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Biomedical subjects

R M Hansen

Publications and source records attributed to R M Hansen.

At least 73 records · Page 4Linked to original sources
PubMed1988

Optokinetic nystagmus thresholds of dark-adapted RCS rats.

The thresholds of dark adapted RCS rats and controls were estimated from optokinetic responses to blue stimuli, and compared to thresholds derived from b-wave stimulus/response functions. The rats were tested at ages 25, 30 and 35 days, a period during which the RCS degeneration is evolving and normal retinal development is proceeding. At all ages the OKN thresholds of control rats were lower than those of the RCS rats, but only by age 30 days did b-wave thresholds discriminate RCS from controls. As the RCS disease progressed b-wave thresholds increased, but OKN thresholds did not change significantly. The discrepancy between the OKN and b-wave results may be due largely to the smaller OKN stimulus field, which probably stimulates mainly the posterior retina where the RCS degeneration is most advanced.

Animals↗
PubMed1988

Visual fields of young children.

A light-emitting diode (LED) perimeter and forced-choice procedures are described that enable quantitative assessment of peripheral visual fields of young children. The visual fields of normal children, aged 2-5 years, and adults are compared. There are no significant differences in the extent of the LED visual field of the children and the adults. For selected neuro-ophthalmology patients, results of LED and kinetic Goldmann perimetry have been compared. The patients' LED and Goldmann fields are similar in overall extent. In all cases, field defects demonstrated by Goldmann perimetry are detected by LED perimetry. However, discrepancies in the severity of quandrantanopic defects of a patient have been discovered that may be stimulus-dependent.

Adolescent↗
PubMed1988

Occult carcinoma of the breast masquerading as primary adenocarcinoma of the small intestine. A case report.

A fifty-year-old woman with abdominal pain, diarrhea, and weight loss ultimately required exploratory laparotomy. The entire small intestine was extensively infiltrated by poorly differentiated adenocarcinoma; mesenteric lymph nodes and surrounding omentum were involved, but no extragastrointestinal tumor was found. A presumptive diagnosis of unresectable primary carcinoma of the small bowel was made. Chemotherapy was initiated with 5-fluorouracil 300 mg/m2/day by continuous intravenous infusion. Nine months later a left breast mass with multiple ipsilateral axillary and supraclavicular lymph nodes developed; biopsy revealed a poorly differentiated adenocarcinoma morphologically identical to the tumor involving her small bowel. In spite of breast irradiation and systemic hormonal therapy, the patient deteriorated rapidly and died from progressive metastatic disease.

Breast Neoplasms↗
PubMed1987

The relation of rhodopsin and scotopic sensitivity in choroideremia.

We examined two patients who had clinical characteristics typical of choroideremia using psychophysical and reflection retinal densitometric techniques. In the dark-adapted state, sensitivity was more compromised than would be predicted on the basis of the modest losses of rhodopsin. In the dark-adapted state, studies of spatial and temporal summation suggested that postreceptoral processes are similar to normal. The kinetics of rhodopsin regeneration after bleaching exposures were abnormal in some retinal regions.

Adult↗
PubMed1987

Foveal cone pigments and sensitivity in young patients with Usher's syndrome.

Psychophysical and reflection retinal densitometric techniques were used to investigate foveal function of three patients (ages 14, 16, and 19 years) with Usher's syndrome who had good central visual acuity and, by ophthalmoscopic examination, normal foveal areas. During dark adaptation foveal sensitivity and its relation to proportion of cone pigment present were normal, but the kinetics of regeneration of the pigments were markedly abnormal. Measurements were made to consider the possibilities that the disorders of regeneration were associated with altered light-catching capacities of the patients' cone pigments, deranged transport of visual cycle substances between the retinal pigment epithelium and photoreceptors, or lingering photoproducts. None of the mechanisms fully accounted for the observed kinetics. The results suggested that abnormal kinetics of regeneration are among the earliest signs of malfunction of the foveal photoreceptor-pigment epithelial complex in some of the retinal degenerative disorders.

Adolescent↗
PubMed1987

Oscillatory potentials of visually inattentive children.

The oscillatory potentials (OPs) are probably generated in the proximal retina. The OPs of 20 visually inattentive infants and children were recorded. All 20 had evidence of abnormalities of the visual parts of the brain. The a- and b-waves, indices of distal retinal function, were normal in 10 patients, abnormal in the other 10. Among the patients with abnormal, attenuated a- and b-waves, OP amplitudes were more attenuated than among those with normal a- and b-waves. However, the timing of the OP wavelets was not correlated with distal retinal activity. These results suggest that in humans OP amplitude may be determined by inputs from the distal retina, but OP latency and periodicity are governed by processes within the proximal retina.

Adult↗
PubMed1987

The relationship of retinal sensitivity and rhodopsin in human infants.

During dark adaptation after full field, greater than or equal to 90% bleaches recovery of sensitivity and regeneration of rhodopsin were studied using electroretinographic and pupillographic techniques in both 10-week-old infants and adults. The courses of scotopic sensitivity recovery and rhodopsin regeneration of infants and adults were similar and were reasonably well fit by single exponentials having tau = 400 sec. For both infants and adults log scotopic sensitivity was linearly related to the proportion of rhodopsin present during dark adaptation. It is concluded that by age 10 weeks human distal retinal processes that occur after photolysis are equivalent to those of adults.

Adult↗
PubMed1987

Continuous 5-fluorouracil infusion and pulse methotrexate/leucovorin for colorectal adenocarcinoma. A report of excessive toxicity.

Thirteen patients with metastatic colorectal adenocarcinoma underwent treatment with continuous ambulatory 5-fluorouracil (5-FU) infusion 300 mg/m2/day and intermittent bolus methotrexate (MTX) (200 mg/m2) with calcium leucovorin (LCV) 10 mg/m2 orally every 6 h X four to eight doses given 24 h after MTX. Although MTX administration was planned every 14 days, the average time between treatments exceeded 19 days (range 14-42) because of excessive toxicity. All patients experienced toxicity at some time in their treatment course, requiring interruption of 5-FU infusion in 12 of 13 patients. Significant toxicities included stomatitis (13 of 13 patients), hand-foot syndrome (8 of 13 patients), and diarrhea (3 of 13 patients). Toxicity did not appear to be minimized by attenuation of MTX and/or 5-FU dosage or by increasing the dose and/or duration of LCV. At this dosage schedule the addition of MTX/LCV to 5-FU infusion results in excessive and unacceptable toxicity and does not appear to improve treatment results.

Adenocarcinoma↗
PubMed1987

Ketoconazole in the prevention of candidiasis in patients with cancer. A prospective, randomized, controlled, double-blind study.

A prospective, randomized, controlled, double-blind study was performed between 1982 and 1985 to assess the ability of ketoconazole to prevent fungal infections in selected patients with cancer. Fifty-six patients receiving induction chemotherapy for acute leukemia, autologous bone marrow transplant for refractory nonhematopoietic malignant neoplasms, multidrug chemotherapy for malignant lymphoma, or corticosteroids for brain metastases were randomized to receive either oral ketoconazole, 400 mg/d, or placebo and observed until leukopenia resolved or corticosteroid therapy was stopped. Oral candidiasis developed in eight (28%) of 29 patients receiving placebo compared with none of 27 receiving ketoconazole. However, ketoconazole failed to prevent Candida esophagitis and vulvovaginitis in two patients and one patient, respectively. Furthermore, prophylactic use of ketoconazole did not significantly alter the total number of hospital days, febrile days, or antibiotic days or the requirement for amphotericin B in patients with acute leukemia and autologous bone marrow transplant. Since oral candidiasis can be successfully managed by several different treatment modalities when it does occur, we do not think that the routine prophylactic use of ketoconazole is justified.

Candidiasis↗
PubMed1986

T-cell chronic lymphocytic leukemia with pure red cell aplasia: laboratory demonstration of persistent leukemia in spite of apparent complete clinical remission.

A 40-year-old woman presented with splenomegaly, macrocytic anemia, and red cell aplasia. Although lymphocytosis was absent in the peripheral blood, large atypical lymphoid aggregates were present in the bone marrow. Splenectomy resulted in partial remission of red cell aplasia, but a gradual increase in the number of peripheral blood lymphocytes followed during the next 36 months. Flow cytometric analysis demonstrated that the majority of these peripheral blood lymphocytes had suppressor, natural killer T-cell phenotype. No other treatment was given until red cell hypoplasia worsened 42 months after initial presentation. Repeat bone marrow evaluation again demonstrated severe erythroid hypoplasia and large abnormal lymphocytic infiltrates. Cyclophosphamide given for 8 months resulted in complete resolution of the red cell aplasia and complete clinical remission of CLL. However, flow cytometric analysis revealed persistent increase in bone marrow T-cells, and bone marrow co-culture studies demonstrated residual ability of peripheral blood mononuclear cells to inhibit erythropoiesis in vitro, suggesting that residual, clinically undetectable leukemia persists in spite of complete clinical remission.

Adult↗
PubMed1986

Background adaptation in human infants.

Human infants' thresholds for detecting 10 degrees diameter 50 and 1000 msec stimuli in the dark adapted condition and in the presence of steady red backgrounds were determined using a preferential looking method. Dark adapted sensitivity and the slope of the linear portion of the increment threshold function increased with age. The slope was 0.5 at 4 weeks, but by 10 weeks it was not different from the adult value (approximately 1.0). At all ages the eigengrau was approximately the same as that of adults (-2.3 log scot. td). These results suggest that visual mechanisms involved in detection of flashes and adaptation to steady background lights mature postnatally.

Adult↗
PubMed1986

Sequential methotrexate, 5-fluorouracil, and calcium leucovorin in colorectal carcinoma.

Forty-four patients with locally recurrent or metastatic colorectal adenocarcinoma were treated with methotrexate (MTX) 100 mg/m2 i.v. followed 1 h later by 5-fluorouracil (5-FU) 600 mg/m2 i.v. Calcium leucovorin 10 mg/m2 p.o. q 6 h X four doses was given 24 h after MTX. The regimen was given on days 1 and 8 and repeated every 28 days. Six of 44 patients (14%) obtained either complete or partial response with a mean response duration of 6.8 months. Of 26 previously untreated patients there were one complete response (4%), four partial responses (15%), and 12 (46%) instances of stabilization of disease. Patients obtaining response or stabilization of disease experienced improved survival compared to those with progressive disease. Toxicity consisted of stomatitis and hematopoietic suppression requiring dose attenuation in six patients (14%); there were no treatment-related deaths. Sequenced MTX/5-FU is modestly active with acceptable toxicity in previously untreated patients with colorectal adenocarcinoma but offers no apparent advantage over single-agent 5-FU.

Adenocarcinoma↗
PubMed1986

Poor correlation between pulmonary arterial wedge pressure and left ventricular end-diastolic volume after coronary artery bypass graft surgery.

The authors studied 12 surgical patients in the intensive care unit post coronary artery bypass graft surgery and ten nonsurgical patients in the coronary care unit with chronic heart failure to determine the usefulness of the pulmonary arterial wedge pressure as an indicator of left ventricular preload. Left ventricular end diastolic volume was derived from concomitant determination of ejection fraction (gated blood pool scintigraphy) and stroke volume (determined from thermodilution cardiac output). In the nonsurgical patients, there was a significant correlation between changes in pulmonary arterial wedge pressure and left ventricular end-diastolic volume (P less than 0.05, r = 0.57). In the 12 patients studied during the first few hours after surgery, there was a poor correlation between changes in pulmonary wedge pressure (range = 4-32 mmHg) and left ventricular end-diastolic volume (range = 25-119 ml/m2), and a poor correlation between pulmonary arterial wedge pressures and stroke work index. In contrast, there was a good correlation between left ventricular end-diastolic volume and stroke work index. The poor correlation between the pulmonary arterial wedge pressure and left ventricular end-diastolic volume was not explained by changes in systemic or pulmonary vascular resistance. The altered ventricular pressure-volume relationship may reflect acute changes in ventricular compliance in the first few hours following coronary artery bypass graft surgery. While measurement of pulmonary arterial wedge pressure remains valuable in clinical management to avoid pulmonary edema, it cannot reliably be used as an index of left ventricular preload while attempting to optimize stroke volume in patients immediately following coronary artery bypass graft surgery.

Aged↗
PubMed1986

Assessment of acuity of amblyopic subjects using face, grating, and recognition stimuli.

For amblyopic subjects, square-wave gratings, such as those used in preferential looking tests of infants' vision, yield more optimistic estimates of visual acuity than complex stimuli such as letters. A complex stimulus--a schematic face pattern--has recently been shown (Harris et al, IOVS 25:782, 1984) to permit preferential looking estimates of acuity of infants with normal eyes. In the present study, older amblyopic subjects had acuities measured with the face stimulus as well as gratings and standard recognition tests. Acuities measured with the face stimulus agreed better with the results of the standard recognition tests than did those obtained with gratings. Thus, if amblyopia of infants and young children affects spatial vision in a manner similar to that of older children and adults, one would anticipate that complex stimuli, such as the face pattern, would complement current assessments of young pediatric patients.

Adolescent↗
PubMed1986

Aleukemic leukemia cutis.

A 46-year-old man presented with nodular skin lesions, a biopsy specimen of which demonstrated a poorly differentiated malignancy. Touch preparations with histochemical staining and electron microscopy confirmed leukemia cutis. Results from a bone marrow aspirate disclosed focal areas of increased myeloblasts, and cytogenetic analysis revealed an abnormal karyotype as follows 46,XY, t(1;2) (q44p13). Antileukemic therapy resulted in prompt disappearance of the skin nodules, and a return of the patient's bone marrow to normal was noted, but after six months of intensive chemotherapy leukemia cutis recurred without morphologically identifiable leukemia in the bone marrow. The patient underwent successful bone marrow transplantation from an HLA-identical sibling but died 70 days after the transplant from disseminated aspergillosis.

Acute Disease↗