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Biomedical subjects

J Davis

Publications and source records attributed to J Davis.

At least 37 records · Page 2Linked to original sources
PubMed2000

Buoyant magnetic flux tubes enhance radiation in Z pinches

In numerous experiments, magnetic energy coupled to strongly radiating Z-pinch plasmas exceeds the thermalized kinetic energy, sometimes by a factor of 2-3. We demonstrate that the enhanced energy coupling may be due to the buoyancy rise of toroidal magnetic flux tubes converging to the axis through the unstable pinch plasma. We derive an explicit formula for the enhanced dissipation rate and apply this formula to reconsider an old problem of power balance in a steady-state Z pinch, and then to analyze a new challenge of producing K-shell 3 to 10 keV radiation in long-pulse Z-pinch implosions.

Journal Article↗
PubMed2000

Increased levels of leukemia inhibitory factor mRNA in muscular dystrophy and human muscle trauma.

Leukemia inhibitory factor (LIF) is an important muscle trauma factor both after crush injury and in the mdx mouse dystrophy model. It is important to establish which growth factors have a role in human muscle regeneration due to potential clinical therapeutic applications. As there is limited information concerning LIF expression in human muscle, we investigated the relative levels of LIF messenger ribonucleic acid (mRNA) in human muscle injury. Semiquantitative reverse transcriptase followed by polymerase chain reaction was used to amplify LIF message. We found that although LIF mRNA is expressed in low levels in control muscle, a sevenfold increase occurred after orthopedic muscle trauma and a marked 19-fold increase in dystrophic muscle (P < 0.002). These results indicate that LIF mRNA is upregulated in surgical and especially medical muscle injury with repeated myonecrosis. Muscle growth factors such as LIF may assist in future muscle rehabilitation after injury.

Adolescent↗
PubMed2000

Sonoelectroanalytical detection of lead at a bare copper electrode.

The sonochemically facilitated, mercury free detection of Pb2+ at a copper electrode has been investigated as a means of simplifying the quantification of this important analyte and to minimise the interference of copper ion. The procedure relies upon maximising the formation of Pb-Cu intermetallic compounds leading to the emergence of a single, easily quantifiable stripping signal. Linear responses to Pb2+ were obtained with a sensitivity comparable to that obtained at a bare glassy carbon electrode. Interference from Cu2+, Zn2+ and Cd2+ was assessed on the copper electrode with no appreciable change in the Pb2+ voltammetric profile observed. In contrast, bare glassy carbon showed a significant change in Pb2+ voltammetric profile as Cu2+ was added, due to the formation of intermetallic species.

Calibration↗
PubMed2000

The modern National Kidney Foundation: broad scope, clear vision, better lives.

The mission of the National Kidney Foundation is very broad, going well beyond what its name implies. The Foundation works for, cares about, and represents millions of Americans, from the child who wets the bed to the diabetic with hypertension to the grandfather on dialysis. It is dedicated to making lives better through a variety of educational programs for patients and their families as well as physicians, social workers, nurses, dietitians, technicians, administrators, and clinical and transplant coordinators. It supports research, promotes organ and tissue donation, provides direct services to patients, and advocates for patients through public policy and legislative initiatives. Its programs aid people at risk of kidney and urinary tract disease, individuals affected by these diseases, living organ donors and families of donors, and recipients of all types of lifesaving organ and tissue transplants.

Adult↗
PubMed2000

Proapoptotic functions of cytotoxic lymphocyte granule constituents in vitro and in vivo.

Recent advances in our understanding of cytolytic effector mechanisms include the partial characterization of caspase-independent apoptotic pathways triggered by granzymes, a realization of the vital importance of perforin and granzymes in the defence against certain virus infections in vivo and the first description of hereditary immunodeficiency due to disordered perforin expression in humans.

Animals↗
PubMed2000

The Scottish and Manchester randomised trial of neo-adjuvant chemotherapy for advanced cervical cancer.

204 eligible patients were entered into a multicentre randomised trial of neo-adjuvant chemotherapy prior to radical radiotherapy. The aim of this study was to assess whether there was any survival advantage in patients undergoing chemotherapy and radiotherapy compared with those given radiotherapy alone. Patients were aged up to 70 years, performance status 0-1/2, with bulky stage IIb, stage III or stage IVa squamous or adenosquamous carcinoma. Three cycles of methotrexate 100 mg/m2 and cisplatin 50 mg/m2 were given at 2-weekly intervals before radical radiotherapy. 104 eligible patients received the combination treatment and 100 radiotherapy only. The two arms of the study were well balanced for tumour and patient characteristics. The response rate to chemotherapy was 49%, 33% of patients in the radiotherapy (XRT) alone arm and 45% of the combination arm were clinically free of tumour at the end of treatment. The median follow-up for surviving patients is 5.4 years (range: 11 months-8 years) and 84% have been followed-up for more than 4 years. 134 patients have died (68 XRT only, 66 combined arm). The median survival RT alone was 111 weeks (95% confidence interval (CI) 72-151 weeks), combination arm 125 weeks (95% CI 79-170 weeks). The estimated death ratio is 0.79 (P = 0.19, 95% CI 0.56-1.12). The estimated 3-year survival is 40% (95% CI 30-50%) RT only compared with 47% (95% CI 37-57%) in the combination arm. Acute and late toxicity of radiotherapy was not increased by the addition of chemotherapy.

Adult↗
PubMed2000

Red-carpet rodent care: making the most of dollars and sense in the animal facility.

Cutting-edge biomedical research programs have entered an era in which phenotypic characterizations for genetically altered rodents can facilitate appropriate care. The veterinary care requirements necessary to support such animal models can include the procedures already adapted as standard practice in companion animal hospitals, and can decrease data variability while increasing survival rates.

Journal Article↗
PubMed2000

Air flight disaster, posttraumatic stress, and postventive rescue and response: the aftermath of the San Diego PSA 182 plane crash recovery operation, 20 years on.

San Diego in 1978 was the scene of one of the USA's most tragic and traumatic air flight disasters, when an inbound Boeing 727 collided with a small private Cessna 172. The collision occurred in the vicinity of North Park, a suburb of San Diego. All aircraft occupants were killed or injured and many residents were injured. The wreckage was mainly concentrated in an area about the size of a city block, in a temperature of 100 degrees F or more. The whole experience was unlike anything any of the professionals involved had been prepared for, and beyond anything the civilians involved could have imagined. Many sought out intervention and help and counselling, and this paper examines the implications of the event 20 years on.

Accidents, Aviation↗
PubMed2000

Effect of single versus multiple courses of antenatal corticosteroids on maternal and neonatal outcome.

OBJECTIVE: Treatment of pregnant mothers with a single course of antenatal corticosteroids significantly reduces neonatal mortality and morbidity. Multiple weekly courses are often given. However, the safety and efficacy of repeated courses of antenatal corticosteroids have not been adequately studied. STUDY DESIGN: A retrospective study was performed for 609 mothers and their 713 infants who were treated with 1 to 12 courses of antenatal corticosteroids. Data for 369 singleton preterm infants born at < or =34 weeks' gestation, 210 multiple gestations, and 134 infants delivered at > or =35 weeks' gestation were analyzed separately. RESULTS: The incidence of respiratory distress syndrome was 45% for single-course and 35% for multiple-course groups (P =.005; odds ratio, 0.44; 95% confidence interval, 0.25-0.79). The multiple-course group also had significantly less patent ductus arteriosus (20% vs 13%; P =.016). Incidence of death before discharge and other neonatal morbidities were similar. The multiple-course group had a reduction of 0.46 +/- 0.19 cm in head circumference at birth (P =.013) when adjusted for gestational age and preeclampsia. The 2 groups had similar birth weights. Infants born at > or =35 weeks' gestation, multiple-gestation infants, and infants who were born >7 days after the last corticosteroid dose had similar outcomes, regardless of the number of courses they received. Mothers treated with multiple courses compared with a single course had a significantly higher incidence of postpartum endometritis (P =.013), even though they had a lower incidence of prolonged rupture of membranes (24% vs 33%, P =.06) and similar cesarean delivery rates. CONCLUSION: Exposure to multiple courses of antenatal corticosteroids compared with a single course resulted in a significant reduction in the incidence of respiratory distress syndrome in singleton preterm infants delivered within a week of the last corticosteroid dose. This was associated with a reduction in birth head circumference and an increased incidence of maternal endometritis. Whether the potential benefits of repeated therapy clearly outweigh the risks will ultimately be determined in randomized prospective controlled trials.

Adrenal Cortex Hormones↗
PubMed2000

Quantitative trait loci and candidate gene mapping of bud set and bud flush in populus.

The genetic control of bud phenology in hybrid poplar was studied by mapping quantitative trait loci (QTL) affecting the timing of autumn bud set and spring bud flush. The founders of the mapping pedigree were collected from widely separated latitudes to maximize segregating variation for dormancy-related traits in the F(2) generation-the female Populus trichocarpa parent is from Washington State (48 degrees N) and the male P. deltoides parent is from Texas (31 degrees N). Bud set and bud flush timing were measured on the F(2) generation in a replicated clonal field trial. Using a linkage map constructed of AFLP and microsatellite markers, three QTL controlling bud set and six QTL controlling bud flush were detected. Additionally, five candidate genes believed to be involved in perception of photoperiod (PHYB1, PHYB2) or transduction of abscisic acid response signals (ABI1B, ABI1D, and ABI3) were placed on the QTL map. PHYB2 and ABI1B were found to be coincident with QTL affecting bud set and bud flush.

Base Sequence↗
PubMed2000

Corrugator supercilii muscle resection and migraine headaches.

This study was conducted to determine whether there is an association between the removal of the corrugator supercilii muscle and the elimination or significant improvement of migraine headaches. Questionnaires were sent to 314 consecutive patients who had undergone corrugator supercilii muscle resection during endoscopic, transpalpebral, or open forehead rejuvenation procedures. The patients were queried as to whether they had a history of migraine headaches and, if so, whether the headaches significantly improved or disappeared after surgery. If the answer was affirmative, then the patients were further questioned about the duration of the improvement or cessation of the headaches and the relationship to the timing of the surgery. After an initial evaluation of the completed questionnaires, a telephone interview was conducted to confirm the initial answers and to obtain further information necessary to ensure that the patients had a proper diagnosis based on the International Headache Society criteria for migraine headaches. The charts of the patients who had migraine headaches were studied to ascertain and classify the type of surgery they had undergone. Patient demographics were reviewed, and the results were statistically analyzed. Of the 314 patients, 265 (84.4 percent) either responded to the questionnaire, were interviewed, or both responded to the questionnaire and were interviewed. Of this group, 16 patients were excluded because of the provision of insufficient information to meet the International Headache Society criteria, the presence of organic problems, and other exclusions mandated by study design. Thirty-nine (15.7 percent) of the remaining 249 patients had migraine headaches that fulfilled the Society criteria. Thirty-one of the 39 (79.5 percent) with preoperative migraine noted elimination or improvement in migraine headaches immediately after surgery (p < 0.0001; McNemar), and the benefits lasted over a mean follow-up period of 47 months. When the respondents with a positive history of migraine headaches were further divided, 16 patients (p < 0.0001; McNemar) noticed improvement over a mean follow-up period of 47 months, and 15 (p < 0.0001; McNemar) experienced total elimination of their migraine headaches over a mean follow-up period of 46.5 months. When divided by migraine headache type, 29 patients (74 percent) had nonaura migraine headaches. Of these patients, the headaches disappeared in 11 patients, improved in 13 patients, and did not change in five patients (p < 0.0001). Ten patients experienced aura-type headaches, which disappeared or improved in seven of the patients and did not change in three of the patients (p < 0.0001). This study proves for the first time that there is indeed a strong correlation between the removal of the corrugator supercilii muscle and the elimination or significant improvement of migraine headaches.

Adult↗
PubMed2000

Effects of fosinopril or sustained-release verapamil on blood pressure and serum catecholamine concentrations in elderly hypertensive men.

A randomized, double-blind, placebo-controlled clinical trial showed 14 of 18 (78%) of the elderly hypertensive men in this study had an uncomplicated and beneficial response to either fosinopril or verapamil. There was a well-tolerated reduction in systolic blood pressure (SBP) and diastolic blood pressure (DRP). There were no significant adverse drug events. Only the sitting SBP and the sitting DBP were significantly lowered by fosinopril and verapamil SR. Because reduction in both SBP and DBP in elderly hypertensives has been shown to be beneficial, these findings take on further importance when considering the choice of medication for antihypertensive therapy in the elderly. The increase in norepinephrine in the fosinopril-treated patients may explain why patients treated with long-term angiotensin-converting enzyme inhibitors alone or in combination with diuretics rarely complain of orthostatic symptoms.

Aged↗
PubMed2000

A randomised comparison and economic evaluation of laparoscopic-assisted hysterectomy and abdominal hysterectomy.

OBJECTIVES: To determine the safety, cost effectiveness and effect on quality of life of laparoscopic-assisted vaginal hysterectomy (LAVH) compared with total abdominal hysterectomy (TAH) in the management of benign gynaecological disease. DESIGN: Randomised controlled trial and economic evaluation. SETTING: Three hospitals in the West of Scotland. PARTICIPANTS: Two hundred women scheduled for an abdominal hysterectomy for benign gynaecological disease. MAIN OUTCOME MEASURES: Conversion rate of LAVH to TAH, complication rates, NHS resource use and costs, quality of life using EuroQol 5 D visual analogue scale, and achievement of milestones. RESULTS: The overall incidence of operative complications was 14% in the TAH group and 8% in the LAVH group, with an 8% conversion rate. Length of operation was significantly greater in the women having LAVH at 81 +/- 30 min vs 47 +/- 16 min (P < 0.001). There was no difference in analgesic requirements between the groups although there was a significantly shorter hospital stay for those having LAVH. The rate of post-surgery recovery, satisfaction with operation and quality of life at four weeks post-operative were similar in the two groups of women. LAVH was significantly more expensive than TAH and remained more expensive for all but the most extreme scenario. CONCLUSIONS: This study demonstrates that despite the decreased length of hospital stay, LAVH is more expensive than TAH. In addition, recovery following operation and patient satisfaction were not affected by the route chosen. It is unlikely that LAVH represents an efficient use of NHS resources.

Adult↗
PubMed2000

Cerebrovascular smooth muscle cell surface fibrillar A beta. Alteration of the proteolytic environment in the cerebral vessel wall.

Cerebrovascular deposition of the amyloid beta-protein (A beta) is a common pathologic event in patients with Alzheimer's disease (AD) and certain related disorders including hereditary cerebral hemorrhage with amyloidosis Dutch-type (HCHWA-D). A beta deposition occurs primarily in the medial layer of the cerebral vessel wall in an assembled fibrillar state. These deposits are associated with several pathological responses including degeneration of the smooth muscle cells in the cerebral vessel wall. Severe cases of cerebrovascular A beta deposition are also accompanied by loss of vessel wall integrity and hemorrhagic stroke. Although the reasons for this pathological consequence are unclear, altered proteolytic mechanisms within the cerebral vessel wall may be involved. Recent studies from our laboratory have shown that cell-surface assembly of A beta into fibrillar structures causes cellular degeneration via an apoptotic pathway and creates an altered proteolytic microenvironment on the cell surface of human cerebrovascular smooth muscle cells (HCSM cells). For example, HCSM cell-surface A beta fibrils serve as a site for tight binding of cell-secreted amyloid beta-precursor protein (A beta PP). Since A beta PP is a potent inhibitor of key proteinases of coagulation cascade, its enhanced localization on the A beta fibrils would provide an strong anticoagulant environment. In addition, HCSM cell-surface A beta fibrils are potent stimulators of tissue plasminogen activator (tPA) creating a profibrinolytic milieu. Our findings indicate that A beta fibril assembly on the HCSM cell surface causes cellular degeneration and results in both a strong anticoagulant and fibrinolytic environment. Together, these altered proteolytic events could create a setting that is conducive to loss of vessel wall integrity and hemorrhagic stroke.

Alzheimer Disease↗
PubMed2000

Utility of tissue culture for detection of Toxoplasma gondii in vitreous humor of patients diagnosed with toxoplasmic retinochoroiditis.

Laboratory recovery and confirmation of the etiologic agent in necrotizing retinochoroiditis are problematic. Tissue culture and intraocular antibody titers were compared as adjuncts to clinical diagnosis for toxoplasmic retinochoroiditis: the correlations were 91 and 67%, respectively. Isolation of Toxoplasma gondii may establish a definitive diagnosis in patients with toxoplasmic retinochoroiditis.

Animals↗
PubMed2000

Differential role of melanocortins in mediating leptin's central effects on feeding and reproduction.

Leptin serves as a humoral link coupling the status of energy reserves to the functional activity of the reproductive system. Leptin is thought to act through melanocortinergic pathways in the brain to regulate ingestive behaviors; however, whether melanocortins mediate leptin's actions on the neuroendocrine-reproductive axis is unknown. We tested this hypothesis first by determining whether the effects of leptin on feeding behavior and reproduction in the ob/ob mouse could be blocked by the melanocortin receptor (MC-R) antagonist SHU9119 and second, by examining the effects of the MC-R agonist MTII on feeding and the endocrine-reproductive system. Administered by intracerebroventricular injections, leptin inhibited food intake, raised plasma gonadotropin levels, and increased seminal vesicle weights compared with controls; SHU9119 (intracerebroventricularly) attenuated leptin's effects on food intake and body weight but did not alter leptin's stimulatory effect on the reproductive axis. MTII (intracerebroventricularly and intraperitoneally) decreased food intake and increased body temperature compared with controls but had no effect on the reproductive-endocrine axis. These results suggest that although leptin acts centrally through melanocortinergic pathways to inhibit ingestive behaviors and stimulate metabolism, leptin's activational effect on the reproductive axis is likely to be mediated by other, unknown neuroendocrine circuits.

Animals↗