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Biomedical subjects

D Jones

Publications and source records attributed to D Jones.

At least 901 records · Page 50Linked to original sources
PubMedDate not supplied

[Cell differentiation of a human bone marrow cell culture under the influence of UHMW-PE debris].

AIM: The purpose of the present study was to evaluate the influence of ultra-high-molecular-weight polyethylene (UHMW-PE), which is the major constituent of the material debris formed as a result of orthopaedic implant wear, on the cellular differentiation in a modified in vitro model. METHODS: UHMW-PE particles (Ø < or = 7.5 microm) were suspended in soluble collagen type I and subsequently solidified in different concentrations (10(5), 10(6) and 10(7) particles per well) on the bottom of the wells. Human bone marrow cells in a concentration of 3 x 10(6) cells per well were seeded on the collagen-particle substrate and maintained for up to 72 h. The response of the cells to the particles was examined by light microscopy, scanning electron microscopy and FACS analysis compared to cells on control collagen surfaces without any particles. RESULTS: Light and scanning microscopic evaluation revealed that the UHMW-PE particles, which had built large conglomerates (Ø 7.5 microm), were mainly surrounded by the cells and less phagocytosed. The results of the FACS analysis revealed significant differences in CD3/CD4 positive, CD14 positive and CD19 positive cells (p < 0.05). A significant elevation of CD3/CD4 positive and CD14 positive cells (p < 0.05) was observed after the period of culture (72 h) whereas a significant decrease could be detected in the case of CD19 positive cells. CONCLUSION: The results demonstrate that the particle-induced response by UHMW-PE limits itself not only to the particle macrophage contact but influences also the differentiation of the bone marrow. Moreover, the results confirm that the present method is useful to evaluate the in vitro effects of UHMW-PE wear particles with direct particle cell contact. Although the particles built large conglomerates, it could be shown that a change of the immune-competent cells also occurred.

Bone Marrow Cells↗
PubMedDate not supplied

Burn-associated peripheral polyneuropathy. A search for causative factors.

This study sought to evaluate the timing of burn-associated polyneuropathy (BAPN) and its relationship to burn severity or size. Seventeen burned subjects were studied 1 wk after thermal burns. Eleven subjects remained in the study to complete 6-wk follow-up studies. Nerve conduction studies were done on at least three nerves in two unburned limbs; results were numerically summarized by calculating Z scores for each parameter. A composite Z score, termed Ztotal, measured global nerve function. One week postburn, motor and sensory distal latencies were prolonged (mean Z, -0.72 and -0.85, respectively), motor conduction velocities slowed (mean Z, -1.31) and sensory nerve action potentials reduced in amplitude (mean Z, -0.66). Associations of Ztotal scores with total burn surface area and depth were not statistically significant. Those with severe neuropathy had higher levels of c-reactive protein (Spearman correlation, -0.624; P = 0.0129). There were no significant changes in Z scores at 6 wk. We conclude that BAPN is common after thermal injury, and the electrophysiologic manifestations of BAPN are present within the first week. Thermal injuries may induce an inflammatory cascade that results in alterations of nerve function.

Adolescent↗
PubMedDate not supplied

Experimental drug-induced changes in renal function and biodistribution of 99mTc-MDP.

Increased renal uptake of 99mTc methylene diphosphonate (MDP) was observed irregularly in rats after methotrexate, vincristine or gentamicin, administered separately. Cisplatin regularly induced a dose-related increased MDP uptake which correlated with the degree of tubular damage histologically. The augmented MDP renal uptake was not consistently accompanied by a decreased clearance of simultaneously injected I-131 Hippuran, particularly at lower drug dose levels. This observation agreed with previous evidence that the mechanisms of tubular transport of diphosphonates and organic acids like Hippuran are different. At higher dose levels, the augmented MDP uptake was accompanied by increased renal calcium, hypophosphatemia, elevated serum urea nitrogen and creatinine, and only occasional, mild hypercalcemia. The magnitude of the increased renal uptake of MDP observed could not be explained by alterations in iron metabolism or by dehydration. Drug-induced renal retention of MDP by a factor of 2 or more above normal appears to be a useful indicator of tubular damage when other parameters of renal function are sometimes normal.

Animals↗
PubMedDate not supplied

Comparative renal tubular toxicity of chemotherapy regimens including ifosfamide in patients with newly diagnosed sarcomas.

PURPOSE: The aim of this study was to assess renal tubular toxicity (RTT) of ifosfamide-containing regimens (ICR) in patients with newly diagnosed sarcomas at St. Jude Children's Research Hospital. METHODS: The authors reviewed the records of 199 patients receiving ICR at St. Jude between June 1986 and December 31, 1994 for evidence of RTT. Their median age was 13.3 years (range 1.2-24.8); 150 patients were white and 112 were male patients. Diagnoses included osteosarcoma (n = 82), Ewing sarcoma (n = 82), rhabdomyosarcoma (n = 28), and a group of other tumors (n = 7). RESULTS: The authors estimated the proportion of patients with severe RTT during the first five cycles of ICR and within 1 year after therapy for three groups of patients receiving ifosfamide (IFOS, n = 110), ifosfamide/cisplatin (IFOS/CDDP, n = 51), and ifosfamide/carboplatin (IFOS/CARBO, n = 38). The IFOS/CDDP patients received three cycles of IFOS before receiving CDDP and received only 200 mg/m2 by cycle 5, whereas the IFOS/CARBO patients received both agents simultaneously. The authors compared the probability of severe RTT among treatment groups using a generalized linear model for the first five cycles of ICR, as well as the probability of severe RTT within 1 year after therapy among treatment groups for patients receiving all prescribed IFOS using an exact chi-square test with pairwise comparisons when the three-way P value was less than 0.10. The proportion of patients with severe RTT during the first three cycles of ICR was significantly greater in the IFOS/CARBO group than in the other two. Although the proportion of patients with severe RTT in the IFOS/CDDP group increased during cycles 4/5, the proportion of patients with severe RTT remained significantly greater in the IFOS/ CARBO group. Within 1 year after therapy, the proportion of patients with severe RTT differed among the three groups, and pairwise comparisons revealed a significant difference between the IFOS and the IFOS/CDDP group. Severe RTT developed in four IFOS/CDDP patients more than 1 year after therapy, suggesting a long-term effect of CDDP on tubular function. CONCLUSIONS: Chemotherapy regimens including IFOS/ CARBO produce severe acute RTT more frequently than regimens including IFOS or IFOS/CDDP. Patients receiving IFOS/ CDDP appear at risk for delayed RTT. Long-term follow-up of these patients is essential to assess whether the number of patients receiving IFOS/CDDP with severe RTT continues to increase over time and to evaluate the long-term significance of these abnormalities.

Adolescent↗
PubMedDate not supplied

Nursing assessment of altered sexuality: a review of salient factors and objective measures.

TOPIC: Nursing assessment of altered sexuality. PURPOSE: To review salient factors affecting assessment and objective measures available for use in assessment. SOURCE: Literature specific to nursing assessment of sexuality and to instruments measuring altered sexuality. CONCLUSIONS: Many standards of care include the assessment of sexuality, and nurses believe it to be an important aspect of care. However, the assessment of altered sexuality does not often occur in actual practice. The use of an objective measure of sexuality is recommended for both initial and on-going assessments in acute-care and community-based settings.

Female↗
PubMedDate not supplied

Comparison of the perturbation correction in a parallel plate and a cylindrical ion chamber.

The perturbation correction factors for a 0.03 cc parallel plate chamber and a 0.6 cc cylindrical ionization chamber have been compared. The current from these ion chambers was measured in electron beams of energy in the range 7 to 12 MeV and in a cobalt-60 gamma ray beam. It is concluded that there is no difference between the perturbation correction factor for these two chambers. A significant polarity effect was observed for the parallel plate chamber, which was a function of energy and depth in the phantom. This work supports the ICRU recommendation for displacement correction.

Cobalt Radioisotopes↗
PubMedDate not supplied

Mechano-reception in osteoblast-like cells.

Response to mechanical stimulation is a basic biological phenomenon. Nearly all cells process mechanical input and respond to it by inducing and modulating biochemical pathways. In organisms with tissues, if the average mechanical load is increased, some tissues can increase their performance and often increase their bulk by cell division. A reduction in mechanical loading decreases performance, catabolic activity gains, and the tissue degenerates. The process of anabolism and catabolism regulated by mechanical loading is a second-to-second, minute-to-minute, and hour-to-hour process that works together with local and systemic hormones to ensure that the tissue can meet the demands of the mechanical environment. On the other hand, a mechanical load that is too high can cause tissue and matrix failure and damage to the cells, which can result in inflammation. In this paper, we review the possible biophysical and cell biological mechanisms that might be responsible for transducing physiological and hyperphysiological mechanical loading into the biological response of skeletal cells. We speculate on what the mechanism of mechano-transduction in bone might be compared with that of other cells and on how information produced by mechanical loading might be passed on to other cells to achieve a coordinated tissue response.

Cell Communication↗
PubMedDate not supplied

Neuritogenic-neurotoxic effects of membrane-associated forms of amyloid precursor protein.

The membrane-bound glycoprotein, amyloid precursor protein (APP), plays a central role in Alzheimer's disease (AD). The present paper investigates the neuritogenic-neurotoxic properties of this protein and relates them to possible aetiopathological mechanisms in AD. Marked differences in neuritic differentiation were detected when comparing untransfected tetraploid mouse neuroblastoma cells (or vector only cells) with transfected cells overexpressing APP(751). Transfected cells developed neurites quicker, and whereas all transfected cells differentiated, the degree of differentiation of untransfected cells was more variable. Fully differentiated transfected and untransfected cells had marked differences in neuritic morphology. Transfected cells had more neurites per cell, these being shorter and more branched than neurites on untransfected cells. The precocious differentiation of transfected cells was not maintained with neuritic process disintegration and cell death occurring from the seventh day onwards. Untransfected cells continued to extend their neuritic processes for up to five weeks. Membrane-associated forms of APP were responsible for these effects, rather than secreted APP or the beta/A4-peptide. Combined data from Western blot and immunocytochemical procedures showed a prominent accumulation of APP-C-terminal fragments in the perinuclear region, neuritic varicosities and growth cones of transfected cells, suggesting their involvement in the neuritogenic-neurotoxic process. Similar neuritogenic-neurotoxic mechanisms occurring in vivo, in association with compensatory synaptoplastic responses in the aged brain, may be part of the pathological process in AD.

Alzheimer Disease↗
PubMedDate not supplied

Development of symptomatic Chiari malformation in a child with craniofacial dysmorphism.

We present the case of a 28-month-old child with craniofacial anomalies who presented for evaluation of apnea. The patient had associated symptoms referable to a Chiari malformation and MRI scanning of the head and cervical spine revealed some, but not all, of the anatomical features classically associated with the Chiari II malformation. The child has mid-face hypoplasia and it appeared that his posterior fossa hypertension was partially caused by anterior compression of the brain stem as a result of the malformation at the base of the skull. The patient responded dramatically to posterior fossa decompression. Evidence from this and other cases from the literature suggests that different pathophysiological mechanisms may cause the classic Chiari malformation and/or other anatomical abnormalities in the continuum between Chiari I and II.

Arnold-Chiari Malformation↗
PubMedDate not supplied

Archetypal healing.

With emphasis on healing versus curing, the authors draw from a wide assortment of treatment methods for psychospiritual relief of pain in the terminally ill. These archetypal methods include: life-review therapy; ministry of presence; clinical hypnosis; myths, symbols, rituals, and community; creative therapies. In life-review therapy, the ill person shares his/her life story with the provider much like the healing rituals of the ancient storyteller did in his community. In the ministry of presence, the caregiver focuses on sharing his vulnerability, not his professional skills. Clinical hypnosis emphasizes the naturalness and simplicity of accessing the unconscious along with problem areas of the hypnoclinician. Myths, symbols, rituals, and community serve as nurturing agents in the intervention of pain, while creative therapies such as music, drama, crafts, and art continue to be powerful healing instruments. Archetypal healing produces relief of pain in the caregiver, as well as the ill, with emphasis on healing versus curing.

Adult↗
PubMedDate not supplied

Characteristics of elderly people taking psychotropic medication.

A sample of 253 elderly people who had been taking psychotropic medication for at least 3 months were interviewed to establish their levels of morbidity and their subjective health status. The findings were compared with those of a control sample of 484 elderly people in the same area. Those taking psychotropic medication were older and more were female and widowed than were the control sample. Their subjective assessments of health status were worse as were the more objective measures of mental and physical morbidity; in addition they were taking more medication of other types. There were more falls among those taking psychotropic medication than those who were not; most excess falls took place indoors. It is possible that a proportion of this morbidity is a result of or exacerbated by medication, but care needs to be taken in interpreting a cross-sectional study. Older people, we suggest, may benefit from regular review of the need for psychotropic medication. Larger studies need to be initiated to investigate the association between morbidity and psychotropic medication.

Accidental Falls↗