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Biomedical subjects

J M Johnson

Publications and source records attributed to J M Johnson.

At least 163 records · Page 9Linked to original sources
PubMed1987

Nosocomial graft fragmentation and healing response of an ePTFE angioaccess graft.

This investigation was directed toward the tissue reaction and wound healing response of an ePTFE prosthesis implanted in a human subject as an arteriovenous fistulae for over 7 years. Due to the frequent puncture of the prosthesis for hemodialysis access, the pattern of healing is markedly different from that normally observed in ePTFE grafts in humans. The ePTFE graft material of the AV fistula was completely incorporated in fibrous tissue with prominent pseudointima formation (inner capsule), fibrous tissue within the graft and a well-adhered periadventitial layer (outer capsule). In the portion of the graft most frequently punctured, the wall of the graft was composed mainly of fibrous tissue containing dissociated fragments of ePTFE. Biochemical analysis of the fibrous tissue across the wall of the graft revealed that it contained types I, III, and V collagen, with type I greater than III greater than V. The type V collagen was present in largest percentage at the luminal surface and in decreasing percentage in the ePTFE material and outer capsule. This analysis suggests that collagen type deposition in this prosthesis occurs in a manner similar to a normal healing wound, except for the unusual pattern of type V collagen deposition, which may be an adaptive variation of the healing response.

Adult↗
PubMed1987

Implementing a computer software system.

A great deal of time and energy goes into deciding what software computer system to purchase for the nursing department. Too often following purchase, we think our work is over, when in reality, the most critical phase is starting--installing the system. This article discusses critical responsibilities of both nurse administrators and installers during implementation of the system.

Administrative Personnel↗
PubMed1987

Comparing participants' and managers' perception of services in a congregate meals program.

Managers and participants in a Title III C meals program were surveyed to explore how differences in perception of program and service quality affect participant acceptance and evaluation of the program. A nutrition monitoring instrument was designed for managers at 14 meal sites to assess major components of the foodservice operation. A survey addressing participant perception of meal quality, meal acceptance, program administration and management, and foodservice personnel was designed and administered to 264 participants. The two surveys contained 17 identical or similar questions to determine any perceptual differences. The influence of social variables on participant response was examined. A significant positive correlation was found for age vs. food temperature, age vs. frequency of participation, and education level vs. evaluation of foodservice workers. Significant negative correlations were found for sex vs. special diets, sex vs. food aversion, education level vs. food temperature, and education level vs. evaluation of the nutrition education component. Manager vs. participant response significantly differed for food temperature, special diets, nutrition education, transportation, and accuracy of posted menus. Assessment of participant vs. manager perception of meal and service quality is recommended to management for more effective program planning, evaluation, and continuous quality assurance.

Administrative Personnel↗
PubMed1987

Predictors of successful alcohol rehabilitation in an Air Force population.

In order to find predictors of success in alcohol treatment, the authors conducted a 1-year follow-up of 71 active duty military personnel treated in a 28-day inpatient program. Success at 1 year follow-up was then compared with variables collected on a patient questionnaire completed at the beginning of rehabilitation. A family history of emotional disorders, together with a single incident precipitating treatment, was associated with a positive alcohol rehabilitation outcome.

Aerospace Medicine↗
PubMed1986

Biophysical profile scoring in the management of the postterm pregnancy: an analysis of 307 patients.

Management and outcome were reviewed in 307 consecutive postterm pregnancies assessed by biophysical profile scoring. Twice-weekly scores accurately differentiated normal fetuses from those at risk for intrauterine hypoxia. When the profile score is normal, waiting for spontaneous labor results in healthy neonates and a much lower cesarean section rate (15% versus 42% for "prophylactic" induction). Confident conservative management of postterm pregnancy is possible.

Cesarean Section↗
PubMed1986

Nonfatal chromobacterial sepsis.

We have described a case of multiple liver abscesses caused by Chromobacterium violaceum. This organism should be considered in any case of unexplained liver abscess occurring in the southeastern United States. Successful treatment of liver abscesses caused by this organism may be accomplished with appropriate antibiotic therapy.

Adult↗
PubMed1986

Effect of local warming on forearm reactive hyperaemia.

Measurement of minimal vascular resistance has proved useful in quantifying structural changes in regional circulations. Accurate measurement of minimal vascular resistance requires full relaxation of all resistance vessels within the region under examination. The usual procedure in humans involves the measurement of maximal forearm blood-flow following 6-10 min of forearm ischaemia. We conducted this study to find whether forearm skin was fully vasodilated by this procedure. Peak forearm blood-flow was measured by plethysmography in six healthy subjects following 10 min of ischaemia while the arm was at a neutral temperature (33 degrees C) and while the arm was locally warmed to 42 degrees C. Peak reactive hyperaemia blood-flow was significantly elevated by local heating (P less than 0.001) to 79.6 ml 100 ml-1 min-1 from a value of 50.2 ml 100 ml-1 min-1 during normothermia. Peak reactive hyperaemia blood-flow in the contralateral unheated forearm showed no significant change between the two periods of ischaemia (P greater than 0.05). These findings were confirmed in four subjects by laser Doppler velocimetry, which gives a linear index of skin blood-flow. In normothermic conditions, this index rose to 0.89 V following 10 min of ischaemia and to 1.26 V with local warming to 42 degrees C (P less than 0.001). Ischaemia plus local warming did not cause a further significant rise in this index of skin blood-flow (1.35 V, P greater than 0.05). These data suggest that 10 min of ischaemia during normothermia is insufficient to relax fully cutaneous resistance vessels and that maximal forearm blood-flow is underestimated by this procedure.

Adult↗
PubMed1986

Nonthermoregulatory control of human skin blood flow.

Although it is well accepted that skin blood flow (SkBF) in humans is controlled by thermoregulatory reflexes, the conclusion that the cutaneous circulation is also controlled by reflexes of nonthermoregulatory origin is not universally held. This review considers the extent to which the cutaneous circulation participates in baroreceptor-mediated reflexes and in the reflexes associated with exercise. Exercise is explored in some detail, because it elicits both thermoregulatory and nonthermoregulatory reflexes. The overall conclusion reached is that thermoregulatory control of SkBF is subject to modification by or competition from several other sources. The fundamental pattern for control of SkBF is described by the threshold and slope of the SkBF-internal temperature relationship. Reflex effects of skin temperature act to shift the threshold of this relationship such that lower levels of skin temperature are associated with higher threshold internal temperatures at which cutaneous vasodilation begins. Similarly, baroreceptor reflexes, reflexes associated with exercise, and effects of some cardiovascular disease also operate against this background. Although modification of the SkBF-internal temperature slope is occasionally seen, the most consistent effect of these nonthermoregulatory factors is to elevate the threshold internal temperature for cutaneous vasodilation. The consequence of this modification of thermoregulatory control of SkBF is that temperature regulation will often suffer when increases in SkBF are delayed or limited. Blood flow to other regions, possibly including active skeletal muscle, may also be compromised when thermoregulatory demands for SkBF are high.

Body Temperature Regulation↗
PubMed1986

Regulation of the cutaneous circulation.

In this symposium, a diversity of perspectives was focused on how blood flow to the skin is controlled. Thus, control of the cutaneous circulation by reflexes aimed at body temperature regulation, blood pressure regulation, and the reflexes attending muscular exercise was discussed in detail, as were the similarities and differences between control of cutaneous arterioles and arteriovenous anastomoses. A mechanistic treatment of interaction between adrenergic control of cutaneous blood vessels and their temperature brought physical factors and pharmacological approaches to the consideration of reflex control. Finally, the more slowly developing changes in the control of the skin circulation that accompany circadian rhythms, changes in blood volume or its distribution, physical training, and acclimatization were discussed. Because the cutaneous circulation has potentially large vascular conductance, blood flow, and blood volume, control of the resistance and compliance vessels within the skin has an importance well beyond that of tissue nutrition. Indeed, overall hemodynamics are dependent on how much blood flow and how much blood volume are distributed to skin. Consequently, reflex factors, physical factors, and their interaction all have roles of importance with respect to exchange of heat with environment as well as maintenance of blood pressure, cardiac output, and blood flow to other tissues.

Adrenergic Fibers↗
PubMed1985

Redox activation of galactose oxidase: thin-layer electrochemical study.

The redox activation of galactose oxidase by various oxidants is characterized by using a unique thin-layer electrochemical cell. Activation is shown to be strictly a redox process and can be rapidly accomplished by using ferricyanide, cobalt terpyridine or tetracyanomonophenanthroline ferrate, and a control electrode to control solution potential. This oxidation is a one-electron process and does not result in modified galactose oxidase which exhibits enhanced activity. On the contrary, this oxidation is required for activity. The solution potential dependence of activity is independent of which of these mediator-titrants is used, the concentration used, and which of various substrates is used in the determination. The substrates used were acetol, dihydroxyacetone, glycerin, 2-propyn-1-ol, allyl alcohol, 2-butyne-1,4-diol, furfuryl alcohol, benzyl alcohol, 4-pyridylcarbinol, galactose, and stachyose. The E1/2 and n values obtained are 0.40 +/- 0.005 V vs. SHE and 0.9 +/- 0.1 electron at pH 7.3. E1/2 is defined as the potential at which half the maximal enzymatic activity is observed and probably reflects the E0' of the enzymic group involved in activation. A model is proposed in which activation occurs during turnover due to the redox buffering (by oxidants) of an enzymic Cu(II)/Cu(I) state which has a higher E0' than in resting galactose oxidase. The pH dependence of E1/2 is 60 mV/pH unit in the pH range 6.0-8.0. The data suggest that the deprotonation of an amino acid residue facilitates the one-electron oxidation (activation) of galactose oxidase.

Electrochemistry↗
PubMed1985

Natural history of asymptomatic carotid plaque.

In April 1981, a total of 297 carotid arteries were examined prospectively. All patients were asymptomatic and were referred to the peripheral vascular laboratory at Good Samaritan Medical Center, Phoenix, for real-time B-mode ultrasonography. A measurement of luminal area stenosis was determined to be either greater or less than 75%. In addition, the ultrasound echo pattern was used to classify plaque as either calcified, dense, or soft. If, for any reason, the patient or physician felt that carotid endarterectomy should be performed, the patient was dropped from the study. In addition, the use of antiplatelet medication or anticoagulants constituted disqualification. Three groups of patients were observed for three years or until symptoms became apparent. Patients in all three groups with stenosis greater than 75% at the time of initial study were at greater risk than their peers without significant narrowing; however, even those patients with less than 75% stenosis were at greater risk if the associated plaque was less organized, ie, soft. A definite trend toward higher risk is seen in plaques of lower density. Only 10% of those patients with calcified plaque and a significantly stenotic vessel have developed symptoms. In contrast, only three patients of the original 42 with soft plaque and a tight stenosis are still being observed. This study appears to confirm that soft plaques have a greater tendency toward subintimal hemorrhage, ulceration, or primary embolization than more well-organized plaques.

Arterial Occlusive Diseases↗
PubMed1985

The effect of prenatal procarbazine treatment on brain development in the rat.

Groups of pregnant Sprague-Dawley rats were treated orally with procarbazine, an antineoplastic drug, at dose levels of 0, 1.0, 2.5, 5.0, 7.5, and 10.0 mg/kg/day from days 12 through 15 of gestation. Following normal delivery, offspring were raised until day 21 and sacrificed, and their brains removed and weighed. A dose-dependent micrencephaly, characterized by hypoplasia of the cerebral hemispheres, was seen starting at 2.5 mg/kg/day. In a second study, groups of pregnant female rats were given a single dose of 10 mg/kg procarbazine on gestation day 12, 13, 14, or 15. Micrencephaly occurred in 21-day-old offspring from all groups, with the greatest effect induced on days 13, 14 and 15. Analysis of brain region weights revealed a maximum reduction in neocortex weight in offspring from groups treated on days 13 and 14. The hippocampus, cerebellum, and diencephalon-midbrain were also reduced in size, depending on the day of treatment, while the corpus striatum and pons-medulla were spared. In a final study, embryos from females treated on gestation days 12 through 15 were removed, fixed, and sectioned at 24-hour intervals starting on gestation days 13. Necrosis and cellular degeneration were observed with decreasing severity in the telencephalon, diencephalon, mesencephalon, and medulla. The neocortex of 20-day treated fetuses was characterized by a thickening of the ventricular zone and reduced cellularity of the cortical plate.

Aging↗
PubMed1985

Femoropopliteal bypass using externally supported polytetrafluoroethylene grafts. Early results in a multiinstitutional study.

A multiinstitutional retrospective study was undertaken to evaluate the externally supported PTFE graft to determine whether a nonkinking, noncompressible graft offers advantages in patency and limb salvage. We studied the results of 104 femoropopliteal arterial reconstructions performed on 99 patients between June 1981 and June 1983. The combined above-the-knee and below-the-knee cumulative patency rate at 2 years was 88 percent and the limb salvage rate was 97 percent. We found these results to be comparable to the patency typical of saphenous vein grafts and better than that of reinforced PTFE grafts. The improved patency is due to the lack of kinking and compressibility of the externally supported PTFE graft, as well as histologic evidence of excellent collagen infiltration which stabilizes the graft in position. A longer follow-up period is certainly needed to make definite recommendations, but our preliminary studies are encouraging.

Adult↗
PubMed1985

Mode of neural control mediating rat tail vasodilation during heating.

The purpose of this investigation was to delineate the mode of efferent neural control mediating rat tail vasodilation during body heating. Tail blood flow (venous occlusion plethysmography), tail skin temperature over the ventral vascular bundle, and arterial pressure were measured in Sprague-Dawley rats anesthetized with pentobarbital sodium (45 mg/kg). Three protocols were followed: anesthesia of the lumbar sympathetic chain, bilateral lumbar sympathectomy, and sympathetic nerve stimulation during varying degrees of alpha-adrenergic receptor blockade. Mean tail blood flow and tail vascular conductance (TVC) during body heating were 40.3 +/- 8.7 ml X 100 ml-1 X min-1 and 39.2 +/- 9.2 ml X 100 ml-1 X min-1 X 100 mmHg-1, respectively. Interruption of sympathetic nerve activity by sympathetic nerve anesthetization or sympathectomy during heat stress caused a nonsignificant increase in TVC to 112.7 +/- 1.8 and 121.12 +/- 6.3%, respectively, of the values achieved with body heating. Sympathectomy performed in normothermic animals that had recovered from prior heating caused an increase in TVC to 128.4 +/- 14.0% of the levels achieved during the previous heating period. In addition, sympathetic nerve stimulation after complete alpha-adrenergic receptor blockade failed to produce a vasodilation [control TVC = 10.2 +/- 3.9 vs. TVC during nerve stimulation = 10.4 +/- 3.9 (P greater than 0.05)]. It is concluded that the increase in TVC during body heating occurs solely via a reduction in vasoconstrictor nerve activity.

Animals↗
PubMed1985

A seroprevalence survey of hepatitis B markers among Haitians in a southwest Florida farming community.

We determined the seroprevalence of hepatitis B virus markers among 123 Haitian mothers and children in a southwest Florida farming community. Fifty-five per cent of mothers had one or more markers including two who were HBsAg positive. Only seven (10 per cent) children had markers; none were HBsAg positive. Pregnant Haitian women should be screened for HBsAg and infants born to those who are positive should receive immunoprophylaxis. Medical, dental, and laboratory workers caring for Haitian patients should also receive hepatitis B vaccine.

Adult↗