Biomedical subjects
Publications and source records attributed to C M Anderson.
A method for quantitating flow velocities is presented. The technique tags multiple boli of magnetization in transit across a thick selection slab using rf inversion pulses. Results in phantoms and in vivo demonstrate that the method is robust and can provide velocity determinations in tortuous vessels.
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An unusual food-borne outbreak of gastroenteritis associated with contaminated turkey occurred at a catered company meal. The average incubation period was 10 h, and the predominant symptoms were watery diarrhea and cramps. Vomiting did not occur. Initial epidemiological features and cultures from turkey and feces of infected patients suggested that the causative agent was Clostridium perfringens, but Klebsiella pneumoniae of capsular type K15 was also isolated in large numbers from both the turkey and feces of the same patients. Plasmid analysis and enterotoxin results supported the role of K. pneumoniae as the causative agent in this outbreak. Organisms other than commonly identified pathogens should not be ignored if present in high concentrations in both food and feces of infected persons.
A magnetic resonance imaging coil was developed to improve contrast in direct coronal and sagittal time-of-flight carotid angiograms. The sensitive volume of the coil extends from the carotid origins to the siphons. Angiographic contrast can be optimized for an arterial segment of interest by repositioning the coil to minimize presaturation of blood before it enters the segment.
Proliferation of smooth muscle cells is an important component of pulmonary arterial morphogenesis, both during normal development and pathologic remodeling. However, little is known of the factors that regulate smooth muscle proliferation in these vessels. To investigate the hypothesis that factors produced by endothelial cells may regulate smooth muscle cell growth, we studied the effects of culture medium conditioned by fetal bovine pulmonary arterial endothelium on proliferation of smooth muscle cells in culture. This conditioned medium contains an inhibitor of smooth muscle proliferation that is degraded by nitrous acid, heparinase, and heparitinase, but resists degradation by protease, boiling, and chondroitin ABC lyase, indicating that the inhibitor is structurally similar to heparin. Inhibitor release occurs in both growing and confluent endothelial cell cultures and in the presence and absence of serum. A growth-inhibiting proteoglycan purified to homogeneity from endothelial cell-conditioned medium has physicochemical characteristics similar to those of the prototypic basement membrane heparan sulfate proteoglycan of the Englebreth-Holm-Swarm tumor: an overall size of approximately 10(6) D, heparan sulfate chains of 60,000 D, and a buoyant density of 1.33 g/ml. Antibody raised against the tumor basement proteoglycan recognizes this endothelial heparan sulfate proteoglycan, and Western blotting after SDS-PAGE demonstrates that the core proteins of both proteoglycans migrate as a doublet at apparent molecular weights of 450,000 and 360,000 D. Heparan sulfate glycosaminoglycan prepared from purified medium proteoglycan is a potent inhibitor of smooth muscle cell growth, exhibiting activity approximately 1,000 times greater than that of heparin. These results indicate that endothelial cells cultured from fetal bovine pulmonary arteries produce a basement membrane heparan sulfate proteoglycan that is a potent inhibitor of smooth muscle proliferation. This proteoglycan may mediate endothelial regulation of smooth muscle growth during development or pathologic pulmonary arterial remodeling.
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To reduce stress, most people and organizations need to improve their skills in recognizing and coping with stressors. Department plans like the one described provide a good method of understanding and learning to cope with specific stressors. Researchers analyzed the effects of a stress management plan for registered nurses in an acute care hospital. This plan, called stress inoculation, began with education on stress and coping skills. The nurses were then exposed to the real-life stressors and expected to use the newly learned coping skills. Later, the nurses were asked to evaluate the effectiveness of the coping skills. The results of the study showed that the nurses' stress was reduced through stress management and that coping skills were the key ingredient. Education was needed to teach the coping skills, but by itself, education showed no benefit. If supervisors and employees remain committed to the departmental stress management plan throughout the six phases, the likelihood of reducing stress, improving morale, and increasing productivity is high.
Mating has progressively tended toward pair bonding in a chacma baboon (Papio cynocephalus ursinus) population during eight years of study. Both males and females have been mating with a smaller and smaller percentage of the potential mates available to them. Troop subdivision during the dry winter in the absence of predation was the original cause of mating limitation, but most members of winter subtroops only rarely mated with adults who had not belonged to the same winter subtroop during the summers as well. Following reintroduction of potential predation, both subtroop size and frequency decreased, but mating did not become less exclusive.
A transrectal probe for 1H imaging and 31P MR spectroscopy of the prostate gland is described. The probe is covered with plastic and consists of an insectional portion containing an rf coil and a handle containing a tuning and matching circuit. Using this transrectal probe, 1H MR images and the first 31P MR spectra of the in situ canine prostate were obtained. Serial alterations in prostate size and changes in the ratio of phosphomonoesters to ATP ratio following orchiectomy were observed. Transrectal images of the prostate appear to be superior to conventional whole body coil images in the canine. For the first time a device to obtain high signal-to-noise 1H images and 31P spectra of the in situ prostate has been constructed. This will allow the assessment of transrectal imaging and spectroscopy as tools for medical studies of prostate pathophysiology.
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Rates of hospital admissions and bed usage for infections by Aborigines up to 15 years of age were much higher in Western Australia during 1981-86 than they were for the rest of the population. These rates for Aboriginal infants for gastroenteritis, for example, were 20-25 times and 40-50 times those for other infants. The rates mostly declined over the 6 years except for gastrointestinal and respiratory infections in Aboriginal infants and young children in rural and remote areas. Hospitalization rates reflect many factors which include disease incidence and severity but also distance, climate and access to medical and nursing care and their utilization. Preventative health programmes must be maintained to help improve the health of young Aborigines.
Twelve per cent of Aboriginal infants born in the Kimberley region of Western Australia in 1980 were of low birthweight; this is more than twice the incidence in the non-Aboriginal population of Western Australia. There was widespread faltering of growth (weight and height) after 6 months of age in Aboriginal children whether they were of normal or low birthweight. Growth retardation was more marked in low birthweight babies who showed little evidence of 'catch-up' growth in the first 5 years of life.
A wide variety of MRI techniques is available for vascular imaging, each exploiting a different property of flowing blood to achieve contrast. These include spin-echo, which has been used for the diagnosis of aortic dissection and of great vessel anomalies, as well as for the evaluation of pulmonary flow in patients with pulmonary hypertension and pulmonary embolism. Spin echo excels in detecting infection and hematoma in the tissues around grafts and vessels. Phase display imaging has proven useful in differentiating signal of slow flow from that of intravascular thrombus. Imaging of peripheral vessels can be achieved with gradient refocused sequences, which provide bright intravascular signal over a wide range of flow velocities. These sequences may be combined with subtraction strategies to eliminate the signal from stationary tissues in order to generate an angiographic image. The advent of three-dimensional MR angiographic imaging techniques provides an effective way to display peripheral vessels. Early experience implies that MR angiography will play an important role in vascular imaging in the future, provided that the signal loss from turbulent flow can be minimized.
A survey of monitoring of digoxin treatment in five practices examined the indications for prescribing digoxin, its long term use, and how its use could be monitored. These data were used to generate a protocol for monitoring treatment with digoxin in general practice. The findings of the survey and the protocol were distributed to and discussed with all the partners in the practices participating in the study. One year later similar analysis showed that record keeping (recording of pulse rate and rhythm) had improved significantly in the group of principals carrying out the audit but not in other principals in these practices. Audit may change only the auditors.
The present study mapped the topographic distribution of, and the effect of neuropharmacologically distinct antipsychotic drugs on, the concentration of neurotensin (NT) in the rat brain at the level of discrete nuclei or areas. The chronic administration of either haloperidol or clozapine increased the concentration of NT-like immunoreactivity (NT-LI) in the nucleus accumbens and decreased it in the medial prefrontal and cingulate cortex and in the interstitial (bed) nucleus of the stria terminalis. In contrast, the prolonged administration of haloperidol, but not clozapine, increased the concentration of NT-LI in the anterior caudate nucleus and posterior caudate-putamen. The concentration of NT-LI in the great majority of the rat brain nuclei examined was unaffected by the chronic administration of either antipsychotic drug. This pattern of pharmacological response distinguishes NT from all other neuropeptides which have been shown to be influenced by prolonged antipsychotic drug administration. These findings suggest that the functional information imparted to NT-containing cells by neuronal dopamine (DA) release, as inferred from the consequences of receptor blockade, varies remarkably between different populations of DA neurons and further implicate NT as a neuroanatomically-selective neurochemical substrate of the adaptive responses mediating the therapeutic and motoric side effects of antipsychotic drugs.
Male sexual differentiation is dependent upon the induction of testosterone synthesis by the fetal testis at a critical phase of development. In the rabbit, testosterone synthesis by the fetal testis is initiated after 17.5-18 days of gestation, reaches peak values by day 21 and subsequently declines. In the present study, we analyzed the specific activity and concentration of immunoreactive cholesterol side chain cleavage cytochrome P-450 (cytochrome P-450scc) in the fetal rabbit testis during development to assess its possible role as a key regulatory enzyme in fetal testicular steroidogenesis. The effects of human chorionic gonadotropin (hCG) and dibutyryl cyclic AMP on the specific activity and synthesis of cytochrome P-450scc in fetal rabbit testes in vitro also were evaluated. We observed that changes in cholesterol side chain cleavage activity paralleled the induction of testosterone synthesis; the specific activity of this enzyme which was approximately equal to 0.25 pmol min-1 mg-1 protein in testes from 19-day fetal rabbits was increased approximately equal to 10-fold in testes of 21-day fetuses and thereafter declined dramatically. Immunoreactive cytochrome P-450scc, which was first detectable in gonads of 19-day fetal rabbits, was induced markedly in 21-day fetal testes, reached maximum levels on day 24 and declined slightly thereafter. Incubation of testes from 19- and 21-day gestational age fetal rabbits with hCG or dibutyryl cyclic AMP for 24 h resulted in an induction of testosterone synthesis, cholesterol side chain cleavage activity and synthesis of cytochrome P-450scc. These findings are suggestive that androgen synthesis by the fetal Leydig cell is mediated by an induction of the synthesis and specific activity of cytochrome P-450scc. In addition, these data support the hypothesis that the developmental changes in the synthesis of cytochrome P-450scc are regulated by fetal gonadotropin and are mediated by cyclic AMP.
Populations of DA neurons innervating the component nuclei of the amygdaloid complex differ in their inferred density of innervation, estimated rate of impulse activity, and adaptive response to the prolonged administration of antipsychotic drugs. Mesoamygdaloid DA neurons have in common the absence of tonically inhibitory, nerve terminal autoreceptors regulating DA synthesis, the nonassociation with a DA-stimulated adenylate cyclase, and the regulation of DA synthesis by receptor-mediated neuronal feedback mechanisms and end-product inhibition. The output of the amygdaloid complex appears to be organized into distinct functions subserved by component nuclei. The present findings suggest a differing role for DA afferents in modulating the functional output of discrete nuclei. The significance of this focal influence will be speculative pending a more complete understanding of the physiology of DA neurotransmission in the amygdaloid complex. Populations of DA neurons innervating discrete amygdaloid nuclei exhibit a composite of mechanisms of regulation and signal transduction and pharmacology that differ from that of other mesotelencephalic DA systems. These comparisons highlight the fact that the nucleus accumbens and olfactory tubercle do not represent or reflect DA neurotransmission in the limbic system. The study of the physiology, pharmacology, and pathology of mesolimbic DA neurons can and should extend beyond the nucleus accumbens and olfactory tubercle to the amygdala and other brain structures central to the organization of the limbic system. It is our opinion that the term "mesolimbic" DA system has purely anatomical connotations and that a more specific terminology (e.g., meso-central amygdaloid nuclear) would express the functional organization of this system more accurately.
A retrospective study of sequential obstetric patients delivering at University Hospital and receiving epidural anesthesia was conducted to determine if a suggested association exists between the recurrence of oral herpes simplex lesions and the use of epidural morphine. In a retrospective study of 291 patients, 13 of 134 (9.7%) receiving epidural morphine developed recurrent oral herpes lesions in contrast to 1 of 157 (0.6%) not receiving the drug (P less than 0.001). In a prospective hospital-based study of 729 consecutive obstetric patients, 146 patients received epidural opioids (morphine, fentanyl, or both) and 583 did not. Recurrent HSVL lesions occurred in 13 of 140 (9.3%) patients given epidural morphine but in only 6 of 583 (1.0%) not given epidural opioids (P less than 0.001). Three of the 13 patients with HSVL received both epidural morphine and fentanyl and 10 received only epidural morphine. Because of the small numbers of patients receiving only fentanyl, no relation between HSVL reactivation and epidural fentanyl could be established. In patients having caesarean sections, the association of recurrent HSVL and the use of epidural morphine was significant (P = 0.04), suggesting cesarean delivery was not a confounder. A hitherto undescribed triggering agent, epidural morphine, appears to be associated with reactivation of HSVL in obstetric patients in the postpartum period.