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M J Johnson

Publications and source records attributed to M J Johnson.

At least 19 recordsLinked to original sources

Genetic diagnosis of haemophilia and other inherited bleeding disorders.

Inherited deficiencies of plasma proteins involved in blood coagulation generally lead to lifelong bleeding disorders, whose severity is inversely proportional to the degree of factor deficiency. Haemophilia A and B, inherited as X-linked recessive traits, are the most common hereditary hemorrhagic disorders caused by a deficiency or dysfunction of blood coagulation factor VIII (FVIII) and factor IX (FIX). Together with von Willebrand's disease, a defect of primary haemostasis, these X-linked disorders include 95% to 97% of all the inherited deficiencies of coagulation factors. The remaining defects, generally transmitted as autosomal recessive traits, are rare with prevalence of the presumably homozygous forms in the general population of 1:500,000 for FVII deficiency and 1 in 2 million for prothrombin (FII) and factor XIII (FXIII) deficiency. Molecular characterization, carrier detection and prenatal diagnosis remain the key steps for the prevention of the birth of children affected by coagulation disorders in developing countries, where patients with these deficiencies rarely live beyond childhood and where management is still largely inadequate. These characterizations are possible by direct or indirect genetic analysis of genes involved in these diseases, and the choice of the strategy depends on the effective available budget and facilities to achieve a large benefit. In countries with more advanced molecular facilities and higher budget resources, the most appropriate choice in general is a direct strategy for mutation detection. However, in countries with limited facilities and low budget resources, carrier detection and prenatal diagnosis are usually performed by linkage analysis with genetic markers. This article reviews the genetic diagnosis of haemophilia, genetics and inhibitor development, genetics of von Willebrand's disease and of rare bleeding disorders.

Blood Coagulation Disorders, Inherited↗

Palliative care for patients with heart failure: description of a service.

Over the past 10 years, there has been an increasing demand for heart failure patients to have access to palliative care services. The concerns of this group have been highlighted and there is growing recognition in national palliative care and cardiology bodies that these concerns should be addressed. In spite of this, there is little improvement. There are concerns about the acceptability of hospice services to heart failure patients, worries about service overload, lack of appropriate knowledge and skills and difficulty in knowing when to refer a heart failure patient for palliative care. In Scarborough, a joint approach by a cardiologist and palliative care physician was set up in September 2000. This paper describes the service so far in an attempt to address some of the above reservations and to provide a catalyst and encouragement to others beginning a similar venture.

Aged↗

Pancam multispectral imaging results from the Opportunity Rover at Meridiani Planum.

Panoramic Camera (Pancam) images from Meridiani Planum reveal a low-albedo, generally flat, and relatively rock-free surface. Within and around impact craters and fractures, laminated outcrop rocks with higher albedo are observed. Fine-grained materials include dark sand, bright ferric iron-rich dust, angular rock clasts, and millimeter-size spheroidal granules that are eroding out of the laminated rocks. Spectra of sand, clasts, and one dark plains rock are consistent with mafic silicates such as pyroxene and olivine. Spectra of both the spherules and the laminated outcrop materials indicate the presence of crystalline ferric oxides or oxyhydroxides. Atmospheric observations show a steady decline in dust opacity during the mission. Astronomical observations captured solar transits by Phobos and Deimos and time-lapse observations of sunsets.

Atmosphere↗

Pancam multispectral imaging results from the Spirit Rover at Gusev Crater.

Panoramic Camera images at Gusev crater reveal a rock-strewn surface interspersed with high- to moderate-albedo fine-grained deposits occurring in part as drifts or in small circular swales or hollows. Optically thick coatings of fine-grained ferric iron-rich dust dominate most bright soil and rock surfaces. Spectra of some darker rock surfaces and rock regions exposed by brushing or grinding show near-infrared spectral signatures consistent with the presence of mafic silicates such as pyroxene or olivine. Atmospheric observations show a steady decline in dust opacity during the mission, and astronomical observations captured solar transits by the martian moons, Phobos and Deimos, as well as a view of Earth from the martian surface.

Atmosphere↗

The relationship between insulin and insulin-like growth factor binding protein-1 is modified by pre-eclampsia.

Insulin is the main negative regulator of insulin-like growth factor binding protein-1 (IGFBP-1) in the non-pregnant state. Although changes in insulin resistance and circulating level of IGFBP-1 occur in pre-eclampsia, little is known about the relationship between insulin and IGFBP-1 in pregnancies complicated by the disease. In this study, we have investigated whether the relationship between insulin and IGFBP-1 is modified by pre-eclampsia. Maternal levels of insulin and IGFBP-1 were measured, at 4-weekly intervals between 16 and 36 weeks' gestation, in plasma samples obtained from ten normal pregnant controls and ten women who developed pre-eclampsia. The controls were chosen to be similar in maternal age and booking body mass index to the pre-eclampsia group. Insulin levels increased in both the normal controls and the women who developed pre-eclampsia. The levels in pre-eclampsia were significantly greater than those in normal pregnancy at 32 and 36 weeks' gestation (p = 0.02 and 0.005, respectively). IGFBP-1 levels were unchanged in normal pregnancy and rose in pre-eclampsia. In normal pregnancy, insulin levels were inversely related to IGFBP-1 levels throughout. In women developing pre-eclampsia, the relationship between insulin and IGFBP-1 was negative at 16 weeks and positive from 24 weeks. These data suggest that whereas the inverse relationship between insulin and IGFBP-1 is maintained during normal pregnancy, this relationship is reversed in women who develop pre-eclampsia.

Adult↗

Morphine for the relief of breathlessness in patients with chronic heart failure--a pilot study.

BACKGROUND: Chronic heart failure (CHF) patients can experience significant breathlessness despite maximum medication for their heart failure. Morphine has long been used to relieve symptoms in acute failure, but there is little evidence about this potentially useful palliative therapy in CHF. AIMS: To determine the efficacy of morphine for the relief of breathlessness in patients with CHF. METHOD: Ten out-patients with NYHA III/IV CHF entered a randomised, double-blind, placebo controlled, crossover pilot study. The active arm was 4 days of 5 mg oral morphine four times daily (2.5 mg morphine if creatinine > 200 micromol/l). There were 2 days wash-out between active and placebo arms. RESULTS: 6/10 patients indicated that morphine improved their breathlessness. On morphine, the median breathlessness score fell by 23 mm (P = 0.022) by day 2. The improvement was maintained. Sedation scores increased until day 3 (P = 0.013), reducing on day 4. Four patients developed constipation (P = 0.026). On placebo, there was no significant difference in breathlessness or sedation. One patient had constipation. There were no significant differences in either arm in nausea, quality of life scores, blood pressure, pulse, respiratory rate, or catecholamines. Brain natriuretic peptide fell in both arms; significantly in the morphine arm. CONCLUSION: Morphine relieves breathlessness due to CHF. A larger study is indicated.

Administration, Oral↗

Palliative physicians persuade procurators fiscal.

Mesothelioma caused by occupational exposure to asbestos is well recognized and sufferers who have been employed in a prescribed occupation can claim compensation. Stringent criteria must be fulfilled in order to establish the link between occupational exposure and mesothelioma, and to this end the procurator fiscal is involved after the patient's death, both to elucidate the individual situation and 'for the common good'. Problems were experienced locally by the use of uniformed police officers, as the appointed Crown agents, as interviewers of recently bereaved relatives, irrespective of the degree of tact and sensitivity shown. The likelihood of an autopsy was also distressing. It is important to recognize the role of the procurator fiscal and to ensure that workers' compensation procedures exist and are followed. However, in order to minimize grief and distress to relatives, discussion took place with the local procurator fiscal. He was appreciative of the issues raised and practice has now changed substantially. In particular, police officers are no longer required to interview relatives either for the purpose of identification or to ascertain the deceased's occupational history. A pro forma has been produced and agreed locally to obviate the need for medical staff to be interviewed by police officers. Following subsequent discussion with the Crown Office our local arrangements have been incorporated in Crown Office guidance for national use.

Asbestos↗

2D electrochemical time of flight and its application in the measurements of the kinetics of lateral electron hopping in monolayer films at the air/water interface.

A 2D electrochemical time-of-flight (ETOF) method was developed to measure diffusion constants of lateral mobility of amphiphiles and lateral electron hopping in Langmuir monolayers at the air/water interface. Photolithographically fabricated generator-collector ETOF devices featured two parallel gold microelectrodes (7 mm in length, 40 microm wide, spaced by a 10-microm gap). In 2D ETOF measurements, such a device is touching the water surface where the generator and collector electrodes function as a collinear pair of line microelectrodes. Bulk measurements, with a generator-collector device submerged in an electrolyte solution, were carried out to calibrate the devices by relating the transit times to the known D values of Ru(NH3)6(2+) in a series of solutions of different viscosity adjusted with sucrose. A new method to define and to measure transit times in the step mode ETOF experiments was developed that requires only the pseudo-steady-state values of the collector current. Reliability of the 2D ETOF technique was established by investigating lateral diffusion of an amphiphilic tetradecane TEMPO derivative for which the D values were also measured by 2D voltammetry. Combination of 2D ETOF and 2D voltammetry allows one to independently measure diffusion coefficients and concentrations of redox species. This advantageous feature was then used to reevaluate kinetics of lateral electron hopping in Os(DPP)3(ClO4)2 (DPP, 4,7-diphenyl-1,10-phenanthroline) solid monolayers on the water surface. The true rate constant of electron self-exchange, kex = 1.0 x 10(9) M(-1) s(-1), was obtained. The fact that the latter is more than 1 order of magnitude larger than its value obtained in a homogeneous acetonitrile solution suggests that the structure and locale of the Os(DPP)3(III+/II+) monolayer system result in a larger electronic coupling and/or smaller reorganization energy.

Journal Article↗

Steam sterilizable probes for dissolved oxygen measurement. Reprinted from Biotechnology and Bioengineering, Vol. VI, Issue 4, Pages 457-468 (1964).

Steam-sterilizable membrane probes for monitoring the dissolved oxygen level in fermentors, or the oxygen content of gas streams, are described. The probes have a silver cathode, a lead anode, and an acetate buffer as an electrolyte. The membrane is Teflon. The current output of the probes in the absence of oxygen is negligible.

Equipment Design↗

Decreased c-fos expression in experimental neonatal hydrocephalus: evidence for reduced neuronal activation.

Although neonatal hydrocephalus often results in residual neurological impairments, little is known about the cellular mechanisms responsible for these deficits. The immediate early gene, fos (c-fos), functions as a "third messenger" to regulate protein synthesis and is a good marker for neuronal activation. To identify functional changes in neurons at the cellular level, the authors quantified fos RNA expression and localized fos protein in the H-Tx rat model of congenital hydrocephalus. Tissue samples from sensorimotor and auditory regions were obtained from hydrocephalic rats and age-matched, normal litter mates at 1, 6, 12, and 21 days of age (four-six animals in each group) and processed for immunohistochemical analysis of fos and Northern blot analysis of RNA. At 12 days of age, hydrocephalic animals exhibited significant decreases in the ratio of fos immunoreactive cells to Nissl-stained neurons from both cortical regions, but no statistical differences were noted in fos expression. At 21 days of age, both the ratio of fos immunoreactive cells to Nissl-stained neurons and fos expression decreased significantly. The number of fos-positive neurons decreased in all cortical layers but was most prominent in layers V through VI. This decrease did not appear to be caused by neuronal death because examination of Nissl-stained sections revealed many viable neurons within the areas where fos immunoreactivity was absent. These results suggest that progressive neonatal hydrocephalus reduces the capacity for neuronal activation in the cerebral cortex, primarily in those neurons that provide corticofugal projections, and that this impairment may begin during relatively early stages of ventriculomegaly.

Journal Article↗

Development and characterization of an adult model of obstructive hydrocephalus.

While hydrocephalus is common in adults its pathophysiology is not fully understood and its treatment remains problematic. Previous animal models have been acute, developmental, or involved non-specific blockage or inflammation and are not suitable for study of chronic adult-onset hydrocephalus. In this study, we describe the development of a canine model which allows basic physiological studies along with diagnostic and treatment procedures via surgical occlusion of the fourth ventricle with a bolus injection of cyanoacrylic gel glue. A total of 26 adult male canine mongrels were used for the induction of chronic hydrocephalus and were monitored for 1-12 weeks post-induction using magnetic resonance imaging (MRI), intracranial pressure measurements, and neurological fitness assessments. Of these, 81% (21/26) developed hydrocephalus that was mild (N = 6), moderate (N = 7), or severe (N = 8). Pressures were mild and transiently elevated, and brain compliance decreased. Clinical symptoms were also mild and transient. This model is unique in its focal obstruction without local compression or general inflammation and should facilitate the study of the pathophysiology and treatment of chronic adult-onset hydrocephalus.

Animals↗

Abnormal coagulation and deep venous thrombosis in patients with advanced cancer.

Many studies have demonstrated increased coagulation activation in cancer patients and have shown evidence of chronic, low-grade disseminated intravascular coagulation, although most patients remained asymptomatic. In general, patients have not been screened for deep venous thrombosis (DVT). We screened 98 patients with advanced malignancy for DVT using light reflection rheography. Coagulation profiles of DVT and non-DVT groups were studied. We found a high prevalence of DVT (50%) on screening. Overall, the patients had raised levels of fibrinogen (66% patients), factor VIII:C (43%), fragment 1 + 2 (71%) and TAT levels (89%). Patients with DVT had a significantly lower level of fibrinogen than those without (4.0 g/dl, SD 1.4, compared with 4.7 g/dl SD 1.6, P = 0.04). There was no significant difference in other coagulation or liver function tests between the DVT and non-DVT groups. The wide variation of results makes their interpretation difficult and unlikely to be of predictive value in estimating individual thrombotic risk.

Adult↗

The prevalence and associated variables of deep venous thrombosis in patients with advanced cancer.

The prevalence of venous thromboembolism (VTE) in cancer patients has been estimated as up to 15% antemortem, and higher (over 50% in pancreatic tumours) postmortem owing to the asymptomatic nature of many episodes of VTE. We investigated the prevalence of deep venous thrombosis (DVT) in a population of 298 hospice inpatients with advanced cancer. They were screened for the presence of DVT using light reflection rheography; 258 (86.6%) patients were evaluable for DVT, which was found in 135 (52%; 95% confidence interval 46-58). Factors associated (multivariate analysis) with the presence of DVT were: poor mobility, reduced serum albumin level and higher serum urea. A DVT risk assessment index was calculated using these variables. The three highest categories all had significant rates of DVT and, although the lowest category had a low rate of DVT, it accounted for less than 10% of all patients tested. DVT is common in patients with advanced cancer. It was found to be significantly associated with the above variables, but a combined index was of limited clinical application. In view of the number of patients identified with DVT, repeated small pulmonary emboli may be responsible for more symptoms than previously recognized in cancer patients.

Adult↗

Patterns of maxillofacial injuries in powered watercraft collisions.

Because of the widespread popularity of water sports, plastic and reconstructive surgeons can expect to manage an increasing number of injuries associated with these activities, particularly those related to powered watercraft vehicles. Although seat belts for motorists and helmets for motorcyclists may be efficacious, such devices currently do not serve a similar role in powered watercraft sports. In this study, a retrospective chart review of 194 consecutive patients who presented to the University of Miami/Jackson Memorial Hospital (Level I trauma center) as a result of powered watercraft collisions is presented. The purpose of this investigation was to assess the incidence, cause, demographics, and available management options for head and neck injuries secondary to powered watercraft. Identified were 194 patients who presented because of watersports-related injuries during the period January 1, 1991, through December 31, 1996. From this group, 81 patients (41.8 percent) sustained injuries directly attributable to powered watercraft collisions, including 41 personal watercraft collisions (50.6 percent), 39 boat collisions (48.1 percent), and 1 airboat collision (1.2 percent). The patient population, as expected, tended to be young and male with an average age of 29 years (range, 8 to 64 years old). Interestingly, 41 of the patients (50.6 percent) who presented to this trauma center as a result of powered watercraft collisions also sustained associated head and neck trauma. Of 74 injuries 24 were facial fractures (32.4 percent), 18 were facial lacerations (24.3 percent), 14 were closed head injuries (18.9 percent), 8 were skull fractures (10.8 percent), 4 were scalp lacerations (5.4 percent), 4 were C-spine fractures (5.4 percent), 1 was an ear laceration (1.4 percent), and 1 was a fatality (1.4 percent). Le Fort fractures were the most commonly identified facial fracture in this series. The number of these injuries seen in hospital emergency rooms will most likely increase in the future as the popularity of water-related recreational activities becomes even more widespread. Based on these findings, it is strongly recommended that future efforts be directed toward the prevention of these injuries through patient education and the eventual development of efficacious and safe protective equipment.

Accidents↗

Adherent and nonadherent medication-taking in elderly hypertensive patients.

Nonadherence to medications is a significant reason why patients fail to control their blood pressure. Little work has been attempted to conceptualize medication-taking behaviors from the patient's perspective. This study examined factors that influence elderly hypertensive patients' adherence or nonadherence to prescribed medications. Using a qualitative descriptive research design, 21 hypertensive elderly people were interviewed. Two domains of adherence were identified: purposeful use of the medication for the control of patient's blood pressure and establishing and maintaining patterns of medication-taking. Two similar domains also emerged for nonadherence: purposeful and incidental. Adherence behaviors were dependent on the person's decision to take hypertension medication, access to medications, and ability to initiate treatment and maintain a medication-taking pattern. The timing and location of pills were integral parts of establishing patterns of taking medications. Inadequate access to medications or interruption of a person's pattern were associated with the incidental missing of medications.

Aged↗