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Results for “multiple linear regression”

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Relation between blood pressure and renin, renin substrate, angiotensin II, aldosterone and urinary sodium and potassium in 574 ambulatory subjects.

Five hundred and seventy-four ambulatory subjects with blood pressures ranging from 94/58 to 250/145 mm Hg were studied on their usual dietary and sodium intake. Renin, renin substrate, angiotensin II, aldosterone and urinary sodium and potassium were compared with blood pressure to access the contribution of these variables to the blood pressure variance. Our analyses revealed that renin substrate was highly and positively correlated with diastolic blood pressure (r = +0.39; p < 0.00001) but all other components of the renin-aldosterone system exhibited a significant negative correlation with blood pressure. A highly significant relationship between potassium, the renin-aldosterone system and blood pressure was found but no such relationship could be demonstrated for sodium. Subjects with higher blood pressures had lower urinary potassium concentrations and lower potassium/creatine ratios. These findings raised the possibility of a significant pathogenetic relationship between potassium and high blood pressure. Multiple linear regression reveals that influences of the renin-angiotensin-aldosterone system can only account for less than 20% of the variance exhibited by the blood pressure in these subjects.

Aging↗

PubMed1976

Respiratory response to tobacco dust exposure.

Results of a study of the respiratory responses of 318 nonsmoking female workers to long-term tobacco dust exposure are reported. The mean total tobacco dust concentrations ranged from 0.9 to 27.5 mg per m3; the respirable fraction, from 0.3 to 3.6 mg per m3. The mean length of exposure to tobacco dust was 14.9 years; 24 per cent of the workers had been exposed to tobacco dust for 20 years or more. Comparatively low prevalences of chronic respiratory symptoms were found, and only the prevalences of chest tightness and wheezing were significantly higher among workers exposed to tobacco dust than those of the control group (P less than 0.01). Calculating the expected 1-sec forced expiratory volume and forced vital capacity values by means of multiple linear regression equations, developed on the basis of data obtained in the 210 control subjects, revealed no significant differences between the measured and expected ventilatory capacity values among any of the groups of the workers observed. In contrast to negative findings with regard to chronic respiratory effects, significant acute decreases in ventilatory capacity during the work shift were recorded. No dose-response relationship was found between the level of exposure and the acute decreases in ventilatory capacity.

Adolescent↗

PubMed2026

Low-Dose Radiation-Induced Expression of Exosomal miRNAs in the Serum of Medical Radiation Workers.

Objective: Long-term low-dose ionizing radiation may alter genomes and cause diseases. This study examined serum exosomal miRNA differences among radiation-exposed medical workers by work types. Methods: High-throughput sequencing screened serum exosomal miRNAs in diagnostic radiologists, interventional radiologists, and nuclear medicine doctors. qRT-PCR validated differentially expressed miRNAs. Results: 410 differentially expressed miRNAs, including 102 downregulated and 308 upregulated miRNAs, enriched in 15 KEGG pathways. Four miRNAs were validated. miR-30e-5p, miR-155-5p and miR-486-5p differed significantly among groups(P<0.01).The expression levels of these three miRNAs were lower in the nuclear medicine group than in the diagnostic group (0.25±0.05vs3.89±8.62,0.10±0.15vs7.03±15.75,0.37±0.39vs4.46±9.64;Z=3.542,3.335,9.859;P<0.01), whereas miR-155-5p was lower in the interventional group than in the diagnostic group(1.32±2.43vs 7.03±15.75;H=11.889,P=0.003), miR-486-5p was higher(9.54±19.39vs4.46±9.64; H=9.859,P=0.007). All four miRNAs showed higher expression in the 14-31-year work-experience group, and all four also showed age-dependent differences, with miR-30d-5p and miR-486-5p showing the age-related differences (P<0.01). Combined detection of the four miRNAs improved discrimination among occupational categories (AUC=0.784). Multiple linear regression analysis showed that sex was associated with all four miRNAs, whereas work type was associated with miR-30d-5p and miR-155-5p (P<0.05). Conclusion: Serum exosomal miR-30e-5p, miR-155-5p, and miR-486-5p are promising biomarkers for monitoring radiation-induced damage, supporting occupational protection and health management.

exosomes↗

PubMed2025

Identification of intragenic variants in pediatric patients with intellectual disability in Peru.

BACKGROUND: Intellectual disability in Latin America can reach a frequency of 12% of the population, these may include nutritional deficiencies, exposure to toxic or infectious agents, and the lack of universal neonatal screening programs. In 90% of patients with intellectual disability, the etiology can be attributed to variants in the genome. OBJECTIVE: to determine intragenic variants in patients with intellectual disability between 5 and 18 years old at Instituto Nacional de Salud del Niño. METHODS: It is a descriptive cross-sectional study with convenience sampling. A total of 124 children diagnosed with intellectual disability were selected based on psychological test results and availability for whole exome sequencing. In addition, a chromosomal analysis of 6.55 M was performed on ten patients with a negative result in sequencing. Relative and absolute frequencies and measures of central tendency and dispersion were determined according to their nature. In addition, multiple linear regression and Poisson regression were used to determine the association between some clinical characteristics and the probability of occurrence in patients with positive results. RESULTS: The median age of the patients was 6.3 (IQR = 5.95), males accounted for 57.3%, and 91.9% of the cases had mild intellectual disability. Exome sequencing determined the etiology in 30.6% of patients with intellectual disability, of which 52.6% were autosomal dominant inheritance. The most frequent genes found were MECP2, STXBP1 and LAMA2. A broad genotype-phenotype correlation was identified, highlighting the genetic heterogeneity of intellectual disability in this population. The presence of dermatologic lesions, dystonia, peripheral neurological disorders, and fourth finger flexion limitation were observed more frequently in patients with intellectual disability with "positive results". CONCLUSIONS: This study shows that one-third of patients with intellectual disability exhibit intragenic variants, highlighting the importance of genetic analysis for accurate diagnosis. The identification of genes such as MECP2, STXBP1, and LAMA2 underscores the genetic heterogeneity of intellectual disability in the studied population. These findings emphasize the need for genetic testing in clinical management and the implementation of early detection programs in Peru.

Humans↗

PubMed1979

Determination of serum bilirubin by skin reflectance: effect of pigmentation.

A noninvasive optical technique by which serum bilrubin can be estimated from skin spectral reflectance measurements has been further investigated. The original work on 30 healthy, full-term white infants and an independent study on 14 white and 30 black infants demonstrate that the method has potential not only for clinical use, but also for the study of the transport of bilrubin to, from and within the skin. The objectives of the present study are to evaluate the method on a larger sample population with special attention to natural skin pigmentation effects and the development of a physical model of the tissue to explain the relationship between serum bilrubin concentration and skin reflectance. Reflectance spectra (380-800 nm) and concurrent serum bilirubin measurements were taken on a sample population of 58 white and 45 full-term black infants (1-3 days of age). Multiple linear regression analysis, comprised of six wavelengths gave a correlation coefficient, r = 0.831 for the white infant group. For the black infant group, a five wavelength analysis provided r = 0.877 with the standard error of estimate being +/- 1.46 mg/100 ml for both groups. The model for establishing a physical basis for the relationship shows that a transformed, normalized Kubelka-Monk function xi (460, 510, 420) is linearly related to serum bilrubin concentration. This function is determined from the spectral reflectance values at three wavelengths, 420, 460, and 510 nm. The wavelength combination is such that effects due to hemoglobin and melanin pigments are minimized. Regression analysis showed that r = 0.778 and r = 0.865 for the white and black infant groups, respectively, with standard error of estimates being +/- 1.4 mg/100 ml for both groups. Routine determinations of total serum bilrubin by laboratory methods have standard errors of estimate ranging from +/- 1 to 1.5 mg/100 ml. Thus, the method herein described shows that the relationship between skin reflectance and serum bilrubin in full-term infants is close to the acceptable limits for clinical use. Furthermore, this work shows that skin pigmentation does not obscure this relationship.

Bilirubin↗

PubMed1977

Moderate alcohol use during pregnancy and decreased infant birth weight.

Maternal alcoholism during pregnancy may result in severe prenatal growth deficiency. In this prospective study, the relationship of moderate maternal alcohol consumption to infant birth weight is explored. Subjects were 263 paying members of a health maintenance organization who delivered single live children. Their alcohol consumption before pregnancy, and in early and late pregnancy, was estimated. In order to control for smoking, which is strongly related to both infant birth weight and maternal alcohol use, the sample was selected so that similar proportions of smokers were represented in both light and heavier drinkers. Multiple linear regression was employed. A regression equation was computed for each of the three periods in which drinking was estimated. Independent variables entered into the equation were maternal age, height, parity, daily cigarettes, alcohol use in the period, and gestational age and sex of child. The regression of birth weight on these variables revealed a significant relationship (p less than or equal to .01) with alcohol consumption in two of the periods. Ingestion of an average of one ounce of absolute alcohol daily before pregnancy was associated with an average decrease in birth weight of 91 grams; the same amount ingested in late pregnancy was associated with a decrease of 160 grams. The associations were independent of the other variables entered into the equation, and in particular, of tobacco use.

Alcohol Drinking↗

PubMed2026

The Impact of Chatbot Type and Normative Messaging on Chatbot Usage Intention Based on the Health Technology Acceptance Model: Randomized Controlled Trial.

BACKGROUND: Digital health tools, such as health chatbots, may improve access to scalable health support, but adoption remains inconsistent. Existing models do not fully integrate technology acceptance factors with health motivation factors relevant to digital health use. OBJECTIVE: This study proposed and tested the health technology acceptance model and examined whether normative message framing and chatbot type were associated with health motivation, technology acceptance, and intention to use a health chatbot. METHODS: In October 2025, we conducted a 4 × 2 between-participants online experiment with 1000 US adults recruited from a nationally representative YouGov panel. Participants were randomized to 1 of 8 conditions varying norm message type (self-oriented, peer-oriented, expert-oriented, or family-oriented) and chatbot type (AI-powered or rule-based) in a cancer prevention and genetic risk information scenario. Outcomes included descriptive norms, injunctive norms, perceived susceptibility, perceived severity, perceived benefits, self-efficacy, perceived ease of use, trust, privacy concerns, and usage intention. Data were analyzed using a multivariate ANOVA with Bonferroni-adjusted post hoc tests and multiple linear regression. RESULTS: Peer-oriented and family-oriented messages produced higher usage intention than expert-oriented messages, and peer-oriented messages also increased descriptive norms, injunctive norms, self-efficacy, and trust. AI-powered chatbots were associated with higher usage intention (P=.02) and greater trust (P=.008) than rule-based chatbots. In regression analyses, the model explained 50.8% of the variance in usage intention. Usage intention was positively associated with descriptive norms (β=0.087; P=.003), injunctive norms (β=0.078; P=.009), perceived susceptibility (β=0.051; P=.03), perceived benefits (β=0.253; P<.001), and trust (β=0.33; P<.001), and negatively associated with perceived severity (β=-0.047; P=.049) and privacy concerns (β=-0.11; P<.001). Perceived ease of use and self-efficacy were not significant predictors. CONCLUSIONS: The health technology acceptance model was a useful framework for explaining the intention to use a health chatbot by combining technology acceptance and health motivation constructs. Both social design features and chatbot design features shaped adoption-related beliefs, with peer-oriented and family-oriented framing and AI-powered chatbots showing particular promise. Trust and privacy concerns remained central determinants of intended use.

Humans↗

PubMed1977

An investigation of the feasibility of predicting outcome indices in the treatment of heroid addiction.

An exploratory study employing multiple linear regression techniques was conducted to investigate the feasibility of predicting outcome indices in the treatment of heroin addiction. Demographic and biographic intake variables were obtained for heroin addicts prior to treatment in one of two different types of residential treatment programs. Length of treatment, further categorized into "split-stay" categories, was chosen as the criterion because of its importance from the standpoint of program management. Subsequent stepwise regression procedures resulted in 11 variables of sufficient predictability to account for approximately 30% of the variability in the split-stay criterion. The employment of the derived equation resulted in correct classification in approximately 75% of the cases. This was beyond what could have been predicted by chance alone or from the knowledge of the observed split-stay ratio. A clear demonstration of the feasibility of the model was obtained; however, as to its utility, implementation in the actual treatment setting would be required. Implications for the use of this type of prediction model were discussed.

Black or African American↗

PubMed1977

Physiological consequences of experimental cerebral missile injury and use of data analysis to predict survival.

The authors describe cerebrovascular and cerebral metabolic changes in monkeys, subjected to cerebral missile injury. After injury with BB pellet at 90 m/sec, there is a rapid rise in intracranial pressure (ICP), which reaches a peak 2 to 5 minutes posttrauma, and then falls to about 20 to 30 mm Hg. This, with a fall in mean blood pressure (MBP), results in a 50% reduction in cerebral perfusion pressure (CPP), Cerebral blood flow (CBF) is also reduced, although acutely there is no close relationship with (CPP). Cerebrovascular resistance falls initially and then at 30 minutes rises to very high values. Cerebral metabolic rates (CMR's) for oxygen fall after injury and remain low for the rest of the animal's life; CMR's for lactate rise immediately after injury and persists for 5 hours, then fall. After injury with a faster missile (180 m/sec), the ICP rises higher and faster, and the peak is shorter. The CCP is reduced in this injury to approximately 30 mm Hg, and only one animal survived more than 1 hour. With the conventional forms of data analysis, the length of survival after injury correlates well with MBP, ICP, and CBF, but separately they were completely unsatisfactory for prediction of an individuals prognosis. With the technique of multiple linear regression analysis, the survival of individual animals could be predicted with great accuracy. This is possible also when two postinjury parameters,CBF and MBP, are used.

Animals↗

PubMed1976

Birth weight of children with Down's syndrome.

The difference in birth weight between children with Down's syndrome and their siblings was estimated to be in the interval from .18 to .37 kg with 90 percent confidence, the Down's syndrome infants having the smaller mean birth weights. When we adjusted their birth weight, using a multiple linear regression analysis, to take into account several factors known to affect it, the difference in birth weight was only slightly less than the unadjusted difference. The data support the hypothesis that an extra chromosome No. 21 results in a smaller than expected birth weight.

Birth Order↗

PubMed1977

Prolonged sleep apnea and respiratory instability: a discriminative study.

This report is based on a study of 53 infants, 28 of whom had clinically observed prolonged apnea (greater than or equal to 20 seconds) during sleep whereas the remaining did not. In addition to the clinical observations, each infant was studied in a sleep laboratory during a complete nap, and a continuous recording was made of respiratory activity and rapid eye movements. Measurements were made of all apneic pauses (greater than or equal to 2 seconds) observed in the laboratory and the two groups of infants were compared in terms of the frequency and average duration of apneic pauses, the longest apneic pause, the amount of periodic apnea, and the relative amount of apnea. The infants with prolonged sleep apnea had, during a single nap, more frequent and longer apneic pauses and more periodic apnea. This supports the hypothesis that respiratory instability during sleep and prolonged apnea have a common etiology. By employing a multiple linear regression model and including all laboratory apnea measures in a single analysis, a composite laboratory score was developed to differentiate members of the two groups. It would thus appear that the study of infants during a single nap could assist in the identification of infants at risk for prolonged sleep apnea and provide an indirect method for determining the influence of a number of variables on the occurrence of prolonged sleep apnea. Pediatrics, 59:962-970, 1977, SLEEP, APNEA, RESPIRATORY INSTABILITY.

Apnea↗

PubMed1975

Interactions between anticonvulsants.

Anticonvulsant drug interactions have been investigated using multiple linear regression analyses. The one statistically significant interaction found was that in which phenytoin dosage decreased plasma carbamazepine concentrations. There was a suggestion that carbamazepine and phenobarb dosage tended to increase phenytoin levels. No interaction was detected between phenytoin and sulthiame. Studies in individuals suggested that ethosuximide may increase plasma phenytoin concentration and that clonazepam tends to decrease carbamazepine and phenytoin concentrations.

Anticonvulsants↗

PubMed1977

Quantitative structure-activity relationships. V. A simple simple algorithm for Fujita-Ban and Free-Wilson analyses.

For quantitative structure-activity analyses a simple algorithm for the calculation of de novo group contributions by Fujita-Ban analysis is given. This algorithm corresponds in all details to a computer program for linear multiple regression analysis. However, the transformation of the original matrix to the normal equations matrix is easily achieved without a computer. The normal equations matrix can be solved with a modern desk calculator being equipped with a matrix ROM. Two examples are given to explain the algorithm; the calculation of all important statistical parameters is illustrated. As for quantitative structure-activity analyses this algorithm can be applied as well for the calculation of other additive parameters, such as pi from log P-values or omega from equilibrium constants.

Electronic Data Processing↗

PubMed1979

Psychosocial factors associated with pressure sores.

To determine if psychosocial factors, not purely mechanical aspects, play an important part in the incidence of pressure sores, 141 subjects were tested on 3 psychosocial measures. Results indicate that differences exist among groups in pressure sore history and psychosocial measures. Contrary to the expectations of a mechanical skin problem model, quadriplegics as a group (rather than paraplegics) had a history of fewer pressure sores. Two variables, the subject's responsibility in skin care (RESPON) and his satisfaction with the activiities of life (SATIS), were significantly associated with the incidence of decubitus ulcers. The combination of RESPON, SATIS, and the total positive score from the Tennessee Self-Concept Scale in multiple linear regression accounted for (1) 26% of the pressure sore history in the total sample, (2) 40% in the paraplegic group, (3) 69% in the paraplegic with help group, and (4) 41% in the paraplegic without help group. The histories in the quadriplegic groups and subgroups did not show reliable associations with the 3 variables. SATIS contributed most in accounting for the incidence of pressure sores. The level of injury and these psychosocial factors are thus related to the incidence of pressure sores.

Activities of Daily Living↗

PubMed1979

A kinetic method for glucose that is insensitive to variations in temperature and enzyme activity.

We have adapted for glucose determination a new approach to kinetic analyses [Anal. Chem. 50, 1611 (1978)]; it is 50-fold less dependent upon some experimental variables than is a more conventional rate method. Modification of a commercially available hexokinase/glucose-6-phosphate dehydrogenase reagent system for glucose provides that the rate of production of NADH be first-order in total glucose concentration within about 30 s after sample and reagent are mixed. In the kinetic method, absorbance vs. time data recorded after 30 s and a multiple-linear-regression program are used to compute the absorbance change that would occur if the reaction were monitored to completion. Results demonstrate a linear relationship between glucose concentration and computed absorbance change. Application of the method to 51 human sera without rigorous control of either temperature or reagent composition yielded a regression equation of y = 1.01x -0.3 when kinetic results (y) were compared with equilibrium results (x) for the same samples analyzed in a hospital laboratory.

Blood Glucose↗

PubMed1979

Pulmonary abnormalities in art glassblowers.

Art glassblowing is a profession bringing the lung in close contact with many potential hazards. Forty-seven art glassblowers with a mean age of 34.5 years answered a questionnaire and had pulmonary function studies performed. While this was generally a young, healthy population, 21% had "usual cough" and 31% had wheezing. Pulmonary functions were most often normal. However, using multiple linear regression analysis, the functions associated with volume, VC and FEV1 showed a significant drop with increase in the total lifetime hours exposed to glassblowing. Both the presence of a cough and the production of phlegm were related to hours of exposure. Thus it seems there may be some unknown toxic effect of art glassblowing which in the future may prove to be hazardous to health.

Adult↗

PubMed1979

Correlation of ultrasonic and endocrinologic assessment of human follicular development.

Human ovarian follicular development measured by peripheral plasma hormone levels and ovarian follicular growth assessed by ultrasonic visualization of the ovary were compared and contrasted in apparently normally menstruating women. The linear correlation coefficient between the mean values for plasma estradiol and follicular diameter on day -5 to day 0 of 15 normal cycles was r = 0.968. When the individual paired data were subjected to multiple linear regression analyses (on days -5 to 0), r = 0.771. These good correlations show that ultrasound measurements of follicular diameter are valuable in the assessment of follicular growth and development. Observations on apparently abnormal cycles are also discussed. Ultrasound measurement of follicular diameter offers an additional technique for the study of ovarian function.

Adolescent↗

PubMed1977

An assessment of community suicide risk.

The contributions of several core variables to the white suicide rates in 24 Florida counties were examined, and a prediction equation, using multiple linear regression, was developed. Age was found to be about 50% more important than divorce. With both age and divorce controlled, loneliness and insanity were found to be significant core variables (p less than .05). A prediction equation including age, crime rate, insanity, and alcoholism was found that accounted for 79% of the variation in the suicide rates across counties. The observed rates were divided by predicted rates to yield standardized mortality ratios. It is proposed that these ratios may serve to assess both the need for and the impact of community suicide prevention services by placing suicide rates in the context of relevant social conditions.

Adult↗