Cent Confidence Limits Research Articles

Occurrence of Non-Hodgkin's Lymphoma after Therapy for Hodgkin's Disease

We studied the clinical and pathological features of six cases of non-Hodgkin's lymphoma (diffuse undifferentiated in four cases and diffuse histiocytic in two cases) occuring in patients treated for Hodgkin's disease. All six patients had received both radiation and chemotherapy. Abdominal or gastrointestinal involvement was present in five of the six cases. None of the patients had evidence of Hodgkin's disease when the diagnosis of non-Hodgkin's lymphoma was made. Five of the six patients were among a study group of 579 patients with Hodgkin's disease, prospectively followed since diagnosis. At 10 years the actuarial risk of development of non-Hodgkin's lymphoma in this study group is 4.4 per cent (1.2 to 15.0) (per cent probability with 95 per cent confidence limits) and is similar to that of developing acute leukemia: 2.0 per cent (0.3 to 12.9). Non-Hodgkin's lymphoma is a second tumor that may occur late in the course of patients treated for Hodgkin's disease--particularly in patients who have received both radiation therapy and chemotherapy. Like acute leukemia, non-Hodgkin's lymphoma may be another cancer that represents a substantial late risk of combined-modality therapy.

Serum bilirubin: a prognostic factor in primary biliary cirrhosis.

We followed up 55 patients with proven primary biliary cirrhosis for several years or until death. A graph of the level of serum bilirubin versus time that was constructed for each patient shows an initial period of variable length in which the serum bilirubin level remained constant. This was followed by a period of rapid rise in serum bilirubin which culminated in the patient's death. Whenever two successive serum bilirubin values taken six months apart exceeded 34 mumol/l (2.0 mg/dl) the patient had entered a late phase of disease and lived an average of 49 months. Ninety-five per cent confidence limits on survival time were 32-74 months. If two successive six month bilirubin values exceeded 102 mumol/l (6.0 mg/dl), calculated survival time was 25 months, and if two successive six month bilirubin values exceeded 170 mumol/l (10.0 mg/dl), survival time was 17 months. Fifteen of the 41 living patients had two consecutive serum bilirubin levels greater than 34 mumol/l (2.0 mg/dl). However, the slope of the rising bilirubin in the living patients is only 35 mumol/l/yr (1.5 mg/dl/yr) compared with 42 mumol/l/yr (2.5 mg/dl/yr) in the dead patients. This means that patients with this disease not may be living considerably longer.

Accuracy sensitivity to carboxyhemoglobin, and speed of response of the Hewlett-Packard 47201A ear oximeter.

We have shown that the Hewlett-Packard 47201A ear oximeter measures arterial O2 saturation within 95 per cent confidence limits of +/- 4 per cent when arterial blood saturation is more than 65 per cent, but at lower saturations the oximeter consistently provides a reading that is too low. The oximeter is sensitive to carboxyhemoglobin, progressively overestimating arterial saturation as carboxyhemoglobin concentration increases from 0 to 18 per cent. The time response is exponential, with a normal time constant of 3 sec, but this is halved in the fast mode or operation.

Lung cancer after employment in shipyards during World War II.

A case-control study, undertaken to identify reasons for the exceptionally high rate of lung cancer among male residents of coastal Georgia, revealed a significantly increased risk associated with employment in area shipyards during World War II. The summary relative-risk estimate, adjusted for smoking, other occupations, age, race and county of residence was 1.6 (95 per cent confidence limits = 1.1 to 2.3). A synergistic relation was found between shipyard employment and cigarette smoking. These findings suggest that asbestos and possible other shipyard exposures during wartime employment account for part of the excess mortality from lung cancer in certain coastal areas of the United States.

Oral contraceptives and birth defects.

We reviewed the birth certificates and hospital records of 7723 infants those mothers had reported using oral contraceptives. The overall frequency of malformation was 4.3 per cent for infants whose mothers terminated use of oral contraceptives shortly before conception, as compared with 3.3 per cent for infants whose mothers did not take oral conceptives diring the three years before conception. The 90 per cent confidence limits for the prevalence ratio were 1.0 and 1.7. No difference was apparent for major malformations. For specific malformations the most notable difference was for undescented testis, but this excess, like the overall excess, could be explained by sampling variability. Despite the slightly greater rate of minor malformations in the short-interval group, a reasonable interpretation of these data would be that oral contraceptives present no major teratogenic hazard.

THE SIGNIFICANCE OF SOIL VARIABILITY FOR FOREST SOIL STUDIES IN NORTH‐EAST SCOTLAND

SummaryA study of 13 sample plots (0.01 ha) in 6 forests showed that the average number of topsoil samples required per plot to secure 95 per cent confidence limits for a range about the mean of 10 per cent was 6 for total nitrogen, 9 for total phosphorus and 29 for 0.5 M acetic acid extractable nutrients (calcium, magnesium, phosphorus and potassium). In some plots 95 per cent confidence intervals, based on 5 composite samples, for extractable nutrients were as large as the range of mean values for different plots within a forest. High variability within plots causes large variation in correlation coefficients between tree growth and soil properties so that the intensity of sampling should be of the order indicated above to identify factors affecting growth. For predicting timber yield the accuracy of regression equations containing predictors of high within‐plot variability is too low to be of practical value. The sampling effort required to achieve a given level of precision does not increase greatly when plot size is increased from 0.01 to 0.1 ha. Since Yield Class, the most useful measure of growth, is not designed for areas less than 0.5 ha, the use of the larger plot size is recommended.

Effect of body position on carbon monoxide diffusing capacity in asymptomatic smokers and nonsmokers.

We measured carbon monoxide diffusion capacity (DLCO) in the sitting and supine position in 73 apparently normal subjects (41 nonsmokers and 32 smokers). The coefficient of DLCO standardized for alveolar volume (KCO) was less in the smokers than in the nonsmokers (P less than 0.05) in the sitting position, but the separation was wider in the supine posture (P less than 0.01). The per cent changes between supine and sitting KCO (deltaKCO) were shown to be age dependent in both nonsmokers and smokers, but this age dependence was more accentuated in the latter group. Only 3 smokers were below the 95 per cent confidence limit of nonsmokers for KCO in the sitting position, but there were 7 smokers below that limit for deltaKCO. An attempt was made, using intravenous injection of xenon-133, to study the mechanism of this impairment. Persons who failed to increase KCO in the supine posture showed an ability to increase apical blood flow in that position. The mechanisms of impairment in deltaKCO remain to be explained and may be due either to a predominant apical defect or to a widespread abnormality of the pulmonary capillary bed.

Electrocardiograms of 32 2-tooth Romney rams

Mean time interval (with 95 per cent confidence limits) for the ECGs of 32 2-tooth Romney rams were: P wave duration, 0.054s (0.044s--0.065s); PR interval, 0.110s (0.081s--0.139s); QRS duration, 0.044s (0.028s--0.071s); QT interval, 0.135s (0.277s--0.356s); and ST segment, 0.192s (0.157s--0.228s).

Spontaneous human lymphocyte-mediated cytotoxicity against tumor target cells: IV. The suppressive effect of normal pregnancy

The effects of pregnancy and other donor characteristics on spontaneous lymphocyte-mediated cytotoxicity (SLMC) were studied. Sex, age, and stage of the menstrual cycle had no significant effect on the SLMC of the control donors, the SLMC was significantly lower in pregnant donors in the second or third trimester. However, this lowered level of activity was still within the 95 per cent confidence limits of the normal population and parity had no cumulative effect. At delivery, fetal cord blood lymphocytes possessed substantial cytotoxic activity, further evidence that the fetus is immunologically competent at birth. The relevance of these data to the immunologic coexistence of the mother and fetus is discussed.

CAMP-phosphodiesterase inhibitors and tracheal smooth muscle relaxation

A series of compounds drawn from a wide variety of chemical and pharmacologic classes were tested for their ability to act as inhibitors of a guinea pig tracheal cAMP-phosphodiesterase. Active compounds, defined as equal to or more potent than 1,3-dimethylxanthine (theophylline), were subsequently tested for guinea pig tracheal smooth muscle relaxant activity in vitro. A strong correlation ( r = 0.988 with 95 per cent confidence limits of 0.933 to 0.988) was found between the two activities, suggesting that, under these conditions, smooth muscle relaxation was due to elevation of tracheal cAMP levels.

Asymmetry of plantar flexion strength in the foot.

A study of plantar flexion strength and calf circumference in 30 conscripts is submitted. It showed an asymmetry of strength amounting to 6--11 per cent (95 per cent confidence limits). The right leg was significantly stronger than the left, but there was no difference in strength between the dominant and non-dominant leg. There was little correlation between circumference and strength.

Fluid pressures in the periodontal ligament of the mandibular canine tooth in dogs

Tissue fluid pressures were monitored in the periodontal ligaments of 19 mandibular canine teeth. Resting (no load) pressures were recorded and changes in the pressure which accompanied the application and removal of forces up to 500 g. All parameters were reexamined after the animals were killed by exsanguination. The resting intraperiodontal pressure (IPP) was −1.86 ± 1.00 mmHg (mean ± 95 per cent confidence limits), markedly less than values obtained by other investigators. As these dogs were positioned with their mandibular canines at a higher elevation relative to the rest of the body than other workers have used, this may indicate that the pressure in the ligament is subject to postural variation. The resting IPP was not correlated with systemic blood pressure, and did not change significantly after exsanguination. Trauma to the ligament raised the resting IPP to −0.36 ± 1.93 mmHg. Application of load resulted in an immediate increase in pressure which decayed rapidly (halving-time less than 1 s). Removal of the load produced the inverse pattern, but with a reduced peak pressure and a longer halving-time. Trauma increased the halving-time for the decay of the load-induced pressures to the point that the pressure increases were judged to be sustained rather than transient. The pressure changes produced by the application of forces to the teeth were small compared to the loads applied, suggesting that the free fluids of the periodontal ligament make only a minor contribution to tooth support.

Synthetic hydroxyapatite-solubility product and stoichiometry of dissolution

The solubility product of a well-characterized sample of hydroxyapatite (Ca:P ratio of 1.664 ± 0.002) was constant over the pH range 4.56 to 9.67, ionic strength range 0.0003 to 1.03 and solid:solution range 0.0625 to 5.55 g/250 ml in spite of non-stoichiometric dissolution of the solid. The mean product for 61 equilibrations was 2.91 × 10 −58 with 95 per cent confidence limits of 0.51 × 10 −58 and 7.89 × 10 −58. The hydroxyapatite sample also yielded solubility product values far in excess of 2.91 × 10 −58 if (a) an irreversible surface layer formed during preparation was not removed, or (b) during successive equilibrations at high solid:solution ratios, the suspension was subjected to a large increase in solution pH.

Echocardiographic assessment of left ventricular filling after mitral valve surgery.

In order to investigate the functional effects of mitral valve surgery, echocardiograms showing left ventricular dimension were recorded and digitised in 14 normal subjects and 129 patients after mitral valve surgery. Measurements were made of peak rate of increase of dimension (dD/dt) and duration of rapid filling, studies on left ventriculograms in 36 patients having shown close correlation between these values and changes in cavity volume. In 14 patients with mitral stenosis, peak dD/dt was reduced to 7-2 +/ 1-5 cm/s, and filling period prolonged to 330 +/- 65 ms, compared with normal (16-0 +/- 3-2 cm/s, and 160 +/- 50 ms, respectively), and after mitral valvotomy, these values improved significantly (10-4 +/- 2-7 cm/s and 245 +/- 55 ms). Characteristic abnormalities were found in 67 patients with mitral prostheses. Values for the Björk-Shiley (10-5 +/- 4-2 cm/s and 180 +/- 80 ms) and Hancock (10-3 +/- 3-7 cm/s, 245 +/- 80 ms) values were similar, and both superior to the Starr-Edwards (7-4 +/- 3-0 cm/s, 295 +/- 105 ms). Results after mitral valve repair in 30 cases were not significantly different from normal (14-4 +/- 5-0 cm/s, 170 +/- 50 ms). Values outside the 95 per cent confidence limits for the valve in question allowed diagnosis of value malfunction in 18 cases. The method is value in comparing different operative procedures and in following up patients after mitral valve surgery.

Liver biopsies from psoriatics related to methotrexate therapy. 3. Findings in post-methotrexate liver biopsies from 160 psoriatics.

The purpose of this paper is to report findings in post-MTX liver biopsies from 160 psoriatics treated with Methotrexate (MTX) in single biopsy and B. 68 patients with serial biopsies. At the time of liver biopsy the 92 patients had received a mehosis and six patients had fibrosis. Comparing these 7 patients with patients having normal liver histology (13 patients) revealed no statistically significant difference in cumulative doses of MTX, but a statistically significant higher admitted alcohol intake during MTX therapy (p less than 0.002) and an older age (p less than 0.01) in the patients with cirrhosis or fibrosis. in the 68 patients MTX had accumulated to a mean dose of 3940 mg (range 32k-8355 mg) at the time the latest liver biopsies were taken. Among the latest liver biopsies were 14 cirrhosis (21 per cent, 95 per cent confidence limits: 12-32 per cent) and 16 fibrosis (24 per cent, 95 per cent confidence limits: 14-35 per cent). The 14 patients with cirrhosis when compared to patients with normal histology (9 patients), had taken an equal total dose of MTX at the latest liver biopsy, but had consumed a statistically significant higher amount of alcohol (p less than 0.05) during MTX therapy and also tended to be older (p less than 0.006). Comparison of a material A and B indicates that the prevalence of cirrhosis and fibrosis among MTX treated psoriatics increases rapidly beyond a cumultative dose of two to four grams of MTX. No MTX treated psoriatics should thus be allowed to pass this dosage range without having a liver biopsy performed.

Interobserver variability in echocardiography

High-quality echocardiograms were performed on 146 normal individuals whose ages ranged from 3 to 73 years (mean 27 years). Normal values for mitral diastolic excursion and E-F slope, the chamber dimensions of the right ventricle, left atrium, and left ventricle, the aortic root dimension, and thickness of the interventricular septum and left ventricular posterior wall were determined. Each tracing was then read independently by two experienced echocardiographers. The extent of interobserver variability was calculated and expressed as a percent of the mean. The 95 per cent confidence limits for these estimates were calculated. Small but significant interobserver variability was found for all nine of these commonly measured echocardiographic parameters. Observer variability is a small but potentially important consideration in investigative echocardiography.

Effects of dietary composition on adipose tissue hexokinase-II and glucose utilization in normal and streptozotocin-diabetic rats.

The control of adipose tissue hexokinase isoenzymes in response to altered dietary composition was investigated. Rats that were fasted and then refed carbohydrate-free diets increased their HK-II activity in epididymal fat pads above the level in fasted animals. However the ultimate activity of HK-II achieved during refeeding with seven diets of varying composition was dependent mainly on dietary carbohydrate; the effect of dietary carbohydrate overcame poor growth due to protein deficiency or decreased food intake. Fat pads from animals fed for three weeks from weaning with 19 per cent protein diets showed a marked increase in HK-II on 51 per cent carbohydrate over those on a carbohydrate-free diet but no further increase on 81 per cent carbohydrate. However, adipocytes from rats on 81 per cent carbohydrate had significantly higher HK-II than those from rats on 51 per cent carbohydrate. In streptozotocin-diabetic rats there was no difference in adipose tissue HK-II between rats on 19 per cent protein-51 per cent carbohydrate and those on 19 per cent protein carbohydrate-free diets. Treatment of diabetic rats with 3 U. lente insulin daily brought HK-II into the range for normal rats, but once again there was no difference between the two diets. The treated rats showed marked weight gain but were still hyperglycemie. Adipocytes from rats on the 19 per cent protein carbohydrate-free diet showed lower HK-II and glucose conversion to CO2 and triglyceride than adipocytes from rats on the 51 per cent carbohydrate diet. There was a high correlation of HK-II to both pathways of glucose utilization on both diets. However, the slope of the regression line of triglyceride production on HK-II was much lower on the carbohydrate-free than on the basal diet. Adipocytes from rats on the 81 per cent carbohydrate diet had HK-II activity and glucose utilization that fell within the 95 per cent confidence limits for the relationship derived from adipocytes from rats on the 51 per cent carbohydrate diet. Values for glucose utilization in adipocytes from treated diabetic rats on the carbohydrate-free diet were above the expected range for this diet for both CO2 and triglyceride production; CO2 production was also above the expected range for diet in treated diabetic rats on the 51 per cent carbohydrate diet. Glucose conversion to both end products was higher for a given level of HK-II in the treated diabetic animals on the 51 per cent carbohydrate diet than on the carbohydrate-free diet. These data indicate that diet has a major effect on HK-II that is probably mediated by carbohydrate and is dependent on insulin. Although there appears to be a relationship between HK-H and glucose utilization in a given diet-and-treatment group, there is a departure from the normal relationship in adipocytes from rats on a high-fat carbohydrate-free diet or from partially treated diabetic rats.

Electrical and mechanical responses in the platysma and in the adductor pollicis muscle: in normal subjects.

In the platysma of 34 normal subjects the amplitude of the action potential and twitch tension and tetanic tension were lower, the contraction time of the isometric twitch was 1.4 times shorter, and the potentiation of twitch tension in a staircase and after tetanus was two to four times greater than in m. adductor pollicis. Differences in twitch kinetics and potentiation were related to the four times higher incidence of fast fibres in the platysma than in the adductor pollicis muscle, as determined by histochemistry. Ninety-five per cent confidence limits were established for comparison with patients with myasthenia gravis.

Ultrasound measurement of the fetal head to abdomen circumference ratio in the assessment of growth retardation.

Fetal head and abdomen circumference measurements have been made using pulsed ultrasound techniques. The mean head to abdomen (H/A) circumference ratio with 95% confidence limits was determined in 568 normal pregnancies from 17 to 41 weeks menstrual age. The mean ratio was 1-18 at 17 weeks, but decreased slowly until 29 weeks when the ratio was 1-11; thereafter there was a sharp fall in the mean ratio to 1-01 at 36 weeks and 0-96 at 40 weeks. The H/A circumference ratio was also determined in 31 small-for-dates fetuses within one week of delivery. In all cases the fetal weight as predicted from the fetal abdomen circumference measurement was below the 5th centile weight for gestation. The ratio was above the 95th centile limit in 22 (71%) of these fetuses and evidence is presented to suggest that the H/A circumference ratio can be used to distinguish between symmetrical and asymmetrical growth retardation.

Stress radiographical measurements of post-traumatic knee instability. A clinical study.

In a prospective, consecutive, clinical and stress radiographical study, comprising 153 traumatic knee injuries, the value of stress radiographical measurements, gonylaxometry, was studied. Clinical evaluation, gonylaxometry and preoperative evaluation under general anaesthesia were carried out in that order. Then the operative findings were recorded as drawings on standard diagrams. These were used as a basis for evaluation of the preoperative tests. Of all the methods evaluated, gonylaxometry was found to provide the most accurate information regarding the knee injury. Very close to this result were the findings under general anaesthesia. Anterior drawer sign was measured gonylaxometrically when damage to the anterior cruciate ligament was present; posterior drawer meant damage to the posterior cruciate ligament. Partial ruptures of cruciate ligaments did not allow antero-posterior displacements exceeding the critical levels of the test. Small positive medial instability was found with ruptures of profound medial structures, higher values with total rupture of the long superficial collateral band, and still higher values when cruciate ligament ruptures were also present. The predictive values of a positive radiographical test were 100 per cent as regards medial instability and 98 per cent for drawer looseness. The predictive values of a negative test were 96 per cent for drawer and 92 per cent for medial instability. These figures are based on the total material. 95 per cent confidence limits are given.