PubMed Health⌕ Search

Biomedical subjects

R J Green

Publications and source records attributed to R J Green.

At least 19 recordsLinked to original sources
PubMed1998

A surface plasmon resonance study of albumin adsorption to PEO-PPO-PEO triblock copolymers.

Pluronic surfactants, PEO-PPO-PEO triblock copolymers, have been investigated widely due to their protein-resistant properties in applications as coatings for implants and in controlled drug release systems. We have studied a wide range of these copolymers, varying in both PEO and PPO block size, by adsorbing them to a polystyrene surface and investigating their subsequent resistance to human serum albumin adsorption. This investigation has been carried out in real time, using surface plasmon resonance, with the surfaces subsequently visualized by atomic force microscopy. This approach has allowed determination of the effect of the lengths of the PEO and PPO polymer chains on protein resistivity. For low-molecular-weight Pluronics a significant, yet not complete, reduction in albumin adsorption has been observed whereas higher molecular weight Pluronics appear to completely inhibit adsorption within the time frame of this experiment. An increase in the PPO block size of the copolymer also appears to increase its protein resistance. This work further confirms that the binding strength of the anchoring block to the hydrophobic surface, rather than the length of the protruding hydrophilic PEO chains, determines a copolymer's protein resistance capability.

Albumins↗
PubMed1997

Surface plasmon resonance for real time in situ analysis of protein adsorption to polymer surfaces.

The adsorption of a range of plasma proteins to metal and polymer surfaces has been examined using surface plasmon resonance (SPR). The adsorption of proteins was initially studied on the SPR silver sensor surface, and then on a model polystyrene film spun coated directly onto this substrate. In both cases, reproducible adsorption profiles for albumin were attained which compared well with corresponding atomic force microscopy (AFM) and ellipsometry data on protein monolayer packing and thickness respectively. The SPR data revealed the influence of concentration on both protein adsorption kinetics and the time for formation of a monolayer coating. SPR data also highlighted different adsorption kinetics and final monolayer SPR angle shift values for three plasma proteins which have been interpreted in terms of their molecular dimensions and orientation at the polymer interface. AFM data confirmed the presence of a closely packed protein layer for all three protein systems. These studies are discussed in terms of employing SPR in the study of protein interactions at surfaces which are important in the design and evaluation of novel biomedical polymeric materials.

Adsorption↗
PubMed1997

Immunolocalization of platelet-derived growth factor A and B chains and PDGF-alpha and beta receptors in human gingival wounds.

Platelet-derived growth factor (PDGF) is a polypeptide growth factor which has been implicated as a major mitogen involved in wound healing. The PDGF appears to promote periodontal regeneration; however, its distribution in gingival tissues is not known and how it participates in gingival wound healing is unclear. Using highly specific antibodies we have studied the distribution of PDGF A and B chains and alpha- and beta-PDGF receptors in healing human gingival wounds. Wounds were created by making a 0.75 mm deep incision in the papilla and healthy gingiva and biopsies were obtained from the same site after 8 h and 1, 3, 7, 14 and 21 d. Frozen sections were immunostained with affinity purified antibodies. The results showed that both epithelium and fibrin clot manifested positive immunostaining for anti-PDGF-A and B-chain antibodies. Staining was present in unwounded and wounded epithelia, and in the fibrin clot it appeared to be more intense for the PDGF-A chain. Blood vessels in connective tissue were also positive while other areas were largely negative. No significant staining was detectable in healthy tissues for anti-PDGF-alpha or -beta receptor antibodies. However, the wound site began to manifest positive immunostaining fro anti-beta-receptor antibody after 3 d of healing, became maximal at 7 d, and then decreased. Our data indicate, but do not prove, that gingival epithelium may be a source of PDGF A and B chains and that the A chain may have a more prominent role to play during early stages of healing. Expression of PDGF beta-receptor appears later at the wound site, indicating that the PDGF B isomer may regulate later wound healing events.

Adult↗
PubMed1997

Clinical presentation of chronic non-infectious rhinitis in children.

UNLABELLED: Chronic rhinitis is one of the commonest conditions affecting humans and there is evidence that its prevalence (and especially that of allergic rhinitis) is increasing. Although common, it is poorly recognised by doctors, parents and patients, particularly in children. AIMS: This study surveyed children with chronic non-infectious rhinitis to describe their presenting symptoms, differences in presentation between preschool and school-aged children and the prevalence of complications. SUBJECTS AND METHODS: We prospectively surveyed patients with a diagnosis of chronic rhinitis that was subsequently confirmed by response to therapy. Symptoms of rhinitis were assessed via an interview-conducted questionnaire. RESULTS: 567 children (357 boys), with a mean age (+/-SD) of 5.3 +/- 3.6 years, were studied over 14 months. Three hundred and fourteen were preschool children. Symptoms of a blocked or a runny nose were reported in 85% of patients, both symptoms occurring simultaneously in 59.9%. A blocked nose occurred more frequently in school-aged children, while a runny nose was commoner in preschool children. Sneeze and itch occurred less frequently in 56.1% and 33.6%, respectively. Complicating recurrent ear infections were reported in 46.9% of patients, more frequently in preschool children (P = 0.01); almost one-third (32.02%) had had grommets inserted. Learning problems, possibly secondary to somnolence as a result of poor sleep induced by sleep apnoea (snoring was reported in 58.4%), were reported in 24.1% of school-going children. CONCLUSION: As chronic rhinitis in South Africa commonly manifests with a blocked nose, patients display a high prevalence of associated complications. Doctors need to be aware of the presenting symptoms to diagnose and treat chronic non-infectious rhinitis earlier to prevent these complications.

Child↗
PubMed1996

Intrusiveness and closeness-caregiving: rethinking the concept of family "Enmeshment".

This article analyzes the concepts of "enmeshment" and "cohesion" and their entanglement in the field of family therapy. Early theories in this area were concerned primarily with processes of self/other differentiation. More recent theories have favored spatial metaphors that emphasize closeness-distance. We contend that self/ other differentiation and closeness-distance are different classes of behavior and that their linkage in the literature has obscured useful distinctions. Our analysis reveals two separate dimensions that clinicians and researchers should consider: Intrusiveness (including coercive control, separation anxiety, possessiveness/jealousy, emotional reactivity, and projective mystification); and Closeness-Caregiving (including warmth, time together, nurturance, physical intimacy, and consistency). We give definitions of these constructs and briefly examine their clinical and gender-related implications.

Affect↗
PubMed1996

Why ask, why tell? Teaching and learning about lesbians and gays in family therapy.

The article by J.K. Long (1996) in this issue of Family Process helps puncture the conventional secrecy around homosexuality, challenging the silence of many supervisors. In this commentary, I will expand on the themes raised by Long and offer some tangible steps we can take to teach and learn about lesbians/gays in couples and families.

Family Therapy↗
PubMed1996

Necrotizing fasciitis.

Necrotizing fasciitis is an uncommon soft-tissue infection, usually caused by toxin-producing, virulent bacteria, which is characterized by widespread fascial necrosis with relative sparing of skin and underlying muscle. It is accompanied by local pain, fever, and systemic toxicity and is often fatal unless promptly recognized and aggressively treated. The disease occurs more frequently in diabetics, alcoholics, immunosuppressed patients, i.v. drug users, and patients with peripheral vascular disease, although it also occurs in young, previously healthy individuals. Although it can occur in any region of the body, the abdominal wall, perineum, and extremities are the most common sites of infection. Introduction of the pathogen into the subcutaneous space occurs via disruption of the overlying skin or by hematogenous spread from a distant site of infection. Polymicrobial necrotizing fasciitis is usually caused by enteric pathogens, whereas monomicrobial necrotizing fasciitis is usually due to skin flora. Tissue damage and systemic toxicity are believed to result from the release of endogenous cytokines and bacterial toxins. Due to the paucity of skin findings early in the disease, diagnosis is often extremely difficult and relies on a high index of suspicion. Definitive diagnosis is made at surgery by demonstration of a lack of resistance of normally adherent fascia to blunt dissection. Treatment modalities include surgery, antibiotics, supportive care, and hyperbaric oxygen. Early and adequate surgical debridement and fasciotomy have been associated with improved survival. Initial antibiotic therapy should include broad aerobic and anaerobic coverage. If available, hyperbaric oxygen therapy should be considered, although to our knowledge, there are no prospective, randomized clinical trials to support this. Mortality rates are as high as 76%. Delays in diagnosis and/or treatment correlate with poor outcome, with the cause of death being overwhelming sepsis syndrome and/or multiple organ system failure.

Fasciitis, Necrotizing↗
PubMed1996

Pulmonary capillaritis and alveolar hemorrhage. Update on diagnosis and management.

Pulmonary vascular inflammatory disorders may involve all components of the pulmonary vasculature, including capillaries. The principal histopathologic features of pulmonary capillaritis include capillary wall necrosis with infiltration by neutrophils, interstitial erythrocytes, and/or hemosiderin, and interalveolar septal capillary occlusion by fibrin thrombi. Immune complex deposition is variably present. Patients often present clinically with diffuse alveolar hemorrhage, which is characterized by dyspnea and hemoptysis; diffuse, bilateral, alveolar infiltrates on chest radiograph; and anemia. Pulmonary capillaritis has been reported with variable frequency and severity as a manifestation of Wegener's granulomatosis, microscopic polyarteritis, systemic lupus erythematosus, Goodpasture's syndrome, idiopathic pulmonary renal syndrome, Behçet's syndrome, Henoch-Schönlein purpura, IgA nephropathy, antiphospholipid syndrome, progressive systemic sclerosis, and diphenylhydantoin use. In addition to history, physical examination, and routine laboratory studies, certain ancillary laboratory tests, such as antineutrophil cytoplasmic antibodies, antinuclear antibodies, and antiglomerular basement membrane antibodies, may help diagnose an underlying disease. Diagnosis of pulmonary capillaritis can be made by fiberoptic bronchoscopy with transbronchial biopsy, but thoracoscopic biopsy is often employed. Since many disorders can result in pulmonary capillaritis with diffuse alveolar hemorrhage, it is crucial for clinicians and pathologists to work together when attempting to identify an underlying disease. Therapy depends on the disorder that gave rise to the pulmonary capillaritis and usually includes corticosteroids and cyclophosphamide or azathioprine. Since most diseases that result in pulmonary capillaritis are treated with immunosuppression, infection must be excluded aggressively.

Anemia↗
PubMed1991

Outcomes of systemic/strategic team consultation: III. The importance of therapist warmth and active structuring.

This is the third in a series of reports on a small-sample study of systemic/strategic team consultations. It sheds new light on aspects of the therapeutic alliance in Milan-informed therapy. Ratings of the end-of-session interventions and ratings of the therapist's relationship skills (warmth, active structuring) significantly predicted client improvement at 1-month and 3-year followups. These results dispute the Milan team's idea that an intervention's effects are unpredictable. Also, our findings challenge the way some teams have adopted an impersonal, emotionally unresponsive style under the guise of "neutrality." In view of this and other recent studies, we conclude that systemic/strategic therapists should devote more attention to collaborative and affective qualities of the therapeutic alliance.

Attitude of Health Personnel↗
PubMed1990

A comparison of stepfamilies with and without child-focused problems.

Stepfamilies in therapy for a child-focused problem were compared to those without such a problem and not in therapy. Differences were found in reciprocity within the stepparent-stepchild relationship, satisfaction with the stepparent's role, level of stepfamily conflict, and degree of stepfamily expressiveness. Results are discussed in terms of current research and clinical implications.

Adolescent↗
PubMed1990

Objective methods for evaluation of interferential therapy in the treatment of incontinence.

Electrotherapy is a treatment for various conditions, and can be difficult to quantify in effect. This paper examines the form known as interferential therapy, with particular application in the management of urinary incontinence. Objective validation of the treatment is described, which allows optimal positioning of the electrodes for a particular patient.

Electric Conductivity↗
PubMed1989

Differential ontogeny of working memory and reference memory in the rat.

In two experiments we examined the ability of 15-, 21-, and 27-day-old rats to perform two spatial working memory problems (delayed alternation and discrete-trials delayed alternation) and a reference memory problem (position habit) in a T-maze. In the delayed alternation problem, each animal was presented with a series of free-choice trials and was rewarded for regularly alternating responses to the left and right arms of the T-maze. In the discrete-trials delayed alternation problem, each animal was forced to one maze arm and rewarded (forced run) and was then placed back into the start box and given a choice of arms (choice run). The direction of forced runs followed an irregular, counterbalanced series, and animals were rewarded for choosing the alternate maze arm on choice runs. In the position habit problem, animals were rewarded for consistently choosing one of the two arms of the T-maze. Performance on these problems was assessed relative to control conditions in which reward was not contingent on choice behavior. At all ages, rat pups learned to perform the delayed alternation and position habit problems (Experiment 1). However, only 21- and 27-day-old rats were able to learn the discrete-trials delayed alternation problem. The 15-day-olds were unable to learn this task (Experiment 2). The results of these experiments show that reference memory capacity is present by at least 15 days of age in the rat and does not develop further at later ages.(ABSTRACT TRUNCATED AT 250 WORDS)

Aging↗
PubMed1989

Outcomes of systemic/strategic team consultation: I. Overview and one-month results.

This is the first in a series of reports on an experimental, small-sample study of systemic/strategic team consultations. This report describes a "Milan-informed" method of team consultation for resolving therapy impasses. It then focuses on the initial one-month outcomes from the larger 3-year project. Eleven therapists were asked to select two ongoing cases matched for difficulty. While all cases continued in regular therapy, one of each therapist's cases was also selected at random to participate in a systemic/strategic, five-part team consultation. Analyses of one-month follow-up data showed that clients who participated in the team consultation were more likely to achieve their main and overall treatment goals than clients who received only regular therapy (p's less than .05, eta2 as a measure of effect size ranging from 32% to 41%). The strong findings of this initial study encourage more widespread use of team consultations as a context for treatment, training, and research.

Adult↗