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Biomedical subjects

P Johnson

Publications and source records attributed to P Johnson.

At least 91 records · Page 5Linked to original sources
PubMed2000

Measuring blood pressure at the wrist: more comfortable for patients and more convenient for doctors?

OBJECTIVES: To compare the agreement between conventional measurement of blood pressure and measurements obtained using two automated devices; and to compare how comfortable each of the three methods of measurement were for patients. METHODS: Blood pressure measurements and patient comfort scores were recorded using three different devices in 125-surgery and 40-community patients. The devices used were a conventional aneroid sphygmomanometer, an automated device that measured blood pressure on the upper arm and an automated device that measured blood pressure at the wrist. In each patient, the difference between the conventional and automatic measurement was calculated. The limits of agreement of each device were then calculated as the mean difference +/-1.96 standard deviations. RESULTS: In surgery patients, the width of limits of agreement of wrist measurement were 20.0 mm Hg and 12.1 mm Hg for systolic and diastolic blood pressure respectively, compared with 26. 4 mm Hg and 27.7 mm Hg for automatic arm measurement. In community patients, the width of limits of agreement of wrist measurement were 11.6 mm Hg and 11.0 mm Hg for systolic and diastolic blood pressure respectively, compared with 19.5 mm Hg and 12.1 mm Hg for automatic arm measurement. Surgery patients also reported that wrist measurement of blood pressure was significantly more comfortable than either manual or automatic arm measurement (mean comfort scores 4.03 for automatic wrist and 2.13 for automatic arm measurement, Friedman's Test, P<0.001). CONCLUSIONS: Blood pressure measurements taken using the wrist device agreed more closely with those obtained using a conventional aneroid sphygmomanometer than the arm device. The wrist device was also more comfortable for patients than two other methods of blood pressure measurement. Public Health (2000) 114, 165-168

Aged↗
PubMed2000

Fetal penile length.

OBJECTIVE: To construct a reference range for fetal penile length. METHODS: The length of the penis was measured during ultrasound assessment of 95 structurally normal male fetuses of gestational ages 16-38 weeks. Two fetuses with bladder outflow obstruction were also examined. RESULTS: Fetal penile length increases significantly with gestational age, from a mean value of 6.0 mm at 16 weeks to 26.4 mm at 38 weeks. One fetus with urethral agenesis had a penile length on the 0.3rd centile. CONCLUSIONS: Measurement of the fetal penis is easy and not time-consuming. In cases of bladder outflow obstruction, assessment of penile length assists in the differentiation between urethral agenesis and posterior urethral valves.

Female↗
PubMed2000

The pulmonary vein Doppler flow velocity waveform: feature analysis by comparison of in vivo pressures and flows with those in a computerized fetal physiological model.

OBJECTIVES: Doppler flow velocity waveforms (FVW) in fetal veins that discharge into the atria show fluctuations related to atrial events. Pulmonary veins are of particular interest because both ends (atrial and collecting venule) are within the intrathoracic pressure environment reducing fetal breathing artifacts. Indices, such as pulsatility index for veins (PIV), have been suggested to classify FVWs and relate them to fetal well being. We wished to examine the relationship between function and FVW in circumstances which cannot ethically be examined in vivo, by studying the mechanisms which produced altered 'flows' in a detailed fetal computer model. We then related these findings to current flow indices. METHODS: A computer model of the feto-placental unit, responding to changes in organ oxygenation and regional flow is briefly described. In vivo intracardiac pressures and FVWs obtained from other studies were used to extend detail in the model until matching 'pressures' and 'flows' resulted. The effects of flow redistribution in the hypoxic fetus on pulmonary vein 'Doppler' flow velocity waveforms were then studied. RESULTS AND CONCLUSIONS: Flow reversal in pulmonary veins during atrial contraction indicates hypoxia, but change of shape of the FVW envelope reflects the changes in the pressure waveform of the left atrium. Of the major veins the pulmonary vein Doppler FVW gave the truest representation of atrial pressure response to both intracardiac and systemic vascular status. Although current indices indicate general fetal condition, more specific indices are needed if pulmonary venous flow is to be used as an end-point. A pulmonary vein pressure gradient index is suggested.

Blood Flow Velocity↗
PubMed2000

Fetal hydrolaparoscopy and endoscopic cystotomy in complicated cases of lower urinary tract obstruction.

OBJECTIVE: Vesicoamniotic shunting may be difficult or impossible in selected cases of fetal lower obstructive uropathy. The purpose of this article is to describe the performance of fetal hydrolaparoscopy and endoscopic fetal cystotomy in two fetuses with complicated lower obstructive uropathy. STUDY DESIGN: Fetal hydrolaparoscopy-endoscopic fetal cystotomy was performed in a patient with a markedly thickened bladder that could not be entered percutaneously. A peritoneoamniotic (bridge) shunt was also placed. Fetal hydrolaparoscopy-endoscopic fetal cystotomy was performed in a second patient with a collapsed bladder from a previous vesicocentesis, because vesicoinfusion resulted in further ascites. Fetal cystoscopy was performed after endoscopic fetal cystotomy, and posterior urethral valves were ablated with neodymium:yttrium-aluminum-garnet laser energy. A vesicoamniotic shunt was left in place. RESULTS: Adequate bladder drainage was obtained in both cases. The first baby required bilateral nephrotomy and a permanent cystotomy at birth and is scheduled for a bladder expansion procedure at the age of year. The second patient had premature rupture of membranes and fetal death from treatment of this complication 5 days after the original procedure. CONCLUSION: Fetal hydrolaparoscopy-endoscopic fetal cystotomy can be performed in complicated cases of lower obstructive uropathy. The procedure involves the creation of a defect in the bladder dome under direct endoscopic visualization within a spontaneous or intentional hydroperitoneum. Peritoneoamniotic shunting, vesicoamniotic shunting, or ablation of posterior urethral valves may then be performed. Fetal hydrolaparoscopy-endoscopic fetal cystotomy should be reserved only for complicated cases of lower obstructive uropathy in which conventional vesicoamniotic shunting is not safely possible. Further experience with fetal hydrolaparoscopy-endoscopic fetal cystotomy is necessary to establish its risks and benefits.

Adult↗
PubMed2000

Effects of carnosine and related compounds on the stability and morphology of erythrocytes from alcoholics.

The effects of carnosine and related compounds on erythrocytes from alcoholics were studied. In their presence, erythrocytes showed an increased ability to resist haemolysis and showed a more normal morphology, with carnosine and N-acetyl-carnosine being the most effective compounds. These beneficial properties of the dipeptides do not appear to be directly related to their antioxidant or buffering properties.

Adult↗
PubMed2000

The pros and cons of data analysis software for qualitative research.

PURPOSE: To explore the use of computer-based qualitative data analysis software packages. SCOPE: The advantages and capabilities of qualitative data analysis software are described and concerns about their effects on methods are discussed. FINDINGS: Advantages of using qualitative data analysis software include being freed from manual and clerical tasks, saving time, being able to deal with large amounts of qualitative data, having increased flexibility, and having improved validity and auditability of qualitative research. Concerns include increasingly deterministic and rigid processes, privileging of coding, and retrieval methods; reification of data, increased pressure on researchers to focus on volume and breadth rather than on depth and meaning, time and energy spent learning to use computer packages, increased commercialism, and distraction from the real work of analysis. CONCLUSIONS: We recommend that researchers consider the capabilities of the package, their own computer literacy and knowledge of the package, or the time required to gain these skills, and the suitability of the package for their research. The intelligence and integrity that a researcher brings to the research process must also be brought to the choice and use of tools and analytical processes. Researchers should be as critical of the methodological approaches to using qualitative data analysis software as they are about the fit between research question, methods, and research design.

Humans↗
PubMed2000

A cell cycle-specific requirement for the XRCC1 BRCT II domain during mammalian DNA strand break repair.

XRCC1 protein is essential for viability in mammals and is required for efficient DNA single-strand break repair and genetic stability following DNA base damage. We report here that XRCC1-dependent strand break repair in G(1) phase of the cell cycle is abolished by mutations created within the XRCC1 BRCT domain that interact with DNA ligase III. In contrast, XRCC1-dependent DNA strand break repair in S phase is largely unaffected by these mutations. These data describe a cell cycle-specific role for a BRCT domain, and we conclude that the XRCC1-DNA ligase III complex is required for DNA strand break repair in G(1) phase of the cell cycle but is dispensable for this process in S phase. The S-phase DNA repair process can remove both strand breaks induced in S phase and those that persist from G(1) and can in part compensate for lack of repair in G(1). This process correlates with the appearance of XRCC1 nuclear foci that colocalize with Rad51 and may thus function in concert with homologous recombination.

Amino Acid Sequence↗
PubMed2000

Intracardiac pressures in the human fetus.

OBJECTIVE: To obtain normal values for intracardiac pressures in the human fetus. DESIGN: Intracardiac pressures were measured directly in the four chambers of the human fetal heart during clinically indicated invasive obstetric procedures. SETTING: Department of fetal medicine in a tertiary referral centre. PATIENTS: 39 fetuses between 16 and 29 weeks of gestation. RESULTS: The ventricular waveforms obtained were similar to those found in postnatal life. There was an increase in ventricular systolic and end diastolic pressures with advancing gestation. There was no difference between left and right ventricular pressures. Atrial pressures were equal and remained constant in the gestational age range studied. CONCLUSIONS: Fetal cardiovascular pressure measurements in the normal fetus assist in understanding the fetal circulation, and provide a basis for the assessment of cases of congenital heart disease that may be amenable to intrauterine treatment.

Female↗
PubMed2000

Myelomatous involvement of the dura mater: a rare complication of multiple myeloma.

A case of myelomatous involvement of the dura mater is reported. The patient presented with blurring of vision in the right visual field and left sided facial numbness. A magnetic resonance imaging scan of the head revealed extensive infiltration of the dura mater. Cerebrospinal fluid (CSF) analysis showed no plasmacytosis and although there was a raised CSF protein concentration, no paraprotein band was detected, despite the presence of serum paraprotein. The infiltration of the dura mater is likely to have arisen by spread from contiguous bone lesions, contrasting with the pattern of spread seen in myelomatous involvement of the leptomeninges, which probably occurs through haematogenous seeding of the meninges. Leptomeningeal involvement is associated with a very poor prognosis; however, this patient had a favourable response to combined chemotherapy and cranial radiotherapy, suggesting that myelomatous involvement of the dura mater should be considered as a distinct complication of myeloma.

Dura Mater↗
PubMed2000

Exercise modulates antioxidant enzyme gene expression in rat myocardium and liver.

Our previous studies have shown that exercise caused changes in the tissue activities of the antioxidant enzymes glutathione peroxidase, superoxide dismutase, and catalase in spontaneously hypertensive (SH) and Wistar-Kyoto (WKY) rats. To determine whether the changes observed were due to changes in mRNA levels of the enzymes, levels of tissue mRNA were determined by quantitative RNase protection assay. Comparisons of tissue enzyme activities and mRNA levels in sedentary and exercised animals showed that, in some cases (e.g., glutathione peroxidase in SH and WKY myocardium), parallel changes in enzyme activity and mRNA levels occurred, whereas in other cases (e.g., catalase in SH and WKY liver), nonparallel changes were found. Exercise of hypertensive rats altered antioxidant enzyme mRNA levels to those seen in normotensive animals in some, but not all, cases. The results suggest that transcriptional control over changes in exercise-related antioxidant enzyme activities is operative in some cases, although in other cases posttranscriptional regulatory mechanisms may exist.

Animals↗
PubMed2000

A pilot study of radiotelemetry for continuous cardiopulmonary monitoring of patients at home.

We have conducted a trial of a wireless device for continuous cardiopulmonary monitoring. Its performance, user acceptance and safety were assessed for monitoring in the patient's home. The study included 20 patients: six with chronic obstructive pulmonary disease, six with chronic heart failure, seven with atrial fibrillation and palpitations, and one with a snoring problem. The system recorded the heart rate and respiratory rate, blood pressure, electrocardiogram and body temperature. The results were transmitted automatically to a central monitoring station. The accuracy of the measurements was checked by a comparison system and also by conventional measurements performed by a nurse. The system was acceptable to patients and functioned satisfactorily in the home. An important facet of home telemonitoring may turn out to be its greater reliability in collecting objective data.

Adult↗
PubMed2000

Effect of ethanol on the hemolytic stability of erythrocytes.

The stability of rabbit erythrocytes to hemolysis induced by different compounds in the presence or absence of ethanol or acetaldehyde has been analyzed. Ethanol slightly reduced erythrocyte stability against acidic hemolysis only after long-term preincubation, but the effect of ethanol on stability to oxidative hemolysis manifested itself immediately after its addition to the cells. Ethanol decreased both stability of cells to oxidative damage and dispersion of the hemolytic curve. Comparison of the effects of ethanol and acetaldehyde showed that the destabilizing effect of ethanol might be caused by either its direct action or the effect of its metabolites formed during preincubation of ethanol with erythrocytes. Possible mechanisms of ethanol and acetaldehyde effects on erythrocyte stability are discussed.

Acetaldehyde↗
PubMed2000

Effects of irradiance and spectral quality on leaf structure and function in seedlings of two Southeast Asian Hopea (Dipterocarpaceae) species.

We studied the development of leaf characters in two Southeast Asian dipterocarp forest trees under different photosynthetic photon flux densities (PFD) and spectral qualities (red to far-red, R:FR). The two species, Hopea helferi and H. odorata, are taxonomically closely related but differ in their ecological requirements; H. helferi is more drought tolerant and H. odorata more shade tolerant. Seedlings were grown in replicated shadehouse treatments of differing PFD and R:FR. We measured or calculated (1) leaf and tissue thicknesses; (2) mesophyll parenchyma, air space, and lignified tissue volumes; (3) mesophyll air volumes (V(mes)/A(surf)) and surfaces (A(mes)/A(surf)); (4) palisade cell length and width; (5) chlorophyll/cm and a/b; (6) leaf absorption; and (7) attenuance/absorbance at 652 and 550 nm. These characters varied in response to light conditions in both taxa. Characters were predominantly affected by PFD, and R:FR slightly influenced many characters. Leaf characters of H. odorata were more plastic in response to treatment conditions. Characters were correlated with each other in a complex fashion. Variation in leaf anatomy is most likely a consequence of increasing leaf thickness in both taxa, which may increase mechanical strength and defense against herbivory in more exposed environments. Variation in leaf optical properties was most likely affected by pigment photo-bleaching in treatments of more intense PFD and was not correlated with A(max). The greater plasticity of leaf responses in H. odorata helps explain the acclimation over the range of light conditions encountered by this shade-tolerant taxon. The dense layer of scales on the leaf undersurface and other anatomical characters in H. helferi reduced gas exchange and growth in this drought-tolerant tree.

Journal Article↗
PubMed2000

The behavioral response of zebrafish to hypergravity conditions.

Previous reports of the behavior of aquatic organisms in the microgravity environment of space (~10(-6) g) or during the brief weightless period of parabolic flight indicate that most species display a dramatic "looping" or "circling" response (De Jong et al. 1996, Anken, Ibsch and Rahmann 1998). However, the behavior of aquatic species under hypergravity conditions is less clear. Our objectives in the present study were to examine the behavioral response of adult zebrafish (Danio rerio) to hypergravity conditions (2-g), quantify changes in adult swimbladder volume, and to determine if the larvae of zebrafish are capable of accessing the air-water interface for initial swimbladder inflation under hypergravity conditions.

Air Sacs↗
PubMed1999

Efavirenz plus zidovudine and lamivudine, efavirenz plus indinavir, and indinavir plus zidovudine and lamivudine in the treatment of HIV-1 infection in adults. Study 006 Team.

BACKGROUND: Efavirenz is a nonnucleoside reverse-transcriptase inhibitor of human immunodeficiency virus type 1 (HIV-1). We compared two regimens containing efavirenz, one with a protease inhibitor and the other with two nucleoside reverse-transcriptase inhibitors, with a standard three-drug regimen. METHODS: The study subjects were 450 patients who had not previously been treated with lamivudine or any nonnucleoside reverse-transcriptase inhibitor or protease inhibitor. In this open-label study, patients were randomly assigned to one of three regimens: efavirenz (600 mg daily) plus zidovudine (300 mg twice daily) and lamivudine (150 mg twice daily); the protease inhibitor indinavir (800 mg every eight hours) plus zidovudine and lamivudine; or efavirenz plus indinavir (1000 mg every eight hours). RESULTS: Suppression of plasma HIV-1 RNA to undetectable levels was achieved in more patients in the group given efavirenz plus nucleoside reverse-transcriptase inhibitors than in the group given indinavir plus nucleoside reverse-transcriptase inhibitors (70 percent vs. 48 percent, P<0.001). The efficacy of the regimen of efavirenz plus indinavir was similar (53 percent) to that of the regimen of indinavir, zidovudine, and lamivudine. CD4 cell counts increased significantly with all combinations (range of increases, 180 to 201 cells per cubic millimeter). More patients discontinued treatment because of adverse events in the group given indinavir and two nucleoside reverse-transcriptase inhibitors than in the group given efavirenz and two nucleoside reverse-transcriptase inhibitors (43 percent vs. 27 percent, P=0.005). CONCLUSIONS: As antiretroviral therapy in HIV-1-infected adults, the combination of efavirenz, zidovudine, and lamivudine has greater antiviral activity and is better tolerated than the combination of indinavir, zidovudine, and lamivudine.

Adult↗