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Biomedical subjects

J M Johnson

Publications and source records attributed to J M Johnson.

At least 127 records · Page 7Linked to original sources
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↗
PubMed1990

Maternal serum alpha-fetoprotein in twin pregnancy.

Maternal serum alpha-fetoprotein concentration was measured at 14 to 20 weeks' gestation in 138 twin pregnancies. All patients had at least one ultrasonographic examination (86% before 20 weeks' gestation). Two pregnancies were discordant for open fetal defects (one anencephaly, one gastroschisis). The median serum alpha-fetoprotein value in the remaining 136 twin pregnancies paralleled a curve 2.5 times the median curve for singleton pregnancies over the gestational range studied. Higher serum alpha-fetoprotein values correlated significantly with increasing incidence of fetal and neonatal death, premature delivery (less than 35 weeks' gestation), and twin-to-twin birth discordance (greater than 20%), most pronounced at greater than 4 multiples of the singleton median level. A significant negative correlation between alpha-fetoprotein and birth weight was observed (p less than 0.001), but was related more to prematurity than to poor fetal growth. Theoretically, serum alpha-fetoprotein screening detected 56.5% of the twins in this study when a cutoff level of 2.5 multiples of the median was used, enhancing twin detection in the study population by 40%. These data indicate that maternal serum alpha-fetoprotein screening has a valuable role in the management of twin pregnancy, both in the detection of twins and in the prediction of perinatal outcome in twin pregnancy.

Female↗
PubMed1990

Roles of absolute and relative load in skin vasoconstrictor responses to exercise.

Systemic hemodynamic responses to exercise (e.g., heart rate, blood pressure) depend on the relative intensity, the active muscle mass, and the mode of exercise. It is not known whether regional vasomotor responses follow the same pattern. To answer this question, in five men we examined cutaneous vascular responses to dynamic and isometric exercise of two legs, one leg, one arm, and one hand, each at high and low work loads. Skin blood flow was monitored by laser-Doppler flowmetry (LDF) at the forearm. Mean arterial pressure (MAP) was measured each minute. Cutaneous vascular conductance (CVC) was indexed as LDF/MAP. Reductions in CVC during the 1st min of dynamic exercise were statistically significant for two-leg exercise at either level and for one-leg exercise at the higher level. Dynamic exercise of smaller muscle groups at either intensity was not associated with significant changes in CVC. The reduction in CVC correlated with external work load (r = 0.75). Work load relative to the capacity of a given muscle group had no identifiable role in the response of CVC to dynamic exercise but did have a role in the increase in MAP at the beginning of exercise. Isometric exercise did not have a measurable effect on CVC regardless of the muscle group or the intensity of the exercise. We conclude that the level of external work determines the redistribution of blood flow from skin to active muscle. Furthermore, absolute rather than relative work and dynamic rather than isometric modes of exercise are the dominant factors.

Adult↗
PubMed1990

Baroreflex control of the cutaneous active vasodilator system in humans.

Cutaneous arterioles are controlled by vasoconstrictor and active vasodilator sympathetic nerves. To find out whether the active vasodilator system is under baroreceptor control, laser-Doppler velocimetry and the local iontophoresis of bretylium were combined to allow selective study of the active vasodilator system. Each of six subjects had two forearm sites (0.64 cm2) treated with bretylium to abolish adrenergic vasoconstrictor control. Laser-Doppler velocimetry was monitored at those sites and at two adjacent untreated sites. Subjects underwent 3 minutes of lower-body negative pressure (LBNP) and 3 minutes of cold stress to verify blockade of vasoconstrictor nerves. They were then subjected to whole-body heat stress (water-perfused suits), and the 3 minutes of LBNP was repeated. Finally, subjects were returned to normothermia, and LBNP and cold stress were repeated to verify the persistence of blockade. During the application of LBNP in normothermia, cutaneous vascular conductance (CVC) fell at untreated sites by 22.7 +/- 4.7% (p less than 0.01) but was unaffected at bretylium-treated sites (p greater than 0.20). During cold stress, CVC at untreated sites fell by 30.2 +/- 1.7% (p less than 0.01) and at treated sites rose by 0.7 +/- 4.6% (p greater than 0.10). Both control and bretylium-treated sites reflexly vasodilated in response to hyperthermia. With LBNP during hyperthermia, CVC at untreated sites fell by 23.3 +/- 7.1% (p less than 0.05) and at treated sites 17.9 +/- 9.2% (p less than 0.05) with no significant difference between sites (p greater than 0.10). After return to normothermia, neither LBNP application nor cold stress caused CVC to fall at treated sites (p greater than 0.10). Thus, the vasoconstrictor system was blocked by bretylium treatment throughtout the study, whereas the active vasodilator response to heat stress was intact. Because LBNP in hyperthermia induced similar falls in CVC at both sites, we conclude that baroreceptor unloading elicits a withdrawal of active vasodilator tone and that the baroreflex has control of the active vasodilator system.

Adult↗
PubMed1990

A method for transcribing signed and spoken language.

Transcribing sign communication used simultaneously with spoken English presents investigators with a unique problem: the singular quality of the bimodal communicative interactions cannot be accurately depicted using accepted conventions for recording either spoken or signed language samples. This article proposes guidelines for transcribing such data. The need for guidelines arose during an earlier study of the language development of a hearing child of deaf parents. To meet the immediate needs of that study, rules and conventions from previous studies were combined with newly generated ones, resulting in the guidelines proposed in this article. The guidelines can be applied to data in which intermodal linguistic influence is suspected.

Communication Methods, Total↗
PubMed1990

Is schizophrenia genetically transmitted?

Clinicians and researchers alike have questioned and studied the origin of schizophrenia for decades. Since the early 1900s, a genetic hypothesis has been suggested. This article reviews studies on a possible genetic cause of schizophrenia by use of various methods of comparison: twins, adoption, family history, family studies, and studies of biologic markers. Most researchers conclude that schizophrenia is likely caused by a genetic predisposition coupled with environmental influences.

Adoption↗
PubMed1990

Human immunodeficiency virus disease training: a 'how to' guide.

As the HIV epidemic spreads, throughout the United States, and as an increasing number of persons become infected with the virus and manifest its many complications, more and more physicians are being asked to give presentations on HIV disease to professional and community groups. This is especially true since AIDS education has become a primary prevention tool. The author provides guidelines for giving a talk on AIDS. The general principles are applicable to presentations both to other health professionals and to lay-community groups. The outline can be varied, and the lecture material can be expanded or summarized to meet the needs of the particular audience. Sources for further information are also provided.

Acquired Immunodeficiency Syndrome↗
PubMed1990

A new generation patient classification system.

The traditional approaches to monitoring reliability and validity are time consuming and costly and frequently lead to the abandonment of reasonable classification instruments. With the advent of micro computers and relational database software, nursing executives are now able to track reliability and validity on an ongoing basis. Because patient classification data are retained, they can be used to provide more accurate work load predictions and descriptions. Further, the ability to identify the source of problems with unit-specific instruments or nurse classifiers leads to the required corrective mechanism. Increased confidence in the reliability and validity of the work load data provides the staff nurse with direct evidence of the accuracy of the patient classification instrument and the nursing executive with a significantly stronger tool in budget planning and tracking, contract negotiations and financial risk reduction.

Activities of Daily Living↗
PubMed1989

Quality control of custom block making in radiation therapy.

Custom blocks are the most commonly used field shaping device in radiotherapy. They offer many advantages in daily clinical use. However, as with all accessories used for patient treatments, care must be taken with their use. As such, a quality control program to check block cutting accuracy is recommended as a routine part of their clinical use. We have developed a three step method for checking custom blocks before they are used for patient treatment. These steps include: a static light check, a parallel opposed film check, and a block check involving the patient. By completing these three steps, we feel that we have improved the overall accuracy of our custom block making system which has resulted in more accurate treatments for our patients.

Humans↗
PubMed1989

Transabdominal chorionic villus sampling in a patient with a bicornuate uterus.

In our preliminary experience with transabdominal chorionic villus sampling, we encountered a patient with a uterus bicornis bicollis and anterior fundal placenta, which posed particular technical difficulties for the transcervical approach, but in whom sampling was easily accomplished by the transabdominal route. A description of this case, as well as a discussion of our technique and experience to date, is provided.

Abdomen↗