Biomedical subjects

K Yuen

Publications and source records attributed to K Yuen.

At least 55 records · Page 3Linked to original sources

PubMed1991

Factors influencing 20-hour increments after platelet transfusion.

The 20-hour posttransfusion platelet count determines transfusion policy for patients requiring platelet support, and yet factors influencing the 20-hour count have been poorly defined. The clinical factors influencing both the 1- and 20-hour corrected count increment (CCI), were studied in 623 human leukocyte antigen (HLA)-unmatched platelet transfusions in 108 patients. The 1- and 20-hour CCIs were highly correlated (r = 0.67, p less than 0.001). On average, the 20-hour CCI was 64 percent of the 1-hour CCI. Multiple linear regression analyses identified splenectomy, bone marrow transplantation, disseminated intravascular coagulation, administration of amphotericin B, palpable spleen, and HLA antibody grade as the major factors influencing the 20-hour posttransfusion CCI. Platelet-specific antibodies, number of concurrent antibiotics, clinical bleeding, and temperature did not significantly influence the 20-hour posttransfusion CCI. The 1-hour CCI was the only significant factor influencing the 20-hour CCI in a regression model containing the 1-hour CCI and the above factors. Thus, the same clinical factors exert a major influence on the CCI at both 1 and 20 hours after platelet transfusion, with no evidence that any factor has more influence at 20 hours after transfusion than at 1 hour.

Blood Platelets↗

PubMed1990

Etoposide, carboplatin, cyclophosphamide and vincristine in previously untreated patients with small-cell lung cancer.

The efficacy and toxicity of 120 mg/m2 etoposide and 100 mg/m2 carboplatin given i.v. daily x 3 together with 750 mg/m2 cyclophosphamide and 1.4 mg/m2 vincristine given i.v. on day 1 (ECCO) in a regimen given every 28 days for 6 courses was assessed in 90 (40 limited stage, 50 extensive stage) previously untreated patients with small-cell lung cancer. Mediastinal irradiation using 50 Gy in 25 fractions was given to limited-stage patients without progression after 3 courses of chemotherapy. Cranial irradiation with 30 Gy in 10 fractions was given to all patients attaining a complete response (CR). Objective responses were seen in 83% [CR, 60%; partial response (PR), 23%] of patients with limited and 76% (CR, 22%; PR, 54%) of those with extensive disease. The median relapse-free survival for objective responders with limited disease was 13.4 months, with a median of 8.0 months for extensive-stage patients. The median relapse-free survival for patients achieving a CR was 13.4 months, with a median of 7.8 months for those undergoing a PR. The median survival was 13.3 months for patients with limited disease, with a median of 9.6 months for those with extensive disease. The median survival following a CR was 18.2 months, with a median survival of 9.9 months for those showing a PR. The combination was well tolerated, with either no nausea or nausea only (WHO grade 0 or 1) in 56% of patients and minimal mucositis, renal toxicity, neurotoxicity or ototoxicity. Neutropenia measuring less than 1.0 x 10(9) WBC/l (WHO grade 3 or 4) was seen in 74% of patients, with two deaths due to infection occurring during neutropenia. Thrombocytopenia of less than 50 x 10(9) platelets/l (WHO grade 3 or 4) occurred in 24% of patients. ECCO is a new, active, well-tolerated program for previously untreated patients with small-cell lung cancer.

Adult↗

PubMed1989

A randomized trial of cisplatin versus cisplatin plus methotrexate in advanced cancer of the urothelial tract.

One hundred eight patients with recurrent or metastatic transitional cell carcinoma of the urothelial tract were randomized to receive cisplatin (C) 80 mg/m2 on day 1 every 4 weeks, or methotrexate (M) 50 mg/m2 on days 1 and 15 plus C 80 mg/m2 on day 2 every 4 weeks (C + M). Fifty-three eligible patients were randomized to C + M and 55 to C. In the C + M arm, 45% of patients responded (complete response [CR], 9%) and 31% (CR, 9%) in the C arm (P = .18). In the C arm, 20 patients failing or relapsing after C received M. Two patients responded, and four with progressive disease (PD) and one with a previous partial response (PR) showed no change. The median survival was 8.7 months (C + M arm) and 7.2 months (C arm), P = .7. Relapse-free survival was not significantly different, but C + M was associated with a significantly increased time to disease progression (median, 5.0 months, v 2.8 months for C arm). The response of untreated patients (37%) was not different from those with prior treatment (39%). On the C + M arm, 92% of patients and 96% of patients on the C arm received 85% or more of the scheduled C dose. Significantly more grade 3 or 4 hematological toxicity (27% v 2%; P = .01) and mucositis (20% v 0%; P = .0005) occurred in patients on the C + M arm. Although the initial response rates seen on the combination arm look superior, and the time to disease progression is increased, these effects have not translated into a clinically important increase in the duration of survival and were associated with increased toxicity.

Adult↗

PubMed1989

Cytologic diagnosis of the maxillary sinus reevaluated.

Preoperative cytologic diagnosis of the maxillary sinus was performed on 57 patients by examining of solutions obtained by local washing following sinus puncture. There were 6 cases of cancer (5 squamous cell carcinomas and 1 adenoid cystic carcinoma), 1 malignant melanoma, 1 odontoma, 8 aspergillosis, 1 inflammatory pseudotumor, 9 odontogenic maxillary sinusitis and conventional chronic sinusitis in residual cases. There were 2 false-negative cytologies in the 7 cases of malignant tumor (i.e., 1 adenoid cystic carcinoma and 1 squamous cell carcinoma). The significance and usefulness of the cytologic approach to preoperative diagnosis of malignancies, including malignant melanoma and fungal infection were discussed.

Adolescent↗

PubMed1988

Clinical factors influencing the efficacy of pooled platelet transfusions.

To determine the relative importance of clinical factors on the efficacy of platelet transfusions, 941 pooled platelet transfusions from HLA-unmatched donors were studied prospectively in 133 patients with bone marrow failure. Multiple linear regression analyses identified the major factors influencing one-hour-corrected increments (CI) as prior splenectomy, bone marrow transplantation, disseminated intravascular coagulation, concurrent intravenous amphotericin B, splenomegaly, and HLA antibody grade. The relative impact of these factors on CI has been quantitated by using a formula developed from these data. A linear relationship was demonstrated between increasing percentage of HLA antibody grade and decreasing CI. A number of other factors were less important in the linear regression model than the aforementioned major factors. These included platelet-specific antibodies, concurrent antibacterial antibiotics, clinical bleeding grade, and temperature. Factors that did not influence CI included the number of prior platelet transfusions, prior granulocyte transfusions, prior red cell transfusions, infection, age, blood group, diagnosis, sex, pretransfusion platelet count, prior pregnancies, and concurrent antineoplastic drugs. This study identified major clinical factors that significantly influenced CI and were major causes of refractoriness to pooled platelet transfusions.

Antibodies↗

PubMed1987

Carboplatin (CBDCA, JM-8) and VP-16-213 in previously untreated patients with small-cell lung cancer.

The efficacy and toxicity of carboplatin 100 mg/m2, administered intravenously (IV) daily X 3, and VP-16-213 120 mg/m2, IV daily X 3, administered every 28 days for six courses, was assessed in 94 (36 limited stage, 58 extensive stage) previously untreated patients with small-cell lung cancer. Mediastinal irradiation using 50 Gy in 25 fractions was given to all limited-stage patients with a complete (CR) or partial response (PR) after three chemotherapy courses. Cranial irradiation was administered to all patients with CR. Objective responses were seen in 77% (CR 40%, PR 37%) of patients with limited-stage and 58% (CR, 9%; PR, 49%) with extensive-stage disease. Median relapse-free survival for objective responders with limited stage was 14.6 months and 7.9 months for extensive-stage patients. Median relapse-free survival following CR was 15.4 months and 8.5 months for PR. Median survival was 15.3 months for limited-stage and 8.1 months for extensive-stage patients. The combination was well tolerated with mild nausea or less (World Health Organization [WHO] grade 0 or 1) in 62% of patients and minimal mucositis, renal, neurotoxicity, or ototoxicity. Neutropenia less than 1.0 X 10(9)/L (WHO grade 3 or 4) was seen in 63% of patients, with two deaths from infection while neutropenic. The combination of carboplatin and VP-16-213 is a new, active program with low toxicity when applied intensively in previously untreated patients with small-cell lung cancer.

Adult↗

PubMed1987

Serum osteocalcin and total body calcium in normal pre- and postmenopausal women and postmenopausal osteoporotic patients.

Serum osteocalcin was measured in 51 normal pre- and 114 postmenopausal women and in 41 postmenopausal osteoporotic patients. Total body calcium (TBCa) was determined in the same individuals by neutron activation analysis. Many of the perimenopausal nonosteoporotic women had increased serum osteocalcin values, but 15 yr or more after the menopause most of the women had serum osteocalcin levels in the normal range. Comparing normal women before and after menopause, the mean serum osteocalcin levels [7.8 +/- 4.7 (+/- SE) and 10.1 +/- 9.4 ng/mL] were not significantly different; however, the TBCa values (898 +/- 99 and 806 +/- 111 g) were significantly different (P less than 0.001). When the normal postmenopausal women were regrouped according to high vs. low osteocalcin values, TBCa and phosphorus content as well as forearm linear bone density were significantly lower in the high osteocalcin group, even though most of the other variables, including urinary hydroxyproline excretion, serum alkaline phosphatase, age, height, and weight, were not different. Osteoporotic women had a mean serum osteocalcin concentration of 17.4 +/- 8.6 ng/ml and a TBCa of 657 +/- 83 g, both significantly different from the respective values in normal and pre- and postmenopausal women (P less than 0.001 for both variables in comparison to each group). These data suggest that high serum osteocalcin levels, at least on a group basis, are an index of low skeletal mass.

Body Constitution↗

PubMed1987

Randomized, double-blind, cross-over study comparing prochlorperazine and lorazepam with high-dose metoclopramide and lorazepam for the control of emesis in patients receiving cytotoxic chemotherapy.

To further define optimal combinations of antiemetics, high-dose metoclopramide and lorazepam (M+L) were compared with prochlorperazine and lorazepam (P+L) in a randomized, double-blind, cross-over study. Both patient and observer assessments were documented in 66 patients receiving cisplatin and noncisplatin chemotherapy. M+L significantly reduced the severity of vomiting (P = 0.01), duration of vomiting (P = 0.05), and number of vomiting episodes (P = 0.003). Comparing the severity or duration of nausea, M+L and P+L were not significantly different. M+L significantly reduced severity of vomiting (P = 0.005) and number of vomiting episodes (P = 0.03) in the cisplatin subset. The number of vomiting episodes was also reduced in the noncisplatin subset (P = 0.03). When asked to nominate a preferred regimen, 41% of patients preferred P+L, 35% preferred M+L, and 24% rated them equally. M+L was associated with significantly more anxiety and less sedation than P+L. Patient assessments produced similar results to observer assessments but gave a broader understanding of our patients' tolerance to chemotherapy. M+L is a superior regimen in controlling vomiting induced by chemotherapy.

Adult↗

PubMed1986

Women at risk for developing osteoporosis: determination by total body neutron activation analysis and photon absorptiometry.

With stepwise multiple logistic regression (MLR), probabilistic classification equations were developed to identify asymptomatic women who are at risk for development of fracture of the spine. Clinically normal women with low TBCa/square root H ratios can be classified as at risk for osteoporosis prior to their developing spinal compression fractures. With receiver operating characteristic (ROC) analysis, it was possible to verify the accuracy of the MLR model to discriminate "normal" women at risk, with high sensitivity and specificity. With the MLR model, discrimination of osteoporotic women (50-59 years) was made correctly for 86.2% of the total osteoporotic subjects with the TBCa data. Similar models were derived from the photon absorptiometry data. From the spinal density (BDs) data, correct classification in the 50-59 year group was 55.6% of the total osteoporosis subjects; from the radius density (BMCr) data, the corresponding value was 31%. The highest probability of identifying osteoporosis in all age categories was, therefore, on the basis of TBCa data. Similar, but less accurate discrimination was achieved with the BDs and BMCr data. These conclusions were confirmed by the application of receiver operating characteristic (ROC) analysis. Correct identification of the population at risk permits the timely and efficient application of therapeutic programs prior to onset of fracture. In a serial study of 104 peri-menopausal women, for example, it was possible to determine the P value for individuals measured annually over a 3-10 year period and thus to predict normal individuals at risk for developing osteoporosis each year.

Age Factors↗

PubMed1985

Risk factors for postmenopausal osteoporosis.

Fifty-eight women with postmenopausal osteoporosis (crush fracture of the spine) were compared with 58 age-matched normal women. The osteoporotic women had lower total-body calcium levels and bone mineral content of the radius, had undergone an earlier menopause, smoked cigarettes more, and had breast-fed less often. They also had lower levels of estrone, estradiol, and testosterone and reduced levels of 25-hydroxyvitamin D, 24,25-dihydroxyvitamin D, and 1,25-dihydroxyvitamin D. These findings suggest the presence of changeable risk factors for the development of osteoporosis. Smoking should be discouraged. An adequate intake of calcium and vitamin D should be ensured. It is the opinion of the authors that those women who have had an early menopause or who have a low bone mass at the time of menopause should be given the choice of medically supervised replacement therapy with estrogen and progesterone.

Bone and Bones↗

PubMed1985

Assessment of cellular mass and lean body mass by noninvasive nuclear techniques.

With the nuclear techniques employed in this study, it has been possible to measure total body potassium (TBK), lean body mass (LBM), and body cell mass (BCM). The latter two are derived independently of TBK. LBM is derived from the sum of total body water (TBW), total body protein, and bone mineral ash measurements. The BCM value is, in turn, based on the difference between the LBM (as measured above) and the sum of the extracellular water and extracellular solids. It was demonstrated in 123 normal individuals that, although the TBK/LBM ratio decreases with age, the TBK/BCM ratio does not change significantly with age. It can be deduced that the ratio of TBK to intracellular water should be relatively constant with age. This relative constancy with age was demonstrated independently with the absolute measurements of TBK and intracellular water in normal individuals. Because the BCM is physiologically and chemically more homogeneous than LBM and because it reflects the actively metabolizing cellular compartment more accurately than LBM, it is the preferred parameter to be used for reference or normalization in body composition studies. For most applications, BCM is readily derived from TBK measurement by either whole body counting or isotope dilution techniques.

Adult↗

PubMed1985

A model for involutional bone loss.

Bone mass of the total skeleton and distal radius were measured by in vivo neutron activation analysis and single photon absorptiometry, respectively, in 403 healthy white women and 151 healthy white men. In addition, the density of L-2 to L-4 (bone mineral content of the spine [BMCs]) was measured by dual photon absorptiometry in 159 of these women and in 56 women with the vertebral crush fracture syndrome. The rate of loss of total body calcium (TBCa) and bone mineral content of the radius (BMCr) was linear in men and was slower than in women. The best fit for TBCa and the bone mineral content of the distal radius and spine as a function of age in women was with a two-phase regression. The TBCa and BMCr could be used as well as BMCs to identify women with crush fractures. The ratios of BMCs/TBCa, BMCs/BMCr, and TBCa/BMCr did not differ among women with crush fractures and age-matched normal individuals. Our data do not support the hypothesis that women with vertebral crush fractures have preferential loss of spinal bone.

Adult↗

PubMed1984

Dose-response analysis of cadmium in man: body burden vs kidney dysfunction.

The primary objective of this study was to develop dose-response relationships of cadmium in human beings. In vivo measurements of kidney, liver, urine, and blood cadmium, and urinary levels of beta 2-microglobulin and total protein were obtained in 82 industrially exposed workers and 30 control subjects. The values of 200 micrograms/g creatinine for urinary beta 2-microglobulin and 250 mg/g creatinine for urinary total protein were used to define the upper limit for normal kidney function. Forty-one of the cadmium workers (18 active, 23 retired) were classified as having abnormal kidney function; all control subjects had normal kidney function. Most workers with Cd above 70 ppm in the liver were judged to have some evidence of kidney abnormalities. The dose-response relationship for liver cadmium for the actively employed workers could be described by a linear logistic regression model: (Formula: see text) where p is the individual's probability of having kidney dysfunction. The loss of cadmium from the kidney following dysfunction prohibited a direct logistic analysis of the kidney cadmium data. However, when the linear relationship between kidney and liver cadmium for the subjects with normal kidney function was combined with the logistic equation for the liver, a predicted-response curve was obtained for the kidney. The logistic models predict a 50% probability of having kidney dysfunction at 38.4 mg for the kidney and 42.3 ppm for the liver, respectively.

Body Burden↗

PubMed1984

Improved models for determination of body fat by in vivo neutron activation.

In the present study, two different models of body composition, based on data obtained by nuclear techniques are used. Total body nitrogen, calcium, and chlorine were obtained by total body neutron activation. Total body chlorine was used to estimate extracellular water, and total body calcium to determine bone mineral and extracellular solids. Total body potassium was measured by whole body counting to obtain the body cell mass. In addition, total body water was measured by the tritium dilution technique. It was found that either model can be used equally well to measure total body fat in normal subjects. Estimation of body fat as the difference between body weight and the sum of total body nitrogen (protein), total body water, and bone ash (model 1) appears to have an advantage over model 2, which uses body cell mass, extracellular water, and extracellular solids, particularly for patients with metabolic disorders. This advantage is partly due to the fact that the parameter protein (total body nitrogen) is less affected in metabolic disorders than the more labile total body potassium. The closely correlated results obtained with the two models based on nuclear measurements support the conclusion that these techniques provide reliable measurements of total body fat.

Adipose Tissue↗

PubMed1984

Application of moiré topography to mantle treatment.

We believe moiré topography is a particularly suitable technique for establishing contours on patients receiving mantle treatment. We derive the fundamental moiré equation from a novel, but simple, consideration of moiré phenomena. Our apparatus is designed to give a difference in height of approximately 1.0 cm between successive moiré fringes. Using an inclined plane test object, an accuracy of better than 3 mm is obtained.

Anthropometry↗

PubMed1977

Analysis of the systemic corticosteroid sensitivity of patients with primary open-angle glaucoma.

Patients with primary open-angle glaucoma have an ocular and systemic sensitivity to corticosteroids. We adapted a cellular assay that used peripheral blood lymphocytes to detect this corticosteroid sensitivity in vitro in a microtiter assay. It reduced the time, cost, and amount of blood required to examine a patient. We examined ten subjects on three separate days and demonstrated that the reliability of one 50% inhibitory concentration was about 76%. We then studied 25 patients with primary open-angle glaucoma and 25 control subjects using this in vitro assay. The patients with primary open-angle glaucoma were significantly more sensitive to corticosteroids than the control subjects (P less than .001).

Administration, Topical↗

PubMed1977

Sunlight and cataract: an epidemiologic investigation.

Cataract prevalence data from two large U.S. sources were divided according to small geographic areas for which average annual sunlight hours were determined from a map prepared by the U.S. Weather Bureau. Several non-cataract disease controls were chosen from the same geographic locations (separately for each data set). It was found that the cataract-to-control ratios for persons aged 65 years or older were significantly larger in locations with large amounts of sunlight compared to those in locations with small amounts (P less than .05). Discussion of some possible biases in the data leads to the conclusion that the biases, if they exist, are probably not large. The authors believe, however, that more research should be done before the association between sunshine and cataract is considered established.

Aged↗

PubMedDate not supplied

A differential method for inhomogeneity correction on dose in a photon beam.

For a uniform slab of inhomogeneity in a supervoltage beam, correction factors can be calculated from the Batho equation. In this report, we present a method for calculating the effect of an annular inhomogeneity, concentric about the beam axis, upon the dose at a point on the axis and below the annulus. A derivation of the equation required in the calculation for supervoltage radiation is given. Results from measurements made in 60Co beams for polystyrene foam, cedar, and aluminum annuli, all having 3.0 x 2.0 cm2 in cross section but with different inside diameters, are compared with correction values calculated by the method. For situations where the annulus is just submerged in the phantom, measured and calculated values are in good agreement. For a general situation, two calculation types are proposed and the data show that in general the measured scatter perturbation lies between the calculated values of the two types. Application of our technique predicts a sign reversal in the scatter perturbation due to an inhomogeneity. This reversal has previously been observed and reported and is also demonstrated in our measurements.

Cobalt Radioisotopes↗