Biomedical subjects

R M Hansen

Publications and source records attributed to R M Hansen.

At least 19 recordsLinked to original sources

PubMed1992

The effect of light adaptation on scotopic spatial summation in 10-week-old infants.

Psychophysical area-intensity functions of individual 10-week-old human infants and adults were obtained in the dark adapted state, and in the presence of a steady background that elevated threshold 1 log unit above the dark adapted level. For dark adapted infants, the mean diameter for complete spatial summation (4.42 degrees; SD: 1.67 degrees) was significantly larger than that of adults (2.32 degrees; SD: 0.09 degrees). The background reduced the mean critical diameter to 2.67 degrees for infants (SD: 0.64 degrees) and to 1.16 degrees for adults (SD: 0.08 degrees). Spatial probability summation has similar effects on infant and adult thresholds, and, therefore, does not appear to account for the developmental decrease in critical diameters. Rather, decreases in receptive field size are suspected.

Adaptation, Ocular↗

PubMed1992

Effects of halothane on children's electroretinograms.

BACKGROUND: At times, anesthesia is necessary to test children's electroretinographic (ERG) responses. Halothane, an anesthetic commonly used for pediatric patients, affects some aspects of ERG responses, but it is unknown if halothane affects ERG parameters evaluated by contemporary clinical protocols. METHODS: Scotopic and photopic ERG responses were recorded from children when awake and then under halothane. RESULTS: Halothane has no effect on scotopic b-wave stimulus/response parameters, including amplitude, sensitivity, and implicit time. Scotopic a-wave amplitudes, implicit times, model parameters, and ratio of a- to b-wave amplitudes are unaffected by halothane. The amplitudes and implicit times of photopic responses to red flashes and 30 Hz flickering white light are not altered by halothane. Halothane causes no significant change in amplitudes and implicit times of the oscillatory potential wavelets. CONCLUSION: These results suggest that significant departures of ERG responses (studied with the protocol described herein) from a laboratory's normal values cannot be attributed to halothane.

Adolescent↗

PubMed1992

Imaging of regional spread of breast cancer by internal mammary lymphoscintigraphy, CT, and MRI.

Forty women with breast cancer underwent imaging by internal mammary lymphoscintigraphy (IMLS), which was correlated with the results of CT and MRI of the chest. IMLS was performed and interpreted using the previously described methods of Ege. It identified 22 instances of ipsilateral internal mammary nodal involvement, none of which corresponded to cases of abnormally enlarged (diameter greater than 1.0 cm) internal mammary nodes on CT and/or MRI. Positive IMLS was associated with axillary nodal metastases in 15 out of 22 instances. The authors conclude that IMLS provides information on regional nodal spread of breast cancer that is not available with either CT/MRI imaging or axillary biopsy.

Antimony↗

PubMed1992

Periocular lymphoproliferative diseases: natural history, prognostic factors, and treatment.

A study was undertaken to assess the natural history of periocular lymphoproliferative diseases, identify key prognostic factors, and clarify the role of orbital irradiation. Thirty-four patients with periocular lymphoproliferative disease were treated with orbital irradiation between 1975 and 1990. Eight patients had atypical lymphoid infiltrate, and 26 had malignant lymphoma. Forty-three eyes were irradiated with en-face electrons or 6-MV photons. Five-year disease-free survival for all stages was 65%; it was not significantly affected by bilaterality or site. Stage, distinction between atypical lymphoid infiltrate and malignant lymphoma, and working formulation grade were important prognostic indicators. A complete response during irradiation was achieved in 24 of 43 (56%) eyes at a median dose of 2,400 cGy, and a partial response was achieved in 19 (44%), with resolution at a median of 2.8 months. Patients with periocular reactive lymphoid hyperplasia or atypical lymphoid infiltrate may have or are at significant risk of developing lymphoma and dissemination. Local treatment remains important; orbital irradiation achieves prompt local control with acceptable morbidity.

Adult↗

PubMed1992

The rod sensitivity of dark adapted human infants.

The determinants of infants' low scotopic visual sensitivity are controversial. Some interpret infants' scotopic vision as indicative of immature rod photoreceptor function while others attribute infantile sensitivities mainly to post receptoral immaturities. To date the rod photoreceptor sensitivity of human infants has not actually been measured. In the work reported herein, electroretinographic a-wave responses, which represent the rod photoresponse, were recorded from dark adapted 10-week old infants and adult control subjects. Rod isolated a-waves indicate that 10-week-old infants' rods are less sensitive than adults'. Thus, any explanation of infants' scotopic visual sensitivity must take into account this fundamental property of infants' rods, low sensitivity.

Adult↗

PubMed1992

Current status of interferons in the treatment of cancer.

Interferons produced by recombinant DNA technology began phase I trials little more than a decade ago. Today interferon alfa-2 is a mainstay in the treatment of hairy cell leukemia, and has demonstrated benefit in the more common chronic myelogenous leukemia. Interferon alfa-2 also has activity in other hematologic malignancies, including indolent non-Hodgkin's lymphomas, cutaneous T-cell lymphomas, T-cell lymphoma, and multiple myeloma, and in solid tumors such as disseminated melanoma, renal cell carcinoma, Kaposi's sarcoma, endocrine pancreatic tumors, and malignant carcinoid tumors. Interferon alfa, beta, and gamma remain under investigation to define potential roles in ovarian, breast, bladder, and cervical carcinomas and gliomas. The greatest value of the interferons will be in prolonging the disease-free interval when used in combination with other treatment modalities, including surgery, radiation, chemotherapy, and other biologic agents.

Combined Modality Therapy↗

PubMed1991

Twice-daily tapering dexamethasone treatment during cranial radiation for newly diagnosed brain metastases.

Twenty evaluable patients with newly diagnosed brain metastases underwent treatment with a novel dose/schedule of dexamethasone aimed at reducing steroid toxicity during palliative radiation therapy. All patients received twice daily dexamethasone starting at 8 mg bid for four days then 4 mg bid for four days then 2 mg bid until the last day of radiation therapy. The radiation prescriptions were not standardized varying from 2000 cGy/5 fractions to 5800 cGy/29 fractions. Fourteen patients received dexamethasone for a minimum of 24 hours before their first radiation treatment and 7 (50%) experienced improvement in neurologic symptoms/signs prior to starting radiation treatments. Fourteen patients completed the planned course of radiation and dexamethasone. Only 1 patient needed to restart dexamethasone within 30 days of finishing radiation because of steroid reversible neurologic deficits. Steroid toxicity was mild including hyperglycemia (1), candida esophagitis (1), steroid pseudorheumatism (2), peripheral edema (1) and steroid withdrawal syndrome (1). Only two toxic events were recorded in patients receiving steroids less than 21 days. Twice daily dexamethasone appears to provide good clinical results with minimal morbidity.

Administration, Oral↗

PubMed1991

Skeletal size and bone mineral content in Turner's syndrome: relation to karyotype, estrogen treatment, physical fitness, and bone turnover.

Bone mineral content (BMC), bone mineral density, and metacarpal dimensions were studied in 50 women with Turner's syndrome aged 21-45 years in relation to karyotype, estrogen treatment, physical fitness, and biochemical markers of bone turnover. No differences were found between the 25 women with karyotype 45.X and women with other karyotypes. Forty-six women had received estrogen. Significant partial correlations were found between bone mineral density of the forearm and duration of estrogen treatment and physical fitness. BMC of the lumbar spine corrected for vertebral height (BMC(C)spine) was directly correlated with duration of estrogen treatment and height, marginally correlated with physical fitness, and inversely correlated with age. Outer metacarpal width was positively correlated with duration of estrogen treatment, age at initiation of therapy, and body weight. The diameter of medullary space showed negative correlation with physical fitness and height, and positive correlation with age at initiation of estrogen treatment. Cortical thickness was positively correlated with duration of estrogen treatment, physical fitness, and height. No convincing effects of estrogen could be demonstrated in women below the age of 30. Above the age of 30, all bone mineral measurements were markedly elevated in women treated for longer than the average of this age group. BMC(C)spine was inversely correlated with biochemical markers of bone formation. Our results demonstrate that estrogen treatment and physical fitness are important determinants of bone mineral status in Turner's syndrome and add to the evidence that estrogen treatment increases BMC in Turner's syndrome.

Adult↗

PubMed1991

Dark adapted thresholds in young RCS rats.

The dark adapted thresholds of black-eyed RCS rats and cogenic controls were measured using a new psychophysical procedure that permits determination of thresholds at earlier ages than previously possible. Rats were tested longitudinally between about ages 1 and 3 months. At all ages, thresholds of RCS rats were higher than those of controls. Thresholds did not change systematically with age for either RCS rats or controls. At age 3 months, when the RCS rats' b-wave is no longer recordable, RCS thresholds are about 2.2 log units higher than those of controls.

Aging↗

PubMed1991

Temporal summation in dark-adapted 10-week old infants.

The effect of stimulus duration on the b-wave and psychophysical responses of dark-adapted 10-week-old infants and adult control subjects is reported. Both infant and adult b-wave sensitivities vary with stimulus duration, show summation for brief duration stimuli, critical durations estimated at 88-155 msec, and little variation in sensitivity for longer durations. There are however, substantial differences between the infant and adult psychophysical temporal summation functions. The infant function is described by a straight line, slope about -0.5, across all flash durations while adults show summation at durations less than 100 msec and critical durations of 136 to 151 msec. Adult, but not infant, b-wave integration times and b-wave rise and fall times show duration-dependent changes. Thus, both ERG and psychophysical measures demonstrate immaturities in the rod mediated function of the infant retina.

Adult↗

PubMed1991

Electroretinographic assessment of background adaptation in 10-week-old human infants.

Full field, scotopic b-wave stimulus/response functions of 10-week-old infants and adults were measured in the dark-adapted condition, and in the presence of steady backgrounds. Dark adapted b-wave sensitivity (log sigma) differed significantly between infants and adults; the median dark adapted sensitivity of infants was 0.50 log unit less than that of adults. The median eigengraus of infants (-1.32 log scot. td) and adults (-1.55 log scot. td) did not differ significantly. The median slope of the linear portion of the background adaptation function was about 0.9 for infants and adults. These results argue for post-receptoral immaturities, but do not rule out receptoral immaturities.

Adaptation, Ocular↗

PubMed1991

Continuous 5-fluorouracil infusion and alpha interferon in advanced cancers: a report of initial treatment results.

Twenty-four patients with advanced metastatic cancer were treated with continuous intravenous 5-fluorouracil infusion 200-300 mg/m2/day and alpha interferon 3 million units subcutaneously 3 times per week. The average duration of treatment was 87 days (range 22-204 days). 5-fluorouracil could be infused 66% of the planned time on treatment, and patients received an average of 60% of the planned interferon injections. Objective tumor responses were seen in 6 of 17 previously untreated patients (35%). Twenty-two of the 24 patients (92%) experienced toxicity (greater than or equal to ECOG grade II) that required treatment interruption and subsequent dose reduction predominantly for the following reasons: mucositis (67%), hand-foot syndrome (21%), and leukopenia (25%). The incidence of treatment limiting toxicity is higher than previously observed with 5-fluorouracil infusion alone. This suggests true augmentation of 5-fluorouracil effect by interferon. 5-Fluorouracil infusion and alpha interferon is a potentially useful combination that needs further evaluation in future phase II and phase III trials.

Adult↗

PubMed1991

Allogeneic bone marrow transplantation for relapsed and refractory lymphoma using genotypically HLA-identical and alternative donors.

Twenty-two patients, ages 16.6 to 43.9 years (median age, 30 years), with relapsed or refractory lymphoma were treated by allogeneic bone marrow transplantation after high-dose chemotherapy with or without total body irradiation (TBI). Seven patients had Hodgkin's disease, four had low-grade histology non-Hodgkin's lymphoma (NHL), seven had intermediate-grade NHL, and four had high-grade NHL. Of the 22 patients, 17 received T-cell (CD-3)-depleted marrow after intensive pretransplant chemoradiotherapy, and five received T-cell-replete grafts after chemotherapy-based preparative regimens. Five patients were transplanted from donors other than genotypically HLA-identical siblings: four from partially HLA-matched relatives, and one from a phenotypically HLA-identical unrelated donor. Acute graft-versus-host disease (GVHD) was less than or equal to grade II in all patients, and chronic GVHD was limited or absent in all but one patient. Of the 21 assessable patients, 17 (80.9%) achieved complete remissions. Death due to transplant-associated complications occurred in five patients, and five patients have relapsed. Thirteen patients are alive, and 12 are continuously relapse-free at a median follow-up of longer than 28 months (range, greater than 10 to greater than 58 months) from transplant. The cumulative probability of treatment failure from relapse or progression of lymphoma was 29% (95% confidence interval [CI], 12% to 51%), while the actuarial lymphoma-free (ie, event-free) survival plateau is 54.6% (95% CI, 34% to 76%). For young patients with advanced malignant lymphoma, allogeneic bone marrow transplantation appears superior to salvage chemotherapy for achievement of long-term, lymphoma-free survival and may be preferable to autologous bone marrow transplantation for selected patients.

Actuarial Analysis↗

PubMed1991

The quantity of rhodopsin in young human eyes.

The rhodopsin content of 20 eyes of infants and children ages 27 weeks gestation to 8 years (11 donors) was assayed and compared to the rhodopsin content of adults (36 eyes; 19 donors). Infants have significantly lower rhodopsin contents than adults. On average the rhodopsin content of young infants is about a third of adults. Previously reported full-field b-wave sensitivity of young infants is about 0.5 log units, that is about a third, less than adults. Thus, as previously found in infant rats, photon capture by rhodopsin appears to limit the dark adapted sensitivity of young human infants.

Adolescent↗

PubMed1991

Protracted intravenous infusion of 5-fluorouracil in combination treatments. A review.

5-fluorouracil (5-FU) administered by protracted intravenous infusion has been shown to have clinical utility against colorectal cancer and several other advanced tumors. However, additional therapeutic strategies are needed to further improve treatment results. Although the addition of low-dose cisplatin appeared to improve the clinical activity of 5-FU infusion in early phase II studies, subsequent evaluation has failed to substantiate these early reports. In addition, toxicity has been significantly increased. Combinations of cisplatin and other drugs with 5-FU infusion are currently being evaluated. Phase I studies demonstrate that only low doses of concomitant leucovorin are necessary to potentiate 5-FU infusion; phase II studies to evaluate efficacy are underway. Although combinations of 5-FU and biological therapies such as alpha 2a-interferon appear to be very promising, they will require extensive phase II and III testing to define their clinical utility and toxicity.

Antineoplastic Combined Chemotherapy Protocols↗

PubMed1991

5-Fluorouracil by protracted venous infusion: a review of recent clinical studies.

The pharmacokinetics of continuous infusion 5-fluorouracil make it an ideal drug to administer as a protracted infusion (continuous infusion more than 30 days). During the last decade numerous clinical studies have been conducted to evaluate the efficacy of 5-fluorouracil (5FU) administered as a protracted venous infusion. Phase II studies in metastatic colorectal cancer in 345 patients have demonstrated an average response rate of 36% (range 15-59%) and a prospective randomized study performed by the Mid-Atlantic Oncology Program (MAOP) has confirmed a higher response rate with 5FU infusion compared with a bolus schedule. Phase II studies in refractory carcinoma of the breast in 177 patients have demonstrated a 30% response rate (range 17-50%); studies in pancreatic, gastric, and refractory prostate cancer have also demonstrated clinical utility. The major toxicities of 5FU infusion are mucositis and hand-foot syndrome; life-threatening myelosuppression is rare and treatment-related deaths have not been reported. 5FU infusion is a useful palliative treatment for many adult patients with advanced malignancies.

Antineoplastic Combined Chemotherapy Protocols↗

PubMed1991

Gold induced hepatitis and pure red cell aplasia. Complete recovery after corticosteroid and N-acetylcysteine therapy.

A 54-year-old man developed severe cholestatic jaundice and pure red cell aplasia shortly after beginning treatment with gold sodium thiomalate. Although the hepatic toxicity began to spontaneously improve, the pure red cell aplasia was progressive. Treatment with prednisone and N-acetylcysteine (NAC) infusions was followed by prompt and complete hematologic recovery. Gold induced pure red cell aplasia should be added to the list of gold induced hematologic toxicities that can be potentially reversed with NAC infusion therapy.

Acetylcysteine↗

PubMed1990

Hyperopia in complicated Leber's congenital amaurosis.

We studied the refractive status of 13 children with Leber's congenital amaurosis. Seven had the disease complicated by neurological or other systemic abnormalities, while the other 6 patients had only ophthalmic abnormalities. All 13 patients were hyperopic. The magnitude of hyperopia did not differ significantly between the complicated and uncomplicated groups. Therefore, one cannot, as previously suggested, use the presence of high hyperopia to differentiate an uncomplicated form of Leber's congenital amaurosis from one complicated by neurologic or other systemic abnormalities. The concurrence of hyperopia with Leber's congenital amaurosis should not steer the physician away from careful neurologic systemic or biochemical evaluation of the child.

Age Factors↗