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PubMed2003

Comparison of urea reduction ratio and hematocrit data reported in different data systems: results from the Centers for Medicare & Medicaid Services and the Renal Network Inc.

BACKGROUND: Urea reduction ratio (URR) and hematocrit values reported on the Centers for Medicare & Medicaid Services (CMS) claims were compared with data from two different databases. METHODS: URRs and hematocrits from two different CMS databases (National Claims History and End-Stage Renal Disease Clinical Performance Measures [CPM] Project) and one Network database (The Renal Network Data System [TRNDS]) were compared for October through December 1998 and December 1998, respectively. A sample of records from the regional database was validated by independent chart review. RESULTS: Nationally, the percentage of agreement for patients with URRs of 65% or greater and less than 65% was 94% (kappa, 0.81; 95% confidence interval [CI], 0.80 to 0.83); regionally, the percentage of agreement was 95% (kappa, 0.85; 95% CI, 0.84 to 0.86). Nationally, linear regression of hematocrit values from both data sources yielded r(2) congruent with 0.61 each month and r(2) = 0.70 for average values during the 3-month study period. Nationally, the percentage of agreement for patients with hematocrits of 33% or greater and less than 33% was 84% (kappa approximately 0.66) each month. Regionally, linear regression of monthly hematocrit values from both data sources yielded r(2) = 0.66, and percentage of agreement for patients with hematocrits of 33% or greater and less than 33% was 87% (kappa, 0.71; 95% CI, 0.70 to 0.73). Validation of a sample of records in the TRNDS database resulted in 98% agreement for patients with URRs of 65% or greater and less than 65% and 96% agreement for patients with hematocrits of 33% or greater and less than 33%. CONCLUSION: Although there is general agreement between clinical variables submitted on the claims and in the CPM Project, some variation exists. Data from either source yield the same information when classifying patients as above or below threshold values.

Anemia↗

PubMed1987

The effect of pH and concentration on the rates of kill of benzoic acid solutions against E. coli.

Mathematical models were developed which related benzoic acid concentrations to their D-values at room temperature. Linear regression was used to determine D-values (i.e. the time required for a particular concentration of preservative at specified pH, temperature and medium to cause a 90% reduction in the number of viable organisms, e.g. Escherichia coli. A number of concentrations of benzoic acid at either pH 3 or pH 4 were used. Linear regression of the log D-values versus the log of the concentration was used to derive power curves (a minimum of four points per pH were examined). Concentration exponents, eta-values (the logarithmic values relating changes in rates of kill to specified changes in concentrations) and A-values (extrapolated D-values at 1% concentration), were determined. The effect of pH on the eta and A-values of benzoic acid on E. coli was investigated. Benzoic acid was found to be more sensitive to pH changes than was anticipated from the Henderson-Hasselbalch equation which relates dissociated and undissociated fractions at the two pH levels investigated. However, the sensitivity of preservative activity to dilution at both pH values (3 and 4), as given by the eta-value, remained similar.

Anti-Infective Agents, Local↗

PubMed2001

Relation of acoustical parameters with and without audiences in concert halls and a simple method for simulating the occupied state.

Five acoustical parameters-reverberation time RT, early decay time EDT, clarity C80, strength G, and interaural cross-correlation coefficient IACC-were measured using identical procedures with and without audiences in six concert and opera halls. Reverberation times without audiences were measured in 15 additional halls using the same measuring techniques as for the six halls above, but for full occupancy the data were taken from musical stop chords at symphonic concerts. This paper shows that in all halls (1) the occupied RT can be predicted from the unoccupied RT using a linear regression equation, y = a - b exp(x), within acceptable limits, at low- and mid-frequencies. It is also shown for the six halls that (2) occupied C80's are predicted accurately from unoccupied values by the newly proposed equation; (3) G's with and without audiences are highly correlated by a first degree linear regression equation; and (4) IACCs have nearly the same value in both occupied and unoccupied halls. As a separate subject, the successful use of a cloth covering for seats in a concert or opera hall to simulate the occupied condition has been developed.

Acoustics↗

PubMedDate not supplied

Protein concentration of subcutaneous interstitial fluid in the human leg. A comparison between the wick technique and the blister suction technique.

The wick technique and the blister suction technique are the most common methods for sampling of subcutaneous interstitial tissue fluid in man. The blister suction technique has the advantage of being less invasive than the wick technique, but the reliability of this method is still controversial. The aim of this study was to evaluate whether the simpler blister suction technique using large (8 mm) blisters could replace the wick technique in the investigation of patients with postreconstructive leg edema. Fifteen patients with ipsilateral leg edema following infrainguinal bypass surgery for lower limb atherosclerosis were investigated. The two different fluid sampling techniques were applied simultaneously on both legs. The concentration of total protein and albumin as well as colloid osmotic pressure of the subcutaneous interstitial tissue fluid in the leg were measured in all fluid samples. Agreement analysis was applied to compare the two methods, while the correspondence between the methods was estimated with linear regression analysis. The agreement index was found to be positive for all variables from the operated as well as from the contralateral control limb. Furthermore, all values were within the agreement limit. The best agreement between the two methods was found for colloid osmotic pressure on the operated side. According to the equation of linear regression, there was a slight overestimation of the wick values compared to the observed blister values. In conclusion, there was a good methodological agreement between the blister suction technique and the wick technique. The less invasive blister suction technique should be regarded as the method of choice for the investigation of subcutaneous interstitial tissue fluid in patients with postreconstructive leg edema.

Aged↗

PubMed1984

The effect of prior cisplatin therapy on the pharmacokinetics of high-dose methotrexate.

The pharmacokinetics of high-dose methotrexate (MTX, 5-15 g/m2) were evaluated in 11 children and adolescents who had previously received two to eight doses of cisplatin (90 mg/m2) in the treatment of malignant solid tumors. The half-life for disappearance of MTX from serum during the first 24 hours after infusion was determined from serum samples obtained at the end of a six-hour infusion and six, 12, and 24 hours after infusion. These values were compared to a mean half-life of 2.83 (+/- 0.34) hours following 489 courses administered to 71 patients who had not received cisplatin. Stepwise multiple linear regression analysis of patient variables revealed cumulative cisplatin dosage and time from last cisplatin dose as the best predictors of MTX half-life (r2 = 65.4%, p less than 0.001). The best predictors of 24-hour serum concentration were cumulative cisplatin dosage and MTX dosage (r2 = 54.2%, p less than 0.001) in the multiple linear regression model. Patients with delayed MTX clearance received additional leucovorin and experienced no severe toxicity. Patients receiving up to 270 mg/m2 of cisplatin appear to have minimal increases in MTX half-life, while the likelihood of delayed clearance increases in patients who have received 360 mg/m2 or more of cisplatin. All patients who have previously received cisplatin should be treated cautiously with high-dose MTX and prospective pharmacokinetic monitoring should be routinely performed.

Adolescent↗

PubMedDate not supplied

[Evaluation of the potency of the allergen preparation Ambrosia elatior using a skin test and the inhibition radioallergosorbent test].

The total allergenicity of a pollen extract Ambrosia elatior was measured by quantitative prick test applied to the skin of seven highly sensitive patients and by standardized method of RAST-inhibition. Five 10-fold dilutions of the allergen concentration together with histamine hydrochloride 1 mg/ml (H1) were used. The induced wheal diametres for each concentration in per cent of the patient's own histamine wheal, were calculated. There was highly significant correlation (r = 0.9951) between the intensity of IgE mediated skin reactions and the IgE binding molecules in whole pollen extract. The concentration which provides the wheal equivalent to those of H1, found by linear regression analyses, was 54.9 micrograms/ml) in order to inhibit radioallergosorbent test with a pooled serum from the same patients, containing specific IgE antibodies against relevant allergens. Relevant allergen was a disk-allergen W1 (Pharmacia Diagnostics, Uppsala) The quantity of inhibition was proportional with allergen concentration (r = 0.9813). The concentration of 55.9 micrograms/ml, by linear regression analyses elicits inhibition of 50 per cent in RAST. It is concluded that quantitative prick test and histamine estimated skin sensitivity have a good clinical applicability in assessment of releaseability of skin mast cells, and together with RAST inhibition, provides the precise combined method for calibration of an allergenic extract potency.

Adolescent↗

PubMed2004

[Bioavailabilities of manganese sources based on heart manganese-containing superoxide dismutase gene expression for broilers].

OBJECTIVE: Two experiments were conducted to determine whether heart manganese-containing superoxide dismutase (MnSOD) gene expression could detect the differences in bioavailabilities of Mn sources more quickly, sensitively and constantly than other indices. METHODS: In experiment 1, a total of 546 day-old commercial male Arbor Acres (AA) broilers were randomly assign to each of thirteen treatments with six cage replicates according to a completely randomized design involving a 4 x 4 factorial arrangement. Each group of birds was fed Mn-unsupplemented corn-soybean meal basal diets (Control) or basal diets supplemented with 60, 120 or 180 mg/kg Mn as either Mn sulfate, Mn-Met E, Mn-AA B or Mn-AA C for 21 days. At 21 days of age, three birds from each cage were selected according to average bodyweight of the cage and killed. Heart and left leg were excised immediately. Mn concentrations in tissues, MnSOD activity and gene expression of MnSOD in heart were analyzed. In experiment 2, two hundred and seventy day-old AA commercial male broilers were randomly allotted to one of five treatments with six cage replicates in a completely randomized design, and fed a Mn-unsupplemented corn-soybean meal basal diet (Control) or the basal diet supplemented with 120 mg/kg Mn as each of the four Mn sources in experiment 1 for 21 days. The methods in experiment 1 were used to select and slaughter birds from each cage on the 7th, 14th or 21st day. The tissues were collected and analyzed as well. RESULTS: (1) In experiment 1, ash Mn content, heart Mn content, and MnSOD activity in heart mitochondria on the 21st day were affected (P = 0.0001) by dietary added Mn level. Based on slope ratios from multiple linear regressions of these three indices on dietary added Mn intake, the relative bioavailabilities of organic Mn sources did not differ from that of MnSO4 (P > 0.14). Heart MoSOD mRNA level on the 21st day was affected by both Mn source (P < 0.10) and Mn level (P = 0.0001). Based on slope ratios from the multiple linear regression of heart MnSOD mRNA level on dietary added Mn intake, if 100% was set for Mn sulfate, the relative bioavailabilities of organic Mn sources with weak, moderate, and strong chelation strengths were 99.0%, 132.3% and 112.7%, respectively. The organic Mn source with the moderate chelation strength was more available (P < 0.05) than Mn sulfate and organic Mn sources with the weak or strong chelation strengths; (2) In experiment 2, the seven day-old chicks fed on the diet supplemented with the organic Mn source with the moderate chelation strength showed a higher (P < 0.02) MnSOD mRNA level than those fed on the diets supplemented with Mn sulfate and the organic Mn source with the weak chelation strength, and the same tendency was observed on the 14th day or 21st day (P < 0.05). Ash Mn content and heart MnSOD activity were less sensitive in detecting the differences among Mn sources in bioavailability than MnSOD mRNA level. CONCLUSION: The results indicate that dietary Mn significantly affected heart MnSOD gene expression pretranslationally, and heart MnSOD mRNA level as early as on the 7th day could detect differences in bioavailabilities of Mn sources more quickly, sensitively and constantly than all other indices. There was a close correlativity between chelation strengths of these organic Mn sources and their relative bioavailabilities for broilers, in which the organic Mn source with the moderate chelation strength was the most available. The estimation of relative bioavailabilities of Mn sources based on heart MnSOD mRNA level could request a shorter time of experimental period and smaller number of animals, and thus could be a new method for a quick and effective assessment in bioassays of Mn sources for broilers.

Animal Feed↗

PubMed2001

Correlation between 8-methoxypsoralen bath-water concentration and photosensitivity in bath-PUVA treatment.

BACKGROUND: Bath-PUVA treatment, originally established in Scandinavia, offers several advantages over oral PUVA and has become increasingly popular in recent years. Outside Scandinavia 8-methoxypsoralen (8-MOP) is the prevailing photosensitizer for this PUVA modality and is used arbitrarily in a wide range of concentrations. Up to the present, data are lacking on the impact of 8-MOP bath-water concentration on UVA dosimetry. OBJECTIVE: We investigated the influence of increasing 8-MOP bath-water concentrations on photosensitivity in bath-PUVA treatment. METHODS: Fifteen healthy volunteers without abnormal photosensitivity or recent exposure to ultraviolet radiation were included in an intraindividually controlled comparison study. In all volunteers the minimal phototoxic dose (MPD) was determined on the volar side of their forearms after immersion for 20 minutes in 4 different 8-MOP bath-water concentrations (0.5, 1, 2.5, and 5 mg/L). The correlation between 8-MOP concentration and photosensitivity (defined as the reciprocal value of the MPD) was analyzed by linear regression analysis. In addition, the time course of erythema formation and the UVA dose-erythema response curve was assessed for each psoralen concentration. RESULTS: The median MPD and the 25%-75% interquartile were 5.7 J/cm(2) (5.7-8), 4 J/cm(2) (4-5.7), 2.8 J/cm(2) (2.8-5.7), and 2 J/cm(2) (2-2.8) at an 8-MOP concentration of 0.5, 1, 2.5, and 5 mg/L, respectively. Linear regression analysis revealed a significant correlation between 8-MOP bath-water concentration and photosensitivity (r = 0.98; P =.019). Bath-PUVA-induced erythema peaked after a median time interval of 3 days, with a range of 2 to 4 days. The slope of the UVA dose-erythema response curve was similar for all psoralen concentrations. CONCLUSION: UVA dose requirements in bath-PUVA treatment decrease linearly with increasing 8-MOP concentrations. A single MPD assessment at 72 hours after the UVA exposure is inappropriate for accurate determination of the patients' photosensitivity. The hazard of wrong UVA dosimetry is comparable at all psoralen concentrations.

Adult↗

PubMed2005

Changes in disease specific and generic quality of life related to changes in lower urinary tract symptoms: the Krimpen study.

PURPOSE: We determined if and to what extent longitudinal changes in lower urinary tract symptoms are related to disease specific and generic quality of life in men. MATERIAL AND METHODS: A longitudinal, population based study with a followup of 4.2 years was done in 1,688 who were 50 to 79 years old. Data were collected through self-administered questionnaires, including the Sickness Impact Profile (3 domains), Inventory of Subjective Health, International Prostate Symptom Score (I-PSS) and Benign Prostatic Hyperplasia Impact Index. Moreover, they completed various physical and urological measurements. Mean I-PSS and quality of life scores at baseline and followup were analyzed for certain subgroups. Multiple linear regression was used to determine the change in quality of life in relation to baseline I-PSS, I-PSS changes between baseline and followup, and age. RESULTS: Although mean I-PSS increased with time, the average generic quality of life improved and almost a third of the men reported better disease specific quality of life. Multiple linear regression revealed that disease specific quality of life was associated with I-PSS at baseline, changes in I-PSS between baseline and followup, and age. However, generic quality of life scores were not associated with these parameters. CONCLUSIONS: Changes in lower urinary tract symptoms severity had little impact on disease specific quality of life in 50 to 79-year-old men or on generic quality of life during the 4.2-year followup.

Activities of Daily Living↗

PubMed2000

Morphometry of Macaca mulatta forelimb. I. Shoulder and elbow muscles and segment inertial parameters.

The present study examined the morphometric properties of the forelimb, including the inertial properties of the body segments and the morphometric parameters of 21 muscles spanning the shoulder and/or elbow joints of six Macaca mulatta and three M. fascicularis. Five muscle parameters are presented: optimal fascicle length (L(0)(M)), tendon slack length (L(S)(T)), physiological cross-sectional area (PCSA), pennation angle (alpha(0)), and muscle mass (m). Linear regressions indicate that muscle mass, and to a lesser extent PCSA, correlated with total body weight. Segment mass, center-of-mass, and the moment of inertia of the upper arm, forearm, and hand are also presented. Our data indicate that for some segments, radius of gyration (rho) predicts segment moment of inertia better than linear regressions based on total body weight. Key differences between the monkey and human forelimb are highlighted.

Animals↗

PubMed1986

Serum immunoreactive insulin responses to a glucose load in Asian Indian and European type 2 (non-insulin-dependent) diabetic patients and control subjects.

The serum immunoreactive insulin response to an oral glucose load was estimated in 15 Asian Indian and 29 European non-diabetic subjects, and in 45 Asian Indian and 72 European Type 2 (non-insulin-dependent) diabetic patients. In the non-diabetic group, basal insulin values were higher in the Asian Indians than the Europeans (16.7 +/- 3.0 vs. 6.9 +/- 0.7 mU/l, p less than 0.001), and remained higher throughout the glucose tolerance test. Total insulin response was also higher in the Asian Indians (p less than 0.001), and linear regression analysis revealed basal insulin, body mass index and race to be important predictors of insulin response. Amongst the diabetic patients, basal insulin values were again higher in the Asian Indians compared with the Europeans (18.0 +/- 5.0 vs. 11.5 +/- 0.9 mU/l, p less than 0.05). Total insulin response was also greater (p less than 0.01). Linear regression analysis revealed the basal insulin value to be the only significant predictor of insulin response. The results demonstrate higher insulin levels in Asian Indians than Europeans in both normal subjects and Type 2 diabetic subjects. The insulin response to a glucose load is also greater in the Asian Indians. In the control subjects, ethnic differences contribute to this response, whereas in the diabetic patients this is a function of the elevated basal insulin values of the Asian Indians.

Adult↗

PubMed1990

The relationship between erythrocyte transketolase activity and the 'TPP effect' in Wernicke's encephalopathy and other thiamine deficiency states.

Patients (n = 104) were judged to be thiamine deficient by the criteria of erythrocyte transketolase activity (ETK) less than 0.6 U/g of hemoglobin, or greater than 17% increase in this activity on addition of thiamine pyrophosphate in vitro (TPP effect). ETK activated by TPP in vitro (AETK) was related to ETK by a linear regression of slope greater than or equal to 1, implying that transketolose apoenzyme (apoTK) was constant or decreased as ETK decreased. For most patient groups the value of apoTK was 0.1 U/g and the slope 1.033 to 1.050. In the subgroup of non-vomiting drinkers with Wernicke's encephalopathy (WE), the slope of the linear regression of AETK on ETK was 1.21, so that apoTK decreased as ETK decreased. Comparison of these data is consistent with a difference in the TK of WE drinkers from that of others. Generally, any variation of TPP effect was due only to variation of ETK. We recommend measurement of ETK, without TPP effect, for the assessment of thiamine nutrition.

Enzyme Activation↗

PubMed1990

Effect of ozone on growth of mosses on disturbed forest soil.

Mixed forest floor organic matter and upper mineral soil from a 1580 m elevation conifer-hardwood stand in the Pisgah National Forest, NC, was placed in 4-cm diameter x 21-cm deep tubes and exposed to 0.00, 0.08, 0.16, 0.24 or 0.32 microl O3/liter air (ppm). Twelve tubes in each of three replications/treatment were fumigated in continuously-stirred tank reactors in a greenhouse for 6 h/day on 4 consecutive days/week. Soil was watered 3 days/week with deionized water amended with ions and adjusted to pH 4.3 with H2SO4 + HNO3 (70 meq SO4(2-): 30 meq NO3(-)). After 10 weeks the amount of soil surface covered by moss (predominantly Ditrichum pusillum, but also D. lineare, and Pohlia nutans) was estimated visually and assigned a rating on a scale of: 1 = 0-25%; 2 = 26-50%; 3 = 51-75%; 4 = 76-100%. Linear regression analysis revealed a significant (p < 0.001) negative relationship between coverage ratings and O3 concentration. Surface coverage in tubes exposed to 0.32 or 0.24 ppm was about half of that for 0.00 ppm (mean ratings of 1.1, 1.4 and 2.6, respectively). Coverage differences appeared to be due in part to O3 suppression of plant numbers. Linear regression analysis also revealed a significant (p < 0.001) negative relationship between heights of D. pusillum plants (measured after 12 weeks treatment) and O3 concentration.

Journal Article↗

PubMed2005

Mean diffusivity and fractional anisotropy histogram analysis of the cervical cord in MS patients.

The spinal cord is frequently involved in multiple sclerosis (MS), and cord damage may be an important contributor to disability. Diffusion tensor magnetic resonance imaging (DT-MRI) provides quantitative information about the structural and orientational features of the central nervous system. In order to assess whether diffusion tensor-derived measures of cord tissue damage are related to clinical disability, mean diffusivity (MD) and fractional anisotropy (FA) histograms from the cervical cord were acquired from a large cohort of MS patients. Diffusion-weighted sensitivity-encoded (SENSE) echo planar images of the cervical cord, and brain dual-echo and diffusion-weighted scans were acquired from 44 patients with MS and 17 healthy controls. Cord and brain MD and FA histograms were produced. An analysis of variance model, adjusting for cord volume and patient age, was used to compare cord DT-MRI parameters from controls and patients. A multivariate linear regression model was used to identify DT-MRI variables independently associated with disability. Average cervical cord FA was significantly lower in MS patients compared to controls. Cord cross-sectional area, average FA and average MD were all significantly correlated with the degree of disability (r values ranging from 0.36 to 0.51). The multivariate linear regression model retained average cord FA and average brain MD as variables independently associated with disability, with a correlation coefficient of 0.73 (P < 0.001). DT-MRI reveals a loss of cervical cord tissue structure in MS patients. The strong correlation found between a composite DT-MRI score and disability suggests that a full and accurate assessment of cervical cord damage in MS provides information that usefully contributes to an explanation of the clinical manifestations of the disease.

Adult↗

PubMed2002

Microsequential injection: anion separations using 'lab-on-valve' coupled with capillary electrophoresis.

Microsequential injection (microSI) has been successfully coupled with capillary electrophoresis (CE). Presented is the microSI-CE system, interfaced with an integrated Lab-on-Valve (LOV) manifold that provides an efficient sample delivery conduit and a versatile means of sample pretreatment along with total automation of the separation process. Programmable microSI protocols control all critical system peripherals to perform various types of CE sample injections automatically such as electrokinetic (EK) injection, hydrodynamic (HD) injection, and head column field amplification (HCFA) sample stacking injection. Novel features of the microSI-CE technique are demonstrated on assays of samples containing 10 anions that had been used previously as a model system. Calibration studies by EK sample injection yielded linear concentration ranges of 0.5-3.0 mM with linear regression responses of r2 = 0.9999 for both chloride and sulfate using conductivity corrected peak area (CCPA) as concentration responses. Calibration using an internal standard was studied at the same concentration range giving r2 = 0.9992 for both chloride and sulfate and r2 = 0.9997 for both when CCPA correction was deployed. With HCFA sample stacking injection, a linear concentration dynamic range of 0.034-3.419 mM for chloride and 0.014-1.408 mM for sulfate were produced with linear regression responses of r2 = 0.9999 for chloride and r2 = 0.9998 for sulfate.

Anions↗

PubMed2000

Continuous pH and Pco2 monitoring during respiratory failure in children with the Paratrend 7 inserted into the peripheral venous system.

CONTEXT: The Paratrend monitor provides continuous arterial blood gas monitoring after insertion through a >/=20-gauge arterial cannula. OBJECTIVE: To determine the correlation of arterial blood gas values and the Paratrend monitor placed through a peripheral intravenous catheter. DESIGN: Prospective, open-label evaluation. SETTING: University-based pediatric intensive care unit. PATIENTS: Infants and children with respiratory failure and arterial access. RESULTS: The cohort included 23 infants and children. A total of 100 sample sets (Paratrend/ABG Pco(2) and pH values) were collected. The absolute difference between the arterial and Paratrend Pco(2) was 2. 9 +/- 1.8 mm Hg (range 0 to 9 mm Hg). Linear regression analysis of Paratrend Pco(2) versus arterial Pco(2) resulted in r = 0.97 and r(2) = 0.9479 (P <.001). Bland-Altman analysis of Pco(2) values demonstrated a bias +/- precision of -2.1 +/- 2.7 mm Hg. The absolute difference between arterial and Paratrend pH was 0.04 +/- 0. 02 units (range 0 to 0.15 units). Linear regression analysis of Paratrend pH versus arterial pH resulted in r = 0.83 and r(2) = 0. 7016 (P <.0001). Bland-Altman analysis of pH values revealed a bias +/- precision of 0.03 +/- 0.03 units. CONCLUSIONS: Inserted through a peripheral intravenous cannula, the Paratrend monitor can be used to provide an accurate estimation of arterial blood gas values in children with respiratory failure.

Adolescent↗

PubMed1993

Menadione nicotinamide bisulfite is a bioactive source of vitamin K and niacin activity for chicks.

Young chicks were fed a vitamin K-deficient soybean concentrate basal diet containing graded levels of menadione from menadione nicotinamide bisulfite (MNB) or menadione dimethyl-pyrimidinol bisulfite (MPB) to assess prothrombin time as a function of menadione intake. Prothrombin time decreased linearly as menadione dose increased from 0 to 400 micrograms/kg. Multiple linear regression slope-ratio calculations indicated that both sources of menadione were of equal potency. To assess niacin bioactivity of MNB, graded doses of nicotinamide (0 to 5 mg/kg) from MNB or nicotinamide were added to a niacin-deficient diet based upon corn, corn gluten meal and vitamin-free casein. Weight gain increased linearly as a function of nicotinamide dose, and multiple linear regression analysis of weight gain as a function of supplemental nicotinamide intake revealed no significant differences in slope between the two sources of nicotinamide. Using excess doses, MNB was compared with MPB in acute (single crop intubation) or chronic (fed in the diet for 14 d) toxicity trials. With a single menadione dose of 1600 mg/kg body wt, weight gain in the subsequent 14-d period was reduced by MNB but not by MPB. Mortality rates of 25 and 17% occurred for MPB and MNB, respectively, at this dose level. Doses lower than 1600 mg/kg body wt caused neither morbidity nor mortality. When provided in the diet for a 14-d feeding period, menadione doses of 3000 mg/kg diet from MNB reduced gain, feed intake, gain:feed ratio and blood hemoglobin concentration. Menadione doses of 6000 mg/kg diet were required to produce morbidity of this type when MPB was fed.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗

PubMedDate not supplied

Dosimetric characterization of the 18-MV photon beam from the Siemens Mevatron 77 linear accelerator.

A comprehensive set of dosimetric measurements has been made on the Mevatron 77.80.67 18-MV photon beam. Percentage depth dose, dose in the buildup region, field size dependence of output, transmission through lead, tray attenuation, and isodose curves for the open and wedged fields were measured using an ionization chamber in water and polystyrene phantoms. These dosimetric measurements sufficiently characterized the beam to permit clinical use. The depth dose at 10-cm depth for a 10 X 10 cm2 field at 100-cm source-to-skin distance (SSD) is 80.9%, which meets design specifications. Central axis depth-dose data were fitted to within 0.5% by a set of polynomial equations utilizing a two-dimensional linear regression analysis. Tissue-maximum ratios calculated from depth-dose data agree with measured data to within 2%. Output differences as large as 2.5% were measured for rectangular fields depending on which collimator jaws defined the long dimension of the field. The field size dependence of output was fit to within +/- 0.1% by a linear regression. The half-value thickness of the beam was measured to be 13 mm of lead.

Models, Structural↗