Biomedical subjects
J Johnson
Publications and source records attributed to J Johnson.
Portrayal of adrenergic denervation in the presence of myocardial infarction: a feasibility study.
Myocardial infarction interrupts adrenergic neurons beyond the region of necrosis to give peri-infarct denervation. A method to define the regions of denervation would be a valuable aid in determining the role that loss of adrenergic neurons plays in myocardial infarction and particularly in causing arrhythmias. [123I] meta-iodobenzylguanidine (MIBG) was used to portray scintigraphically the intact neurons in dog hearts. Occlusion of the left circumflex (LCX) or the left anterior descending coronary artery (LAD) produced defects that appeared to be regularly larger in the [123I]MIBG images than in the [201T1]images of the same heart; the differences were considered to be the regions of denervation which were relatively larger after LCX than LAD infarcts. Ex vivo measurements of endogenous norepinephrine and residual [125I]MIBG concentrations gave confirmation of neuronal injury. A computer program to quantify the regions of denervation appeared imprecise, but gave some promise. Scintigraphy of [123I]MIBG offers a method to define patterns of denervation in the living animal and man.
Cerebral oxygen consumption during asphyxia in fetal sheep.
Cerebral blood flow and cerebral arteriovenous oxygen content difference were measured in 17 fetal sheep, and cerebral oxygen uptake was calculated. The measurements were made under control conditions and after profound fetal asphyxia induced of uterine blood flow for up to 90 min. In 14 of the fetal sheep, sequential measurements were made to examine hemodynamic changes and cerebral oxygen consumption at comparable intervals up to 36 min of asphyxia. These fetuses initially had elevated blood pressure and lowered heart rate became hypoxemic, hypercarbic, and acidotic. There was an initial decrease in cerebral oxygen consumption. Sequential measurements, however, showed a relative stability in this decreased oxygenation during 4 to 36 min of asphyxia despite a progressive metabolic acidosis. The cerebral fractional oxygen extraction remained unchanged despite a mean pH of 6.98 at 36 min. The calculated cerebral oxygen uptake during asphyxia in all 17 sheep was grouped according to whether the ascending aortic oxygen content was greater or less than 1.0 mmol/l. In the first group with mean ascending aortic oxygen content of 1.3 mmol/l, blood flow to the brain was increased and cerebral oxygen consumption was 85% of control. In the second group with mean arterial blood oxygen content of 0.8 mmol/l, there was a narrowing of the arteriovenous oxygen content difference, but no further increase in cerebral blood flow. Cerebral oxygen consumption was only 48% of control in this more asphyxiated group. We conclude that the degree of hypoxemia in the second group represents a point where physiologic mechanisms cannot compensate, and may be associated with neuronal damage.
Effects of a rapid antigen test for group A streptococcal pharyngitis on physician prescribing and antibiotic costs.
Decision analysis and opinion survey suggest that introduction of rapid antigen detection tests should decrease the number of patients with negative test results for group A streptococcal pharyngitis treated by antibiotics. We reviewed all cases in which a test for group A streptococcal pharyngitis was performed during the last 7 months of culture diagnosis and the first 7 months of antigen test diagnosis at an inner city community health center, recording culture or antigen test results, whether antibiotics were prescribed, and patient status (as regular health center patients or patients referred to the center). Positive rates for culture and antigen-test periods were similar (10% and 12%), but 53% of patients with negative culture were treated, where only 32% of patients with negative antigen-test results received prescriptions. Significant reductions in the treatment of patients with negative test results were found in both patient-status subpopulations: health center patients, 43% to 29%; referred patients, 91% to 52%. Among health center patients reductions were consistent for both adult (30% to 21%) and child and adolescent (55% to 45%) age groups. For all patients with negative test results, direct costs of diagnostic reagents and antibiotic prescriptions fell from $3.58 per patient with culture to $3.45 with antigen testing; the $0.13 savings per patient was due to less treatment of referred patients. Thus, rapid antigen testing led to (1) significantly fewer patients with negative test results receiving antibiotic prescriptions; and, (2) savings in antibiotic costs offsetting reagent cost of antigen detection diagnosis.
Subzonal insemination for the alleviation of infertility.
Methods were developed to facilitate the use of subzonal insemination to achieve fertilization in vitro. A clinical trial was undertaken in those patients having previously failed to achieve fertilization by in vitro fertilization, and in those presenting with severe oligospermia/oligoasthenospermia. From 85 patients, 585 oocytes were obtained. Of these, 0.3% had been "activated" parthenogenetically in vivo, 369 (72%) at metaphase II underwent subzonal insemination, 15% were fertilized, and 0.5% had three pronuclei. Thirty-eight percent of the patients had fertilization with 36% having a replacement. One conceptus was replaced in 19 patients, two conceptus in 8 patients, and three in 4 patients. A twin and two singleton pregnancies were established.
Development and validation of an index for scoring baseline respiratory disease in the very low birth weight neonate. Severity Index Development and Validation Panels and Newborn Lung Project.
An accurate description of the population at risk for neonatal chronic lung disease is clearly of prime importance for comparative studies and the planning of interventions. Attempts to explain variations in chronic lung disease rates in such studies have been compromised by lack of a way of estimating the severity of the initial pulmonary disease as a risk factor. Therefore, a severity index was developed for use in very low birth weight (less than 1501 g) neonates. Special emphasis was placed on applicability of the index in the multicenter observational setting. Development followed a clinician panel approach, with the resulting index designed to capture clinical judgment of severity. The index was validated prospectively on neonates in a neonatal intensive care unit, and retrospectively using charts from nine hospitals nationwide. Correlations of the index with clinical judgment in the two samples were .95 and .93, respectively. In an additional validation the index combined with birth weight correctly predicted oxygen dependence status at 30 days in 36 of 42 neonates consecutively admitted to five neonatal intensive care units (P = .002). Birth weight and the severity index contributed about equally to the prediction, and therefore they seem to represent partly independent components of baseline propensity for prolonged oxygen dependence.
William Scott Wadsworth: an appreciation of an anomalous career.
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Group forms to address the lack of opportunity for doctoral education in nursing in Canada.
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Clinical trials booklet evaluation.
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Crystallographic structure of an RNA helix: [U(UA)6A]2.
The crystallographic structure of the synthetic oligoribonucleotide, U(UA)6A, has been solved at 2.25 A resolution. The crystallographic refinement permitted the identification of 91 solvent molecules, with a final agreement factor of 13%. The molecule is a dimer of 14 base-pairs and shows the typical features of an A-type helix. However, the presence of two kinks causes a divergence from a straight helix. The observed deformation, which is stabilized by a few hydrogen bonds in the crystal packing, could be due to the relatively high (35 degrees C) temperature of crystallization. The complete analysis of the structure is presented. It includes the stacking geometries, the backbone conformation and the solvation.
Prognostic factors in mobile tongue and floor of mouth carcinoma.
This study identifies significant prognostic factors in squamous cell carcinomas of the anterior tongue and floor of mouth. It is clear that the TMN staging system does not account for other important variables that affect tumor prognosis. Tumor thickness and the presence of perineural invasion and intralymphatic tumor emboli should be examined in all resected tumors. Tumor thickness, tumor size, and perineural invasion all have an impact on survival and must be considered in treatment plans. Tumors measuring between 2 mm and 3 mm may or may not have metastases and further evaluation of this group needs to be done. Most importantly, the data in this study supports a multiinstitutional prospective evaluation of pathology specimens. Precise guidelines must be established for handling of the specimen, which must then be evaluated for the variables mentioned above. In this way, more definitive conclusions can be reached in the management of tumors of the anterior tongue and floor of mouth.
Promoting children's health--the role of the school nurse.
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Forearm and finger hemodynamics, blood pressure control, and lipid changes in diabetic hypertensive patients treated with atenolol and prazosin. A brief report.
Hypertension and diabetes mellitus frequently coexist and are independent risk factors for reduced peripheral perfusion. Antihypertensive medications that reduce blood pressure and improve peripheral perfusion would have advantages in diabetic hypertensive patients. In a randomized, two-placebo-period, single-blind, two-way, crossover study, finger and forearm blood flow, lipid levels, and blood pressure control were determined in 19 diabetic hypertensive patients given prazosin and atenolol, with each drug and placebo period lasting four weeks. Both drugs reduced blood pressure (sitting, 157/95 to 142/84 mm Hg for atenolol and 155/95 to 138/82 mm Hg for prazosin; standing, 154/94 to 144/84 mm Hg for atenolol and 154/94 to 133/81 mm Hg for prazosin). Lipid levels did not change, except that low-density lipoprotein levels decreased from 148 to 127 mg/dl with prazosin. Atenolol did not change forearm or finger blood flow or vascular resistance. Prazosin increased blood flow and reduced vascular resistance in both finger and forearm. In conclusion, prazosin demonstrated a potentially more appropriate hemodynamic profile than atenolol in diabetic hypertensive patients in this study.
A sexually transmitted diseases curriculum in adolescent medicine.
We conducted a needs assessment and developed and evaluated a model curriculum on sexually transmitted diseases (STDs) for house officers on an adolescent medicine rotation. Residents thought it important for physicians to acquire skill in treating STDs during residency (mean rating, 4.4 on a five-point scale) and were willing to provide medical care for adolescents likely to have an STD (mean rating, 4.4). Knowledge was measured before and after presentation of both of the two curriculum levels. There were significant increases in knowledge after each level, with a mean increase of 4.4 (of 50 possible) points for level 1 and a mean increase of 1.8 (of 38 possible) points for level 2. This improved knowledge about STDs should reflect increased competence and enhanced willingness to treat STDs in adolescents.
Electron microscopic study of subcutaneous and intraperitoneal splenules in the mouse.
The development of splenules derived from slices of freshly removed autologous spleen implanted subcutaneously or intraperitoneally was followed by light and electron microscopy from day 2 to day 70. Within 48 hr after transplantation, a rough space filled with blood, unlined by endothelium, formed just under the surface of the splenic fragment. The tissue central to this vascular space was disrupted and necrotic. In the outer portion of the vascular space, fibroblasts appeared and created locules which developed into a highly vascular, hematopoietic red pulp. From the inner portion, blood percolated into the central necrotic tissue. At 1 week the splenule was divisible into concentric structures. The capsule was outermost. A shell of vascularized, highly hematopoietic red pulp lay within the capsule, having replaced the vascular space. Central to the red pulp lay a band of fibroblasts and macrophages. Next was a layer of fibroblasts in a matrix of degenerating cells, and, at the center, a necrotic core. As fibroblasts and macrophages moved centrad, the red pulp moved with them, expanding and replacing the necrotic tissue. The splenule differed in character from the original spleen. Splenular red pulp, especially near the surface, was unusually hematopoietic. The circumferential reticulum of white pulp was reduced or absent, and the boundary between red and white pulp was sometimes indistinct. Some white pulp was subcapsular, and the capsule and surrounding connective tissue were infiltrated by lymphocytes. The necrotic core of the splenule was typically surrounded by a zone containing large blood vessels, connective tissue, and adipocytes.
Developmental levels of processing in metaphor interpretation.
We outline a theory of metaphor interpretation. The theory posits varying levels of semantic processing and formalizes them in terms of kinds of semantic-mapping operators that transform properties of the metaphoric vehicle (i.e., predicate) into properties of the metaphoric topic (i.e., subject). We used cognitive-developmental theory to estimate the mental-processing complexity of the various mapping operators, and thereby to predict the timing of their emergence in childhood, and to construct a measure of the metaphoric-processing levels. Metaphor interpretations collected from children (aged 6-12 years) and adults were coded and scored according to the processing levels. In two separate developmental studies, processing score increased with age in a predictable way. Growth in a mental-attentional resource accounted for much of the developmental variance in metaphor interpretation. Possible moderating effects of knowledge and context are discussed.
The struggle to be thin: a survey of anorexic and bulimic symptoms in a non-referred adolescent population.
Ninety-one per cent of a county-wide high school population (N = 5596) completed the Eating Symptoms Inventory (ESI) and the Eating Attitudes Test (EAT). Being female, older and heavier are far more strongly associated with anorexic and bulimic symptoms than is social class. ESI approximations of the DSM-III criteria for anorexia nervosa or bulimia suggest that while both conditions are rare (less than 1%), bulimia is the more prevalent disorder.
An assessment of the dual-analyte enzyme immunoassay for ovulation timing.
In a search for simpler, more efficient methods of monitoring ovulatory function, either to assist in the investigation of the infertile couple or for contraceptive or fertility control purposes, a number of new methods have been developed. One of these, the OVEIA dual-analyte system is now available for laboratory use. The principle behind the system is the simultaneous measurement of urinary oestrone-glucuronide and pregnanediol-glucuronide. The resultant signal is quantified using an enzymatic photometric endpoint denoted by the relative absorbance (RA%). The application of the OVEIA system to the monitoring of urine samples over the periovulatory period in ovulatory and non-ovulatory cycles from regularly cycling but infertile women is described and the changes in RA% compared with synchronously measured changes in plasma LH and plasma oestradiol concentrations, salivary progesterone profiles and measurements of follicular volume. It is concluded that the OVEIA system is simple and quick to perform and the results obtained compare reasonably well with equivalent direct and indirect indicators of impending ovulation (e.g. increasing plasma oestradiol concentrations or changes in the volume of the follicle). However, as is the case with other endocrine methods, definitive information about the presence or absence of follicular rupture cannot be obtained.