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Biomedical subjects

D Johnson

Publications and source records attributed to D Johnson.

At least 577 records · Page 32Linked to original sources
PubMed1986

Pathophysiology of soman intoxication in primates.

Adult baboons were monitored during intravenous infusion of Soman (1,2,2-trimethylpropyl ester, phosphonofluoridate). Three groups of animals were studied. Two groups were anesthetized with sodium pentobarbital (initial dose, 20 mg/kg), instrumented for measurement of systemic blood pressure (BP), pulmonary artery pressure, cardiac output (CO), ECG, ventilatory flow, translaryngeal pressure (PTL), transdiaphragmatic pressure (Pdi), transpulmonary pressure (PTP), diaphragm EMG, and efferent phrenic nerve traffic (Eph). One group received no Soman and served as controls. In the other group, Soman was infused over 10 min at doses of 13.1, 8.21, 4.92, or 3.3 micrograms/kg. The onset of intoxication occurred within 7-8 min (before the end of the 10-min infusion), manifested by muscular fasciculations, stridorous breathing, copious secretions, and atrioventricular arrhythmias. Mean BP decreased to 30 mm Hg by the combination of decreased CO and decreased vascular resistance. There was a dose-related response in the onset and duration of these effects. Apnea occurred in most animals and coincided with cessation of the Eph signal. Stimulation of the diaphragm via the phrenic nerve following apnea yielded Pdi values unchanged from baseline, indicating an intact neuromuscular apparatus. All animals required ventilatory support. Some surviving animals exhibited severe behavior changes. The third group of animals was studied without anesthesia. Instrumentation was performed 3 days before using a tether system for the measurement of BP, CO, and ECG, and an arterial line for blood withdrawal. Soman was infused over 10 min at a dose of 13.1 micrograms/kg. The onset of intoxication occurred within 2-3 min, manifested by hyperactivity, severe muscle fasciculations which simulated grand-mal convulsions, stridorous respiratory sounds, copious secretions, and cardiac arrhythmias. Apnea and severe lactic acid acidosis developed in all animals and all required ventilatory assistance. None recovered spontaneous ventilation at the end of 4 hr.

Animals↗
PubMed1986

Deposition of the myelin-associated glycoprotein in specific regions of the developing rat central nervous system.

In developing optic nerve and medulla of the rat, the concentration of the myelin-associated glycoprotein (MAG) increases rapidly between 10 and 30 days of age to reach adult levels of 4.4 and 4.1 ng per micrograms total protein, respectively. The general shapes of the developmental curves for MAG and basic protein (BP) are similar, but the rapid accumulation of MAG progresses earlier than that of BP by about 3-6 days.

2',3'-Cyclic-Nucleotide Phosphodiesterases↗
PubMed1986

Cell-mediated immunity to myelin-associated glycoprotein, proteolipid protein, and myelin basic protein in multiple sclerosis.

Peripheral blood lymphocytes (PBL) from active and stable multiple sclerosis (MS) patients, patients with other neurologic diseases (OND), and control subjects were tested for sensitization to two myelin antigens not previously examined in multiple sclerosis, using a [3H]thymidine incorporation assay. The antigens investigated were myelin-associated glycoprotein (MAG) and proteolipid protein (PLP). In addition, sensitization to myelin basic protein (MBP) was also tested. Lymphocyte stimulation indices in active MS patients that were greater than 2 standard deviations above controls were as follows: 9/30 for MAG, 0/17 for PLP, and 8/81 for MBP. No control subjects responded to MAG or PLP, and only 1/29 control subjects responded to MBP. Three of the patients that responded to MAG also responded to MBP. Although the mean proliferative response to MAG and to MBP was greater in the population of active MS patients than in stable MS, ONDs, or controls, the difference was not statistically significant. The OND group was the only population which proliferated to PLP (6/16). The only statistically significant differences among the groups for all myelin antigens tested were the proportion of individuals with active MS vs. controls that responded to MAG (P less than 0.05), and OND vs. controls and active MS that responded to PLP (P less than 0.025). The greatest individual responses to the three antigens tested were to MBP in active MS patients. Elimination of the T8 (cytotoxic/suppressor) subset amplified the responses to myelin antigens in some patients and ONDs studied. These studies have demonstrated reactivity to MAG but not PLP in some patients with active MS, and reactivity to PLP in some patients with other neurologic diseases.

Antibodies, Monoclonal↗
PubMed1986

An improved technique for long saphenous vein harvesting for coronary revascularization.

A prospective study was undertaken to assess the functional quality of long saphenous vein for coronary revascularization when it has been harvested by means of multiple small incisions and use of the Mayo "stripper." This avoids a "long cut" and the major wound problems commonly associated with it. Between January, 1979, and July, 1984, 2,439 patients underwent coronary artery bypass graft with long saphenous vein harvested by this technique. No major wound problems occurred, and minor wound problems were seen in only 23 patients (0.9%). Vein quality was assessed by histological studies of veins, postoperative graft angiography, and exercise testing. Both light electron microscopy and scanning electron microscopy demonstrated that the vein was of good quality and that the intima had been preserved. Postoperative graft angiography and exercise testing confirmed high patency rates for the vein grafts (93%). Vein harvesting with this technique is easy, gives good quality vein, both morphologically and functionally, for grafting, is associated with a minimum of wound problems, and has cosmetically superior results.

Adult↗
PubMed1986

Effort angina with adequate beta-receptor blockade: comparison with diltiazem alone and in combination.

Calcium channel blockers and beta-receptor blockers improve symptoms of myocardial ischemia by potentially different mechanisms. Accordingly, combination therapy may entail additive benefits. Twenty-four patients with symptomatic stable effort angina despite full beta-blockade were randomized to a double-blind Latin square protocol in which they received propranolol in a dose producing full beta-receptor blockade, diltiazem, 240 mg/day, in divided doses and a combination of propranolol and diltiazem, 240 or 360 mg/day. Treadmill testing (Bruce protocol) was utilized to assess exercise tolerance, radionuclide ventriculography to assess left ventricular function and clinical follow-up to assess adverse effects and overall clinical response. Comparable treadmill exercise times were observed with monotherapy (344 +/- 83 seconds with propranolol and 341 +/- 87 seconds with diltiazem) and the lower dose combination (361 +/- 87 seconds). With propranolol and diltiazem, 360 mg/day, however, there was a significant increase in treadmill time (393 +/- 106 seconds; p less than 0.05). In five patients whose treadmill exercise was limited by angina on all therapies, there was a significant improvement in the time to onset of chest pain with both low dose and high dose combinations (311 +/- 71 seconds, p less than 0.05 and 336 +/- 76 seconds, p less than 0.01, respectively). Improved treadmill performance was supported by the clinical response, while an increase in adverse effects was not observed. Thirteen of 24 patients blindly selected the higher dose diltiazem combination as their optimal therapy. Left ventricular dilation was observed (by radionuclide ventriculography) in response to exercise in each phase of therapy; this was related to stress-induced ischemia.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenergic beta-Antagonists↗
PubMed1986

Long saphenous vein harvesting.

There is described an easy and rapid technique using the Mayo Vein Stripper to facilitate safe harvesting of the long saphenous vein for vascular reconstruction. It provides good quality vein and a superior cosmetic result without wound complications.

Coronary Artery Bypass↗
PubMed1986

Quantitation of the myelin-associated glycoprotein in human nervous tissue from controls and multiple sclerosis patients.

Myelin-associated glycoprotein (MAG) was measured by radioimmunoassay in the human CNS and peripheral nervous system (PNS). The level of MAG, expressed as ng/microgram of total protein, was approximately 20-fold higher in whole homogenates of cerebral white matter (4.7 +/- 0.60) than of peripheral nerve (0.12-0.28). MAG concentrations were only slightly higher in the isolated myelin fractions from these tissues: CNS myelin, 5.6 ng/microgram; PNS myelin, 0.37 ng/microgram. The levels of MAG were measured in nine plaques, periplaque regions, and areas of macroscopically normal-appearing white matter (NAWM) from six separate multiple sclerosis brains and compared with the levels of other myelin proteins in the same samples. MAG and other myelin proteins were reduced to very low levels in plaques. The levels of MAG and basic protein (BP) and the activity of 2',3'-cyclic nucleotide 3'-phosphodiesterase (CNP) in periplaque areas were significantly lower than those in control white matter, and MAG and BP levels were also significantly reduced in NAWM. In a periplaque region and NAWM from the most rapidly progressing case of multiple sclerosis examined, the MAG content was between 30 and 35% of the control level, whereas BP and PLP levels and CNP activity were between 50 and 85% of control values. The reduction of MAG content in periplaque regions from all nine multiple sclerosis plaques examined was significantly greater than the reductions of BP level and CNP activity. In NAWM samples, the mean reduction of MAG content was also greater than the reductions of BP level and CNP activity, but the difference was only statistically significant in comparison to CNP.(ABSTRACT TRUNCATED AT 250 WORDS)

2',3'-Cyclic-Nucleotide Phosphodiesterases↗
PubMed1986

Questionnaire survey of pruritus and rash in grain elevator workers.

51.4% of 1,954 grain elevator workers surveyed in 1978 and 1979 complained of pruritus following exposure to grain dusts. 95% of 796 grain elevator workers surveyed in 1985 noted that pruritus following exposure to grain dust was of short duration. Exposure to barley dust and oat dust provoked the greatest number of complaints. Those with a past history of infantile eczema were significantly more likely to complain. Younger workers were more likely to complain than older workers. 13.1% of those surveyed in 1985 complained of a rash following exposure, in 35% of whom it lasted more than 1 day. Nasal congestion, ocular and oropharyngeal irritation were also frequent complaints.

Adult↗
PubMed1986

Late results of right ventricular outflow tract reconstruction with Björk-Shiley valved conduits.

Between 1971 and December 1976, 27 children with congenital heart disease underwent right ventricular outflow tract reconstruction with conduits incorporating a Björk-Shiley valve. The conditions corrected were pulmonary atresia with ventricular septal defect (14 patients), truncus arteriosus (6 patients), and complex disease (7 patients). At operation the children were aged from 12 days to 16 years (five patients were less than one year old). Overall mortality for the group was high (52%). There were nine early deaths and five late ones. Actuarial survival till death or reoperation was 55% at four years, 35% at eight years, and 28% at 12 years. Ten children subsequently underwent reoperation for conduit stenosis caused by neointimal proliferation and valve obstruction. The new conduits incorporated a biological valve. Mortality was highest in patients aged less than one year, and in those with truncus arteriosus, severe pulmonary hypertension, or complex heart disease. Mechanical valves should be avoided in conduit reconstruction of the right ventricular outflow tract for congenital heart disease.

Adolescent↗
PubMed1986

The prevention of wound contamination by skin organisms by the pre-operative application of an iodophor impregnated plastic adhesive drape.

Prior to preparing the skin for surgery, samples for bacterial growth were taken from 107 patients. The same site was sampled after preparation with povidone-iodine and at the end of surgical procedure the deep part of the wound was also sampled. This demonstrated that the wounds of 15% of patients became contaminated by organisms present on the skin prior to disinfection. A comparison was made with a further 122 patients undergoing hip surgery in whom an iodophor impregnated plastic adhesive drape ('Ioban') was applied to the operation site 24 hours prior to surgery. Bacterial sampling of the wound at the end of the procedure showed that wound contamination was reduced from 15% to 1.6% by this method. When patients are to have implant surgery, the protection from contamination by skin organisms afforded by 'Ioban' drape is likely to prove a valuable tool in the fight to prevent infection.

Antisepsis↗
PubMed1986

Cellular uptake and cell-associated activity of third generation cephalosporins.

The ability of the third generation cephalosporins to penetrate human polymorphonuclear leukocytes (PMNs) and their antibacterial activity against cell-associated Staphylococcus aureus (SA) and Haemophilus influenzae, type b (Hib) were studied. Utilizing radioactive uptake experiments, the cellular to extracellular concentration ratios were determined to be less than one for all cephalosporins at 10 and 120 min: cefotaxime (0.08 +/- 0.02, 0.34 +/- 0.08), ceftizoxime (0.21 +/- 0.11, 0.52 +/- 0.18), ceftriaxone (0.12 +/- 0.04, 0.38 +/- 0.23), and N-formimidoyl thienamycin (0.18 +/- 0.09, 0.33 +/- 0.14). Third generation cephalosporins were similar to penicillin in their exclusion from PMNs. The killing of cell-associated SA and Hib were evaluated in a preopsonized cell-associated bacterial assay with radiolabelled SA/Hib (cfu/cpm) comparing activity of PMNs + antibiotics to the PMN cell control (no antibiotics) at 0.5, 2, and 4 h. PMNs alone killed less than or equal to 0.5 log SA/Hib over 4 h. Clindamycin killed significantly more SA (p less than 0.01) than all other antibiotics; nafcillin killed significantly fewer SA (p less than 0.05) than all other antibiotics. Although each third generation cephalosporin showed good activity against cell-associated Hib, chloramphenicol had a significantly greater effect (p less than 0.05). N-formimidoyl thienamycin demonstrated good activity only after the concentration was increased in vitro to 8 micrograms/ml. Although cellular penetration of antibiotics may be important in the eradication of cell-associated pathogens, the overall cellular activity would appear to be multifactorial.

Adult↗
PubMed1986

Monoclonal gammopathy and neuropathy: myelin-associated glycoprotein reactivity and clinical characteristics.

Immunoblot analysis was performed on the serum from 29 patients with polyneuropathy and monoclonal gammopathy. Nine patients had IgM spikes, and six of the nine had reactivity against myelin-associated glycoprotein (MAG) associated with a slowly progressive, predominantly sensory neuropathy. In contrast, 23 patients who lacked anti-MAG reactivity had more severe sensory motor neuropathy. Thus, IgM monoclonal gammopathy with reactivity against MAG may define a distinct clinical entity.

Adult↗
PubMed1986

Effects of Florida's Personal Fitness Course on cognitive, attitudinal and physical fitness measures of secondary students: a pilot study.

The effects of Florida's Personal Fitness Course were studied on 60 secondary students' cognitive achievement, physical fitness, and attitude toward physical activity. Significant improvement in knowledge of fitness concepts, selected physical fitness parameters, and over-all attitude toward participation in physical activity suggests the course was effective.

Adolescent↗