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Biomedical subjects

R E Carr

Publications and source records attributed to R E Carr.

At least 19 recordsLinked to original sources
PubMed1992

Panic symptoms in asthma and panic disorder: a preliminary test of the dyspnea-fear theory.

Ley's (Behaviour Research and Therapy, 27, 549-554, 1989) dyspnea-fear theory was tested on three groups of subjects: 10 with panic disorder, 24 with asthma, and 12 who were nonanxious and nonasthmatic, using measures of pulmonary function, muscle tension; and self-report measures of generalized anxiety, dyspnea, and psychopathology. Results are supportive of dyspnea-fear theory for asthmatics but not for individuals with panic disorder. Differences between groups on panic/fear measures were explained by a combination of general anxiety and dyspnea. Within-group regression analyses showed that only generalized anxiety symptoms contributed significantly to scores on the Asthma Symptom Checklist scale of panic/fear within the panic disorder group; while only dyspnea contributed to panic/fear among asthmatics. Additional results show that panic disorder subjects performed normally on pulmonary function tests but reported respiratory symptoms as severe as did asthmatics. Compared with normal subjects, both patient groups displayed lower correlations between self-rated symptoms of bronchoconstriction and objective pulmonary measures. Panic disorder subjects showed a negative relationship between pulmonary function and hyperventilation symptoms, suggesting a heightened sensitivity to, and discomfort with, sensations associated with normal pulmonary function. Asthmatics displayed a significant relationship between degree of airway obstruction and both trapezius surface EMG and ratings of hyperventilation symptoms.

Age Factors↗
PubMed1992

Phospholipid-containing toxic malaria antigens induce hypoglycaemia.

Hypoglycaemia is associated with severe malaria and is an important prognostic indicator. Molecules liberated during overnight incubation of erythrocytes infected with Plasmodium yoelii induce marked hypoglycaemia in normal mice, with a delayed time course compared with insulin; some, though weaker, activity could also be obtained by overnight incubation of uninfected erythrocytes. The active component shares many properties with the phospholipid-containing molecules which we have previously shown to be toxic and to induce the release of tumour necrosis factor (TNF) from macrophages. However a MoAb which neutralizes the cytotoxicity of tumour necrosis factor in vitro did not prevent this induction of hypoglycaemia, whereas antiserum against the toxic antigens did, as did immunization of normal (but not the immunoglobulin-deficient SCID) mice with the same material. Furthermore, normal mice injected with the antigens after immunization with phosphatidyl inositol or inositol monophosphate did not develop hypoglycaemia; the latter compound was also inhibitory when mixed with the antigens before injection. These compounds were previously shown to block the induction of TNF by the antigens and to induce the production of inhibitory antibodies. The role of these molecules in the etiology of the hypoglycaemia of malaria is discussed.

Animals↗
PubMed1990

Autosomal dominant congenital stationary night blindness and normal fundus with an electronegative electroretinogram.

We studied three members of three successive generations of a family with autosomal dominant congenital stationary night blindness and normal fundi. Psychophysical studies on two members showed normal final cone thresholds and mildly increased rod thresholds. Full-field electroretinograms on all three members showed normal photopic b-wave amplitudes and implicit times. Under scotopic conditions, the rod response was absent, and with a bright flash stimulus, there was a normal a-wave with no b-wave. This electronegative dark-adapted electroretinogram resembled the Schubert-Bornschein type seen in congenital stationary blindness, which has been seen only in autosomal and X-linked recessive pedigrees.

Adult↗
PubMed1990

Clofazamine-induced generalized retinal degeneration.

Clofazamine is an iminophenazine dye with antimycobacterial activity which has recently been used to treat mycobacterium avium complex infections in patients with acquired immunodeficiency syndrome. The authors present the second report of a presumed clofazamine-induced bull's-eye maculopathy and generalized retinal degeneration in a patient with AIDS. The importance of closely following patients on clofazamine, especially those with AIDS who may be particularly susceptible to developing this toxicity, is stressed.

Acquired Immunodeficiency Syndrome↗
PubMed1989

The clinical utility of visual-evoked potential acuity testing.

We assessed the clinical utility of objectively measured acuity using visual-evoked potentials. The technique was first standardized in normal emmetropic subjects and then applied to uncorrected myopic subjects. We found that visual-evoked potential acuity could accurately indicate Snellen acuity in emmetropia and corrected myopia; however, the two measures were highly correlated only in those uncorrected myopic subjects with visual acuities of 20/100 or better. In subjects with poorer than 20/200 uncorrected visual acuity caused by myopia, estimates of visual-evoked potential acuity could not be obtained. The correlation between these two measures of visual acuity was also lower in patients with decreased Snellen acuity attributable to retinal or ocular disease. We found that patients with unexplainable claims of decreased visual acuity could be diagnosed as having functional visual loss based on objective visual-evoked potential acuities.

Adolescent↗
PubMed1989

The golden tapetal sheen reflex in retinal disease.

A mother and son with dominant cone dystrophy manifested the retinal reflexes seen in Oguchi's disease (mother) and the carrier female of X-linked retinitis pigmentosa (son). Another patient with cone dystrophy (simplex) showed localized areas of a golden reflex in each eye. A patient with juvenile macular dystrophy exhibited a diffuse golden-orange reflex throughout the posterior pole. The latter two patients did not have the Mizuo phenomenon.

Adult↗
PubMed1989

S (blue) cone pathway vulnerability in retinitis pigmentosa, diabetes and glaucoma.

A variety of retinal disease lead to a decrease in the sensitivity of the S (blue) cone pathways. To determine the possible sites and mechanisms of this loss we compared the sensitivities of an S (blue/pi-1) and an M (green/pi-4) cone pathway in patients with retinal diseases that differ as to their primary locus of sensitivity loss. The sensitivities of an S and an M cone pathway were assessed in patients with retinitis pigmentosa, insulin-dependent diabetes mellitus and open-angle glaucoma using Stiles two-color increment threshold technique. A greater loss in sensitivity of an S than an M cone pathway was found for all three disease groups; however, the diabetic patients showed a more selective loss. The results suggest that multiple sites are involved and that the combined effects of metabolic abnormalities and hypoxia contribute to the selective loss.

Adaptation, Ocular↗
PubMed1988

Progressive peripheral cone dysfunction.

A 22-year-old man had a three-year history of progressive day blindness, most notably peripherally, and denied difficulty with central vision or color vision. Visual function studies demonstrated a diffuse dysfunction of the photopic system and normal scotopic function. The central cone function, however, was essentially normal. Visual acuity was 20/20 in each eye, results on AO-HRR and Ishihara color plate testing were normal, color naming visual fields demonstrated color discrimination in the central 10 degrees, and foveal adaptation was normal.

Adult↗
PubMed1988

Visual system toxicity following intra-arterial chemotherapy.

We studied the effects of intra-arterial chemotherapy on the visual system of 29 consecutive patients with gliomas. As expected, infra-ophthalmic carotid infusion of cisplatin or carmustine (BCNU) was associated with clinically apparent anterior visual pathway lesions. Electroretinography revealed retinal dysfunction in patients without clinical abnormalities. Supra-ophthalmic carotid infusion of cisplatin or BCNU caused no retinal or optic nerve lesions. Electroretinography was abnormal in only one of these patients. Our results indicated that BCNU and cisplatin cause ischemic damage and are toxic to both retinal and neural tissue in patients with gliomas.

Brain Neoplasms↗
PubMed1987

Retinal degeneration with nanophthalmos, cystic macular degeneration, and angle closure glaucoma. A new recessive syndrome.

Seven related patients had a progressive pigmentary retinal degeneration, characterized by nyctalopia, visual field restriction, and cystic macular degeneration in younger patients and a macula of nonspecific atrophic appearance in older patients. In addition, each patient had high hyperopia (+9.50 to +16.00) and nanophthalmos (axial lengths, less than 20 mm), with diffuse choroidal thickening on ultrasound. Younger patients had slitlike anterior chamber angles; older patients developed progressive synechial angle closure and eventual glaucoma. Chromosomes were normal. On electroretinographic testing, younger patients had absent rod signals, with normal cone wave form and near-normal b-wave amplitudes but markedly delayed cone b-wave implicit times; older patients had severely diminished or extinguished electroretinograms. This family appears to represent a newly recognized autosomal-recessive syndrome.

Adult↗
PubMed1987

Cone function in congenital nyctalopia.

A patient with congenital stationary night blindness (CSNB) (Schubert-Bornschein type) transmitted as an autosomal recessive trait was studied with several tests of electrical function as well as a variety of psychophysical procedures. Comparison of the patient's present findings with those obtained 23 years earlier showed that while rod thresholds have remained the same, cone sensitivity has decreased. Subjective flicker thresholds obtained following a bleach were unchanged during the course of dark adaptation. The absence of rod-cone interaction, together with an absent scotopic b-wave, implies that the defect is in the mid-retinal layers. Further, the absence of oscillatory potentials in the photopic electroretinogram (ERG) suggests that the interplexiform cell may be implicated in some manner. The focal ERG of the CSNB patient showed normal amplitude and normal phase delays, supporting the idea that the focal ERG samples primarily cone photoreceptor activity.

Adult↗
PubMed1987

Progressive cone dystrophy.

Psychophysical, reflectometric, and electrophysiologic studies were done on four members of a dominant pedigree with progressive cone dystrophy. The two youngest individuals were asymptomatic at the initial examination, and none of the subjects complained of problems associated with night vision. Nevertheless, absent or grossly reduced cone-mediated electroretinographic (ERG) responses showed the widespread loss of cone function, and moderate elevations (less than 1 log unit) in absolute threshold together with reductions in rhodopsin levels in the mid-peripheral retina provided evidence of impairment of the rod system. The progressive nature of the disease was apparent from the case histories and the changes in visual performance that occurred on re-test after a 5-year interval. Moreover, the results of increment threshold measurements at several retinal loci suggested that peripheral cones may be affected earlier and more severely than those in the central retina.

Adolescent↗
PubMed1987

Progressive cone dystrophy.

Psychophysical, reflectometric, and electrophysiological studies were performed on four members of a dominant pedigree with progressive cone dystrophy. The two youngest individuals were asymptomatic at the initial examination, and none of the subjects complained of problems associated with night vision. Absent or grossly reduced cone-mediated ERG responses revealed the widespread loss of cone function. Moderate elevations (1 log unit) in absolute threshold together with reductions in rhodopsin levels in the midperipheral retina provided evidence of a mild impairment of the rod system also, although not to the degree seen in a cone-rod dystrophy. The progressive nature of the disease was apparent from the case histories and the changes in visual performance that occurred on re-test after a 5-year interval. Likewise, the results of incremental threshold measurements at several retinal loci suggested that peripheral cones may be affected earlier and more severely than those in the central retina.

Adolescent↗
PubMed1987

Testicular swelling associated with desipramine.

Two cases of testicular swelling associated with desipramine therapy are described. In one case, the swelling resolved with discontinuation of desipramine; in the other, the swelling subsided despite continuation and an increase in dose. These cases may represent a local variant of angioneurotic edema; however, further study is required to determine the exact etiologic mechanism.

Adult↗
PubMed1986

Objective assessment of temporal modulation transfer functions using the focal ERG.

Temporal modulation transfer functions (MTF's) were recorded from the macula of nine normal subjects using focal electroretinography (FERG). An array of light emitting diodes (LED's) was used to experimentally manipulate stimulus temporal frequency, modulation depth, and mean luminance values. Two techniques were used to derive FERG modulation thresholds at several temporal frequencies: conventional averaging with extrapolation to a criterion amplitude, and a swept stimulus lock-in retrieval method. These two methods produced comparable results. The electrophysiologically derived MTF's were similar in shape to those obtained psychophysically. Six patients with retinal disease were also examined; all patients showed sensitivity losses which were most marked at the higher frequencies. Such losses tended to be greater in patients with poorer visual acuity.

Adult↗
PubMed1986

Evaluating macular function using the focal ERG.

A stimulus consisting of 96 red LEDs mounted in the rear of a ganzfeld bowl was used to elicit focal electroretinograms (FERG) from the central 9 degrees of the retina in human subjects. The luminance of the stimulus was driven sinusoidally at frequencies from 10-60 Hz. The temporal responsiveness and response phase lags of normal subjects and patients with retinal disease were measured. Normal subjects produced maximum amplitude FERG responses to stimuli between 30-40 Hz. Patients with retinitis pigmentosa showed a low-pass pattern of amplitude loss, with an additional frequency independent loss in sensitivity in those with poorer visual acuity. Patients with macular degeneration showed general amplitude loss associated with a relative sparing of the mid-temporal frequencies. The response phase lags in both patient groups were not significantly different from the normals. These findings point to a loss in temporal responsiveness accompanied by a secondary loss of sensitivity in these heredoretinal degenerations.

Adolescent↗
PubMed1979

Stargardt's disease and fundus flavimaculatus.

A study of 67 patients with a diagnosis of Stargardt's disease (juvenile macular degeneration) or fundus flavimaculatus showed that, apart from the ophthalmoscopic appearance, there is no clear distinction between these two disorders. The disease is an autosomal recessive macular degeneration that is bilateral and symmetrical in appearance, with diminished central vision as the hallmark symptom. The onset of symptoms usually occurred in the first or second decade, but a substantial number of patients were asymptomatic until the fourth or fifth decade. Psychophysical and electrophysiologic tests indicated that this is a localized and not a generalized retinal dystrophy. While the initial vision in the better eye was 6/12 (20/40) or better in one third of the patients, follow-up studies showed progression to levels between 6/30 (20/100) and 6/60 (20/400).

Adolescent↗