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Biomedical subjects

G Johnson

Publications and source records attributed to G Johnson.

At least 307 records · Page 17Linked to original sources
PubMed1992

Clinical experience with a tiered-therapy, multiprogrammable antiarrhythmia device.

BACKGROUND: The purpose of this report is to describe our initial experience with a tiered-therapy, variable detection criteria, multiprogrammable antiarrhythmia device capable of antitachycardia pacing, cardioversion, and defibrillation in 50 cardiac arrest survivors. METHODS AND RESULTS: An epicardial lead system was used in 35 patients. A transvenous lead system was used in 15 patients. The index arrhythmia leading to device implantation was ventricular fibrillation (VF) in 23 patients, ventricular tachycardia (VT) in 21 patients, and both VT and VF in six patients. Postoperatively, all 50 patients benefited from the additional functions available in the new device compared with a device capable only of high-energy termination of arrhythmias using a simple rate detection algorithm. Total patient survival over a mean follow-up period of 15 +/- 5 months was 96%, with no patient succumbing to sudden arrhythmic death, cardiac death, or surgical death. Nine patients (18%) avoided the need for a bradycardia pacemaker because of the device's backup bradycardia pacing function. A programmable tachycardia cycle length stability algorithm prevented inappropriate device intervention into atrial fibrillation in 11 patients (22%). Detection schema flexibility, antitachycardia pacing capabilities, and low-energy cardioversion options allowed the elimination or avoidance of antiarrhythmic drugs in 41 patients (82%). Device data storage facilitated troubleshooting and reprogramming of detection algorithms and therapeutic schema in all 50 patients. Finally, the ability to perform noninvasive programmed electrical stimulation obviated the need for invasive cardiac catheterization in 35 of 35 patients who required electrophysiological testing after device implantation. CONCLUSIONS: These findings indicate that a multiprogrammable antiarrhythmia device can provide a substantial advance in the treatment of patients with disabling or life-threatening ventricular arrhythmias by minimizing the use of painful shocks, reducing the need for antiarrhythmic drugs, lowering the incidence of inappropriate shocks, facilitating electrophysiological evaluation, and obviating the need for dual-device therapy.

Adolescent↗
PubMed1992

An Australian multicentre study of moclobemide versus amitriptyline in the treatment of depression.

This paper reports the results of a multicentre study of the new monoamine oxidase inhibitor, moclobemide, in the treatment of major depression. Moclobemide is a specific monoamine oxidase-A inhibitor which does not bind irreversibly to the enzyme, unlike the currently available MAOIs. Recent studies would suggest that in subjects taking moclobemide blood pressure elevation caused by tyramine is significantly less than that induced by the irreversible MAOIs, particularly when tyramine is administered in an oral form. Forty-eight patients with major depression were randomly allocated to treatment with either moclobemide or amitriptyline for 4 weeks in a double-blind comparison. There were no statistically significant differences between the two groups on measures of efficacy. Patients taking amitriptyline reported a greater number of side-effects and more patients in the amitriptyline group dropped out because of these. There were no reports of interactions with tyramine-containing foods.

Adult↗
PubMed1992

Changes in the structure of wages in the 1980's: an evaluation of alternative explanations.

During the 1980's, a period in which the average level of real wage rates was roughly stagnant, there were large changes in the structure of relative wages, most notably a huge increase in the relative wages of highly educated workers. This paper attempts to assess the power of several alternative explanations of the observed relative wage changes in the context of a theoretical framework that nests all of these explanations. Our conclusion is that their major cause was a shift in the skill structure of labor demand brought about by biased technological change.

Educational Status↗
PubMed1992

Cerebrospinal fluid protein variations in common to Alzheimer's disease and schizophrenia.

Analysis of silver stained two-dimensional (2D) gels of cerebrospinal fluid (CSF) from 27 patients with schizophrenia (SCZ) and 10 patients with Alzheimer's disease (AD) revealed an increase in the relative amount of a polypeptide of 18,000M(r) and isoelectric point of 6.5 when compared to the appropriate controls. This protein was identified by its electrophoretic characteristics and by immune analysis of Western blots as an isoform of alpha-2 haptoglobin, provisionally identified as alpha-2FS haptoglobin. Alzheimer's disease versus control CSF samples showed a 6.8-fold increase in the percent mean density value of this haptoglobin isoform (n = 10 AD vs 11 control; P > 0.025) while a 4.4-fold increase was observed in the schizophrenic patients (n = 17 SCZ vs 10 control; P > 0.001). Two additional polypeptides (proteins '127' and '128') of 40,000 M(r) and isoelectric points 5.7 and 5.9, respectively, described previously by this laboratory, were found in the CSF of 27% of schizophrenics, 23% of the Alzheimer's disease patients, and 4% of the controls in the current study. The presence of proteins 127 and 128, as well as the increased concentrations of alpha-2 haptoglobin in the CSF of Alzheimer's disease and schizophrenic patients, may be useful as diagnostic biological markers. They may also indicate a common pathophysiology between these diseases.

Acute-Phase Proteins↗
PubMed1992

Haloperidol induced CSF protein variations in schizophrenic patients: as studied by two-dimensional electrophoresis.

High resolution two-dimensional electrophoresis of cerebrospinal fluid (CSF) from 10 schizophrenic patients demonstrated a 21% average difference in the number of proteins which could be detected in patients undergoing haloperidol therapy when compared with CSF from the same patients after withdrawal from neuroleptic treatment. Proteins affected were trace proteins, as we found no significant variation in either the total CSF protein content or the integrated protein density on each electrophoretic gel. Three mechanisms which might account for these observations are: (1) a small change in liver protein synthesis or degradation would have little if any visible effect on the concentration of major blood or CSF proteins, such as albumin, but it could significantly alter trace proteins, such as alpha 2-haptoglobin, since their concentrations are orders of magnitude less than that of the major proteins, (2) haloperidol might alter the blood-CSF protein filtration system which could affect the visibility of the trace proteins, and (3) proteins synthesized in the Central Nervous System (CNS) or enhanced in the CSF could be differentially affected by haloperidol. While additional research will be required to determine the basis for the effects of haloperidol on CSF proteins, the current studies provide information which may be helpful in delineating disease specific protein alterations from those induced by drug therapy.

Adult↗
PubMed1992

The course of severe foot infection in patients with diabetes.

Infection of the foot is a limb threatening condition for patients with diabetes mellitus. Identification of patients with diabetes and severe infection of the foot most likely to benefit from early revascularization or major amputation would improve the results of a treatment policy to prevent limb loss and avoid futile delays in amputation. During a nine year period, 79 diabetic patients underwent emergency procedures for severe infection of the foot during the initial hospitalization period. None of the patients underwent arterial reconstruction. Eventually, 21 of the patients required a major amputation, eight during the initial hospitalization and 13 on a subsequent admission. Stepwise discriminant analysis of clinical independent variables revealed that the patients most likely to require a major amputation during the initial hospitalization were those with an absent dorsalis pedis pulse and a polymicrobial infection (p = 0.018). The overall amputation rate (immediate or subsequent amputation) was higher for patients of either sex with nonpalpable pedal pulses when compared with those with at least one palpable pulse (p less than 0.05). Males who were not dependent on insulin had the highest risk of overall limb loss (p = 0.01). Patients undergoing delayed amputation required a significantly higher number (p = 0.01) of readmissions to the hospital for recurrent infection of the foot than those who did not undergo amputation. Data in the current study suggest that early major amputation in a subset of patients would prevent delay in the rehabilitation process of the amputee, decrease long term morbidity and reduce health care cost. An aggressive policy of early revascularization in patients with a pulse deficit may reduce the amputation rate in those with diabetes with severe infection of the foot.

Amputation, Surgical↗
PubMed1991

A comparison of enalapril with hydralazine-isosorbide dinitrate in the treatment of chronic congestive heart failure.

BACKGROUND: To define better the efficacy of vasodilator therapy in the treatment of chronic congestive heart failure, we compared the effects of hydralazine and isosorbide dinitrate with those of enalapril in 804 men receiving digoxin and diuretic therapy for heart failure. The patients were randomly assigned in a double-blind manner to receive 20 mg of enalapril daily or 300 mg of hydralazine plus 160 mg of isosorbide dinitrate daily. The latter regimen was identical to that used with a similar patient population in the effective-treatment arm of our previous Vasodilator-Heart Failure Trial. RESULTS: Mortality after two years was significantly lower in the enalapril arm (18 percent) than in the hydralazine-isosorbide dinitrate arm (25 percent) (P = 0.016; reduction in mortality, 28.0 percent), and overall mortality tended to be lower (P = 0.08). The lower mortality in the enalapril arm was attributable to a reduction in the incidence of sudden death, and this beneficial effect was more prominent in patients with less severe symptoms (New York Heart Association class I or II). In contrast, body oxygen consumption at peak exercise was increased only by hydralazine-isosorbide dinitrate treatment (P less than 0.05), and left ventricular ejection fraction, which increased with both regimens during the 2 years after randomization, increased more (P less than 0.05) during the first 13 weeks in the hydralazine-isosorbide dinitrate group. CONCLUSIONS: The similar two-year mortality in the hydralazine-isosorbide dinitrate arms in our previous Vasodilator-Heart Failure Trial (26 percent) and in the present trial (25 percent), as compared with that in the placebo arm in the previous trial, (34 percent) and the further survival benefit with enalapril in the present trial (18 percent) strengthen the conclusion that vasodilator therapy should be included in the standard treatment for heart failure. The different effects of the two regimens (enalapril and hydralazine-isosorbide dinitrate) on mortality and physiologic end points suggest that the profile of effects might be enhanced if the regimens were used in combination.

Adolescent↗
PubMed1991

A method for studies of an El Tor-associated antigen of Vibrio cholerae O1.

A method for studying the biotype El Tor associated mannose-sensitive haemagglutinin (MSHA) of V. cholerae O1 has been developed. By using crude MSHA adsorbed to chicken erythrocytes as solid phase antigen in an enzyme-linked immunosorbent assay (ELISA), antisera against V. cholerae of the El Tor biotype reacted in high titre with the MSHA-coated cells, whereas antisera against vibrios of the classical biotype did not bind significantly, i.e. in higher titre than pre-immune sera. The binding of anti-MSHA serum, or a monoclonal antibody against MSHA, to the MSHA-coated erythrocytes could be efficiently inhibited by crude MSHA as well as by El Tor vibrios whereas neither V. cholerae lipopolysaccharide nor different strains of classical vibrios had any inhibitory effect. These results support the existence of an El Tor-associated immunogen. They also suggest a possibility of determining antibodies against different haemagglutinins in ELISA without having access to purified antigens.

Animals↗
PubMed1991

Platelet-activating factor induces tyrosine phosphorylation in human neutrophils.

The addition of platelet-activating factor (PAF) to human neutrophils increases the levels of the tyrosine phosphorylation in several proteins. These proteins have molecular weights of 41 (pp41), 54 (pp54), 66 (pp66), 104 (pp104), and 116 (pp116) kDa. The effect of PAF was dose-dependent and could be seen at concentrations as low as 1 nM. The nonmetabolizable bioactive PAF analog, C-PAF, caused an increase in the level of phosphorylation of the same proteins in a time- and dose-dependent manner. On the contrary, lyso-PAF, enantio-PAF, and L-beta,gamma-dihexadecyl-alpha-lecithin failed to stimulate the phosphorylation of any of the aforementioned proteins. The response to PAF was prevented by the PAF antagonist BN-52021. The PAF-induced increases in tyrosine phosphorylation in pp66, pp116, and pp104 were selectively inhibited by pertussis toxin. In contrast, the level of pp41 phosphorylation remained unchanged after the pertussis toxin treatment. The calcium chelator EGTA significantly inhibited the PAF-produced phosphorylation of the pp41 protein. The intracellular calcium chelator 1,2-bis-(O-aminophenoxil)ethane-N,N,N',N'-tetraacetic acid (BAPTA) potentiated the PAF-enhanced levels of tyrosine phosphorylation on the pp41 protein. On the other hand, the PAF-induced phosphorylations of pp66, pp104, and pp116 were inhibited in BAPTA-treated cells. The calcium ionophore A23187 selectively potentiated the phosphorylation of the pp41 protein and reduced the phosphorylation in the pp54 protein. This phosphorylation was dependent on the extracellular calcium and was inhibited in toxin-treated cells. The results suggest that PAF is able to affect either directly or indirectly tyrosine kinase and/or phosphotyrosine phosphatase activities. The phosphorylation of the high and low molecular weight proteins are mediated by two different sets of kinases and/or phosphatases.

Autoradiography↗
PubMed1991

Venous disease.

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Humans↗
PubMed1991

Primary lesser saphenous vein aneurysm in a child.

True primary venous aneurysms are rare. This is the first report of such an aneurysm involving the lesser saphenous vein. Though most often a medical curiosity, such lesions can result in serious morbidity and even mortality. Because of their rarity they are often misdiagnosed. Salient features pertaining to classification, diagnosis, and treatment are reviewed.

Aneurysm↗
PubMed1991

Adhesion and growth of cultured human endothelial cells on perfluorosulphonate: role of vitronectin and fibronectin in cell attachment.

The suitability of neutralized perfluorosulphonic acid (Nafion) as a surface for the attachment and growth of human cells was investigated in tissue culture. Nafion was equivalent to tissue culture polystyrene (TCP), and markedly better than polytetrafluoroethylene (Teflon), for the attachment and growth of human umbilical artery endothelial (HUAE) cells. The attachment and growth of HUAE cells on Fn-coated Nafion was equivalent to that on Fn-coated TCP. The contribution to the attachment and spreading of HUAE cells that is due to adsorption of serum fibronectin (Fn) or vitronectin (Vn) on to the Nafion or TCP was directly tested by selective removal of Fn or Vn from the serum before addition to the culture medium. HUAE cells seeded on to Nafion or TCP in medium depleted of Vn failed to attach and spread on to these surfaces, as measured after 4 or 24 h of culture. HUAE cells seeded in medium depleted of Fn, but containing Vn, attached and spread on to Nafion, albeit to a decreased extent as compared to that in intact serum when measured after 4 h of culture, and there was no effect of depletion of Fn when measured after 24 h of culture. HUAE cells seeded on to TCP in medium depleted of Fn became attached and spread during 4 h of culture. Our results show that Nafion is a suitable polymeric surface for the attachment and growth of human cells, including endothelial cells. For HUAE cells, adsorption on to the surface of an adhesive glycoprotein, such as Vn or Fn, is an essential step for attachment and spreading of the cells onto the Nafion surface.

Biocompatible Materials↗
PubMed1991

Increased synthesis and accumulation of heat shock 70 proteins in Alzheimer's disease.

Postmortem cortical tissues from Alzheimer's disease cases were found to contain significantly higher levels of the heat shock proteins hsp 72 and hsp 73 than control cortical tissues. This elevation was associated with the disease pathology in that it was not observed in Alzheimer's disease cerebella and was not correlated with perimortem characteristics such as age or cause of death of the patient or postmortem interval of the brain tissue. Examination of polysome translation products on two dimensional gels and by immunoprecipitation indicated that the syntheses of hsp 72/73 were increased in Alzheimer's disease tissues. In addition, immunoprecipitation of newly synthesized hsp 72 showed that numerous other nascent polypeptides were co-precipitated, which indicates an irreversible cotranslational association with the hsp 72. These results indicate that induction of specific heat shock proteins is associated with Alzheimer's disease and that cotranslational processes are affected by this induction.

Aged↗
PubMed1991

Cardioprotective effects of authentic nitric oxide in myocardial ischemia with reperfusion.

BACKGROUND AND METHODS: The purpose of this study was to determine the effects of nitric oxide (NO), believed to be endothelium-derived relaxing factor on reperfusion injury after myocardial ischemia (MI). The effects of NO were investigated in a 6-hr model of MI with reperfusion in open-chest, anesthetized cats. A solution containing NO was infused iv starting 30 min after occlusion of the left anterior descending coronary artery, continuing through reperfusion 1 hr later, and lasting for 5.5 hr. Estimated NO concentration in the circulation was 1 to 2 x 10(-9) M. RESULTS: The areas-at-risk expressed as a percentage of the total left ventricular weights were not significantly different among either of the MI groups. However, the necrotic area (expressed as a percentage of the myocardial area-at-risk) was significantly (p less than .01) lower in the NO-treated MI cats compared with the MI + vehicle group. Cardiac myeloperoxidase activities indicated that significantly (p less than .05) fewer neutrophils were attracted to the necrotic zone of the NO-treated MI cats when compared with MI cats receiving only the vehicle. Sodium nitrate (NaNO2) (pH 7.4), a major breakdown product of NO, failed to exert any protective effect in this same model of MI and reperfusion. CONCLUSIONS: NO appears to provide significant myocardial protection after ischemia and reperfusion. NO may afford cardioprotection by incorporation into circulating blood cells (i.e., neutrophils, platelets), thereby inhibiting their accumulation and adherence in the ischemic region, or by a direct cardiac cytoprotective effect. Further studies using NO donors rather than NO would be an appropriate clinically relevant mode of treatment in MI.

Animals↗
PubMed1991

Psychosocial adjustment to cystectomy for bladder carcinoma and effects on interpersonal relationships.

Postoperative adjustment and the psychosocial consequences of cystectomy were studied in 34 patients with bladder carcinoma. Urinary diversion was accomplished via a conduit in 20 patients and a continent caecal reservoir in 14. Interviews with the patients were conducted according to a semistructured outline. The great majority adjusted fairly well, mainly due to support from family members. Help was provided by medical staff in only a few cases. While relationships with friends were unchanged, those with spouse/partner were commonly disturbed by sexual problems and presence of a urostoma. The mode of urinary diversion had no influence on the studied variables. Despite a high acceptance level of their malignant affliction, several patients did not accept their present situation. Lack of psychologic support from the health services was a common experience.

Adaptation, Psychological↗
PubMed1991

Cardioprotective and endothelial protective effects of [Ala-IL8]77 in a rabbit model of myocardial ischaemia and reperfusion.

1 We studied the effects of a form of interleukin-8 (i.e., [Ala-IL8]77) on endothelial dysfunction and myocardial injury in rabbits. Pentobarbitone-anaesthetized rabbits were subjected to 1.5 h occlusion of the marginal coronary artery and 3.5 h reperfusion. [Ala-IL8]77 (50 micrograms or its vehicle) was given i.v. as a bolus 10 min prior to reperfusion. [Ala-IL8]77 was also studied in isolated perfused hearts of rabbits. 2 Myocardial ischaemia plus reperfusion in untreated rabbits produced severe endothelial dysfunction and myocardial injury, including marked myocardial necrosis, elevated cardiac myeloperoxidase (MPO) activity in ischaemic cardiac tissue, and loss of response of marginal coronary rings to the endothelium-dependent vasodilators, acetylcholine (ACh) and A23187. 3 Administration of [Ala-IL8]77 10 min prior to reperfusion resulted in significant protective effects in post-ischaemic reperfusion. Compared with untreated rabbits, [Ala-IL8]77 caused a reduced necrotic zone (P less than 0.01), lower MPO activity in the necrotic zone (P less than 0.05), and significantly preserved vasorelaxant responses of marginal coronary artery rings to endothelium-dependent vasodilators, ACh (P less than 0.001) and A23187 (P less than 0.001). 4 These results indicate that myocardial ischaemia and reperfusion result in a severe endothelial dysfunction and myocardial injury which involved the interaction of neutrophils and endothelial cells. However, [Ala-IL8]77 did not appear to exert a direct endothelial protective effect in the absence of neutrophils in rabbit isolated perfused hearts. 5 Inhibition of neutrophil accumulation in the myocardium, perhaps by prevention of endothelial dysfunction resulting from [Ala-IL8]77, leads to significant protective effects in ischaemia and reperfusion in rabbits.

Acetylcholine↗