Publications by authors named "Nixon A"

Pelage growth cycles are regulated by circulating prolactin in many mammals, but the intercellular mediators of this signaling are unknown. Binding sites for insulin-like growth factors (IGFs) were examined in sheep skin to show changes in distribution and abundance of IGF receptors associated with a prolactin stimulus and the subsequent hair follicle growth cycle. Follicle cycles were induced in New Zealand Wiltshire ewes by a surge in plasma prolactin following a 4-month period of prolactin suppression with bromocriptine.

View Article and Find Full Text PDF

Objective: To clone and determine molecular structure of equine stromelysin 1 (matrix metalloproteinase 3) and examine stromelysin expression in articular cartilage. SAMPLES AND PROCEDURE: Total RNA was harvested from equine arthritic cartilage specimens and was used for reverse transcription and polymerase chain reaction amplification to develop overlapping complementary DNA (cDNA) clones. Four cDNA sequences were ligated into plasmid (pGEM3Z) constructs and subcloned into bacterial expression vectors, and sequence was determined by automated dye terminator sequencing.

View Article and Find Full Text PDF

Prolactin is believed to mediate seasonal cues entraining seasonal reproductive and hair follicle growth cycles. Prolactin receptor binding activity and prolactin receptor gene expression in mammalian skin have recently been described. In this report, prolactin receptor immunoreactivity is identified in sheep skin using a monoclonal antibody against the rat liver prolactin receptor.

View Article and Find Full Text PDF

Objective: To develop a high-performance liquid chromatography (HPLC) assay for insulin-like growth factor I (IGF-I) and to use it to quantify elution of IGF-I from polymerized fibrin in an in vitro system.

Sample Population: Equine fibrinogen and calcium-activated bovine thrombin were used to form fibrin containing human recombinant IGF-I.

Procedure: Multiple fibrin disks were formed from polymerized fibrinogen and thrombin; 6 disks were loaded with 25 micrograms of recombinant human IGF-I at the time of polymerization, and 4 remained as unladen controls.

View Article and Find Full Text PDF

Purpose: To determine the risk of nodal failure in patients with early-stage invasive breast cancer with clinically negative axillary lymph nodes treated with two-field tangential breast irradiation alone, without axillary lymph node dissection or use of a third nodal field.

Methods And Materials: Between 1988 and 1993, 986 evaluable women with clinical Stage I or II invasive breast cancer were treated with breast-conserving surgery and radiation therapy. Of these, 92 patients with clinically negative nodes received tangential breast irradiation (median dose, 45 Gy) followed by a boost, without axillary dissection.

View Article and Find Full Text PDF

In human neutrophils, the choline-containing phosphoglycerides contain almost equal amounts of alkylacyl- and diacyl-linked subclasses. In contrast to phosphatidylinositol hydrolysis which yields diacylglycerol, hydrolysis of choline-containing phosphoglycerides by phospholipase D coupled with phosphohydrolase yields both alkylacyl- and diacylglycerol. While diacylglycerol activates protein kinase C, alkylacylglycerol does not, and its role is unclear.

View Article and Find Full Text PDF

Objective: To evaluate potential stimulatory or matrix-sparing effects of insulin-like growth factor 1 (IGF-1), alone or in combination with a corticosteroid, in an interleukin 1 (IL-1)-induced model of cartilage degradation.

Samples: Cartilage from the weightbearing surfaces of trochlea and condyles of clinically normal 2-year-old male horses.

Procedure: Triamcinolone acetonide and IGF-1 effects were evaluated by assessing: matrix responses by sulfated glycosaminoglycan (GAG) assay and [35S]sulfated GAG synthesis; collagen content by hydroxyproline assay; and mitogenic response by [3H]thymidine incorporation into DNA and fluorometric assay of total DNA concentration.

View Article and Find Full Text PDF

Purpose: To assess the relationship between machine energy (4-8 MV) and treatment outcome in patients treated with conservative surgery and radiation therapy.

Methods And Materials: Between 1968 and 1985, 1624 patients were treated for clinical Stage I or II invasive breast cancer. The study population was limited to 1380 patients who underwent complete gross excision and received greater than or equal to 60 Gy to the tumor bed.

View Article and Find Full Text PDF

Aims: GR117289C is a non peptide, selective angiotensin (AT1) receptor antagonist. The purpose of this study was to determine whether this agent, given orally, could attenuate the vasoconstrictor effects of angiotensin II(AII) infused locally into the forearm circulation in man.

Methods: Eight healthy male subjects were studied on four occasions in a randomized, double-blind, placebo controlled, crossover study.

View Article and Find Full Text PDF

Objective: Studies have proved the importance of substance P (SP) in the development and perpetuation of inflammation in joints, and describe the abundant SP neural network in the soft tissue structures of various articulations. Less information is available on the innervation of the bony structures of joints, and there is a paucity of data describing the changes associated with disease conditions. Our objectives were to evaluate changes in the distribution of sensory nerve fibers in the bony structures of naturally osteoarthritic joints.

View Article and Find Full Text PDF

The feasibility of creating new enzyme activities from enzymes of known function has precedence in view of protein evolution based on the concepts of molecular recruitment and exon shuffling. The enzymes encoded by the Escherichia coli genes purU and purN, N10-formyltetrahydrofolate hydrolase and glycinamide ribonucleotide (GAR) transformylase, respectively, catalyze similiar yet distinct reactions. N10-formyltetrahydrofolate hydrolase uses water to cleave N10-formyltetrahydrofolate into tetrahydrofolate and formate, whereas GAR transformylase catalyses the transfer of formyl from N10-formyltetrahydrofolate to GAR to yield formyl-GAR and tetrahydrofolate.

View Article and Find Full Text PDF

Objective: To examine the site-specific and dose-dependent effects of insulin-like growth factor I (IGF-I) on normal equine tendon in vitro.

Samples: Superficial digital flexor tendon explants derived from a euthanatized 3-year-old horse.

Procedure: Explants in culture were treated with 0, 100, 250, or 500 ng of IGF-I/ml for 14 days with an end-stage radiolabel of 20 microCi of [3H]proline/ml or 5 microCi of [3H]thymidine/ml.

View Article and Find Full Text PDF

Objective: To determine the effects of transforming growth factor-beta 1 (TGF-beta 1) on the synthesis of DNA, collagen, and proteoglycans (PG) by equine chondrocytes.

Sample Population: Articular cartilage obtained from multiple joints of a 4-month-old foal.

Procedure: Chondrocytes were isolated by collagenase digestion, cultured in monolayer, trypsinized, and implanted at a cellular density of 10 x 10(6) chondrocytes/ml in a three-dimensional fibrin matrix.

View Article and Find Full Text PDF

Background: The relationship between the microscopic margins of resection and ipsilateral breast recurrence (IBR) after breast-conserving therapy for carcinomas with or without an extensive intraductal component (EIC) has not been adequately defined.

Methods: Of 1,790 women with unilateral clinical Stage I or II breast carcinoma treated with radiation therapy as part of breast-conserving therapy, 343 had invasive ductal histology evaluable for an extensive intraductal component (EIC), had inked margins that were evaluable for an review of their pathology slides, and received > or = 60 Gray to the tumor bed; these 343 women constitute the study population. The median follow-up was 109 months.

View Article and Find Full Text PDF

It is still very difficult to determine the function of a protein from its sequence. One potential solution to the problem combines the concept of enzyme superfamilies with modern methods of protein structure prediction. Active-site templates can be used as search tools to identify new members of the superfamilies.

View Article and Find Full Text PDF

Background: Although histologic grade has previously been described as a predictor of distant failure, it is uncertain whether histologic grade should be used to decide which patients should undergo axillary lymph node dissection and whether grade should be considered as a selection factor for breast-conserving therapy.

Methods: The authors retrospectively analyzed data from 1081 patients with American Joint Committee on Cancer Stage I or II infiltrating ductal carcinoma treated with breast-conserving therapy at the Joint Center for Radiation Therapy between 1970 and 1986. All patients had pathology slides reviewed by one of two study pathologists.

View Article and Find Full Text PDF

Newly diagnosed, early-stage breast cancer confronts the patient and her clinician with multiple treatment decisions. This review examines some of these local treatment options including the choice between breast-conserving treatment (BCT) and mastectomy, how best to treat the axilla, and the optimal sequencing of local and systemic therapy. Key elements in the selection of patients for BCT or mastectomy include preoperative mammography, careful pathological evaluation, and an assessment of patient desires in order to balance the risk of local recurrence against preservation of a cosmetically acceptable breast.

View Article and Find Full Text PDF

The newly defined eicosatetraenoates (ETEs), 5-oxoETE and 5-oxo-15(OH)-ETE, share structural motifs, synthetic origins, and bioactions with leukotriene B4 (LTB4). All three eicosanoids stimulate Ca2+ transients and chemotaxis in human neutrophils (PMN). However, unlike LTB4, 5-oxoETE and 5-oxo-15(OH)-ETE alone cause little degranulation and no superoxide anion production.

View Article and Find Full Text PDF

5-Oxo-eicosatetraenoate (5-oxoETE) is gaining recognition as a chemotactic factor for eosinophilic (Eo) as well as neutrophilic (Neu) polymorphonuclear leukocytes. We found that the eicosanoid was far stronger than C5a, platelet-activating factor (PAF), leukotriene B4 (LTB4), or FMLP in stimulating Eo chemotaxis. Moreover, it had weak intrinsic degranulating effects on otherwise unstimulated Eo, produced prominent degranulation responses in Eo primed by granulocyte-macrophage CSF, and enhanced the Eo-degranulating potencies of PAF, C5a, LTB4, and FMLP by up to 10,000-fold.

View Article and Find Full Text PDF

In human neutrophils (PMN) the ethanolamine-containing phosphoglyceride fraction (PE), principally plasmalogen-linked PE (1-O-alk-1'-enyl-2-acyl-sn-glycero-3-phosphoethanolamine), is the major store of arachidonic acid (AA). Exogenous AA is initially incorporated into 1-acyl-linked phosphoglycerides and is believed to be transferred into the 1-ether-linked phosphoglycerides via the action of a CoA-independent transacylase (CoA-IT). We have investigated the selectivity for both the "acceptor' lysophospholipids and "donor' AA-containing phospholipid substrates in the CoA-IT reaction.

View Article and Find Full Text PDF

Transforming growth factor-alpha (TGF-alpha) has been associated with cell proliferation of keratinocytes and implicated in hair growth. We therefore examined changes in the immunocytochemical localization of TGF-alpha and cell proliferation markers in the skin of two unrelated species in which hair cycles could be induced, to elucidate the role of this growth factor in the control of fiber growth. Skin was collected from melatonin-treated ferrets (Mustela putorius furo), untreated Romney sheep (Ovis aries), and New Zealand Wiltshire sheep in which interruption of wool growth had been photoperiodically induced.

View Article and Find Full Text PDF

Background: Randomized clinical trials have clearly demonstrated that the use of radiation therapy (RT) following breast-conserving surgery (CS) substantially reduces the risk of local recurrence. However, the low rate of local recurrence after CS and RT for patients without known risk factors, and the recent increase in the detection of smaller cancers due to mammographic screening have led to the speculation that a subgroup of patients who have a low risk of local recurrence without RT might be identified. In 1986, we initiated a one-arm, prospective clinical trial of CS alone for treatment of highly selected breast cancer patients without known risk factors for local recurrence.

View Article and Find Full Text PDF

Aim: To review those cases of Schistosoma haematobium presenting in Wellington during 1993 and 1994.

Method: All patients receiving praziquantel during 1993 and 1994 were traced through local pharmacy records. Their clinical records were reviewed and they were contacted by phone to ensure a complete set of information was obtained.

View Article and Find Full Text PDF