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Biomedical subjects

H Anderson

Publications and source records attributed to H Anderson.

At least 253 records · Page 14Linked to original sources
PubMed1979

Audiologic findings after stereotactic radiosurgery in nine cases of acoustic neurinomas.

Nine cases of acoustic neurinoma were treated by stereotactic radiosurgery between 1969 and 1974. The follow-up period can now be regarded as sufficiently long for a preliminary evaluation of the results. An arrest of growth or shrinkage of the tumour was observed in 8 of the 9 cases. In one case open surgery was performed 2 years after irradiation and histological examination showed regressive changes of the type expected after irradiation. Audiological examination revealed that in the majority of cases radiosurgery could be performed without causing serious damage to the hearing function. The average hearing loss present before treatment increased on average only 20.0 dB in the most successful 7 cases. None of the patients suffered facial nerve involvement. In small and medium-sized acoustic tumours this method offers a satisfactory therapeutic alternative worthy of consideration.

Adult↗
PubMed1978

Efficiency and cost of primary care by nurses and physician assistants.

We conducted a prospective study in a prepaid primary-care practice (health-maintenance organization) of a system in which nurses and physician assistants used protocols, and compared the efficiency and costs of this "new-health-practitioner" protocol system to a physician-only nonprotocol system. In five months, we studied 472 patients with any of four common acute complaints--respiratory infections, urinary and vaginal infections, headache, and abdominal pain; a subset of 203 patients was randomly allocated between the two systems. In the new-health-practitioner system physician time per patient was reduced by 92 per cent, from 11.8 to 0.9 minutes, and average visit costs--including practitioner time and charges for laboratory tests and medications--were 20 per cent less (P = 0.01). We conclude that this protocol system saves physician time and reduces costs.

Abdomen↗
PubMed1978

Postembryonic development of the visual system of the locust, Schistocerca gregaria. I. Patterns of growth and developmental interactions in the retina and optic lobe.

The visual system of the locust, Schistocerca gregaria, has a highly ordered and predictable arrangement of neurons. The retina and the outermost layer, or lamina, of the optic lobe are each composed of repeating units, ommatidia and cartridges respectively. Each ommatidium has eight photoreceptor cells, which send axons directly to a group of five neurons in the lamina to form the cartridge. The importance, for the development of this precise pattern, of the mode of growth of the two arrays and of interactions between them was investigated. The spatial and temporal sequences of cell proliferation, differentiation and death in the developing retina and optic lobe were examined quantitatively under normal and experimental conditions. The retina grows from its anterior margin by addition of new ommatidia formed from recruited epidermal cells. The lamina also grows by addition of new neurons to its anterior margin, but these neurons are derived from a stem cell population. The parallel pattern of growth of the retina and lamina may be important for the formation of neuronal connexions between them. The retina grows and differentiates even when deprived of the underlying lamina. In laminae deprived of the ingrowth of new axons from the retina, the production of new neurons is also autonomous, but these neurons do not differentiate, but degenerate. A limited amount of cell death occurs in the laminae of control insects. These two observations suggest that a plausible mechanism for coordinating the sizes of the two arrays during normal development might be production of lamina neurons in excess of requirements and death of those remaining non-innervated.

Animals↗
PubMed1978

Postembryonic development of the visual system of the locust, Schistocerca gregaria. II. An experimental investigation of the formation of the retina-lamina projection.

In the compound eye of the locust, Schistocerca gregaria, neurons from the retina project to the lamina in a precise topographical mapping. The formation of this projection was investigated in grafting experiments which altered the spatial or temporal relationship between the retina and the lamina. The results show that retina axons tend to grow along the paths of adjacent axons, with no indication of specificity for their normal termination sites. It is suggested that the orderly sequence of retina differentiation during normal development plays a major role in imposing pattern both upon the developing projection and, through some form of inductive interaction between retina and lamina neurons, upon the lamina.

Animals↗
PubMed1978

Health status of styrene-polystyrene polymerization workers.

Styrene monomer is a greatly used chemical, chiefly in the production of polystyrene. A cross-sectional health survey of 493 production workers was undertaken at the oldest and largest monomer production, polymerization, and extrusion facility in the United States. Relative exposure durations and levels were obtained from occupational histories and corroborated by spot air sampling, blood and fat styrene concentrations and levels of urinary mandelic and phenylglyoxylic acids. Statistically significant differences between the prevalence of abnormalities in high and low exposure groups were found for the following: history of acute prenarcotic symptoms, history of acute lower respiratory symptoms, peroneal nerve conduction velocities, relative lymphocytosis, and elevated gamma glutamyl transpetsidase. The following showed no distinct pattern in prevalence when analyzed by exposure group: chest radiographic changes; indices or restrictive, obstructive and small airway dysfunction; other hepatic and hematological parameters; carcinoembryonic antigen level; sputum cytopathology; radial nerve conduction velocities; and ophthalmological findings. Clinically significant abnormalities were rare.

Environmental Exposure↗
PubMed1976

Clinical studies of styrene workers: initial findings.

Styrene monomer is a high volume chemical used chiefly in production of polystyrene. A clinical survey of 493 production workers was undertaken at the oldest and largest monomer production, polymerization, and extrusion facility in the U.S. Relative exposure durations and levels were obtained from occupational histories. Significant differences between the high and low exposure groups were found with regard to history of acute prenarcotic symptoms, acute lower respiratory symptoms, prevalence of FEV 1/FV less than 75 per cent, and elevated GCTP. Other liver function tests, chest x-ray, FVC less than 80 per cent, and hematological parameters showed no distinct pattern. A concomitant mortality study has been mounted and is in progress.

Adult↗
PubMed1976

A headache protocol for nurses: effectiveness and efficiency.

To test the effectiveness and efficiency of a nurse-administered protocol for headache in the primary care setting, we conducted a prospective controlled trial. Two hundred three randomly allocated patients were evaluated by nurses using the protocol who managed independently 55.2% of the patients and received physician consultation on the others. A total of 193 patients were randomly allocated to the physician-control group. Nurse-protocol group patients experienced equivalent symptomatic relief and expressed significantly greater satisfaction with the care they had received than did patients in the physician-control group. A retrospective study of the presenting findings in patients with serious diseases of the CNS provided evidence supporting the safety of the protocol logic. We conclude that nurse-protocol management of headache in this primary care practice was effective and efficient.

Ambulatory Care↗
PubMed1975

Nurse-protocol management of low back pain. Outcomes, patient satisfaction and efficiency of primary care.

To test the validity of a nurse-administered protocol for low back pain, a prospective trial of 419 patients was undertaken in a walk-in clinic. In all, 222 patients were randomly allocated to a "nurse-protocol group" in which they were evaluated by one of five nurses using the protocol; the nurses independently managed 53 percent of the patients and referred to a physician patients with potentially complex conditions. In addition, 197 patients in a randomly allocated control group were managed by one of 32 physicians. Care in the experimental and control groups was compared by follow-up telephone contact and by a four-month chart review. There was no significant difference in symptomatic relief or the development of serious disease in the two groups. Nurse-protocol patients expressed greater satisfaction with the care they had received; patient satisfaction correlated positively with symptom relief. In over 95 percent of the patients, there were noncomplex, nonserious, nonchronic conditions as the cause of back pain. We conclude that nurse-protocol management of this generally benign condition in a primary care setting is both effective and efficient.

Adolescent↗