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Biomedical subjects

B Elliott

Publications and source records attributed to B Elliott.

At least 55 records · Page 3Linked to original sources
PubMed1996

Fibronectin fibrils and growth factors stimulate anchorage-independent growth of a murine mammary carcinoma.

Stromal cells are important regulators of mammary carcinoma growth and metastasis. We have previously shown that a 3T3-L1 adipocyte cell line secretes hepatocyte growth factor (HGF), which stimulates proliferation of a murine mammary carcinoma (SP1) in monolayer cultures (DNA Cell Biol. 13, 1189-1897, 1994). We now examine the role of growth factors and the extracellular matrix protein fibronectin in stimulation of anchorage-independent growth of SP1 cells. Purified transforming growth factor-beta (TGF-beta) stimulated significant colony growth in soft agar cultures, whereas HGF had a lesser effect. Analysis by confocal microscopy revealed that carcinoma cell colonies contained extracellular microfibrils composed of fibronectin. Partial depletion of fibronectin from 7% FBS/agar cultures reduced the number of colonies; colony growth could be recovered by adding back exogenous fibronectin. Addition of the 70-kDa N-terminal fragment of fibronectin, which inhibits fibronectin fibril formation, reduced growth of SP1 cell colonies, but an 85-kDa fragment containing the cell binding domain did not inhibit colony growth. These findings indicate that deposition of extracellular fibronectin fibrils is necessary, but not sufficient, for anchorage-independent growth of SP1 mammary carcinoma cells; growth factors are also required. SP1 cells had less fibronectin mRNA and secreted less fibronectin protein under anchorage-independent conditions than under anchorage-dependent conditions, as determined by Northern blotting and immunoprecipitation analysis. Thus, both growth factors (HGF and TGF-beta) and fibronectin may be important regulators of paracrine stimulation by stromal cells of anchorage-independent growth of mammary carcinoma cells.

3T3 Cells↗
PubMed1996

Hepatocyte growth factor (HGF) is a copper-binding protein: a facile probe for purification of HGF by immobilized Cu(II)-affinity chromatography.

Hepatocyte growth factor (HGF) is a multifunctional protein expressed in a variety of cell types and tissues. Here we describe a novel one-step method to separate and identify HGF, based on a unique interaction between HGF and Cu(II). Conditioned medium (CM) from mouse 3T3-L1 adipocytes which contains HGF or purified human recombinant HGF was used for analysis. Mouse 3T3-L1 adipocyte CM was applied to a Cu(II)-affinity column and rinsed with equilibration buffer. HGF was then eluted with 10 mM imidazole. Fractions eluted from the column were analyzed by SDS-PAGE. Analysis by silver staining revealed an 85kDa protein. Further analysis by Western blotting with polyclonal anti-HGF IgG demonstrated that this protein corresponded to HGF. Human recombinant HGF, when applied to a Cu(II)-affinity column, showed a stronger affinity to Cu(II) than did mouse HGF. Human recombinant HGF was not eluted from the Cu(II) column with either 10 or 20 mM imidazole; however, it was readily eluted with 40 mM imidazole. The percentages of recovery of both human and mouse HGF were greater than 90%. Both mouse HGF and human recombinant HGF eluted from the Cu(II)-affinity column retained their biological activity as measured by HGF-induced cell proliferation of Mv1Lu cells. Our findings provide the first evidence that HGF is a copper-binding protein and that a Cu(II)-affinity column can be used for efficient one-step purification of biologically active HGF.

Adipocytes↗
PubMed1996

The role of upper limb segment rotations in the development of racket-head speed in the squash forehand.

In the squash forehand drive, the contribution that each of the upper limb segment's anatomical rotations make to racket-head velocity towards the front wall (x-direction) during the forward swing and at impact were calculated. Eight squash players (3 females, 5 males) capable of hitting a high-performance squash forehand drive were filmed at a nominal rate of 300 Hz by two phase-locked Photosonics cameras. The three-dimensional displacement histories of 12 selected landmarks were then calculated using the direct linear transformation approach and three-dimensional individual segment rotations were calculated using vector equations. Internal rotation of the upper arm at the shoulder joint (46.1%), hand flexion at the wrist joint (18.2%) and forearm pronation at the radio-ulnar joint (12.0%) were the major contributors to the mean 30.8 m s-1 x-direction velocity of the centre of the racket-head at impact. Pronation of the forearm at the radio-ulnar joint and extension at the elbow joint both played a significant role in generating racket velocity in the period prior to impact.

Arm↗
PubMed1996

Synergy between trehalose and Hsp104 for thermotolerance in Saccharomyces cerevisiae.

We isolated a mutant strain unable to acquire heat shock resistance in stationary phase. Two mutations contributed to this phenotype. One mutation was at the TPS2 locus, which encodes trehalose-6-phosphate phosphatase. The mutant fails to make trehalose and accumulates trehalose-6-phosphate. The other mutation was at the HSP104 locus. Gene disruptions showed that tps2 and hsp104 null mutants each produced moderate heat shock sensitivity in stationary phase cells. The two mutations were synergistic and the double mutant had little or no stationary phase-induced heat shock resistance. The same effect was seen in the tps1 (trehalose-6-phosphate synthase) hsp104 double mutant, suggesting that the extreme heat shock sensitivity was due mainly to a lack of trehalose rather than to the presence of trehalose-6-phosphate. However, accumulation of trehalose-6-phosphate did cause some phenotypes in the tps2 mutant, such as temperature sensitivity for growth. Finally, we isolated a high copy number suppressor of the temperature sensitivity of tps2, which we call PMU1, which reduced the levels of trehalose-6-phosphate in tps2 mutants. The encoded protein has a region homologous to the active site of phosphomutases.

Amino Acid Sequence↗
PubMed1996

Physician detection of family violence. Do buttons worn by doctors generate conversations about domestic abuse?

Family violence is ubiquitous in our society and, thus, is encountered in all medical practices. The purpose of this study was to ascertain whether physicians wearing buttons with an anti-abuse message have more conversations about violence compared with physicians not wearing such buttons. Six of 11 family practice residents wore Minnesota Medical Association buttons that invited conversations about abuse. For four weeks, all 11 residents recorded daily the number of conversations about violence that occurred in the medical setting. Analyses comparing the two groups showed that the physicians wearing buttons had significantly more conversations than those not wearing buttons (c2 = 9.040, p < 0.005). Physicians wearing buttons had a higher percentage of days with conversations about domestic violence than physicians without buttons (c2 = 7.695, p < 0.01). From the significant p-values documented, we conclude that wearing the buttons increases conversations about family violence and makes physicians more consistent in talking about violence with patients.

Curriculum↗
PubMed1996

Identification of a hepatocyte growth factor autocrine loop in a murine mammary carcinoma.

Constitutive activation of growth factor receptors through autocrine/paracrine mechanisms occurs frequently in human cancers and is thought to play an important role in carcinogenesis. We have demonstrated previously that hepatocyte growth factor (HGF) is a potent mitogenic factor for murine mammary carcinoma (SP1) cells in vitro. We report here an autocrine HGF loop in SP1 cells. HGF receptor/Met is expressed in SP1 cells and is constitutively tyrosine phosphorylated. The phosphorylation of HGF receptor/Met is inhibited when cells are exposed to suramin or anti-HGF IgG. This finding suggests that constitutive tyrosine phosphorylation of HGF receptor/Met is sustained by an extracellular factor, most likely HGF. Using Northern blot and Western blot analysis, we detected expression of a 6-kb HGF mRNA in SP1 cells and a M(r) 85,000 HGF protein in SP1-conditioned medium, respectively. In vitro translation of mRNA from SP1 cells and metabolic labeling confirmed expression and synthesis of HGF by SP1 cells. SP1 cells also invade through Matrigel-coated transwell membranes in an in vitro invasion assay, and invasion of these cells was inhibited by neutralizing anti-HGF IgG. In addition, SP1-conditioned medium induced scatter activity of Madin-Darby canine kidney epithelial cells, and this activity was inhibited by neutralizing anti-HGF IgG. We have also shown that several signaling molecules including phosphatidylinositol 3-kinase, Src, focal adhesion kinase, and phospholipase C-gamma in SP1 cells are constitutively tyrosine phosphorylated, suggesting that coexpression of HGF and HGF receptor/Met may in part contribute to sustained tyrosine phosphorylation of these cytoplasmic proteins in SP1 cells. Our observations in the SP1 model suggest that HGF contributes to growth and invasive phenotypes of mammary carcinomas via both paracrine and autocrine mechanisms.

3T3 Cells↗
PubMed1996

The role of upper limb segment rotations in the development of spin in the tennis forehand.

Increased topspin in the tennis forehand is produced by maintaining a perpendicular racket-face to the court surface at impact and increasing the trajectory and vertical velocity of the racket-head. These modifications to stroke technique from those previously identified in the flat forehand drive are the result of changes to the movement patterns of the segments of the upper limb. The contributions that the upper limb segment's anatomical rotations make to racket-head velocity at impact depend on both their angular velocity and the instantaneous position of the racket with respect to these movements. Six high performance tennis players were filmed at a nominal rate of 200 Hz by three Photosonics cameras while hitting flat (no spin) and topspin groundstrokes and a forehand topspin lob. The three-dimensional (3-D) displacement histories of 16 selected landmarks were then calculated using the direct linear transformation approach and 3-D individual segment rotations for the upper limb were calculated using vector equations. Significant differences were recorded in the effect that the various segment rotations made to the x-direction (forward) and y-direction (upward) impact velocities of the racket-head. These differences were not reflected in the contributions to racket-head velocity when the absolute velocities were expressed relative to the impact velocity. Trunk rotation, upper arm flexion/abduction, upper arm internal rotation, hand palmar and ulnar flexion all played integral roles in producing impact racket speed.

Adult↗
PubMed1996

Localization of platelet-derived growth factor beta receptor expression in the periepithelial stroma of human breast carcinoma.

Platelet-derived growth factor (PDGF) BB is secreted by most human breast carcinoma cells; however, only recently have PDGF beta receptors been demonstrated in malignant breast tissue. In the present study, the tissue localization of PDGF beta receptor expression was studied in human breast carcinoma and nonmalignant breast tissues stained using both immunofluorescence and immunoperoxidase techniques. We examined a total of 29 cases of breast carcinomas, which showed both in situ and invasive components. PDGF beta receptor staining was localized in the periepithelial stroma and was particularly intense in regions immediately adjacent to carcinoma in situ components in all tumors examined. A diffuse low level of PDGF beta receptor staining was seen throughout the stroma of eight nonmalignant breast tissues as well as of nonmalignant regions of tumor tissues. Image analysis was used to assess the coincidence of staining of PDGF beta receptor with epithelial or stromal cells in 13 of the 29 tumor tissues studied. Less than 5% of malignant ductal epithelium or myoepithelium showed PDGF beta receptor staining. Analysis with stromal cell type-specific markers indicated significant localization of PDGF beta receptor primarily within alpha smooth muscle actin-staining cells (32%) and vascular endothelial cells (41%) in the periepithelial stroma. PDGF beta receptor positivity was strongly associated with periepithelial stromal cells adjacent to the basement membrane surrounding regions of carcinoma in situ but was less intense in regions of invasive carcinoma where basement membrane was degraded. The absence of PDGF beta receptors on carcinoma cells and their presence in the surrounding stroma suggest a paracrine stimulation of adjacent stromal tissue by malignant epithelial cells in human breast tumors.

Actins↗
PubMed1995

A comparison of the high and low backspin backhand drives in tennis using different grips.

Three-dimensional, high-speed cinematography was used to compare backspin backhand techniques of high performance players hitting low (5.4 cm below hip height) and high (41.6 cm above hip height) bouncing balls using their preferred method of holding the racket (eastern backhand or continental grip: hand generally on top of the handle) and non-preferred ('behind the handle') grip. The Direct Linear Transformation method was used for three-dimensional space reconstruction from two-dimensional images recorded from laterally placed phase-locked cameras operating at 200 Hz. The only significant differences (P < 0.05) caused by the change in grip were that the ball was impacted further in front of the body when using the non-preferred grip, and a lower peak racket-shoulder speed was recorded for a high bouncing ball when using the non-preferred grip. Irrespective of the type of grip, the players significantly modified (P < 0.01) their technique to hit a high bouncing ball by adopting a more upright trunk, more rotated shoulder alignment (racket shoulder pointing more towards opponent), a larger front knee angle and a more abducted upper arm. Hitting a high ball was also characterized by a less inclined approach trajectory of the racket, a more vertical racket-face and a different speed profile for the segments of the upper limb and racket.

Acceleration↗
PubMed1995

A descriptive epidemiology of netball injuries during competition: a five year study.

OBJECTIVE: To investigate the relation between injury profiles - including assessment, treatment, severity, and the perceived reason for the injury - and participation in competitive netball. METHODS: Between 1985 and 1989, approximately 11,228 netball players participated in a 14 week netball competition held at the major competitive centre in Western Australia; 608 netball players presented to the first aid room with an injury and were assessed and treated by the same physiotherapist and St John First Aid officer. RESULTS: The overall incidence rate during competition was 5.4%, with more injuries occurring in the A grade level of play. Ankle injuries (84%) were most frequent, with 67% of these injuries diagnosed as lateral ligament sprains while a further 10% of players who suffered this classification of injury sustained a fracture to the ankle or foot. Few injuries occurred at the knee joint (8.3%) and only 1.8% of these injuries were diagnosed as an injury to the anterior cruciate ligament. The direct probability of a netball players' risk estimate was 0.054 per person per match which implied that netball was a relatively safe game. Injuries sustained during practice were not included in this study. CONCLUSIONS: Netball is a relatively safe game though the potential for injury increases with the level of competition.

Adolescent↗
PubMed1995

Health care for the uninsured in Duluth.

Providing health care for Minnesota's uninsured population continues to be both a clinical and political challenge. Between October 1, 1991, and September 30, 1993, 1,260 previously uninsured people received charity health care in Duluth. No one was excluded because of pre-existing conditions. Their utilization of services and associated costs can help project the health care needs and costs of care for uninsured Minnesotans. This group of uninsured people used a different mix of health care services compared with insured Minnesotans, and their total costs (including prescriptions) were about 15% greater. A large proportion of these uninsured Minnesotans had chronic health conditions and a "pent-up need" for services and medications. This experience demonstrated that it is possible to administer a limited benefits plan in coordination with existing public and private resources.

Adolescent↗
PubMed1995

Cultural diversity as a factor in self-monitoring blood glucose in gestational diabetes.

The routine use of self-monitoring of capillary blood glucose by pregnant diabetic patients currently provides the basis for both clinical management and ongoing investigation. Strategies must therefore be developed to ensure that these data are reliable and accurately reported by patients and are not influenced by diverse socioeconomic levels or varied geographic locations. To explore this issue, we used glucose reflectance meters with a memory microchip capable of storing up to 440 consecutive blood glucose determinations. Two diverse groups of women from Texas and New York who had gestational diabetes performed self-monitoring of blood glucose from diagnosis until delivery. Both groups recorded their blood glucose results daily in a logbook. The reporting performance of all the participating subjects resulted in an actual compliance rate of 60% to 70% of testings required of the patients. Comparison of African-American, Mexican-American, and white populations revealed no significant differences in patient performance or compliance. Moreover, no differences were found between the groups at different geographic locations (New York, Texas) in patients' willingness and ability to comply with the regimen of self-monitoring blood glucose. These findings suggest that the use of memory reflectance meters, in conjunction with patient education and positive interaction between patient and care provider, will result in high patient compliance regardless of socioeconomic level or ethnic diversity.

Adult↗
PubMed1994

A three-dimensional kinematic method for determining the effectiveness of arm segment rotations in producing racquet-head speed.

The contribution that a segment's anatomical rotations make to racquet-head speed depends on both the segment's angular velocity and the instantaneous position of the head of the racquet with respect to the segment's axes of rotation. Any analysis of racquet swing technique that does not consider both of these factors simultaneously is, at best, incomplete. With this in mind, a three-dimensional kinematic method was developed to determine the effectiveness of the anatomical rotations of the upper arm, forearm, and hand in producing racquet-head speed. The method entailed developing a system of vector equations for three-dimensional upper limb rotations that used displacement histories of 10 selected landmarks as input. The required three-dimensional displacement histories were obtained using three cine cameras and the DLT approach. To test the diagnostic capabilities of the method, a tennis serve was selected for analysis. For the player and serve analyzed, the greatest contribution to racquet-head speed at impact was produced by internal rotation of the upper arm (8 m s-1). Forearm pronation, although exhibiting the fastest rotation at impact (24 rad s-1), ranked only fourth in terms of its contribution (4 m s-1) to racquet-head speed. To test the performance of the method, a comparison was made between the racquet-head speed measured directly from film and the racquet-head speed computed by summing all of the individual segment contributions to speed commencing at the start of forward swing and ending at ball contact. The results indicate that the method can successfully determine the individual contributions that the different anatomical rotational velocities of the arm segments make to the measured instantaneous racquet-head speed.

Algorithms↗
PubMed1994

Role of hepatocyte growth factor in breast cancer: a novel mitogenic factor secreted by adipocytes.

Stromal cells can dramatically affect the growth and metastatic capability of breast carcinoma cells. Growth factors, considered to be important mediators of this process, act as either mitogenic or mito-inhibitory regulators. We have developed an in vitro coculture system to examine the influence of adipocytes, a dominant mammary stromal cell type, on the growth of a murine mammary carcinoma, SP1. Previously, we have reported that conditioned medium (CM) from 3T3-L1 adipocytes can promote in vitro growth of SP1 cells. We now show that the major mitogenic signal derived from 3T3-L1 adipocyte CM is mediated by hepatocyte growth factor (HGF). Neutralizing antibody against HGF at 15 micrograms/ml completely abrogated mitogenic activity of 3T3-L1 CM. Furthermore, heparin, an inhibitor of biological activity of HGF, inhibited the mitogenic activity of 3T3-L1 CM. Western blot analysis also confirmed the presence of HGF in 3T3-L1 CM. Although basic fibroblast growth factor (bFGF) and insulin-like growth factor I (IGF-I) were mitogenic for SP1 cells, neutralizing antibodies against IGF-I, bFGF, platelet-derived growth factor (PDGF), and epidermal growth factor (EGF) did not inhibit the mitogenic activity of 3T3-L1 CM. Immunoprecipitation and immunoblotting of HGF receptor/c-met showed that c-met is expressed at high level in SP1 cells, and is phosphorylated following HGF ligation. Together, our present data demonstrate that 3T3-L1 adipocytes secrete HGF, which stimulates SP1 cell growth by a paracrine mechanism. Furthermore, the mitogenic effect of 3T3-L1 CM requires HGF receptor ligation and activation of tyrosine kinase signaling cascades in SP1 cells. These results highlight the importance of stromal-tumor cell interactions and suggest that HGF secreted by adipocytes may be a key regulator of mammary tumor growth.

3T3 Cells↗
PubMed1994

A review of primary health-care organization.

A contract for the provision of community nursing and associated services was drawn up between the Plymouth Community Unit and general practitioners associated with a fundholding practice at a health centre in Devon in October 1991. This project, which aimed at applying purchaser/provider principles, contained some novel features and was subject to evaluation and review after 6 months. An evaluation which had four main aspects was carried out, consisting of interviews and questionnaire assessment of staff attitudes, patients' views of the effectiveness of aspects of the practice health-promotion activity, an analysis of staff activity data before and during the pilot phase and an examination of the documentation concerned with critical issues which had arisen. Questionnaire data indicated that staff motivation and enthusiasm for the project was high and that patients' views on the practice facilities were generally positive. The role of the Macmillan nursing service at this practice was greatly enhanced during the pilot project with a fourfold increase in the number of visits carried out. Over 120 h were spent by health visiting and district nursing staff on issues surrounding the pilot project including attending additional meetings. The results are discussed in relation to service benefits to patients, the effect on the cohesion of the primary health-care team and issues of fundholding and are considered in the context of models put forward for the future development of community-based nursing care.

Adult↗
PubMed1994

Foot types and lower limb injuries in elite netball players.

In assessing the foot types and lower limb injuries of elite netball players, the following summary seems warranted. Ninety percent of elite female netball players had symmetrical foot types for both feet and these players had experienced at least one lower limb injury. Only 7.6% players (N = 16) of the 204 players surveyed had never sustained a lower limb injury during their netball careers. Regardless of foot type, the injury history of these elite netball players presented with a total number of 449 injuries that occurred to both ankle joints (36%), one ankle joint (16%), both knee joints (6%), one knee joint (13%), shin soreness (18%), and retropatellar pain problems (11%). On further inspection, 55% of players experienced one to two lower limb injuries throughout their netball careers. Injured players showed that players with the pronating foot types with rearfoot abnormalities (57%) were the most commonly injured and that compensated rearfoot varus foot type presented the most lower limb injuries for all body sites.

Adolescent↗
PubMed1993

Stress resistance of yeast cells is largely independent of cell cycle phase.

Rapidly growing cells of Saccharomyces cerevisiae are sensitive to heat shock, while non-growing stationary phase cells are highly resistant. We find that slowly growing cells have an intermediate degree of heat shock resistance that can be nearly as great as that of stationary phase cells. This resistance is correlated both with slow growth and with carbon catabolite derepression. Slowly growing cells also showed resistance to Zymolyase digestion of their cell walls. The stress resistance is a property of all the cells in the culture, and cell cycle position makes little difference to the degree of stress resistance. At least some of the properties normally associated with stationary phase cells do not require residence in stationary phase or any other particular compartment of the cell cycle. Stress resistance may be due to a diverse set of physiological adaptations available to cells regardless of their position in the cell cycle. That is, although stress resistance and stationary phase are often correlated, neither is the cause of the other.

Amino Acids↗