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PubMed1996

Is the outcome of traditional lumbar disc surgery related to the size of the exposure?

The purpose of this study was to evaluate whether wide surgical exposures result in poorer outcome of lumbar disc surgery compared to smaller traditional exposures. The aim was also to assess if a dural tear has any impact on the postoperative clinical outcome. One hundred and twenty-two patients (56 women and 66 men, mean age 40.8 years) with herniated intervertebral lumbar disc and no previous back surgery, were included. Postoperatively they were grouped according to surgery as follows: surgery on one vs. two herniated discs (106 vs. 16 patients), partial vs. full laminectomy (93 vs. 29 patients), and the occurrence or not of a dural rent (8 vs. 114 patients). The outcome of surgery was evaluated one years postoperatively mainly by a composite clinical overall score (COS) and by its separate elements, which were: pain intensity in the lower-back or leg (VAS), neurological and clinical examination, functional capacity (Oswestry), and the need for analgesics. The results of the statistical regression analyses did not reveal significant differences in the postoperative outcome scores in the various groups of patients. The groups were comparable; no significant differences were seen in the pre-operative clinical overall scores.

Female↗
PubMed1992

Interpretive criteria for CI-960, fleroxacin and temafloxacin susceptibility tests with Haemophilus influenzae.

Haemophilus influenzae strains with varied ampicillin resistance and beta-lactamase production patterns were tested against three investigational fluorinated quinolones (CI-960, fleroxacin, temafloxacin) using Haemophilus Test Medium (HTM) and National Committee for Clinical Laboratory Standards (NCCLS) methods. The disk diffusion zones and MICs were compared and regression statistics and scattergrams generated. The rank order of the agents according to activity against Haemophilus influenzae was CI-960 (MIC50 0.002 microgram/ml) greater than temafloxacin (MIC50 0.015 microgram/ml) greater than fleroxacin (MIC50 0.03 microgram/ml). The recommended susceptibility interpretive criteria for the 5-micrograms disks of each drug were: for CI-960 greater than or equal to 23 mm (MIC correlate less than or equal to 1 microgram/ml); for fleroxacin greater than or equal to 19 mm (MIC correlate less than or equal to 2 micrograms/ml); and for temafloxacin greater than or equal to 16 mm (MIC correlate less than or equal to 2 micrograms/ml). All recent Haemophilus influenzae isolates tested were susceptible to these potent fluoroquinolones and no interpretive errors were observed.

Anti-Infective Agents↗
PubMedDate not supplied

Pharmacokinetic and pharmacodynamic data and models in clinical trials.

There is current emphasis for extended integration of pharmacokinetics (PK) and pharmacodynamics (PD) into all phases of new drug development, including large-scale clinical trials. In this paper, we focus on study design and data analysis issues for the investigation of pharmacokinetic/pharmacodynamic and blood level/effect relationships in patients. The application of descriptive and model-based regression statistical methodology for including sparse drug systemic concentration data in the analysis of efficacy and safety is illustrated by examples chosen from diverse therapeutic areas. The population approach, based on mixed-effects modelling, is one such methodology, which also provides new tools for analysis of response vs dose and response vs time data. The existence of a variety of statistical techniques for handling complex PK/PD time-varying data should increase the impact of such data analysis on future drug development.

Clinical Trials as Topic↗
PubMedDate not supplied

Serum prolactin and tumors of the prostate: unchanged basal levels and lack of correlation to serum testosterone.

To investigate the possible role of circulatory levels of prolactin on the development of prostatic tumors, and to gain insight into the prolactin-androgen relationship, serum prolactin and testosterone were determined in 73 patients with newly diagnosed prostatic adenocarcinoma. Controls consisted of 32 patients with benign prostatic hyperplasia before treatment, 19 age-matched controls, and 21 young individuals. Hormones were measured under standardized conditions by highly specific and sensitive radioimmunoassays. There was no difference in prolactin in the elderly men regardless of prostate pathology, but a significant increment was found in young controls. Individual prolactin values did not correlate with serum testosterone, and there was no statistical regression in prolactin values of patients in the age range between 50 and 80 years. In a second study, serum testosterone and prolactin were measured in 7 patients with prostate cancer and in 6 individuals with benign prostatic hyperplasia before and 30 and 60 minutes after stimulation with an iv bolus of 200 microgram TRH. Both hormones were within the normal range at time T0, and a significant stimulation of prolactin was achieved (p less than 0.001). Prolactin values did not differ between patients with benign and malignant prostatic disease. Thus, when investigating the role of prolactin in neoplastic prostatic growth in the human, it seems necessary to investigate receptor-mediated prostatic tumor responsiveness, and interferences with androgen converting enzymes on a cellular level, rather than circulating prolactin concentrations.

Adenocarcinoma↗
PubMed1994

[Plethysmechanomyography (PMG). A simple method for monitoring muscle relaxation].

Ideal evaluation of neuromuscular blockade can be done by mechanical or electromyographical registration of muscle contractions evoked by ulnar nerve stimulation. Unfortunately, devices needed for such registration are expensive or complicated to set up, and thus are not often used for routine monitoring in anaesthesia. In this study, we describe a simple and low-priced method permitting intra- and postoperative monitoring of neuromuscular blocking agents. The accuracy of plethysmomechanomyography (PMG) was evaluated by comparing simultaneous electromyographic (EMG) and plethysmographic measurements. METHODS. For plethysmographic registration of muscle response to nerve stimulation a simple infusion system is twisted there to five times around one hand and connected to an anaesthetic monitor via a pressure transducer. The drip chamber is fixed about 20 cm above the hand (Fig. 1). Then, the infusion system is then filled up-with physiologic saline solution and the clamp is nearly closed. Electric stimulation can be carried out using any nerve stimulator. Using this method, PMG mainly records the contractions of abductor digiti minimi muscle, but also partly those of the interossei. Evoked muscle contractions cause stretching of the infusion system, which leads to pressure changes proportional to the strength of contraction. The muscle response to "train-of-four" (TOF) stimulation of the ulnar nerve was recorded simultaneously by EMG and PMG in 11 patients (ASA class I or II) undergoing neurosurgical procedures and therefore requiring muscle relaxation. After induction of anaesthesia by injection of etomidate and fentanyl, supramaximal stimulation and control values (T0) were defined. Anaesthesia was maintained by supplementation with nitrous oxide/oxygen (1:2) and muscle relaxation was carried out with vecuronium. We used the integrated nerve stimulator of a Datex Relaxograph NMT-100 EMG monitor and proceeded to stimulate the ulnar nerve at the forearm with supramaximal strength. The PMG was registered by a Siemens Siredoc 220 printer connected to a Siemens Sirecust 1281 anaesthetic monitor. First twitch ratio (T1/T0) and TOF ratio (T4/T1) were calculated from these recordings. The EMG recordings were made by a Datex Relaxograph NMT-100 monitor, which automatically computes T1/T0 and T4/T1. The comparison of EMG and PMG values was carried out by simple linear regression. Statistical evaluation was performed using analysis of variance. RESULTS. A plethysmographically registered graph of the TOF-evoked muscle response is illustrated in Fig. 2. Simultaneous EMG and PMG recordings of onset and recovery from a nondepolarizing blockade are shown in Fig. 3. A strong positive correlation (P < 0.001) of EMG and PMG was found with correlation coefficients of 0.98 for T1/T0 and of 0.97 for T4/T1. The mean difference between values of both methods was 5%, maximally 18% (T1/T0) and 20% (T4/T1). CONCLUSIONS. Mechanomyography and EMG are well established methods of neuromuscular monitoring. Our data demonstrate that PMG provides a reliable measurement of neuromuscular transmission that correlates well with EMG. Since only materials of daily use in anaesthesia are needed, no substantial costs will arise when the plethysmographic method of measurement is used for routine anesthetic monitoring.

Adult↗
PubMed2004

Chemometric procedure for the study of fractionated wastewater ingredients using RP-HPLC/diode array spectrophotometer.

A fast screening method of domestic wastewater is reported based on fractionation with RP-HPLC and diode array absorption detection implemented by chemometric treatment of the spectra using cluster analysis, deconvolution, simulation, and multiple regression statistical techniques. The proposed method is limited to constituents that absorb in the UV-Vis region which include most of the toxic organic pollutants.

Adsorption↗
PubMed2000

Water-Quality Monitoring and Biological Integrity Assessment in the Indian River Lagoon, Florida: Status, Trends, and Loadings (1988-1994).

/ The Indian River Lagoon (IRL) system that extends from Ponce DeLeon Inlet to Jupiter Inlet is comprised of three interconnected estuarine lagoons: the Mosquito Lagoon (ML), the Banana River Lagoon (BRL), and the Indian River Lagoon (subdivided into North Indian River Lagoon, NIRL and the South Indian River Lagoon, SIRL). The declines in both the areal coverage and species diversity of seagrass communities within the IRL system are believed to be due in part to continued degradation of water quality. Large inflows of phosphorus (P) and nitrogen (N) -laden storm-water from urban areas and agricultural land have been correlated with higher chlorophyll a production in the central, south central, and the south segments of the lagoon. In a system as large and complex as the lagoon, N and P limitations are potentially subject to significant spatial and temporal variability. Total Kjeldahl nitrogen (TN) was higher in the north (1.25 mg/liter) and lower in the south (0.89 mg/liter). The reverse pattern was observed for total P (TP), i.e., lowest in the north (0.03 mg/liter) and highest at the south (0.14 mg/liter) ends of the IRL. This increased P concentration in the SIRL appears to have a significantly large effect on chlorophyll a production compared with the other segments, as indicated by stepwise regression statistics. This relationship can be expressed as follows: South IRL [chlorophyll a] = -8.52 + 162.41 [orthophosphate] + 7.86 [total nitrogen] + 0.38 [turbidity]; R(2) = 0.98**.

Journal Article↗
PubMed2004

Environmental variables for modeling wheat yields in the southwest pampa region of Argentina.

Two types of time scales--10-day intervals (D) and phenological phases (P)--were applied to environmental variables for the development of statistical regression models relating to the southwest pampa region of Argentina, with the aim of detecting the effects of weather on wheat yields for the period 1977-1999. The parameters were grouped as meteorological and processed variables and indices. The processed variables used were total soil water availability (SWA) and the ratio of actual evapotranspiration to potential evapotranspiration (alpha), obtained from a water-balance model in which the moisture anomaly index (Z) and the Palmer drought severity index (PDSI) were calculated according to Palmer's model. For these parameters it was possible to establish the times of year and the phenological phases with the best correlation to grain yield. The regression equation for meteorological variables on a 10-day scale provides one of the best fits. Using mixed parameters, the two models, D and P, give rise to a standard error of estimate of approximately 200 kg ha(-1). Truncated models perform better on a P scale than on a D scale. The use of phenological stages improved yield assessment, particularly for those years with extreme meteorological conditions. The optimum models were tested and root-mean-square errors (RMSE) of 440 kg ha(-1) and 470 kg ha(-1) were obtained for P and D scales respectively.

Argentina↗
PubMed2006

Relationships between self-assessment skills, test performance, and demographic variables in psychiatry residents.

Some researchers have seen the capacity for self-assessment in trainees as a special skill, and some reports have concluded that this skill is positively and crucially correlated with academic competence. Thus, it is believed that those trainees who are most deficient in knowledge are least likely to be aware of their limitations. Other researchers have emphasized the impact of statistical regression and other technical considerations in the studies, which have led to these conclusions. Our study used a relative-ranking design to measure the accuracy of self-assessments of both strengths and weaknesses in psychiatry residents. We analyzed the relationships between indices of self-assessment accuracy and other resident characteristics, particularly current academic strength as measured by a standard test of psychiatric knowledge. A total of 56 residents in two general psychiatry programs evaluated their performance on the Psychiatry Resident in Training Examination by estimating the rank order of their scores in the 11 psychiatry subject areas. For each resident, actual examination results were then used to generate measures of the accuracy of the identification of strengths and weaknesses. Residents' identifications of their strengths and weaknesses were significantly more accurate than chance levels. Strengths and weaknesses were identified with roughly equal proficiency, and accuracy in these assessments was not correlated to any of the following variables: academic competence as measured by examination raw scores, postgraduate year, gender, international vs. American medical education, program membership, or age. Our results do not support the hypothesis that trainees who show the least academic mastery also make the most inaccurate self-assessments. In addition, we found no resident characteristics that accounted for variation in self-assessment accuracy.

Age Factors↗
PubMed1996

Risk factors for injuries among the elderly in Greece.

Extrinsic and intrinsic risk factors for injuries among the elderly in Greece were investigated in a hospital based case-control study. Cases were 200 elderly persons, residents of the Greater Athens area, who contacted the "Laiko" University Hospital for accident-related injuries, during a 10-month period, whereas the control series comprised 385 elderly who, during the same period, contacted the same hospital for non-injury related medical reasons. Data were analyzed by modeling through multiple logistic regression. Statistically significant associations were found for smoking vs non-smoking [odds ratio (OR) 2.40; 95% confidence interval (CI) 1.22-4.70], moderate use of alcoholic beverages vs non use (OR 0.37; CI 0.23-0.61) and house safety score (OR 0.72; CI 0.56-0.93 for an improvement by 1 unit). Non statistically significant positive associations were noted with history of previous hospitalizations for injury, chronic central nervous system conditions, defective hearing, refractive eye disorders, current use of psychoactive drugs, excessive use of alcoholic beverages, other than ground floor residency, cohabitation with fewer members and other than currently married status. Restricted activity was assessed in subsamples of cases and controls and was associated with somewhat reduced risk for injury (OR for one unit increase in a 10 unit modified Groningen activity scale is 1.06; CI 0.99 to 1.13). Overall, these results suggest that there is a constellation of plausible risk factors for injuries among the elderly.

Accidents, Home↗
PubMed1992

Predicting garment pattern dimensions from photographic and anthropometric data.

Traditional linear measurements (lengths and circumferences taken over the body surface with a tape measure) were compared with measurements of frontal and lateral view photographs for usefulness in determining pattern dimensions for the upper torso of the female body form. The statistical regression models developed indicated that, while linear measurements provided slightly more accuracy in predicting a few of the pattern dimensions, the photographic measurements were more accurate in predicting others, particularly pattern angles. Photographic measurements hold promise as an alternative to the more intrusive linear measurements for predicting pattern dimensions.

Journal Article↗
PubMed1979

Use of contraceptives prior to and after conception and exposure to other fetal hazards.

In a large prospective study, set up to determine whether reproductive outcomes are affected by prior contraceptive use, 34,344 women were recruited at their first antenatal visit and followed until pregnancy termination. This paper summarizes the study methods and describes the demographic differences between subjects who used various contraceptives shortly before conception, and those who experienced contraceptive failures. Thirty percent of the women had used oral contraceptives (OCs) during the 5 months prior to conception and 2.4% had continued using them after their LMP. IUDs had been used by 5.8% of women before conception and 1.1% after. If these rates are also true for the whole population of the U.S., they indicate that approximately 70,000 babies are born each year following pill-failures and 30,000 following failures of IUD's. Exposure to other fetal hazards was common, with 48% of pregnant women drinking alcohol, 28% smoking, and 15% receiving diagnostic X-rays. OC use was more common among smokers and drinkers, and OC failures were significantly associated with the use of anti-epileptics, aspirin, and with exposure to radiation.

Adult↗
PubMed1989

Intra-uterine device failure: relation with drug use.

A case-control study was undertaken in order to test the relationship between commonly used anti-inflammatory agents and the efficacy of intra-uterine devices (IUDs). Women who had become pregnant while wearing an IUD were compared with non-pregnant IUD users. 717 cases and 717 controls were recruited from the same medical practices. The case-women (IUD failure) used anti-inflammatory drugs, particularly aspirin, more frequently than the controls (p less than 0.001). In contrast, oral progestins, taken in the second part of the cycle (16th to 25th day) were more frequently used by the control-women group (p less than 0.001). Although cases and controls differed in age and gravidity (younger and higher, respectively) standardization for these items did not change the findings for drug use.

Age Factors↗
PubMed1980

Analysis of bladder tumor recurrence in 178 patients.

The identification of bladder tumor characteristics which may affect tumor recurrence has been of interest to the clinician for a long time. Previous attempts to identify predictive factors of recurrence involved comparisons based on the twelve-month recurrence rate in a prospective clinical investigation of bladder tumor patients observed over a five-year period. A statistical regression model known as the proportional hazards model was employed to identify these factors using the disease-free interval as the outcome variable. Prior bladder cancer history, age at admission, initial tumor stage, grade, number, size, shape, and site were examined. The results confirm that a patient's prior history of bladder cancer must be considered in evaluating his likelihood of tumor recurrence. The analysis then focuses on patients with no prior history for predictive factors of recurrence.

Aged↗
PubMed1979

Classically conditioned heart rate responses in Macaca mulatta after beta-adrenergic, vagal and ganglionic blockade.

Heart rates of 5 rhesus monkeys (Macaca mulatta) were monitored during classical conditioning trials consisting of a visual conditioned stimulus followed after 10 sec by an electric shock to the tail. Heart rates typically increased at the onset of the visual stimulus, and returned to baseline before shock delivery. Autonomic blocking agents were subsequently administered; their effects on resting heart rates, and on acceleratory and deceleratory phases of the biphasic conditioned heart rate responses were examined, both in the raw data, and with a statistical regression technique. Beta-adrenergic blockade by propranolol lowered resting heart rates and was found, after regression analysis, to reduce the heart rate increase phase, and to weakly enhance the subsequent heart rate decrease phase of the conditioned response. Vagal blockade by atropine sulfate elevated resting heart rate, and markedly reduced both acceleratory and deceleratory heart rate phases of the conditioned responses. Ganglionic blockade by chlorisondamine also elevated resting heart rates (less than atropine), and almost completely eliminated conditioned heart rate changes. Several sources of evidence suggest a predominant vagal tone over resting heart rates, as well as mostly vagal mediation (with some sympathetic contribution) of the biphasic conditioned rate response.

Animals↗
PubMed1987

An analysis of numerical models of air pollutant exposure and vegetation response.

A number of empirical (statistical, regression oriented) and mechanistic (process oriented) models are presently available to examine the relationship between air pollution stress and plant response. These models have their strengths and weaknesses. In all these models, a major concern is the numerical definition of the pollutant exposure kinetics (dose). At present there are no numerical definitions of dose which make satisfactory biological sense. A key issue is the existence of a biological time clock where plants respond differently to the pollutant stress at different stages of their growth. On the other hand, policy makers and regulatory personnel prefer a simple approach which would facilitate implementation and administration of ambient air quality standards. Long-term air pollutant averaging techniques create artifacts due to the non-normal distribution of ambient concentrations. A more appropriate approach may be the use of 'median' and 'percentiles' computed from short duration pollutant concentrations. Such an approach would be free of the influence of the non-normal distribution, but would require the development of appropriate exposure-response models. Any transfer of results from unit level models to regional level leads to 'scaling error'. There is no general agreement among researchers on how to deal with the scale problem. While this situation persists, any policy formulated on regional impact assessment must acknowledge the uncertainty.

Journal Article↗
PubMed1993

Cortisol reactivity and anxiety and depression in pregnant adolescents: a longitudinal perspective.

The purpose of this investigation was to examine: (1) the relations among cortisol reactivity (short term changes in cortisol concentration) and anxiety and depression symptoms in adolescents during pregnancy and early postpartum, and (2) cortisol reactivity and psychosocial variables as predictors of anxiety and depression symptoms in pregnancy and early postpartum. Cortisol reactivity, an index of hypothalamic-pituitary-adrenal activity, was hypothesized to be a vulnerability factor for poor physical and mental health outcomes in adolescents. Forty adolescents aged 14 to 19 years (M = 17.3, SD = 1.3) were enrolled in the study and were seen at < 20 weeks gestation (T1), 34-36 weeks gestation (T2), and 2-3 weeks postpartum (T3). Blood was drawn for cortisol at T1 and T3. Psychological assessments of anxiety and depression symptoms, life optimism, and self-worth were administered at T1, T2, and T3. There were significant correlations among cortisol reactivity and anxiety and depression symptoms at T1 and T3, but the correlations were the reverse of the hypothesized direction. Pregnant adolescents with increased cortisol reactivity (cortisol concentrations that increased across a 40-min period) had fewer symptoms of anxiety and depression than other adolescents. Longitudinal analyses showed that anxiety and depression symptoms at T1 were a stronger predictor of postpartum anxiety and depression than was cortisol reactivity, life optimism, self-worth, or age at pregnancy.

Adolescent↗