PubMed Health⌕ Search

Biomedical subjects

L Johnson

Publications and source records attributed to L Johnson.

At least 559 records · Page 31Linked to original sources
PubMedDate not supplied

Exercises illustrating flow in porous media.

A set of physically based exercises is described for illustrating concepts and processes related to fluid movement in porous media. These exercises revolve around a permeameter that costs several dollars to construct and requires no external equipment and no electrical power to operate. The exercises can be used to illustrate concepts related to pressure and fluid statics, Darcy's equation for both gases and liquids, infiltration, and flow in layered media. Although the permeameter was originally developed as a teaching aid, it may also be useful in field applications as a tool to estimate air and hydraulic conductivity. Additional testing is recommended to further assess the accuracy of the results for field applications.

Engineering↗
PubMedDate not supplied

Effect of beta blockade on singing performance.

The symptoms associated with performance anxiety, or the so-called stage fright syndrome, are similar to those of alpha and beta adrenergic stimulation. Suppression of symptoms and improvement in instrumentalist's performance after beta blockade suggest that this modality would be of benefit for singers as well. To evaluate the dose-effect relationship of beta blockade upon singing performance and the possible effect of these agents upon performance maturation, we studied 34 singing students during end of semester juries, using a double-blind crossover paradigm. Students performed once with either placebo, 20, 40, or 80 mg of nadolol, and again 48 hours later, with placebo. There was a significant dose-related, limiting effect upon intraperformance cardiac rate. A small, but statistically significant, dichotomous effect upon performance rating was noted: low-dose nadolol tended to enhance performance, whereas larger doses impaired performance. We conclude that the effects of low dose beta blockade upon singing are minimally helpful and high doses may detract from performance ability.

Adolescent↗
PubMedDate not supplied

The effects of goal setting and self-instruction on learning a reading comprehension strategy: a study of students with learning disabilities.

This study examined the contributions of instruction in goal setting and self-instruction, separately and combined, on the acquisition, maintenance, and generalization of a reading comprehension strategy by fourth-through sixth-grade students with learning disabilities. A previously validated strategy involving the use of story structure to analyze and remember story content was taught to 47 students with learning disabilities using the self-regulated strategy development (SRSD) model. Comparisons were made among students with learning disabilities in four conditions (strategy instruction, strategy instruction plus goal setting, strategy instruction plus self-instruction, and strategy instruction plus goal setting and self-instruction). Result indicated that instruction in the reading strategy produced meaningful, lasting, and generalizable effects on students' story comprehension skills. Furthermore, the comprehension performance of the students with learning disabilities after strategy instruction was indistinguishable from that of a social comparison group of normally achieving students. Explicit instruction in goal setting and self-instruction, however, did not augment the comprehension performance of students with learning disabilities.

Analysis of Variance↗
PubMedDate not supplied

Clinical characteristics of 53 dogs with Doppler-derived evidence of pulmonary hypertension: 1992-1996.

Pulmonary hypertension occurs as a primary or secondary disorder of the pulmonary vasculature. Doppler echocardiography provides a noninvasive tool for the estimation of pulmonary arterial pressure when tricuspid regurgitation or pulmonic insufficiency is present. The cardiology database at Colorado State University was reviewed, and echocardiographic records from cases diagnosed with pulmonary hypertension were evaluated. Application of the modified Bernoulli equation to the maximal instantaneous velocity of a right-sided regurgitant jet provided evidence of pulmonary hypertension in 53 dogs over a 4-year period. Tricuspid regurgitant velocity > or = 2.8 m/second or pulmonic insufficiency velocity > or = 2.2 m/second was considered abnormal and indicative of pulmonary hypertension. Tricuspid regurgitant gradients in 51 dogs ranged from 32 to 145 mm Hg (mean, 63.0 mm Hg; median, 57.0 mm Hg; 25th-75th percentiles, 45.2-76.5 mm Hg). Pulmonic insufficiency gradients in 8 dogs ranged from 20 to 100 mm Hg (mean, 59.5 mm Hg; median, 61.5 mm Hg; 25th-75th percentiles, 32.0-84.5 mm Hg). Affected dogs ranged in age from 2 months to 16 years. Clinical signs were characteristic of cardiopulmonary disease, but a relatively high frequency of syncope was noted (12 of 53 dogs, 23%). Pulmonary hypertension was probably due to increased pulmonary vascular resistance in 23 dogs, pulmonary overcirculation in 2 dogs, and pulmonary venous hypertension in 23 dogs. Five dogs lacked a clinically recognizable cardiopulmonary cause of pulmonary vascular disease. Our results suggest that pulmonary hypertension can occur as a complication of commonly encountered cardiopulmonary diseases, and that Doppler echocardiography can facilitate recognition of this condition.

Animals↗
PubMedDate not supplied

Effect of heparin on capacitation/acrosome reaction of equine sperm.

The onset of sperm capacitation/acrosome reaction was evaluated using heparin. Equine semen was incubated at 38 degrees C for 4.5 h in culture medium with and without 10 micrograms/mL heparin and with and without 0.1 microM of Ca2+ ionophore. Sperm acrosome reaction was detected using chlortetracycline fluorescence (CTC) and transmission electron microscopy (TEM). The CTC assay provided staining patterns that corresponded with the capacitation/acrosome reaction in other mammalian species (man, mouse, guinea pig). The percentages of incapacitated sperm (PUC), capacitated acrosome-intact sperm (PC), and acrosome-reacted sperm (PAR) were evaluated following incubation times of 0.5 and 4.5 h in heparin-free and heparinized medium, and at 4.5 h only in sperm exposed to Ca2+ ionophore. The CTC assay was highly correlated with TEM for estimation of PAR. At 4.5 h, heparinized medium reduced PUC and increased PC and PAR, in comparison with heparin-free medium. Addition of Ca2+ ionophore to the medium reduced PUC and increased PC and PAR at 4.5 h, as compared with sperm in ionophore-free medium. Incubation time also affected PUC, PC, and PAR in heparin-free and heparinized medium without ionophore. The PUC was greater at 0.5 h than at 4.5 h, and PC and PAR were less at 0.5 h than at 4.5 h. It would appear that the initiation of capacitation/acrosome reaction of equine sperm in vitro is accelerated by heparin.

Acrosome↗
PubMedDate not supplied

Transuterine puncture of the fetal stomach provides access to the small bowel in the rabbit.

The prevention of perinatal complications of congenital gastrointestinal (GI) diseases such as cystic fibrosis may require prenatal treatment. New Zealand White rabbits were evaluated as a potential animal model to study gastrointestinal anatomy and transit in the fetus. The lengths of the GI tract of fetuses at 21/31 and 28/31 days gestation were established, and gastric volume was measured. Gastric volume at 28 days gestation averaged 2.6 mL, adequate to permit instillation of a solution into the fetal stomach. A study was then carried out to establish gastric emptying and delivery of the solution into the small bowel. Using ultrasound guidance, the stomachs of 26 fetuses from 7 litters were punctured and 0.5 mL of dilute barium was injected. A cesarean section was performed 4 h later and the progression of barium though the GI tract was measured. In 18/26 (69.2%) of the fetuses barium was successfully delivered to the lumen of the stomach. In these 18 fetuses, barium progressed to the duodenum in 15 (58%), the jejunum in 13 (50%), and the ileum in 8 (31%). The stomach of the 3.5- to 4-week-old fetus is large enough to allow transuterine delivery of a solution of dilute barium. Gastric and intestinal motility in the 25-day-old rabbit fetus is coordinated and results in delivery of barium to the small bowel in 50% of animals successfully injected. The results suggest that the rabbit is an acceptable model for the study of gastrointestinal delivery of therapeutic drugs or genes to the fetus.

Animals↗
PubMedDate not supplied

Prevalence of cardiovascular risk factors in an African, urban inner city community.

With the epidemiological transition phenomenon, more countries are expected to move from a disease pattern dominated by infectious diseases to one characterised by non-communicable diseases. Many developing countries are contending with infectious diseases as well as non-communicable diseases, yet little is known about the prevalence of cardiovascular risk factors in poor urban communities in developing countries. The objective of this community based study was to determine the prevalence of selected cardiovascular risk factors in an urban inner city community which had been followed up prospectively from 1993 to 1998. Results show that the prevalence of hypertension (Blood Pressure BP > 160/95 mm Hg) was 12.4 percent with an age-adjusted rate of 7.4 percent. This is higher than what is found in the rural parts of the country but much lower than what is generally observed in industrialized countries of the world. Though there was no significant difference in the proportion with hypertension by gender (P > 0.05), the mean systolic BP was significantly higher for men (123.9 +/- 23.9) mm Hg) than for women (120.6 +/- 26.8 mg Hg) t = 2.93, p < 0.01. The mean diastolic BP was similarly higher for men (75.8 +/- 14.9) mm Hg than women (74.0 +/- 14.9) mm Hg t = 2.76 p < 0.01). Eight percent of the study population were obese (BMI > 30), and generally, more women than men were obese. However, at ages 15-19 significantly more males than females were obese (X2 = 73, p < 0.01). Both mean systolic and diastolic BP increased with increasing weight. When adjusting for gender, the association between hypertension and other CVD risk factors remained similar for males and females and gender was not a modifier of the factors. Of the CVD risk factors studied, Age > 40 years and obesity, were significantly associated with the presence of hypertension in this community (P < 0.0001 and P < 0.0001), smoking, alcohol intake and gender were not (P > 0.05). It is necessary to implement a national plan for the control of cardiovascular diseases in order to reduce and keep to minimum cardiovascular diseases and its complications in the country.

Adolescent↗
PubMedDate not supplied

Potential daily sperm production, Sertoli cell number, and seminiferous tubule characteristics in beef bulls fed conventional or gossypol-enriched diets.

The objective of this study was to determine the amount of germ cell degeneration throughout spermatogenesis in the bull and to determine if gossypol-enriched diets enhance that degeneration. Twenty-six adult beef bulls in two different sets of treatment groups were chosen for the study. The first set of bulls were broken into three groups, receiving soybean meal (<0.03 g gossypol per bull, per day), cottonseed meal (1.8 g gossypol per bull, per day), or whole cottonseed (16 g gossypol per bull per day). The second set of bulls were fed 4 g of gossypol per day for 180 days and then were placed in their respective treatment groups of 0 g or 4 g of gossypol per day for 72 days to evaluate the effect of continued gossypol treatment versus stopping treatment. Hence, one group received gossypol for 180 days, followed by withdrawal for 72 days. The treated group received gossypol up to castration at 250 days. In both sets of bulls, significant germ cell degeneration occurred between B spermatogonia and primary spermatocytes (i.e., at the end of mitosis and into the beginning of meiosis), with no subsequent degeneration throughout the rest of spermatogenesis. For both sets of bulls, the gossypol-enriched diet fed had no effect on the nuclear volume or number per gram parenchyma of any germ cell or Sertoli cell. Therefore, gossypol did not augment the amount of germ cell degeneration that occurred between B spermatogonia and homogenate-resistant (mature) spermatids in either set of bulls. Gossypol-enriched diets also had no effect on volume density, diameter, luminal diameter, or basement membrane thickness of seminiferous tubules for the first set of bulls. The second set of bulls, with continued diets enriched with gossypol, had a larger number of B spermatogonia per gram than did bulls removed from the gossypol-enriched diet. In conclusion, the bull did experience significant degeneration of germ cells between B spermatogonia and pachytene primary spermatocytes, with no subsequent loss throughout the rest of spermatogenesis, and the gossypol-enriched diet did not further enhance germ cell degeneration.

Animals↗
PubMedDate not supplied

The role of birth/previously adopted children in families choosing to adopt children with special needs.

Engaging birth/previously adopted children during the adoption process is crucial to laying the ground-work for successful placements. When families choose to adopt children with special needs, however, the role their other children will play in the adoption's success is often overlooked. This article presents a practical model that recognizes the dynamics of strength and vulnerability in adoptive families, then applies this model in preparing and supporting the family through the changes that are inevitable in special needs adoption. The model can also be used to assist adoptive parents in identifying and developing the skills they need to manage these shifts within the family.

Adoption↗
PubMedDate not supplied

Factors known to raise intracranial pressure and the associated implications for nursing management.

Raised intracranial pressure is a major, life-threatening complication addressed daily by nurses caring for the neuroscience patient. The primary nursing goal of caring for patients with severe head injury is to prevent secondary brain damage by controlling increases in intracranial pressure. Nursing management is complex and requires structured, specialised care in order to reduce the potential adverse effects of raised intracranial pressure associated with common nursing procedures.

Critical Care↗
PubMedDate not supplied

[Heterotopic heart transplantation: 13-year experience at the Methodist Hospital of the Baylor Medical College].

UNLABELLED: In order to evaluate our experience in heterotopic cardiac transplantation, we conducted a retrospective analysis of the clinical files of patients who underwent this procedure. RESULTS: A total of 405 heart transplants were performed in our institution. In 24 (5.9%), the grafts were placed heterotopically. In group I (12 patients), the indication was irreversible pulmonary hypertension and in group II (remaining 12 patients), it was marginal grafts or size mismatch. Both groups demonstrated similar demographics and the survival rate was slightly better in group I. Nine patients from group I demonstrated an early reduction in pulmonary pressures which normalized in one year. CONCLUSIONS: The heterotopic heart supports the function of the native ventricles. In 9 patients, the heterotopic heart enables the reversal of a state of pulmonary hypertension previously thought to be irreversible. This finding supports the use of pulmonary vaso-dilators on a chronic basis or the use of a left ventricular assist device pre-transplant with the intention of normalizing pulmonary pressures and allowing the patients to become candidates for orthotopic cardiac transplantation and thereby avoiding the necessity of heterotopic cardiac transplantation.

Female↗
PubMedDate not supplied

Comparison of intrauterine insemination, intracervical insemination, and timed intercourse in women treated with human menopausal gonadotropin.

The effects of intrauterine insemination (IUI), intracervical insemination (ICI), and timed intercourse (TI) in women who were treated with human menopausal gonadotropin (hMG) for anovulation were evaluated. The pregnancy rates per cycle following IUI (70 cycles), ICI (62 cycles) and TI (158 cycles) were 20%, 9.6%, and 17.7%, respectively; these differences are not statistically significant. The abortion rate and the multiple pregnancy rate were also not significantly different. This report suggests that in women who are undergoing treatment with hMG, there is no added benefit from artificial insemination (either intrauterine or intracervical insemination) over timed intercourse.

Adult↗
PubMedDate not supplied

Behavior modification approach in a partial day treatment center.

Since the beginning of the program in September 1970, we have found that a combined behavioral program of individual therapy, home intervention, and group therapy to be the most effective for maintaining a person in his community. In addition, we have not seen a need for a full eight-hour day in the clinic. Rather, we operate on the principle that it is more adaptive to keep a patient functioning in the community (natural environment) with support from us. For the extremely or severely disorganized person, we have found the application of behavior modification principles to be the most useful in the terms of establishing and maintaining adaptive behaviors, of interruptin and decreasing maladaptive behaviors and of offering support and guidance (generalization) to patients and families. We have also increased the amount of individual therapy and intensified the home intervention program. These changes have been based upon subjective data as well as objective data (change in patient behavior while receiving and following a particular mode of therapy). The program has undergone many changes since its inception. We have found the behavior modification modality to be effective for establishing a program that patients can generalize to their community setting. Our constant thrust is to utilize already existing agencies in the community and to optimally assist the patient so that he may remain in his community. We have gone from an eclectic program to a systematic behavior modification program. The present behavioral program has been demonstrated to be an effective modality for the training of personnel. We are grateful to our staff for their cooperation and suggestions in making the program successful. In addition, we are indebted to our late Director, Curtis W; Gifford--a loyal and dedicated friend. We particularly appreciate his administrative skills and encouragement in developing an autonomous program.

Anomie↗