeen patients were randomized to each arm. RESULTS: Arm A was better tolerated with 86.7% of 15 evaluable patients receiving > or = 90% of planned dose intensity versus 76.5% of 17 evaluable patients in Arm B. On Arm B, three patients experienced serious adverse events and three patients had to be removed from protocol therapy due to toxicity. The most common side effect was myalgia (33% grade 1-2 on Arm A versus 65% on Arm B with 5 patients experiencing grade 3 and one patient grade 4). Lethargy was more common on Arm A but more severe on Arm B. Other side effects such as nausea, diarrhea and headache were generally mild to moderate in nature and occurred with a similar frequency on both arms. Hematologic and biochemical toxicity were minimal. This trial was closed early because the protocol-stopping rule was met based on lack of required responses and on the number of early progressions on both arms. No partial or complete responses were seen; 3 patients randomized to Arm A had stable disease (duration 9-24 weeks) as did 4 patients (duration 10-38 weeks) randomized to Arm B. CONCLUSION: Arm A was better tolerated than Arm B. We conclude that bryostatin-1 has little efficacy in the treatment of metastatic melanoma with either of the schedules studied.

Adult↗
PubMed2001

Nitrogen deposition to and cycling in a deciduous forest.

The project described here seeks to answer questions regarding the role increased nitrogen (N) deposition is playing in enhanced carbon (C) sequestration in temperate mid-latitude forests, using detailed measurements from an AmeriFlux tower in southern Indiana (Morgan-Monroe State Forest, or MMSF). The measurements indicate an average atmosphere-surface N flux of approximately 6 mg-N m(-2) day(-1) during the 2000 growing season, with approximately 40% coming from dry deposition of ammonia (NH3), nitric acid (HNO3), and particle-bound N. Wet deposition and throughfall measurements indicate significant canopy uptake of N (particularly NH4+) at the site, leading to a net canopy exchange (NCE) of -6 kg-N ha(-1) for the growing season. These data are used in combination with data on the aboveground C:N ratio, litterfall flux, and soil net N mineralization rates to indicate the level of potential perturbation of C sequestration at this site.

Ammonia↗
PubMed2000

Mothers with HIV/AIDS and their children: disclosure and guardianship issues.

For many mothers living with HIV/AIDS, whether, when, and how to disclose their HIV diagnosis to their children and arranging for future care are important although agonizing issues. Due to the increasing number of children who lose their mothers to AIDS and the dearth of empirical information about them, these issues are increasingly important to research. This study of 188 HIV-positive mothers and their 267 children of minor age in New York City revealed that only half the mothers had disclosed their HIV diagnosis to at least one of their children and only 57% had made formal plans for the children's care. As expected, older children were more likely to be informed than younger children. Contrary to some previous research, maternal disclosure was not related to ethnicity, advanced illness, improved psychological well-being, or greater or more satisfying social support resources. Implications for future research and provision of services to this group of women are discussed.

Adolescent↗
PubMed1997

Sinusitis: bench to bedside. Current findings, future directions.

Sinusitis, an inflammatory disease of the sinus, is one of the most commonly reported diseases in the United States, affecting an estimated 14% of the population. The prevalence of sinusitis is rising. Between 1990 and 1992, persons with sinusitis reported approximately 73 million restricted activity days-an increase from the 50 million restricted activity days reported between 1986 and 1988. Because critical questions remain unanswered about its cause, pathophysiology, and optimal treatment, sinusitis continues to generate significant health care costs and affects the quality of life of a large segment of the U.S. population. To identify critical directions for research on sinus disease, the American Academy of Allergy, Asthma and Immunology and the American Academy of Otolaryngology-Head and Neck Surgery Foundation, Inc., convened a meeting in January 1996 in collaboration with the National Institutes of Allergy and Infectious Disease. This document summarizes the proceedings of that meeting and presents what is intended to be the background for future investigation of the many unanswered questions related to sinusitis.

Acute Disease↗
PubMed1997

Sinusitis: bench to bedside. Current findings, future directions.

Sinusitis, an inflammatory disease of the sinus, is one of the most commonly reported diseases in the United States, affecting an estimated 14% of the population. The prevalence of sinusitis is rising. Between 1990 and 1992, persons with sinusitis reported approximately 73 million restricted activity days--an increase from the 50 million restricted activity days reported between 1986 and 1988. Because critical questions remain unanswered about its cause, pathophysiology, and optimal treatment, sinusitis continues to generate significant health care costs and affects the quality of life of a large segment of the U.S. population. To identify critical directions for research on sinus disease, the American Academy of Allergy, Asthma and Immunology and the American Academy of Otolaryngology-Head and Neck Surgery Foundation, Inc., convened a meeting in January 1996 in collaboration with the National Institutes of Allergy and Infectious Disease. This document summarizes the proceedings of that meeting and presents what is intended to be the background for future investigation of the many unanswered questions related to sinusitis.

Acute Disease↗
PubMed1994

Ophthalmic findings in scleromyxedema.

PURPOSE: To catalog ophthalmic findings in a cohort of patients with scleromyxedema. METHODS: Thirty-five biopsy-proven patients with scleromyxedema evaluated at the Mayo Clinic in Rochester, Minnesota, from 1960 to 1991 were identified. Eye examinations were performed on 17 of the patients. Ophthalmic findings not attributable to other systemic or ocular disease were recorded. RESULTS: The following abnormalities were considered secondary to scleromyxedema: corneal opacities (2 patients), thickened eyebrow or eyelid skin (4 patients), lagophthalmos (1 patient), and ectropion (2 patients). One patient who had concurrent polyneuropathy, organomegaly, endocrinopathy, monoclonal gammopathy, and skin changes (POEMS) syndrome also had choroidal folds and papilledema. A corneal biopsy in one patient disclosed deposits of acid mucopolysaccharide, consistent with one of two previously published cases. CONCLUSION: A series of patients with scleromyxedema was reviewed. This systemic disorder infrequently may cause visually significant ophthalmic manifestations, including eyelid changes and corneal deposits. Further study is needed to characterize better the nature of the corneal opacities.

Adult↗
PubMed1993

Can the Yale-Brown Obsessive Compulsive Scale be used to assess trichotillomania? A preliminary report.

Given recent conceptualizations of trichotillomania (TM) as a variant of obsessive compulsive disorder (OCD), clinician-rated measures of obsessive compulsive symptoms have been adapted for use in the assessment of TM. Although the reliability and validity of these instruments have been well-documented in patients with OCD, psychometric properties have not been examined systematically in patients with TM. Here, we evaluate the reliability and validity of the Yale-Brown Obsessive Compulsive Scale (Y-BOCS) in a sample of 11 patients with a primary diagnosis of TM. Data addressed the utility of the Y-BOCS for evaluating symptoms of TM, and provided information regarding the proposed overlap between OCD and TM. Initial analyses suggested that interrater reliability, internal consistency, and test-retest reliability for the total score were adequate. However, the range of scores was somewhat restricted, and suggested in particular that interference in daily functioning from TM symptoms is quite low. Both internal consistency and test-retest reliability for the Target Behaviors subscale were inadequate, suggesting that this combined score is inappropriate for use with TM patients. Concurrent validity data using the total score were mixed, although the Y-BOCS did appear to be sensitive to change in TM symptoms over treatment. Implications for the use of the Y-BOCS with TM patients and hypothesized phenomenological differences between TM and OCD are discussed.

Adult↗
PubMed1993

The effects of premenstrual syndrome (PMS) on the female singer.

A review of the medical literature concerning the psychological, physical, and vocal effects of premenstrual syndrome reveals a wide range of significant effects for the female singer and a larger number of proposed treatments. A survey was conducted to evaluate the frequency and severity of 67 general physical and psychological symptoms and 20 vocal symptoms experienced by 104 female singers. The variables of age, menstrual history, voice type, and performing experience were examined. The average number of general symptoms was 33 and the average number of vocal symptoms three. The most frequently reported general symptom was abdominal bloating, while the most frequently reported vocal symptom was difficulty in singing high notes. The subjects reported that symptoms occurred with moderate regularity and severity. At age 35 symptoms decreased in number and severity.

Adult↗
PubMed1992

A comparison of clinical features in trichotillomania and obsessive-compulsive disorder.

Trichotillomania (TM) recently has been conceptualized as a variant of obsessive-compulsive disorder (OCD). However, no systematic data have compared the clinical features of these two disorders. Here we report data from 8 TM and 13 OCD patients which suggest important clinical differences between groups. First, TM patients reported a significantly greater degree of pleasure during hair-pulling than OCD patients reported during performance of ritualistic behaviors. Second, TM was accompanied by significantly fewer associated obsessive-compulsive symptoms. Third, the groups differed with regard to other clinical features including anxiety, depression, and personality characteristics. We conclude that TM is not conceptualized best as a variant of OCD.

Adult↗
PubMed1991

Lack of evidence of Ki-ras codon 12 mutations in melanocytic lesions.

A number of studies have failed to detect point mutations at codon 12 in the Ki-ras gene in melanocytic neoplasms. One recent study, however, has found a high percentage of Ki-ras codon 12 point mutations. In an effort to resolve this difference, the present study examined noncultured melanocytic lesions (i.e., 5 benign nevi, 10 dysplastic nevi, and 8 primary melanomas: 4 in situ and 4 invasive) for point mutations at codon 12 in the first exon of the Ki-ras proto-oncogene using polymerase chain reaction methodology with oligonucleotide hybridization and direct DNA sequencing. The results of this study indicates no detectable mutations in the 12th codon of the first exon of the Ki-ras gene in any premalignant or malignant melanocytic lesion examined.

Base Sequence↗
PubMed1987

Development of a taxonomy of therapist difficulties: initial report.

While psychotherapists discuss amongst themselves and in supervision the struggles they experience face-to-face with their patients, empirical study of therapists' experience of psychotherapy has been scant and there has been little investigation of therapists' difficulties. We require tools for such investigation and in this initial report we describe the development of a taxonomy of situations that psychotherapists experience as difficult and indicate lines of research to which the taxonomy might be applied. We also suggest that our procedure might serve as a model of collective self-study for other groups of practitioner-researchers. Using accounts of our own difficulties as therapists, we constructed a consensual set of experimental categories that could be applied to describe them. These were designated as Therapist (T)-Incompetent, T-Damaging, T-Puzzled, T-Threatened, T-Out of Rapport, T's Personal Issues, Painful Reality/T's Ethical Dilemma (a combined category), T-Stuck, and T-Thwarted. We then employed a fresh set of 30 accounts, which were also drawn from our own experience but had not contributed to the development of the taxonomy, to study the taxonomy's reliability. Each of us rated the presence and predominance of the categories for each of the 30 accounts. Both presence and predominance of all nine categories in the taxonomy could be reliably identified, with about three raters required to ensure good reliability for all categories; alphas (for our group of seven raters) were in the range 0.88-0.95 for presence-absence and 0.83-0.94 for predominance. We conclude that the taxonomy is a serviceable tool for further investigation. We also show that we are discriminable from one another as therapists in terms of the kinds of difficulty we reported, differences amongst us conforming to what we know of one another's therapeutic practice. We note implications for the diagnostic use of the taxonomy in training and supervision.

Clinical Competence↗
PubMed1985

Bone marrow-derived thymic antigen-presenting cells determine self-recognition of Ia-restricted T lymphocytes.

We previously have demonstrated that in radiation-induced bone marrow chimeras, T-cell self-Ia restriction specificity appeared to correlate with the phenotype of the bone marrow-derived antigen-presenting (or dendritic) cell in the thymus during T-cell development. However, these correlations were necessarily indirect because of the difficulty in assaying thymic function directly by adult thymus transplant, which has in the past been uniformly unsuccessful. We now report success in obtaining functional T cells from nude mice grafted with adult thymuses reduced in size by treatment of the thymus donor with anti-thymocyte globulin and cortisone. When (B10 Scn X B10.D2)F1 nude mice (I-Ab,d) are given parental B10.D2 (I-Ad) thymus grafts subcutaneously, their T cells are restricted to antigen recognition in association with I-Ad gene products but not I-Ab gene products. Furthermore, thymuses from (B10 X B10.D2)F1 (I-Ab,d)----B10 (I-Ab) chimeras transplanted 6 months or longer after radiation (a time at which antigen-presenting cell function is of donor bone marrow phenotype) into (B10 X B10.D2)F1 nude mice generate T cells restricted to antigen recognition in association with both I-Ad and I-Ab gene products. Thymuses from totally allogeneic bone marrow chimeras appear to generate T cells of bone marrow donor and thymic host restriction specificity. Thus, when thymus donors are radiation-induced bone marrow chimeras, the T-cell I-region restriction of the nude mice recipients is determined at least in part by the phenotype of the bone marrow-derived thymic antigen presenting cells or dendritic cells in the chimeric thymus.

Animals↗
PubMed1985

A scanning electron microscopic study of the early response of lung tissue to amosite asbestos exposure.

The early response of the lung to a single exposure of amosite asbestos was examined via scanning electron microscopy and correlated light microscopy in the guinea pig model. At 2 h post-exposure, lesions consisted of discrete areas of atelectasis with influx of neutrophils and macrophages. Free asbestos fibres were evident in affected areas. By 4 h post exposure, affected regions were more extensive with phagocytic cell numbers increased both in reactive sites and in adjacent tissue. By 1 day post-exposure, the inflammatory response was well developed and encompassed wide areas of the lung. Activated phagocytes were congregated in atelectatic regions and on blood vessel walls. Numerous macrophages were present even in alveoli distant to reactive loci. The 6 day and 12 day time frames marked a subsiding of the inflammatory response in which macrophages outnumbered PMNs in the comparably fewer reactive areas. There was a notable decrease both in marginated leucocytes and in accumulations of phagocytes in tissue adjacent to affected regions.

Acute Disease↗
PubMed1984

Self-recognition specificity expressed by T cells from nude mice. Absence of detectable Ia-restricted T cells in nude mice that do exhibit self-K/D-restricted T cell responses.

The presence in athymic nude mice of precursor T cells with self-recognition specificity for either H-2 K/D or H-2 I region determinants was investigated. Chimeras were constructed of lethally irradiated parental mice receiving a mixture of F1 nude mouse (6-8 wk old) spleen and bone marrow cells. The donor inoculum was deliberately not subjected to any T cell depletion procedure, so that any potential major histocompatibility complex-committed precursor T cells were allowed to differentiate and expand in the normal parental recipients. 3 mo after reconstitution, the chimeras were immunized with several protein antigens in complete Freund's adjuvant in the footpads and their purified draining lymph node T cells tested 10 d later for ability to recognize antigen on antigen-presenting cells of either parental haplotype. Also, their spleen and lymph node cells were tested for ability to generate a cytotoxic T lymphocyte (CTL) response to trinitrophenyl (TNP)-modified stimulator cells of either parental haplotype. It was demonstrated that T cell proliferative responses of these F1(nude)----parent chimeras were restricted solely to recognizing parental host I region determinants as self and expressed the Ir gene phenotype of the host. In contrast, CTL responses could be generated (in the presence of interleukin 2) to TNP-modified stimulator cells of either parental haplotype. Thus these results indicate that nude mice which do have CTL with self-specificity for K/D region determinants lack proliferating T cells with self-specificity for I region determinants. These results provide evidence for the concepts that development of the I region-restricted T cell repertoire is strictly an intrathymically determined event and that young nude mice lack the unique thymic elements responsible for education of I region-restricted T cells.

Animals↗