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Biomedical subjects

J M Johnson

Publications and source records attributed to J M Johnson.

At least 19 recordsLinked to original sources
PubMed1992

Hydrolyzable tannins: potent inhibitors of hydroperoxide production and tumor promotion in mouse skin treated with 12-O-tetradecanoylphorbol-13-acetate in vivo.

The anti-oxidant and the anti-tumor-promotion activities of several hydrolyzable tannins (HTs), including a commercial tannic-acid (TA) mixture, were examined in mouse skin treated with 12-O-tetradecanoylphorbol-13-acetate (TPA) in vivo. A single application of TPA gradually increases the hydroperoxide (HPx)-producing activity of the epidermis, which is maximally stimulated at 3 days and returns to control levels at 9 days. Pre-treatments with TA and ellagic acid (EA) strongly inhibit, in a dose-dependent manner, this HPx response to TPA. Total inhibition by TA lasts for about 16 hr, beyond which it is substantially reduced but not completely lost. TA can also reduce the level of epidermal HPx when it is applied 36 hr after the tumor promoter. EA is an antioxidant 10 times more potent than TA and n-propyl gallate (PG), which are equally effective against TPA-induced HPx production. Gallic acid is the least effective of the HTs in inhibiting HPx formation. TA also inhibits the production of HPx induced by several structurally different tumor promoters and the greater HPx responses produced by repeated TPA treatments. When applied 20 min before each promotion treatment, twice a week for 45 weeks, several HTs inhibit the incidence and yield of papillomas and carcinomas promoted by TPA in initiated skin. Overall, TA is more effective than EA and PG in inhibiting skin-tumor promotion by TPA, suggesting that the anti-oxidant effects of HTs are essential but not sufficient for their anti-tumor-promotion activity.

Animals↗
PubMed1992

Antitumor-promoting activities of hydrolyzable tannins in mouse skin.

Ellagic acid and gallic acid and its derivatives, applied topically to female CF-1 mice 20 min before each 12-O-tetradecanoylphorbol-13-acetate (TPA) treatment inhibit the inductions of epidermal ornithine decarboxylase activity, hydroperoxide production and DNA synthesis caused by this potent tumor promoter in relation with their abilities to inhibit the promotion of skin papillomas and carcinomas in the two-step initiation-promotion protocol. Because of its potency against TPA promotion, tannic acid, which is already known to inhibit tumor initiation, may inhibit the multistage process of carcinogenesis.

Animals↗
PubMed1992

Resting and maximal forearm skin blood flows are reduced in hypertension.

To find whether the vasodilator capacity of nonacral skin is reduced in hypertension, we measured forearm blood flow by venous occlusion plethysmography in 10 seated normotensive (mean +/- SD mean arterial pressure, 94 +/- 5 mm Hg) and 10 hypertensive (112 +/- 9 mm Hg) men at rest for 39 minutes while the forearm was heated with water at 42 degrees C, a maneuver known to selectively and maximally vasodilate skin. Blood pressure, measured every 5 minutes, did not change with heating. We found that in the normotensive group resting forearm blood flow was higher (3.64 +/- 1.12 versus 2.48 +/- 0.58 ml/100 ml tissue per minute, p less than 0.001; normotensive group versus hypertensive group) and resting forearm vascular resistance lower (30.17 +/- 10.99 versus 48.88 +/- 17.37 mm Hg.min.100 ml tissue per minute, p less than 0.05; normotensive group versus hypertensive group), and maximal forearm blood flow with local heating was higher (29.32 +/- 11.99 versus 18.19 +/- 4.50 ml/100 tissue per minute, p less than 0.018; normotensive group versus hypertensive group and vascular resistance lower (4.07 +/- 1.04 versus 6.54 +/- 1.17 mm Hg.min.100 ml tissue per minute, p less than 0.005; normotensive group versus hypertensive group). To find whether this degree and duration of local warming maximally vasodilated the skin in hypertensive subjects (as it does in normotensive subjects), we measured forearm skin blood flow before and during local heating plus 10 minutes of ischemia using a laser Doppler flowmeter.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Zinc and iron utilization in young women consuming a beef-based diet.

The purpose of this study was to determine the utilization of zinc in young adult women fed diets containing varying amounts of lean ground beef. A secondary objective was to determine the utilization of iron. The 28-day study was divided into one 7-day preexperimental period, during which a vegetarian diet was fed, and three randomly arranged 7-day experimental periods. During the experimental periods, the diets contained 3, 6, or 9 oz of beef, supplying varying levels of zinc and iron. Complete collections of urine and fecal samples were obtained from each subject. All the diets resulted in positive zinc balance; however, mean zinc balances were significantly higher when subjects consumed the experimental diets containing beef. When data for all diets containing beef were combined, mean values for apparent zinc absorption and zinc retention were not significantly higher than values that resulted from the vegetarian diet. Consumption of all diets resulted in a positive iron balance; however, mean iron balances were significantly higher for diets containing beef. As the amount of beef in the diet increased, the bioavailability of iron increased. We found that zinc and iron utilization was enhanced after consumption of a diet including lean ground beef. Results of this study also suggest that little increase in zinc and iron utilization is realized by including more than 3 oz beef per day in the diet.

Adult↗
PubMed1992

The tendency for temperament to be "temperamental": conceptual and methodological considerations.

Temperament seems to be a concept that stimulates a great deal of enthusiasm among nurses and professionals who "discover" it. Yet "knowing" that you have captured something of value does not necessarily imply full knowledge and understanding of the object. On the contrary temperament enthusiasts guarantee no consensus of opinion about what it is or how to best measure it. And so the conceptual and methodological issues for debate and discussion continue spilling over into both its research and clinical use. Sorting out the issues and the implications for use when there has been so much discussion and debate can be difficult. This article attempts to identify the main issues surrounding temperament, where we stand on some of the issues, and the practical implications for nurses who are interested in incorporating the measurement of temperament into clinical practice and research.

Child, Preschool↗
PubMed1992

Control of skin blood flow during exercise.

When body temperature rises, skin blood flow (SkBF) increases to effect transfer of metabolic heat from the core to the skin. This convective heat transfer is never more important than during dynamic exercise. Control of SkBF involves a complex interaction of regulatory systems (body temperature, blood pressure, metabolism, etc.) and efferent mechanisms (passive withdrawal of constrictor tone, reflex vasoconstriction, active vasodilation). The purpose of this paper is to provide an updated review of this complex control system--control that allows for maintenance of blood pressure and perfusion of active muscle without adverse impact on thermoregulation. Also discussed are vasomotor mechanisms, various components of exercise that are important in the control of SkBF (e.g., intensity, posture, and duration of exercise), and the influences of such factors as blood volume and tonicity, aerobic fitness and heat acclimation, and age.

Age Factors↗
PubMed1992

A comprehensive analysis of preoperative patient education.

1. One of the most important responsibilities of a nurse is preoperative preparation of the patient for surgery. Preoperative teaching helps to relieve some of the emotional stress patients have when facing surgery. 2. By providing a structured preoperative teaching class, the nurse can inform, support, and collaborate with adult surgical patients about the planned care. The nurse can also involve patients as partners in making the best possible decisions about their care. 3. Patient evaluations about the preoperative education class revealed a high level of satisfaction. The classes were believed to be an important contribution to patient education.

Humans↗
PubMed1992

Exercise and the cutaneous circulation.

Our understanding of the control of the cutaneous circulation has increased over the past decade, but is still far from complete. There is a cutaneous vasoconstriction at the beginning of exercise that usually effectively competes with concurrent thermoregulatory drives for vasodilation. This cutaneous vasoconstrictor response, however, requires dynamic activity by a significant muscle mass as small muscle groups or isometric exercise are ineffective or nearly so. Also, exercise causes the threshold internal temperature relative to rest such that SKBF is lower during exercise than in resting conditions for a given thermal stimulus. A further influence by exercise on the cutaneous circulation is to limit the degree of cutaneous vasodilation when heat stress and exercise are combined. These three roles for exercise compete with the thermogenic role that promotes vasodilation. The previously described effects act through the adrenergic vasoconstrictor system and the separate active vasodilator system. The increase in SKBF with heat stress represents the combination of withdrawal of vasoconstrictor activity and elevation of active vasodilator activity. The vasoconstrictor effect of the initiation of exercise is accomplished strictly through enhanced vasoconstrictor activity; vasodilator withdrawal does not participate [72]. However, both the exercise-induced elevation in thermoregulatory threshold for raising SKBF and the limitation to cutaneous vasodilation during exercise are strictly functions of the active vasodilator system [69, 73, 78]. In the first case, active vasodilation is delayed until a higher (relative to rest) level of internal temperature is reached. In the second case, the plateau in SKBF during exercise in the heat is due to a similar plateau in active vasodilator activity. Exercise has also served as a tool for the study of other influences on the cutaneous circulation. The influences of alterations in body fluid volumes, osmolarity, acclimatization, hypertension, time of day, menstrual phase, and others on the control of SKBF have been assessed by using exercise as a calorigenic source. The question as to whether the nonthermoregulatory influences of exercise interact with these other influences to give a modification of the pattern of control different from what might be observed at rest is largely unanswered. Future directions for research are numerous, but several fundamental questions are outstanding. The mechanism of active cutaneous vasodilation has been elusive since its discovery and remains an exceptionally important question. Second, the sensory elements associated with exercise giving rise to the alterations in the pattern of control are unclear. This problem is made challenging by the fact that the efferent control by exercise differs between its initiation and events later in exercise.(ABSTRACT TRUNCATED AT 400 WORDS)

Acclimatization↗
PubMed1991

Impact of prenatal testing on maternal-fetal bonding: chorionic villus sampling versus amniocentesis.

The process of maternal-fetal attachment, considered vital for normal infant development, begins during pregnancy and can be affected by a number of external factors. In this study the impact of prenatal testing on maternal-fetal bonding was evaluated in 253 women undergoing either first-trimester chorionic villus sampling (n = 101) or second-trimester genetic amniocentesis (n = 152). The women were evaluated by means of a modification of the Cranley Maternal-Fetal Attachment Scale, administered before and after the results of the prenatal diagnostic testing were made known to them (mean gestational ages of 10.6 and 15.7 weeks for the chorionic villus sampling group and 16.5 and 21.1 weeks for the amniocentesis group). The results showed: (1) that maternal-fetal attachment begins as early as 10 weeks' gestation and increases significantly as the pregnancy progresses, (2) that maternal-fetal attachment increases significantly, once the results are known to be normal, for both groups (p less than 0.001), (3) that this increase occurs about 5 weeks earlier for patients with chorionic villus sampling in comparison to those undergoing amniocentesis (p less than 0.001). Thus, with regard to the process of maternal-fetal attachment, first-trimester chorionic villus sampling appears to be preferable to second-trimester amniocentesis.

Amniocentesis↗
PubMed1991

The provision of a uniform vaginal surface dose rate by a novel afterloading cylinder.

The administration of a uniform dose rate to the vaginal surface is important in the management of endometrial, cervical, and vaginal malignancies. Unfortunately, conventional vaginal cylinders fail to provide this uniformity, and although dome cylinders do so, they require specialized 137Cs sources. Thus, a new acrylic vaginal cylinder has been developed to use with standard 137Cs sources and provides a uniform dose rate independent of vaginal size. Each contoured cylinder follows a particular isodose line. A metal ring is used to secure the device to minimize vulvar trauma associated with other vaginal cylinders. The construction and use of a set of these cylinders has allowed determination of their utility and limitations, which will be discussed in detail. Although these applicators do not completely replace conventional cylinders, they do offer a useful addition to the brachy-therapeutic armamentarium.

Brachytherapy↗
PubMed1991

Competition between cutaneous active vasoconstriction and active vasodilation during exercise in humans.

Cutaneous vasoconstriction occurs in response to the initiation of dynamic exercise in hyperthermia. To find whether this response was due to increased vasoconstrictor activity or to withdrawal of active vasodilator activity, blood flow monitoring with laser-Doppler flowmetry (LDF) was combined with the local iontophoresis of bretylium. Each of six male subjects had two forearm sites treated with bretylium for selective local blockade of noradrenergic vasoconstrictor nerves in skin. LDF was monitored at those sites and at two adjacent untreated sites. Mean arterial pressure (MAP) was measured, and cutaneous vascular conductance (CVC) was calculated as LDF/MAP. After iontophoresis, subjects underwent 3 min of cold stress (water-perfused suits) to verify vasoconstrictor blockade. CVC at untreated sites fell by 35.9 +/- 3.1% (P less than 0.01) and at bretylium-treated sites was not significantly changed (P greater than 0.10). During strenuous exercise in normothermia, CVC at untreated sites fell by 16.1 +/- 4.1% (P less than 0.05) and was unchanged at bretylium-treated sites (+12.7 +/- 6.6%, P greater than 0.05). Whole body heat stress was then applied. When exercise was repeated in hyperthermia, CVC at untreated sites fell by 11.6 +/- 3.8% (P less than 0.05) but was not significantly changed at bretylium-treated sites (+3.6 +/- 3.0%, P greater than 0.30). Following return to normothermia, cold stress verified the persistence of the blockade. We conclude that exercise initiation causes a cutaneous vasoconstriction largely or entirely due to enhanced active vasoconstrictor tone in both normothermia and hyperthermia. Little or no role in this response can be ascribed to reduced active vasodilator activity.

Adult↗
PubMed1991

Neural control of the forearm cutaneous vasoconstrictor response to dynamic exercise.

This study was designed to evaluate the relative importance of intended effort ("central command") and of the absolute intensity of dynamic exercise to the cutaneous vasoconstrictor response to the onset of exercise in humans. Skin blood flow (laser-Doppler flowmetry) was measured from the forearm in six healthy individuals during 3-min periods of high- and low-intensity exercise with and without partial neuromuscular blockade. Cutaneous vascular conductance (CVC) was calculated from the ratio of skin blood flow to mean arterial pressure and expressed as a percent change from rest. A rating of perceived exertion (RPE) was expressed as a subjective measure of intended effort. Under control conditions, CVC decreased by 22% (median; range 7-42%, P less than 0.05) during high-intensity exercise [218 (186-268) W; RPE 16 (14-19) exertion units]. In contrast, during control low-intensity exercise [106 (88-128) W; RPE 10 (9-14) exertion units], during low-level exercise with curare [77 (54-98) W; RPE 13 (11-16) exertion units], and during maximal exercise with curare [106 (88-124) W; RPE 19 (18-20) exertion units], CVC did not change significantly. These results suggest that factors related to the activity of the exercising muscle and its metabolism rather than intended effort determine the cutaneous vasoconstrictor response to the initiation of intense dynamic exercise in humans.

Adult↗
PubMed1991

Control of internal temperature threshold for active cutaneous vasodilation by dynamic exercise.

Exercise induces shifts in the internal temperature threshold at which cutaneous vasodilation begins. To find whether this shift is accomplished through the vasoconstrictor system or the cutaneous active vasodilator system, two forearm sites (0.64 cm2) in each of 11 subjects were iontophoretically treated with bretylium tosylate to locally block adrenergic vasoconstrictor control. Skin blood flow was monitored by laser-Doppler flowmetry (LDF) at those sites and at two adjacent untreated sites. Mean arterial pressure (MAP) was measured noninvasively. Cutaneous vascular conductance was calculated as LDF/MAP. Forearm sweat rate was also measured in seven of the subjects by dew point hygrometry. Whole body skin temperature was raised to 38 degrees C, and supine bicycle ergometer exercise was then performed for 7-10 min. The internal temperature at which cutaneous vasodilation began was recorded for all sites, as was the temperature at which sweating began. The same subjects also participated in studies of heat stress without exercise to obtain vasodilator and sudomotor thresholds from rest. The internal temperature thresholds for cutaneous vasodilation were higher during exercise at both bretylium-treated (36.95 +/- 0.07 degrees C rest, 37.20 +/- 0.04 degrees C exercise, P less than 0.05) and untreated sites (36.95 +/- 0.06 degrees C rest, 37.23 +/- 0.05 degrees C exercise, P less than 0.05). The thresholds for cutaneous vasodilation during rest or during exercise were not statistically different between untreated and bretylium-treated sites (P greater than 0.05). The threshold for the onset of sweating was not affected by exercise (P greater than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Effects of peanut butter on ruminating.

Barton and Barton (1985) reported that supplementary peanut butter reduced rates of ruminating of 4 children with mental retardation and hypothesized that the effect was due to its thick, sticky consistency. We further examined the effects of peanut butter with 5 subjects with mental retardation by independently manipulating the caloric density versus the consistency associated with peanut butter. Results showed an inverse relation between rates of ruminating and amount of peanut butter consumed. However, this effect appeared to be primarily due to an increase in calories. A weaker and less consistent effect was ascribed to the consistency of peanut butter.

Adult↗
PubMed1990

Fetal assessment based on fetal biophysical profile scoring. IV. An analysis of perinatal morbidity and mortality.

The relationship between the last biophysical profile score result and perinatal outcome was determined among a large referred population of high-risk pregnancies. A highly significant inverse linear correlation was observed for fetal distress, admission to neonatal intensive care unit, intrauterine growth retardation, 5-minute Apgar score less than 7, and umbilical cord pH less than 7.20 but not for the incidence of meconium or major anomaly. A highly significant inverse exponential (log 10) relationship was observed for perinatal mortality in total and by component parts and cause. These data strongly suggest the biophysical profile scoring method of fetal risk assessment is accurate and also provides insight into the extent of fetal compromise.

Female↗