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R Ward

Publications and source records attributed to R Ward.

At least 163 records · Page 9Linked to original sources
PubMed1995

Ipsilateral visual projections in non-eutherian species: random variation in the central nervous system?

The published descriptions of ipsilateral visual pathways in non-eutherian species are reviewed. Such pathways exist in members of all vertebrate classes; since they exist in agnathans, it is suggested that the presence of ipsilateral visual projections is the ancestral condition. None of the published attempts to explain the considerable interspecific variation of these pathways can be generalised to all vertebrate species: in particular, this variation is not generally related to the degree of overlap of the visual fields, to a particular mode of life, nor to taxonomic position within a given vertebrate category and cannot consistently be explained by variation at the albino locus. It is suggested that this variation is the result of purely random variation of unidentified elements of the genetic material or of epigenetic mechanisms and hence that ipsilateral visual projections are functionally neutral. This conclusion is supported by some extremely fragmentary behavioral data indicating that the information they provide is redundant.

Animals↗
PubMed1995

Carbogen breathing with nicotinamide improves the oxygen status of tumours in patients.

Nicotinamide and carbogen breathing are both effective radiosensitisers in experimental tumour models and are even more effective in combination. This study was to investigate the feasibility of using the agents in combination in patients and to measure their effect on tumour oxygenation. Twelve patients with advanced malignant disease were treated with 4-6 g of oral nicotinamide (NCT) in tablet formulation. Ten of these 12 patients breathed carbogen (95% oxygen, 5% carbon dioxide) for up to 20 min at presumed peak plasma NCT concentration (Cpeak) and had tumour oxygen partial pressure (pO2) measured using the Eppendorf pO2) histograph. The mean Cpeak values were 82, 115 and 150 micrograms ml-1 for NCT doses of 4, 5 and 6 g respectively and were dose dependent. The time of Cpeak was independent of dose with an overall mean of 2.4 h (range 0.7-4 h). NCT toxicity occurred in 9 out of 12 patients and was mild in all but one; carbogen was well tolerated in all patients. Following NCT only two patients had significant rises (P < 0.05) in tumour median pO2. During carbogen breathing, eight out of ten patients had early highly significant rises in pO2 (P < 0.0001), of which six continued to rise or remained in plateau until completion of gas breathing. Six patients had hypoxic pretreatment values less than 5 mmHg, which were completely abolished in three and reduced in two during carbogen breathing. In conclusion, the combination of NCT and carbogen breathing was generally well tolerated and gave rise to substantial rises in tumour pO2 which were maintained throughout gas breathing. These results should encourage further study of this potentially useful combination of agents as radiosensitisers in the clinic.

Adult↗
PubMed1995

Mediastinal staging of non-small-cell lung cancer with positron emission tomography.

To determine the usefulness of positron emission tomography with fluoro-2-deoxyglucose (PET-FDG) in assessing mediastinal disease in patients with non-small-cell lung cancer (NSCLC) and to compare its yield to that of computed tomography (CT), we performed a prospective consecutive sample investigation in a university hospital and its related clinics. In 30 patients with NSCLC with clinical stage I (T1-2, NO, MO) disease, we compared the results of chest CT and PET-FDG with the findings at surgical exploration of the mediastinum. Seven (77%) of nine patients with surgically proven mediastinal metastasis were identified by the PET-FDG results, with four false-positives in 21 patients with negative lymph node dissections (p = 0.004). Using the results of pathologic examination of mediastinal lymph nodes as the criterion standard, the diagnostic sensitivity, specificity, accuracy, positive predictive value (PPV), and negative predictive value (NPV) for PET-FDG imaging of mediastinal metastases were 78%, 81%, 80%, 64%, and 89%, respectively. The sensitivity, specificity, accuracy, PPV, and NPV for chest CT in the detection of mediastinal metastasis were 56%, 86%, 77%, 63%, and 87%, respectively. CT and PET-FDG results agreed in 21 patients. The diagnostic accuracy of the combined imaging modalities was 90%. We concluded that mediastinal uptake of FDG correlates with the extent of mediastinal involvement of NSCLC and may contribute to preoperative staging. PET-FDG imaging complements chest CT in the noninvasive evaluation of NSCLC, and strategies for its use merit further investigation.

Aged↗
PubMed1995

Paradoxical embolism. An underrecognized problem.

Despite reports of the clinical presentations and devastating consequences of paradoxical embolus (PDE) for more than a century, this diagnosis continues to be frequently missed. Because the prevalence of patent foramen ovale (PFO) is 27 to 35% in the normal population and the presence of deep vein thrombosis or pulmonary embolus may not be clinically obvious, a high suspicion for PDE is needed in the event of unexplained arterial occlusion. While contrast echocardiography and transcranial Doppler ultrasound have facilitated clinical recognition of PDE, the optimum approach to diagnosis requires clarification. Primary therapy for patients with PDE is anticoagulation, with thrombolytics considered in carefully selected individuals, but there is little published information regarding long-term treatment and outcomes. Prevention remains essential whenever possible. It is not yet defined whether prophylactic treatment of persons with recognized predispositions to PDE (eg, PFO and pulmonary hypertension) is beneficial.

Adult↗
PubMed1995

Pentoxifylline increases RIF-1 tumour pO2 in a manner compatible with its ability to increase relative tumour perfusion.

The time course and dose response of 600 mm3 subcutaneous RIF-1 tumours to pentoxifylline was measured in terms of relative tumour perfusion, assayed by 86Rb extraction, and pO2 distribution measured by the Eppendorf histograph. Both perfusion and pO2 distribution were maximally increased by 20 mg/kg pentoxifylline 15 min after administration, perfusion to 141 +/- 15% (2 SE) of control, and median pO2 from 3 to 15 mmHg, with the percentage of values < 2.5 mmHg falling from 44 +/- 8% to 22 +/- 7%. Fifteen minutes after administration the pO2 increases were linearly dose-dependent up to 20 mg/kg. Correlation coefficients for perfusion data with the percentages of low values were, for time course and dose response data respectively, 0.76 and 0.84 for median pO2, 0.84 and 0.97 for percentage < 2.5 mmHg and 0.81 and 0.87 for percentage < 10 mmHg. The data show good correlation between changes in perfusion and pO2 distribution parameters, with better correlation for percentage of low values than for median pO2.

Animals↗
PubMed1995

Interspecific variation in the chelonian primary visual system.

The primary visual system of 21 species of turtles, distributed among nine of the existing 12 families, were studied by autoradiography. In all species, contralateral visual projections exist to 15 targets: two hypothalamic structures (nucleus suprachiasmaticus and n. periventricularis), three major thalamic visual centres (nucleus ovalis, n. geniculatus lateralis ventralis and n. geniculatus lateralis dorsalis) and two minor thalamic targets (nucleus dorsolateralis anterior and n. ventrolateralis), five pretectal sites (nucleus geniculatus pretectalis, n. opticus pretectalis ventrolateralis, n. lentiformis mesencephali, n. posterodorsalis and n. griseus tectalis), two strata of the optic tectum (stratum opticum and s. fibrosum et griseum superficiale), and a single tegmental target (nucleus opticus tegmenti). In contrast to the stability of contralateral visual projections, their ipsilateral counterparts varied considerably between species, being limited to the hypothalamus in some species, and involving the majority of the primary visual centres in others. This variation is not readily explainable in terms of taxonomic position or of differences in mode of life.

Animals↗
PubMed1995

Burns Clinic links up with national firm to tackle managed care.

The Burns Clinic Medical Center, PC, headquartered in Petoskey, has for many years been an innovator in state medical practice. Founded in 1931, the Burns Clinic today offers a range of medical and surgical services at eight sites in northern Michigan. With 120 physicians on staff and 550 support employees, the Burns Clinic is a major health care operation as well as a proven success.

Hospital-Physician Joint Ventures↗
PubMed1995

A note on the distribution of dendritic spines.

Some previously published data concerning the spatial distributions of dendritic spines are re-examined. It appears that such distributions are not completely random, but show a tendency towards repulsion, that is to say a deficiency of short inter-spine distances and an excess of long distances when compared to a totally random model. While this lack of total randomness contradicts an assumption underlying a previously published technique for estimating total spine number, it does not appear to seriously interfere with this technique.

Algorithms↗
PubMed1994

Direct measurement of attentional dwell time in human vision.

In vision, attentional limitations are reflected in interference or reduced accuracy when two objects must be identified at once in a brief display. In our experiments a brief temporal separation was introduced between the two objects to be identified. We measured how long the object continued to interfere with the second, and hence the time course of the first object's attentional demand. According to conventional serial models, attention is assigned rapidly to one object after another, with a dwell time of only a few dozen milliseconds per item. But we report here that interference lasts for several hundred milliseconds--an order of magnitude more than the prediction of conventional models. We suggest that visual attention is not a high-speed switching mechanism, but a sustained state during which relevant objects become available to influence behaviour. This conclusion is consistent with recent physiological results in the monkey.

Adult↗
PubMed1994

Organization of the serotoninergic system in the brain of two amphibian species, Ambystoma mexicanum (Urodela) and Typhlonectes compressicauda (Gymnophiona).

An immunocytochemical investigation was made of the distribution of serotonin (5-HT) in the brain of larval and adult Ambystoma mexicanum and adult Typhlonectes compressicauda. Immunoreactive perikarya can be identified in the caudal diencephalon (paraventricular organ and infundibular nucleus), in the ventral mesencephalon (interpeduncular nucleus) and in the raphe of the rhombencephalon. Immunopositive fibers and terminal arborizations are widely distributed, extending from the whole telencephalon to the spinal lemniscus area. However, the retinorecipient structures of the thalamus and mesencephalon are either very weakly innervated (Ambystoma) or completely immunonegative (Typhlonectes). The habenular system also exhibits very few 5-HT-positive structures. The major serotoninergic neuron clusters, in both Urodela and Gymnophiona, tend to gather, from the paraventricular organ to the raphe, on both sides of the sagittal plane, showing no tendency to "lateralization". A new interpretation of the limited development of the serotoninergic system in amphibians is given.

Ambystoma mexicanum↗
PubMed1994

The distribution of GABA-immunoreactive neurons in the brain of the silver eel (Anguilla anguilla L.).

The distribution of GABA-immunoreactivity was studied in the brain of the silver eel (Anguilla anguilla) by means of antibodies directed against GABA. Immunoreactive neuronal somata were distributed throughout the brain. Positive perikarya were detected in the internal cellular layer of the olfactory bulb, and in all divisions of the telencephalon, the highest density being observed along the midline. Numerous GABA-reactive cell bodies were found in the diencephalon, particularly in the preoptic and tuberal regions of the hypothalamus, and the dorsolateral, dorsomedial and ventromedial thalamic nuclei. In the optic tectum, the majority of GABA-positive cell bodies were located in the periventricular layer. A number of immunolabeled cell bodies were observed in different tegmental structures, notably the torus semicircularis. In the cerebellum, the Purkinje cells were either very intensely or very weakly immunoreactive. In the rhombencephalon, reactive cell bodies were observed in the eminentia granularis, the valvula cerebellaris, the octavolateral nucleus, the lobus vagus and in the vagal and glossopharyngeal motor nuclei. Intensely immunoreactive axons and terminals were observed in the external granular layer and internal cellular layer of the olfactory bulb. In the telencephalon, the highest density of reactive fibres and boutons was found in the fields of the medial wall. Many immunolabeled fibres were seen in the medial and lateral forebrain bundles. In the diencephalon, intense labelling of fibres and terminals were observed in the nuclei situated close to the midline. In the optic tectum the highest density of reactive fibres was seen in the sfgs, the layer to which the retina projects massively. Finally, in the rhombencephalon the strongest labelling of neurites was observed in the nuclei of the raphé, the nucleus octavocellularis magnocellularis and the nuclei of the IXth and Xth cranial nerves. The GABAergic system of the eel, which is well developed, appears to be generally comparable to that described in tetrapod vertebrates.

Anguilla↗
PubMed1994

Stereotyped human behavior: a nonlinear dynamical analysis.

Some forms of stereotyped human behavior seem to occur randomly in time. A dynamical analysis of several topographies demonstrates that while such stereotypies have the spectral characteristics of random noise, the rate at which each subject exhibits his/her stereotypy is to some extent predictable and, unlike uncorrelated noise, prediction accuracy declines with increasing prediction interval. Rhythmic stereotypies appear to be more predictable than nonrhythmic topographies but both show a similar decline in prediction accuracy. Furthermore, the distribution of interresponse times exhibits self-similar behavior. These results point to a deterministic, rather than stochastic, origin for the variability of observed rates of stereotyped behaviors.

Adolescent↗
PubMed1994

BW12C perturbs normal and tumour tissue oxygenation and blood flow in man.

The effects of escalating doses of BW12C on normal tissue and tumour blood flow and pO2 in patients were studied. BW12C infusion resulted in a significant reduction in median subcutaneous tissue pO2, and an increase in the proportion of hypoxic values (< or = 2.5 mmHg). In 8 of 9 patients with accessible tumours there was a significant reduction in pO2 during BW12C infusion, but no effect on the proportion of hypoxic values. A rapid decline in normal tissue pO2 in the first 10 min was associated with an increase in skin red cell flux and a reduction of normal subcutaneous tissue, muscle, and tumour red cell flux of 30-50%, that was maintained throughout a subsequent 1-h infusion of BW12C. Tumour perfusion, as measured by dynamic computed tomography, was slightly reduced in five out of six patients studied during BW12C infusion. BW12C reduces both subcutaneous tissue and tumour pO2 in patients. Both haemoglobin modification and reduction in blood flow are probably associated with this effect.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1994

Continuously improving primary care.

BACKGROUND: This article describes efforts to understand and improve the daily work processes of primary care within the Henry Ford Health System, where continuous quality improvement (CQI) has been a key business strategy since 1988. We began a pilot project in 1990 that attempted to accelerate the implementation of continuous improvement in primary care. The clinical site was the general internal medicine (GIM) ambulatory clinic, which has 50,000 patient visits annually. STRATEGIES FOR IMPROVEMENT: For four key elements--physicians as leaders, prevention and primary care, patient access, and innovation and team work--we planned and implemented continuous improvement based on three questions: What were we trying to accomplish? What can we change that would lead to an improvement? How would we know a change is an improvement? EXAMPLE: Prevention and Primary Care. In our primary care setting, an appropriate clinical process to improve would include preventive medicine, specifically Pap-smear performance. In our partnership with the department of obstetrics/gynecology, GIM physicians wanted to improve the rate of adequate Pap smears. To reduce variation in the rates with which physicians collected specimens that were adequate for cytologic examination, the team recommended use of a specific tool, a cervi-brush, which should be more effective in producing adequate specimens. As cervi-brush use increased, rates of inadequate Pap smears dropped from 20%-25% in 1989 to less than 10% for the first six months of 1991. CONCLUSIONS: By focusing attention and resources on a limited number of improvement teams, our initial success built enthusiasm and commitment within GIM and accelerated changes that were incorporated into strategic planning for the Henry Ford Health System as a whole.

Female↗