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Biomedical subjects

P Hellings

Publications and source records attributed to P Hellings.

At least 19 recordsLinked to original sources
PubMed2001

B7 interactions with CD28 and CTLA-4 control tolerance or induction of mucosal inflammation in chronic experimental colitis.

CD28-B7 interaction plays a critical costimulatory role in inducing T cell activation, while CTLA-4-B7 interaction provides a negative signal that is essential in immune homeostasis. Transfer of CD45RB(high)CD4(+) T cells from syngeneic mice induces transmural colon inflammation in SCID recipients. This adoptive transfer model was used to investigate the contribution of B7-CD28/CTLA-4 interactions to the control of intestinal inflammation. CD45RB(high)CD4(+) cells from CD28(-/-) mice failed to induce mucosal inflammation in SCID recipients. Administration of anti-B7.1 (but not anti-B7.2) after transfer of wild-type CD45RB(high)CD4(+) cells also prevented wasting disease with colitis, abrogated leukocyte infiltration, and reduced production of proinflammatory cytokines IL-2 and IFN-gamma by lamina propria CD4(+) cells. In contrast, anti-CTLA-4 treatment led to deterioration of disease, to more severe inflammation, and to enhanced production of proinflammatory cytokines. Of note, CD25(+)CD4(+) cells from CD28(-/-) mice similar to those from the wild-type mice were efficient to prevent intestinal mucosal inflammation induced by the wild-type CD45RB(high) cells. The inhibitory functions of these regulatory T cells were effectively blocked by anti-CTLA-4. These data show that the B7-CD28 costimulatory pathway is required for induction of effector T cells and for intestinal mucosal inflammation, while the regulatory T cells function in a CD28-independent way. CTLA-4 signaling plays a key role in maintaining mucosal lymphocyte tolerance, most likely by activating the regulatory T cells.

Abatacept↗
PubMed2001

Deletion of the hypoxia-response element in the vascular endothelial growth factor promoter causes motor neuron degeneration.

Hypoxia stimulates angiogenesis through the binding of hypoxia-inducible factors to the hypoxia-response element in the vascular endothelial growth factor (Vegf) promotor. Here, we report that deletion of the hypoxia-response element in the Vegf promotor reduced hypoxic Vegf expression in the spinal cord and caused adult-onset progressive motor neuron degeneration, reminiscent of amyotrophic lateral sclerosis. The neurodegeneration seemed to be due to reduced neural vascular perfusion. In addition, Vegf165 promoted survival of motor neurons during hypoxia through binding to Vegf receptor 2 and neuropilin 1. Acute ischemia is known to cause nonselective neuronal death. Our results indicate that chronic vascular insufficiency and, possibly, insufficient Vegf-dependent neuroprotection lead to the select degeneration of motor neurons.

Amyotrophic Lateral Sclerosis↗
PubMed2000

The Waldeyer's ring.

The palatine tonsils, nasopharyngeal tonsil (adenoid) and lingual tonsil constitute the major part of Waldeyer's ring or nasal-associated lymphoid tissue (NALT), with the tubal tonsils and lateral pharyngeal bands as less prominent components. The lymphoid tissue of Waldeyer's ring is located at the gateway of the respiratory and alimentary tract and belongs to the mucosa-associated lymphoid tissue (MALT). As tonsils are the first site of encounter with inhaled and ingested micro-organisms, they are considered the first line of defense against exogenous aggressors. The generation of B cells in the germinal centers of the tonsil is one of the most essential tonsillar functions. This manuscript aims to review the anatomy and current knowledge on the immunologic function of the Waldeyer's ring.

Antigens, CD↗
PubMed1996

Routine determination of flumequine in kidney tissue of pig using automated liquid chromatography.

A high-performance liquid chromatographic assay is described as a routine analytical method for the determination of flumequine (FLU) and its hydroxylated metabolite (OH-FLU) in pig kidney tissue. Kidney samples (2 g) containing FLU and OH-FLU were extracted by liquid-liquid extraction with ethyl acetate (10 ml). Analytical separations were performed by reversed-phase HPLC with fluorometric detection at 252 nm excitation and 356 nm emission under gradient conditions. The mobile phase was acetonitrile-2.7.10(-3) M oxalic acid in water (pH 2.5). The assay is specific and reproducible within the flumequine range of 0.050-2.5 micrograms/g and recovery at 0.050 microgram/g was 94.8%.

Administration, Oral↗
PubMed1995

Determination of fumagillin in muscle tissue of rainbow trout using automated ion-pairing liquid chromatography.

A high-performance liquid chromatographic assay is described as a routine analytical method for the determination of fumagillin in rainbow trout muscle tissue. Muscle tissue samples (1 g) containing fumagillin were deproteinized with 8 ml of an acetonitrile-water mixture (2:6, v/v). The extracts were purified with a Bond Elut Octyl C8 cartridge column, washed with a water-methanol mixture (95:5, v/v; 4 ml) and fumagillin was eluted with acetonitrile (1 ml). Analytical separations were performed by reversed-phase HPLC with UV detection at 351 nm under gradient conditions. The mobile phase was acetonitrile-0.005 M tetrabutyl ammonium phosphate in water (pH 7.8). The assay is specific and reproducible within the fumagillin range of 20-1000 ng/g and recovery at 20 ng/g was 69.2%. Sample preparation involves the use of a robotic sample preparation system. Gravimetric validation of all operations enabled Good Laboratory Practices to be observed.

Animals↗
PubMed1989

A case study of qualitative versus quantitative reviews: the maternal-infant bonding controversy.

This study used meta-analysis methodology to examine a series of studies in maternal-infant attachment. The results of this quantitative analysis were compared with those of a classic qualitative analysis of the same subject. The advantages and disadvantages of both quantitative and qualitative approaches to literature reviews are discussed and compared with quantitative and qualitative analyses of individual research studies.

Female↗
PubMed1975

A short-term intensive training program for pediatric nurse practitioners.

A pediatric nurse practitioner course has been described in which 30 nurse trainees spent six seeks in an intensive training program followed by six months of preceptorship with a pediatrician in their own agency. This short but intensive program had advantages of permitting the PNP student to retain her health care agency position during the intensive part of the program and of assuring her a position as a PNP once the course was completed. Evaluation of the students by written and practical examinations indicated that they had made significant gains in their knowledge and understanding of pediatrics and in their ability to evaluate and refer patients and to provide well-child care and maternal counseling.

California↗
PubMedDate not supplied

Breast-feeding problems and telephone consultation.

Parents and health care providers may have difficulty obtaining accurate and current information for the management of breast-feeding concerns. This study documents the types of problems that lead family members and health care professionals to seek telephone consultation from a breast-feeding service managed as an activity of a school of nursing faculty practice. During the 6-month study period, calls from 387 individuals (64% mothers and 31% health care providers) were received, for a mean of 64 calls per month. These calls required approximately 9.5 hours monthly to manage. Thirty-one percent of the calls were requests for general information (including stooling and urination or frequency and duration of breast-feeding); an additional 24% requested consultation from or referral to the service. Twenty-five percent of the calls resulted in a consultation with either the clinicians (9.9% inpatient; 9.6% outpatient) or referral to another health care professional (6%). Suggestions for pediatric nurse practitioner practice with breast-feeding mothers and babies were developed from the results of this clinical study.

Breast Feeding↗
PubMedDate not supplied

Assessment of breastfeeding knowledge of nurse practitioners and nurse-midwives.

The purpose of this study was to replicate a national study of physician knowledge, experience, and attitudes about breastfeeding. All family, pediatric, and women's health care nurse practitioners and nurse-midwives in a northwestern state were surveyed using a mail questionnaire; the response rate was 60.4%. Respondents were nearly unanimous in believing that "breast is best" and in recommending breastfeeding to expectant mothers as a part of their role. In general, 70% of respondents considered themselves effective or very effective in meeting the needs of breastfeeding patients. Although respondents were very supportive of breastfeeding, they were less knowledgeable about specific management strategies. There were differences in attitudes among nursing specialties and with years of experience. Overall, this statewide sample of nurse practitioners and nurse-midwives had a better understanding of the benefits of breastfeeding and an increased sense of effectiveness in managing breastfeeding problems than the physician participants in the national study. A national sample of nurse practitioners and nurse-midwives is needed to verify and expand on the results from this single jurisdiction, where 40% of the respondents were graduates of the home institution of the co-investigators.

Breast Feeding↗