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Biomedical subjects

C R Gordon

Publications and source records attributed to C R Gordon.

At least 19 recordsLinked to original sources
PubMed2005

Benign paroxysmal positional vertigo as the cause of dizziness in patients after severe traumatic brain injury: diagnosis and treatment.

OBJECTIVES: To identify patients with benign paroxysmal positional vertigo (BPPV) among patients with severe traumatic brain injury (TBI) and to evaluate the effectiveness of the Particle Repositioning Maneouvre (PRM). DESIGN AND METHODS: Eighteen months prospective study of 150 consecutive patients with severe TBI referred to an in-patients rehabilitation department. INTERVENTIONS: A structured interview emphasizing the possible presence of vertigo followed by a detailed neuro-otological examination. Patients diagnosed with BPPV were immediately treated with the PRM. MAIN OUTCOMES AND RESULTS: BPPV diagnosis was based on a positive Dix-Hallpike positional test. PRM efficacy was determined by repeating the positional test 1 or 2 weeks after treatment. Twenty out of 150 (13.3%) patients complained about positional vertigo. The diagnosis of BPPV was confirmed in 10 patients. Signs and symptoms were completely relieved in six patients after a single PRM, while the other four patients needed repeated treatment for complete resolution of BPPV. CONCLUSIONS: About half of the patients with severe TBI who complain about positional vertigo suffer from BPPV. These patients can be efficiently treated by physical maneouvres improving the rehabilitation outcome.

Accidents↗
PubMed2004

The saccadic system more readily co-processes orthogonal than co-linear saccades.

Real-life visual tasks such as tracking jumping objects and scanning visual scenes often require a sequence of saccadic eye movements. The ability of the ocular motor system to parallel process saccades has been previously demonstrated. We recorded the monocular eye movements of five normal human subjects using the magnetic search coil technique in a double step paradigm. Initial target jumps were always purely horizontal or purely vertical. We were interested in the latency to onset of the second saccade as a function of direction in relation to the first saccade. When the inter stimulus interval (ISI) was 150 or 180 ms orthogonal second saccades were of significantly shorter latency than second co-linear saccades. When the ISI was 250 ms the latencies of orthogonal and co-linear second saccades were statistically indistinguishable. Based on these findings it is postulated that the ocular motor system can more readily co-process orthogonal than co-linear saccades.

Adult↗
PubMed2004

Repeated vs single physical maneuver in benign paroxysmal positional vertigo.

OBJECTIVES: To evaluate the effectiveness and possible side effects of a single session of repeated particle repositioning maneuver (PRM) to treat posterior canal benign paroxysmal positional vertigo (BPPV) and the usefulness of post-treatment restrictions. MATERIALS AND METHODS: A total of 125 consecutive patients with idiopathic BPPV participated in the study. Fifty patients received a single session of repeated PRM only (group I). Results were compared with those of 50 patients with BPPV who received a single PRM (group IIb), and 25 patients who received a single PRM followed by the use of a neck collar and keeping the head upright for 48 h (group IIa). RESULTS: Forty-six patients (92%) of group I, 40 patients (80%) of group IIb, and 21 patients (84%) of group IIa were completely free of signs and symptoms when re-examined 1 week after treatment. Transient nausea and disequilibrium following treatment were reported equally in all subgroups and well tolerated. Nearly all patients of group IIa considered the post-treatment restrictions very inconvenient. CONCLUSIONS: A single session of repeated physical procedure seems to be clinically superior to one single maneuver and well tolerated. Additional post-treatment measurements are inconvenient and should be abandoned.

Adult↗
PubMed2004

Electro-oculographic measures in patients with chronic whiplash and healthy subjects: a comparative study.

BACKGROUND: Despite their high incidence, costs, and long lasting disability, whiplash associated disorders (WAD) lack an identifiable objective pathology that explains their acute or chronic symptoms. OBJECTIVE: In view of previous suggestions of a possible effect of neck torsion on several electro-oculography (EOG) parameters, the main objective of this study was to examine their applicability in differentiating patients from uninvolved subjects. METHODS: Smooth pursuit and saccadic eye movements were assessed in 26 patients with chronic WAD and 23 healthy subjects. All tests were executed in three neck positions: neutral and rotations to left and right. RESULTS: Neck torsion did not influence eye movement performance of either the WAD or healthy groups. However, compared with the healthy group, patients with WAD had significantly lower smooth pursuit velocity gain (SPVG) (p = 0.01) and prolonged saccadic latency (p = 0.001), irrespective of neck position. CONCLUSIONS: Despite scattered differences that reached significance, the electro-oculographic measures used in this study do not seem to offer a clinically relevant method for differentiating between patients with WAD and normal subjects.

Adult↗
PubMed2003

Vestibulo-ocular arreflexia in families with spinocerebellar ataxia type 3 (Machado-Joseph disease).

OBJECTIVE: To identify the presence of vestibulo-ocular arreflexia in patients with Machado-Joseph disease (MJD), which can easily be diagnosed at the bedside. METHODS: Seven patients with MJD from five unrelated families and 11 patients with sporadic or hereditary cerebellar ataxia other than MJD underwent a detailed neuro-otological and oculomotor examination. Six MJD and five non-MJD patients also underwent electro-oculographic recordings and caloric tests. RESULTS: Gaze evoked nystagmus, smooth pursuit, and saccade abnormalities were found in both MJD and non-MJD patients. However, in all seven MJD patients but in none of the non-MJD patients, sudden passively induced head thrust to both sides elicited pathological corrective catch-up saccades, indicating bilateral loss of the horizontal vestibulo-ocular reflex. This was further confirmed in six MJD patients who had absent vestibular response to both a standard caloric test and ice water ear irrigation. Nystagmus was induced by standard caloric irrigation in all non-MJD patients examined. There was no correlation between the loss of vestibular function and the severity of cerebellar impairment. CONCLUSIONS: The presence of vestibulo-ocular arreflexia, as measured by the head thrust test in a patient with dominant cerebellar ataxia, strongly suggests the diagnosis of MJD.

Adult↗
PubMed2001

Inner ear decompression sickness in sport compressed-air diving.

OBJECTIVE: We report our experience over the past 12 years with recreational diving-related inner ear decompression sickness (IEDCS). STUDY DESIGN: Retrospective, consecutive case series. METHODS: Twenty-four divers, representing 29 cases of IEDCS, are presented with regard to evaluation, treatment, and follow-up. RESULTS: These 29 cases represent 26% of the severe decompression sickness (DCS) cases treated in that period. The patient group includes 22 divers who had a single event of IEDCS, one diver who had two events, and one with five repeated episodes. The cause of injury in 23 cases (79%) was violation of the decompression schedule. The mean time from surfacing to appearance of symptoms was 47 +/- 65 minutes. In 83%, symptoms appeared within 1 hour of ascent, in 97% within 2 hours, and in only one diver after 5.5 hours. Ten divers (34%) had pure vestibular involvement, 4 (14%) had cochlear insult alone, and 15 (52%) had combined vestibulo-cochlear injury. Except for one patient who had central as well as peripheral vestibulo-cochlear DCS, all the remaining patients had end organ involvement only, as demonstrated by physical examination and laboratory test results. Fifteen (52%) had isolated IEDCS, whereas 14 had additional symptoms of DCS. Twenty-six cases were treated by hyperbaric oxygenation with supplementary daily hyperbaric sessions. Of the 25 cases with vestibular injury and the 19 with cochlear damage, only 7 (28%) and 6 (32%), respectively, made a full recovery, whereas the others remained with residual damage. Of the 17 treated within 6 hours of symptom appearance, 9 (53%) were cured, compared with one of the 9 treated later (P <.05). CONCLUSIONS: IEDCS related to compressed-air recreational diving is more common than previously thought, and might occur even when no decompression schedule violation took place. Prompt diagnosis leading to the early commencement of hyperbaric oxygen recompression therapy is the key to complete recovery of cochlear and vestibular function.

Adult↗
PubMed2001

The effects of dimenhydrinate, cinnarizine and transdermal scopolamine on performance.

We assessed the influence of dimenhydrinate, cinnarizine and transdermal scopolamine on the ability to perform simulated naval crew tasks. The effect of single doses of dimenhydrinate, 100 mg, cinnarizine, 50 mg, and one transdermal scopolamine patch on psychomotor performance was evaluated using a double-blind, placebo-controlled, randomized, crossover design in three separate studies. A total of 60 young naval crew (20 for dimenhydrinate, 15 for cinnarizine and 25 for transdermal scopolamine) underwent a battery of computerized and paper and pencil performance tests, and filled out a questionnaire on side-effects and well-being self-assessment. Dimenhydrinate significantly impaired decision reaction time and auditory digit span. Most of the subjects who took dimenhydrinate also reported a subjective decrease in well-being and general performance abilities. Cinnarizine and transdermal scopolamine did not affect performance abilities. Cinnarizine was free of significant side-effects. Dry mouth was the only significant side-effect of transdermal scopolamine. These findings could be explained by the well-known sedative properties of dimenhydrinate and not by a specific effect on any particular cognitive or motor function. Our results suggest that dimenhydrinate, 100 mg, adversely affects psychomotor function, whereas single doses of cinnarizine, 50 mg, and transdermal scopolamine appear to be free of side-effects on performance and seem to be a preferable anti-seasickness drug for use by a naval crew.

Administration, Cutaneous↗
PubMed2001

Exposure of hooded capuchin monkeys (Cebus apella cay) to a rabid bat at a zoological park.

On 27 May 1999, a big brown bat (Eptesicus fuscus) was discovered on an island exhibit at the Denver Zoo that contained a troop of 15 hooded capuchin monkeys (Cebus apella cay). The monkeys were attacking the bat when it was discovered. The bat was collected and humanely euthanatized without direct handling and submitted to the Colorado Department of Public Health and Environment Virology Laboratory for rabies evaluation. The monkeys had not been vaccinated against rabies virus. The next day, the laboratory confirmed that the bat was positive for rabies. The recommendations from the Colorado Department of Public Health and Environment and the Centers for Disease Control and Prevention were to euthanatize the monkeys or quarantine them and comply with the human nonvaccinated postexposure protocol. A 1-ml dose of a killed rabies vaccine was administered i.m. in the hip on each of days 2, 7, 12, 19, and 33 postexposure, and a single dose of human rabies immune globulin was administered i.m. 5 days postexposure. Blood was collected under anesthesia in order to evaluate the immune response after rabies vaccination from six monkeys 5 days postexposure, six monkeys 19 days postexposure (five of the six monkeys were the same monkeys bled 5 days postexposure), 15 monkeys 67 days postexposure, and 13 monkeys approximately 1 yr postexposure. All of the monkeys developed and maintained levels of rabies virus neutralizing antibody above 0.05 IU/ml by 67 days postexposure. Although a serologic titer of 0.05 IU/ml indicates an adequate human response after rabies vaccination, no similar information is available for nonhuman primates. To date, none of the monkeys has succumbed to rabies.

Animals↗
PubMed2000

[Pitfalls in the diagnosis of benign paroxysmal positional vertigo].

Benign paroxysmal positional vertigo (BPPV) is a common but often unrecognized cause of treatable vertigo. Possible causes of misdiagnosis of BPPV were studied by review of the records of 191 patients referred to our neurology clinic; 36 were identified as having BPPV not previously diagnosed. On referral the patients carried the following diagnoses: unspecified dizziness/vertigo (33%), transient ischemic attacks (28%), cervicogenic vertigo (19%), psychogenic dizziness/vertigo (11%), and others (8%). The paroxysmal nature of the vertigo and position-precipitating factors were not spontaneously reported by 31%. Atypical, even bizarre, symptoms including dizzy sensations were reported by 19%, and neck pain and headache were cardinal symptoms that accompanied vertigo. The Dix-Hallpike maneuver, which is essential for the diagnosis of BPPV, was not performed in any of the patients prior to referral. 30 (83%) experienced complete resolution of signs and symptoms after the first physical treatment session. We conclude that non-paroxysmal, non-positional vertigo does not rule out BPPV. Atypical and even bizarre complaints of dizziness, as well as neck pain and headache could be cardinal symptoms of BPPV. The Dix-Hallpike maneuver is mandatory in those complaining of dizziness and vertigo.

Adult↗
PubMed1999

Characterization of genetic instability in radiation- and benzene-induced murine acute leukemia.

This study, using the CBA/Ca mouse as a model, compares genetic lesions associated with radiation- and benzene-induced acute leukemias. Specific types of leukemia included in the analyses are radiation-induced acute myeloid leukemia (ML), and benzene-induced lymphoblastic leukemias, lymphomas, or mix-lineage leukemias. These leukemias have histopathological characteristics similar to those seen in human acute leukemias. G-band cytogenetic analysis showed that specific deletions involving regions D-E of one copy of mouse chromosome 2 [del(2)(D-E)] were frequently associated in both radiation- and benzene-induced acute leukemias. In addition, translocations of chr2(D-E) were also observed in some cases. These results suggest an important role of chr2 (D-E) deletions and translocations in the development of radiation- and benzene-induced murine acute leukemias. Fluorescence in situ hybridization with DNA probes specific for 2(D-E), constructed in our laboratory by means of chromosomal microdissection and PCR amplification, also demonstrate 2(D-E) deletions and/or translocations in these leukemic cells. Aneuploidy of chromosomes 3, 15, 16, and Y were also frequently detected in benzene-induced leukemic cells with or without lesions on chr2. These cytogenetic findings support the previous observations that metabolites of benzene lead to spindle-fiber disruption or abnormal cytokinesis in exposed animals. In summary, genetic instabilities observed in leukemic cells isolated from mice that had developed leukemia after exposure to radiation or benzene are syntenic with those frequently detected in patients with myelodysplastic syndrome, acute ML, and acute lymphoblastic leukemia. Thus, the CBA/Ca mouse has several characteristics that make it an excellent model for the study of radiation or benzene leukemogenesis in humans.

Animals↗
PubMed1999

The effects of boron neutron capture irradiation on oral mucosa: evaluation using a rat tongue model.

The ventral surface of the tongue of male Fisher 344 rats was used to evaluate the response of oral mucosa to boron neutron capture irradiation. Three hours after i.p. injection of 700 mg/kg of the boron delivery agent p-boronophenylalanine (BPA), the boron concentrations in blood and tongue mucosal epithelium were approximately 21 and 23 microgram (10)B/g, respectively. The doses required to produce a 50% incidence of ulceration with X rays, the Brookhaven Medical Research Reactor thermal neutron beam alone, or the thermal neutron beam in the presence of BPA were 13.4 +/- 0.2, 4. 2 +/- 0.1, and 3.0 +/- 0.1 Gy, respectively. Ulceration of the tongue was evident by 6 to 7 days after irradiation, irrespective of the irradiation modality; healing was related to dose and was relatively rapid (</=19 days). Compared to 100 kVp X rays, the relative biological effectiveness factors were 3.2 for the thermal neutron beam and 4.9 for the products of the boron neutron capture reaction, (10)B(n,alpha)(7)Li. Oral mucosa is highly sensitive to BPA-mediated BNC irradiation and could be a dose-limiting normal tissue in BNCT of brain tumors, or if BPA-based BNCT is applied to the treatment of head and neck tumors.

Animals↗
PubMed1998

A comparison of two serological methods for detecting the immune response after rabies vaccination in dogs and cats being exported to rabies-free areas.

Levels of rabies virus neutralizing antibody in sera from dogs and cats were titrated to endpoint by the Rapid Fluorescent Focus Inhibition Test (RFFIT) and retested by the RFFIT and the Fluorescent Antibody Virus Neutralization test (FAVN). The two tests were compared for their ability to detect the 0.5 international units/ml (I.U.) of antibody required by the World Health Organization and the Office International des Epizooties as the minimum response for proof of rabies immunization. No difference was observed in sensitivity or specificity for either method in tests of 168 sera from unvaccinated animals or 70 sera from vaccinated animals with high levels of neutralizing antibody (an initial RFFIT titre of > or = 1.0 I.U.). Test to test variation occurred for results obtained by both RFFIT and FAVN for 95 sera from vaccinated animals with low to moderate levels of neutralizing antibody (RFFIT titre < 1.0 I.U.). No significant differences were detected for the 95 sera in the frequency for one methodology more often than the other to have a positive response (> or = 0.5 I.U.), nor were significant differences detected for the symmetry (P = 0.43) or the marginal homogeneity (P = 0.39) of results obtained by the two methods. Both methods can adequately identity unvaccinated animals, but false positive and false negative results are possible for either method when a single test is used to measure the antibody response of low-responding vaccinated animals. Nucleotide sequence analysis identified several amino acid differences in stocks of the challenge rabies virus from different laboratories. The small differences in neutralizing antibody titre that may result from mutations in the challenge virus are not important for evaluating immunity induced by vaccines which are themselves prepared from a variety of different rabies virus strains, but differences in the challenge virus, rather than differences in methodology, may account for at least some of the discrepant results reported in inter-laboratory surveys. Comparative studies of serological methods for measuring rabies antibodies should use well-characterized unpassaged virus stocks obtained from a single reference laboratory.

Amino Acid Sequence↗
PubMed1998

Motor learning in the "podokinetic" system and its role in spatial orientation during locomotion.

The present study characterizes a previously reported adaptive phenomenon in a somatosensory-motor system involved in directional control of locomotor trajectory through foot contact with the floor. We call this the "podokinetic" (PK) system. Podokinetic adaptation was induced in six subjects by stepping in-place over the axis of a horizontally rotating disc over a range of disc angular velocities (11.25-90 degrees/s) and durations (7.5-60 min). After adaptation, subjects were blindfolded and attempted to step in-place on the floor without turning. Instead they all rotated relative to space. The rate of the "podokinetic afterrotation" (PKAR) was linearly related to stimulus amplitude up to 45 degrees/s, and the ratio of initial PKAR velocity to that of the adaptive stimulus was approximately 1:3. PKAR exhibited exponential decay, which was composed of "short-" and "long-term" components with "discharging" time constants on the order of 6-12 min and 1-2 h, respectively. The effect of stimulus duration on PKAR revealed a "charging" time constant that approximated that of the short-term component. A significant suppression of PKAR occurred during the 1 st min of the postadaptive response, suggesting functional interaction between the PK and vestibular systems during the period of vestibular stimulation. During PKAR subjects perceived no self-rotation, indicating that perception as well as locomotor control of spatial orientation were remodeled by adaptation of the PK system.

Adaptation, Physiological↗
PubMed1998

Evaluation of carborane-containing porphyrins as tumour targeting agents for boron neutron capture therapy.

A number of carborane-containing porphyrins were administered to mice bearing subcutaneously transplanted mammary carcinomas. Administration was via serial intraperitoneal (i.p.) injections to assess their relative toxicities and tumour affinities. Three analogues of the natural porphyrin heme and four tetraphenylporphyrins (TPPs) were given at total doses of 78-245 micrograms g-1 body weight. The water-insoluble TPPs were less toxic to mice, and delivered greater amounts of boron to tumour than did the water-soluble TPPS and the heme analogues. One such compound, NiTCP-H, delivered more than 100 micrograms B g-1 to tumour tissue with a tumour:blood boron concentration ratio greater than 500:1 and a tumour: brain boron concentration ratio greater than 50:1, 4 days after the last of six i.p. injections given over 2 days. Another TPP analogue, NiTCP, delivered approximately 50 micrograms B g-1 to tumour with similar boron concentrations in normal tissues. Neither compound was toxic to mice at total doses of approximately 200 micrograms g-1 body weight. In contrast, the heme analogues were toxic and, with the exception of VCDP, delivered less boron to tumour than NiTCP and NiTCP-H. The two porphyrins with the greatest potential for application to boron neutron capture therapy (BNCT), NiTCP and NiTCP-H, yielded higher tumour:blood and tumour:brain boron concentration ratios in mice than could be achieved with p-boronophenylalanine (BPA) and sodium mercaptoundecahydrododecaborate (BSH), the compounds which are currently being used in clinical trials of BNCT in the treatment of glioblastoma. The boron delivered by each of the porphyrins tested remained in tumour tissue longer than did boron delivered by either BPA or BSH. The copper and nickel chelates of these porphyrins behave identically in vivo. The former offer the potential for imaging by 67Cu-mediated single photon emission computed tomography (SPECT) to aid BNCT treatment planning.

Animals↗
PubMed1997

Alterations in R-R variability associated with experimental motion sickness.

Motion sickness is a complex integration of responses from multiple physiological systems. Whether the changes that occur during the time course of motion sickness are mediated by the sympathetic or parasympathetic systems is still controversial. The present study evaluates alterations in R-R variability during experimental motion sickness in motion sick and non-motion sick subjects. Ten motion sick subjects and 7 non-motion sick subjects participated in the study. Power spectrum analysis of R-R variation was conducted for all subjects 10 min before a brief vestibular disorientation test (BVDT), for 5-10 min of the test, and 10 min after the test. Subjects were also asked to report their symptoms during the test. The motion sick group showed a significant reduction in the power spectrum density of the R-R interval at the mid and high frequencies during the BVDT test period (BVDT), in comparison with the rest period (Rest). These changes probably indicate a decrease in parasympathetic activity during the time course of motion sickness. The non-motion sick group did not show significant differences at any of the frequencies during BVDT. Power spectrum analysis of the R-R interval provides an objective measure of the autonomic response to experimental motion sickness.

Adolescent↗
PubMed1997

Evidence for an uncommon microsatellite instability on mouse chromosomes 2 and 4 and its possible role in radiation leukemogenesis.

Although microsatellite instability (MSI), usually detected by DNA length polymorphisms, has been implicated in the induction of solid tumors in both humans and animals, its role in leukemogenesis is unclear. The goal of this study was to investigate whether there is an association between MSI and radiation leukemogenesis in CBA/Ca mice. Microsatellite lengths at 55 loci, mapped to eight different mouse chromosomes, were examined in two groups of DNA samples: 1) 10 normal DNA samples collected from the bone marrow cells of control male CBA/Ca mice, and 2) 17 DNA samples isolated from the spleens of mice that developed myeloid leukemia (ML) after exposure to neutrons, or X rays, or gamma rays. Microsatellite markers were amplified using the non-radioisotopic multiplex-touchdown PCR protocols developed in our laboratory, and the sizes of amplicons were examined on 6% non-denaturing polyacrylamide gels. Although no correlation between microsatellite length polymorphisms and radiation leukemogenesis was observed at the 55 CBA/Ca mouse loci tested in this study, an uncommon MSI, manifested as the absence of DNA bands after PCR amplification at 2 loci (D2MIT140 and D4MIT104), was observed in both control and ML samples. However, the frequency of ML samples showing this type of MSI is statistically significant (p<0.05). Although there is no direct evidence that this type of MSI predisposes mice to the development of leukemia, the results suggests that genes flanking the D2MIT140 and D4MIT104 are susceptible to spontaneous mutation and perhaps to damage caused by ionizing radiation.

Animals↗