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Biomedical subjects

A Johnson

Publications and source records attributed to A Johnson.

At least 577 records · Page 32Linked to original sources
PubMed1983

Effect of complement depletion on lung fluid balance after thrombin.

We examined the effect of complement depletion on lung fluid and protein exchange after thrombin-induced pulmonary thromboembolization. Sheep were prepared with lung lymph fistulas to assess pulmonary transvascular fluid and protein dynamics. Studies were made in three groups: in group I (n = 5) pulmonary thromboembolization (PT) was induced by an iv infusion of thrombin (55.0 +/- 12.9 NIH U/kg); in group II (n = 6) cobra venom factor (CVF) was given ip (94.5 +/- 18.8 U/kg/day) for 2 days to deplete complement, and then thrombin (66.4 +/- 37.0 NIH U/kg) was infused to raise pulmonary vascular resistance to the same level as in group I; in group III (n = 10) left atrial pressure (Pla) was increased by 10-15 Torr in normal animals by inflation of a Foley balloon catheter. In group I, thrombin infusion caused an increase in pulmonary lymph flow (Qlym) with a gradual increase in the lymph-to-plasma protein concentration ratio (L/P). In complement-depleted sheep, thrombin caused a transient increase in Qlym, which was associated with a decrease in L/P. In group I an increase in Pla further increased Qlym but without a change in L/P, indicating an increase in lung vascular permeability to proteins; whereas in the decomplemented-thrombin sheep raising Pla increased Qlym but decreased L/P. Results in the latter group were similar to those obtained in normal animals after left atrial hypertension (group III). Therefore the complement system participates in the increase in lung vascular permeability following thrombin-induced microembolization.

Animals↗
PubMed1983

Low-dose captopril titration in patients with moderate-to-severe hypertension treated with diuretics.

To study the value of low-dose captopril (6.25 and 12.5 mg) and a diuretic combination, the blood pressure and heart rate of 17 patients with moderate-to-severe hypertension were monitored for 6 hours (hospital) or 3 hours (office) after the single low-dose or larger (25, 50, 100 and 150 mg) captopril dosage. All patients had preserved renal function and were taking an oral diuretic (hydrochlorothiazide or furosemide) for at least 4 weeks. The supine and upright acute blood pressure lowering with 6.25 mg was not different from the larger captopril doses; none produced persistent or profound hypotension. There was no deterioration of renal function, new or persistent increase in proteinuria, neutropenia or agranulocytosis acutely or during 17 +/- 2 weeks of follow-up. Low-dose captopril (6.25 or 12.5 mg three times daily) normalized the supine blood pressure of 35% of these patients acutely. We suggest that in hypertensive patients already taking a diuretic, a lower starting dose of captopril than the recommended 25 mg three times daily may be desirable.

Adult↗
PubMed1983

Thrombin-induced lung vascular injury. Roles of fibrinogen and fibrinolysis.

We examined the contributions of fibrin and the fibrinolytic mechanism in mediating the thrombin-induced lung vascular injury. Studies were made in sheep in which alterations in lung transvascular fluid and protein exchange were assessed using the lung lymph fistula preparation. Group I(n = 10) control sheep in which left atrial pressure was raised to increase pulmonary lymph flow (Qlym); Group II(n = 8) control sheep in which thrombin was infused intravenously (58.3 +/- 12.6 U/kg) to induce pulmonary thromboembolization; Group III (n = 6) sheep were defibrinogenerated using Ancrod (purified fraction of venom of Agkistrodon rhodostoma) prior to embolization with thrombin (124.5 +/- 2.5 U/kg); Group IV (n = 13) sheep were treated with tranexamic acid to inhibit fibrinolysis prior to embolization with thrombin (140.0 +/- 25.8 U/kg). In Group II, pulmonary thromboembolization increased Qlym without a change in the steady-state lymph-to-plasma protein concentration ratio (L/P). Raising left atrial pressure (increases Pla) postembolization to test for an increase in pulmonary vascular permeability to proteins further increased Qlym but did not alter L/P, indicating an increase in permeability. In Group III, the thrombin-induced increase in Qlym was blunted and the L/P decreased; increases Pla further increased Qlym but decreased L/P. In Group IV, Qlym also increased after thrombin-induced embolization and L/P decreased; increases Pla further increased Qlym but decreased L/P. The responses to increases Pla of Groups III and IV were similar to the response of Group I rather than to that of Group II, indicating that defibrinogenation and fibrinolytic inhibition prevented the increase in lung vascular permeability. The results indicate that circulating fibrinogen and activation of plasmin are necessary for development of lung vascular injury after pulmonary thromboembolization.

Animals↗
PubMed1983

Studies on avian erythrocyte metabolism. XIII. Changing organic phosphate composition in age-dependent density populations of chicken erythrocytes.

These studies were performed to determine whether the erythrocytes (RBC's) of chickens are able to alter the concentrations of organic phosphates, particularly inositol pentakis (dihydrogen phosphate) (inositol-P5), in response to anemia. Acute anemia with 33.5% reticulocytes (retics) in the peripheral blood of 4-month-old White Leghorn cockerels was produced after two successive days of controlled bleeding. Five populations of RBC's were prepared from blood of these anemic birds based upon age-dependent density by angle rotor centrifugation. The relative increase in age of Fraction 1 (younger cells) through Fraction 5 (oldest cells) was verified by increased hemoglobin concentration and decreased retic count and cell volume. The acid aqueous-soluble phosphates from each RBC fraction were extracted, fractionated by ion exchange column chromatography, and the concentration of inorganic phosphate (Pi), adenosine triphosphate (ATP), and inositol-P5 quantitated by wet-ash phosphate analysis. Determination of Pi, ATP, and inositol-P5 in Fraction 1 (younger cells, 7.4% retics) from the initial (Day 1) blood withdrawn gave 4.3, 5.7, and 18.6 mumoles Pi/ml RBC, respectively. On Day 4 of controlled-bleeding, Pi, ATP, and inositol-P5 concentrations in Fraction 1 (95.1% retics) were 12.7, 10.6, and 12.3 mumoles Pi/ml RBC, respectively. On Day 11, after 1 week recovery from controlled-bleeding, the values for Pi, ATP, and inositol-P5 in Fraction 1 (37.7% retics) were 5.0, 5.4, and 19.0 mumoles Pi/ml RBC, respectively, which were similar to the values before bleeding.(ABSTRACT TRUNCATED AT 250 WORDS)

2,3-Diphosphoglycerate↗
PubMed1982

Ability of primary care physicians to make accurate ratings of psychiatric symptoms.

The ability of 45 family practice residents to make accurate ratings of psychiatric symptoms among their patients was assessed by comparing their ratings with the symptom levels of their patients as reported on a psychiatric screening questionnaire. The findings confirmed an earlier survey with experienced primary care physicians by showing that ability to make accurate ratings is partly determined by interview style, and partly by certain personality attributes. Self-confident, outgoing physicians with high academic ability tend to make more accurate assessments, as do those who display certain specified behaviors during their diagnostic interviews. The tendency to make many, or to avoid making psychiatric assessments ("bias") is shown to be determined by different factors from those that determine accuracy of the assessments.

Family Practice↗
PubMed1982

Left ventricular emptying dynamics in patients with asymmetric septal hypertrophy and concentric hypertrophic cardiomyopathy.

We studied the dynamics of left ventricular (LV) emptying in 8 patients with asymmetric septal hypertrophy (ASH), 6 patients with concentric hypertrophic cardiomyopathy (CHC), and 6 normal controls. Four patients with ASH had resting systolic gradients greater than 20 mmHg, all had significant post premature ventricular contraction (PVC) systolic pressure gradients. LV volume (V) was obtained by frame-by-frame analysis of cineangiograms. End-diastolic volume was similar for all groups; end-systolic volume was significantly less in ASH and CHC patients than in normals. Maximum dV/dt was similar in ASH and CHC, and significantly greater than normals. Total systolic contraction time (SCT), i.e., time from peak volume to last cine frame at minimum volume, was similar for all groups, but the time required to eject 90% of stroke volume (90%T), as a fraction of SCT, was shorter for ASH (0.52 +/- 0.07) and CHC patients (0.51 +/- 0.05) than normals (0.67 +/- 0.07) (p less than 0.05 vs myopathy groups). In the sinus beat following a PVC, however, this ratio decreased significantly in normals and CHC patients, but did not change in ASH patients. We conclude that ASH and CHC have similar exaggerated systolic LV ejection dynamics in the basal state; the failure of ASH patients with post-PVC systolic outflow gradient to reduce 90% T/SCT post PVC may reflect obstruction to LV emptying.

Cardiac Output↗
PubMed1982

Pregnancy after autografting and allografting vascularized ovaries and en bloc vascularized ovaries with adnexa in rabbits.

Initially, techniques for autografting ovaries with or without adnexa were developed but a 30% vascular failure rate was experienced by day 14. Of the technically successful grafts, 50% proved fertile. Single vascularized ovaries with their oviducts were then allografted into bilaterally ovariectomized rabbits by microsurgical techniques and the vascular failure rate was reduced to 5% of 40 grafts. The time-course of rejection in untreated recipients was mapped by histological examination and by 24-h culture of fallopian tubes after autopsy at different times after transplantation. Control allografts were consistently rejected by day 20. Striking prolongation of both types of graft was obtained with a short 17-day course of cyclosporin A at 10 or 15 mg day-1 kg-1. Indeed, significant evidence of rejection was found in only two ovaries out of 20 so far examined histologically. Mating behaviour, ovulation, ciliary function and transport of ova appeared normal in 80% of the recipients as long as 18 weeks after stopping cyclosporin A treatment. Only one of the ovarian allografted rabbits has so far been mated and this produced seven normal young 126 days after transplantation. However, none of the five animals mated after being allografted with en bloc adnexa have so far become pregnant.

Adnexa Uteri↗
PubMed1982

Mechanisms of lung vascular injury after intravascular coagulation.

Pulmonary intravascular coagulation and the resultant microembolization increase lung vascular permeability to proteins. The increase in permeability is mediated by the activation of cellular and humoral factors after intravascular coagulation. In particular, intravascular coagulation results in sequestration and activation of leukocytes, which appears to be of primary importance in mediating the lung vascular injury. In addition, fibrin entrapment and the generation of fibrin-degradation products after fibrinolysis also contribute to the vascular injury. The classical inflammatory agents, such as prostaglandin, histamine, bradykinin, and serotonin, may modulate the degree of injury after pulmonary vascular thrombosis, but they do not appear to be the primary mediators of the injury. Platelet aggregation did not mediate the lung vascular injury after intravascular coagulation, but was responsible for the pulmonary gas-exchange impairment that occurs with pulmonary vascular thrombosis.

Animals↗
PubMed1982

Does psychiatric illness affect the recurrence rate of genital herpes?

The progress of 58 patients with first attacks of genital herpes was monitored for up to 30 weeks. The effects of sex (gender), age, social class, and non-psychotic psychiatric illness (as measured by the "general health questionnaire," GHQ) on the recurrence rate of herpes was studied. The recurrence rates, measured by the actuarial percentage recurrence-free curves, showed that the 29 patients with GHQ scores above 11 had a significantly higher recurrence rate than those who scored less than 11 (P = 0.002). There were no important differences between recurrence rates according according to sex, age, or social class. These findings suggest that non-psychotic states, such as anxiety or obsessionality resulting in GHQ scores above 12, may possibly cause an excess production of adrenergic substances which encourages reactivation of latent genital herpes. Thus, to lessen the recurrence rate in such patients, a psychological or chemical approach to treatment could be used to modify the autonomic sympathetic response.

Adolescent↗
PubMed1982

Lung fluid balance after pulmonary embolization: effects of thrombin vs. fibrin aggregates.

We examined the relationship between the activation of fibrinolysis and the increase in lung vascular permeability after pulmonary microembolization (PM). Sheep were prepared with lung lymph fistulas to assess pulmonary transvascular fluid and protein dynamics. Studies were made in three groups: group I (n = 8) in which PM was induced by an iv infusion of thrombin (60 +/- 13 NIH U/kg); group II (n = 7) in which PM was induced by an iv infusion of 50-micrometers-diameter fibrin microaggregates (0.32 +/- 0.009 g/kg); and group III in which the left atrial pressure was increased by 10-15 Torr by inflation of a balloon catheter. Thrombin caused an increase in pulmonary lymph flow (Qlym) without a change in the lymph-to-plasma protein concentration ratio (L/P ratio) indicating an increase in the lung vascular permeability to proteins. Fibrin microaggregates also increased Qlym, but the increase was associated with a decrease in the L/P ratio. The results in the latter group were similar to those obtained after left atrial hypertension in normal sheep. The increase in permeability after PM induced with thrombin was associated with large increases in the plasma concentration of fibrin degradation products, as compared with PM induced by fibrin microaggregates. The process of intravascular coagulation with the resultant generation of fibrinolysis and fibrin degradation products may be required for the increase in lung vascular permeability to proteins after pulmonary microembolization.

Animals↗
PubMed1982

Effect of converting enzyme inhibition on pulmonary edema after microembolization.

We examined the effect of converting enzyme inhibition with captopril (SQ 14,225) on pulmonary hemodynamics and on accumulation of extravascular lung water after microembolization in dogs. Pulmonary microembolization, induced with glass beads (200 microns diam), increased the mean pulmonary arterial pressure to approximately 40 Torr in both control and captopril-treated animals. The increase in pulmonary vascular resistance (PVR) in control animals was sustained during the 75 min of study and was associated with an increase in the extravascular lung water content-to-bloodless dry lung weight ratio (W/D) from a normal value of 2.84 +/- 0.22 to 4.53 +/- 0.24 ml/g (P less than 0.01) after embolization. In the captopril-treated group, the PVR increased gradually, such that the value at 75 min postembolization was greater than in controls (P less than 0.05). The W/D in the captopril-treated group of 4.62 +/- 0.19 ml/g was greater than the value of 2.83 +/- 0.10 ml/g in nonembolized captopril-treated animals, but the degrees of edema in the control and captopril-treated animals were not different. A similar degree of embolization induced during infusion of 5 micrograms X kg-1 X h-1 of bradykinin also did not enhance the pulmonary edema, and there was also a greater increase in PVR than in control animals after embolization. These findings suggest that bradykinin does not contribute to the degree of pulmonary edema after microembolization.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1982

Plasma zinc status of protein energy malnourished children.

The plasma zinc status, albumin level and alkaline phosphatase activity of 44 protein energy malnourished Nigerian children were compared with those of 10 normal children. Results were classified according to the type and degree of malnutrition. Plasma zinc levels were low in the malnourished groups and tended to vary with the degree of malnutrition as indicated by the level of growth retardation. Levels in the 'normal' group of children suggest a possible presence of marginal zinc nutrition among Nigerian children.

Alkaline Phosphatase↗