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Biomedical subjects

R T Ross

Publications and source records attributed to R T Ross.

At least 19 recordsLinked to original sources
PubMed1995

Geographic similarities between varicella and multiple sclerosis: an hypothesis on the environmental factor of multiple sclerosis.

The environmental factor causing multiple sclerosis (MS) is unknown. Kurtzke et al. (Neurology 1979; 29: 1228-1235) depicted a north to south diminishing gradient in the case/control ratios for MS among American veterans in the United States. A similar, but less precise, gradient emerged when the incidence rates of varicella from 37 states during 1978-91 were compared. A loose correlation appears to exist between the mean incidence of varicella and the MS risk ratio (n = 0.344 Spearman rank correlation coefficient, p = 0.037). Further, the data on the fat of migrants moving from a high risk MS country to a low risk country and the reverse, plus the great importance of the age at migration, raise the question of a possible connection between the two diseases. Because of these epidemiological and other similarities between the two diseases a further comparative study was suggested.

Adolescent↗
PubMed1995

Varicella zoster virus and multiple sclerosis in a Hutterite population.

There are similarities between multiple sclerosis and varicella. They are common in the same parts of the world and both are scarce in other areas. Immigration studies suggest the environmental cause of multiple sclerosis (MS) must be contracted prior to age 15 years and will usually remain dormant for years. At age 10 years varicella has occurred in greater than 95% of children living in the high-risk areas for both of these diseases. The varicella zoster virus (VZV) could be etiologically important in multiple sclerosis. The known host containment of the virus for decades with recrudescence and the variable cell-mediated immunity of the host, which can wax and wane without clinical manifestations, all lend themselves to the natural history of multiple sclerosis. A population-based study of the medical records of 5601 Hutterite Brethren was performed to determine the occurrence of multiple sclerosis, varicella, and herpes zoster. Compared to their matched non-Hutterite neighbors who acted as controls, these events were significantly less common among the Hutterites. Included in the study was an assessment of other common neurological diseases and "autoimmune" diseases among the Hutterites and the controls. There is evidence of a relationship between MS and VZV that may not be coincidental.

Adolescent↗
PubMed1993

Kurtzke scale.

Explore the source record for details and available documents.

Disability Evaluation↗
PubMed1991

Dissociated loss of vibration, joint position and discriminatory tactile senses in disease of spinal cord and brain.

The clinical functions of the posterior columns of the spinal cord and the signs of disease of these structures have been debated for years. Todd in 1847 and Schiff in 1858 knew the functions of the posterior columns and 10 years later Brown-Séquard knew as well. Reynolds, Romberg, and Duchenne, each described a posterior column syndrome based on a disease in which the primary lesion was not in the posterior columns. In the last 150 years almost every white matter structure of the cord has been credited with serving the sensations that we now know are a function of the posterior columns. Vibration, joint position and movement as well as discriminatory touch each seem to be served by separate fibres of the posterior columns and medial lemniscus. There is evidence of this in cat and man. These sensations may be lost individually, totally, or in certain stereotyped combinations. Vibration or joint sense is commonly lost alone. When a discriminatory touch sensation is lost with one other sense, it is almost inevitably joint position sense. Absent discriminatory touch and vibration sense with normal joint position sense appears to be unknown. This functional separation continues into the thalamus. At the highest level there is no evidence that vibration sense has any conscious somatosensory cortical affiliation, while joint position and discriminatory touch senses definitely do.

Brain↗
PubMed1990

Factor analysis of the near-ultraviolet absorption spectrum of plastocyanin using bilinear, trilinear, and quadrilinear models.

Factor analysis was used to resolve the spectral components in the near-uv absorption spectrum of plastocyanin. The data set was absorption as a function of four variables: wavelength, species of plastocyanin, oxidation state of the copper center, and environmental pH. The data were fit with the traditional bilinear model, as well as with trilinear and quadrilinear models. Trilinear and quadrilinear models have the advantage that they uniquely define the components, avoiding the indeterminacy of bilinear models. Bilinear analysis using the absorption spectra of tyrosine and copper metallothionein as targets resulted in a two-component solution which was nearly identical to that obtained using trilinear and quadrilinear models, for which no targets are required. The two-component models separate the absorption into tyrosine and copper center components. The absorption of tyrosine is found to be pH dependent in reduced plastocyanin, and the absorption magnitude of the reduced copper center is the same in the four different plastocyanin species. Further resolution is provided by a three-component quadrilinear model. The results indicate that there are at least two different electronic transitions which cause the absorption of the reduced copper center and that one of them couples to a tyrosine residue. It is the absorption of this coupled tyrosine residue which is pH dependent. Correlation of the results with previous studies indicates that it is Tyr 83 which is the perturbed residue. The separation of the absorption of the copper center and Tyr 83 provides spectroscopic probes for the conformations of the north pole and east face reaction sites on the plastocyanin protein.

Binding Sites↗
PubMed1990

Drug-induced parkinsonism and other movement disorders.

This is a review of reserpine, haloperidol, and various phenothiazines that produce parkinsonism and other movement disorders. The by-products of illicit meperidine synthesis, MPTP and its more sinister companion, MPP, are also discussed. Movement disorders, transient or fixed, frank parkinsonism and/or dyskinesia, due to a variety of other medications and toxic agents are included. These are methanol, lithium, methyldopa, antimetabolites, antidepressants, sympathomimetic anorexiants, some types of antihistamines, and various combinations of agricultural chemicals.

Haloperidol↗
PubMed1990

Retraction of Ross and LoLordo findings concerning blocking in serial feature-positive discriminations.

Findings concerning the effectiveness of stimuli from various conditioning procedures in blocking conditioned excitation and occasion-setting functions of an added stimulus in a serial feature-postive discrimination training procedure (LoLordo & Ross, 1987; Ross & LoLordo, 1986, 1987) are retracted. Videotapes on which the published data were based were rescored by 2-5 people, most of whom were uninformed about group memberships of the subjects. In no case did the rescoring confirm any of the orginal findings of blocking. Possible factors contributing to the discrepancies are discussed. The experiments should be repeated with feature stimuli that are less similar to each other and with several scorers, at least one of whom is unaware of the group assignment of the subjects.

Retraction Notice↗
PubMed1988

The relationship of brachiocephalic vessel atheroma to transient ischemia of the brain and retina.

The relationships between transient cerebral and retinal ischemic symptoms and brachiocephalic angiographic findings were studied in 464 patients. The arterial abnormalities were more often bilateral than the symptoms suggested. Normal angiographic appearances were common, although abnormal arteries in patients without related symptoms were also common. When stenosis of the carotid system was 75 per cent or more, there was a strong correlation with symptoms.

Adult↗
PubMed1987

Evaluation of the relation between Pavlovian occasion-setting and instrumental discriminative stimuli: a blocking analysis.

Experiments with rat subjects used a blocking design (A+, then AB+) to assess the relation between Pavlovian occasion-setting and instrumental discriminative stimuli. Prior conditioning of both associative and occasion-setting functions of A in a serial feature-positive procedure blocked acquisition of an instrumental discriminative function by a novel stimulus (B) trained in compound with A. However, neither prior conditioning of only an A-US (unconditioned stimulus) association nor prior conditioning of Stimulus A using a Pavlovian simultaneous feature-positive procedure, which does not endow A with an occasion-setting function, blocked acquisition of an instrumental discriminative function by B. Prior acquisition of an instrumental discriminative function by A blocked acquisition of a Pavlovian occasion-setting function by a novel stimulus (B) trained in compound with A, but did not block acquisition of an association between B and the US. These outcomes indicate that Pavlovian occasion-setting and instrumental discriminative properties of a stimulus are functionally equivalent and that both Pavlovian occasion-setting and instrumental discriminative properties of a stimulus are functionally independent of simple associative relations between that stimulus and other events.

Animals↗
PubMed1986

Malignant intracranial fibrous histiocytomas. Histologic, ultrastructural and immunohistochemical studies of two cases.

Two cases of malignant intracranial fibrous histiocytoma are presented. In Case 1 the tumour arose from the meninges and showed a disseminated spread throughout the neuroaxis. In the second case the tumour appeared to arise from within the brain substance. In this case surgical intervention and radiotherapy appeared to have achieved a cure, since no residual tumour was found at autopsy. The tumours were examined using ultrastructural and immunohistochemical techniques, which appeared advantageous in delineating this rare tumour from other intracranial neoplasms.

Aged↗
PubMed1986

Pavlovian second-order conditioned analgesia.

Three experiments with rat subjects assessed conditioned analgesia in a Pavlovian second-order conditioning procedure by using inhibition of responding to thermal stimulation as an index of pain sensitivity. In Experiment 1, rats receiving second-order conditioning showed longer response latencies during a test of pain sensitivity in the presence of the second-order conditioned stimulus (CS) than rats receiving appropriate control procedures. Experiment 2 found that extinction of the first-order CS had no effect on established second-order conditioned analgesia. Experiment 3 evaluated the effects of post second-order conditioning pairings of morphine and the shock unconditioned stimulus (US). Rats receiving paired morphine-shock presentations showed significantly shorter response latencies during a hot-plate test of pain sensitivity in the presence of the second-order CS than did groups of rats receiving various control procedures; second-order analgesia was attenuated. These data extend the associative account of conditioned analgesia to second-order conditioning situations and are discussed in terms of the mediation of both first- and second-order analgesia by an association between the CS and a representation or expectancy of the US, which may directly activate endogenous pain inhibition systems.

Analgesia↗
PubMed1986

Casualty and surgical services in Perthshire general practitioner hospitals 1954-84.

The results are reported of a study of casualty and surgical services in five general practitioner hospitals in Perthshire - Aberfeldy, Auchterarder, Blairgowrie, Crieff and Pitlochry. Details of the total workload, the nature of the conditions treated and the referral rate to major hospitals are given. Figures for the Royal Infirmary, Perth, the main referral hospital for the county, are also given for comparison. The surgical service at one of the rural hospitals is described.Experience has demonstrated the usefulness of these hospitals in providing casualty and surgical services to both the local population and to visitors, and their superiority in providing these services over health centres because staff and beds are available 24 hours a day.Rural general practitioner hospitals merit a continuing share of resources and bed allocation as they spare major hospitals surgical and medical work. The general practitioners serving the hospitals studied here undertook almost 40% of the total accident and emergency workload in the Perth and Kinross area of Scotland.

Adolescent↗