Cox Method Research Articles

An Evaluation of Two New Inference Control Methods

An evaluation method is developed to measure the cost/ effectiveness of two new inference control methods. The factors of the evaluation function consist of: 1) preparation cost for the control method, 2) query complexity, and 3) security level under various attacks. Each control method combines the merit of some popular concepts; the first method is based on restriction, and the second on perturbation. Simulation results indicate that both methods have higher preparation cost, better security, and faster response time than Cox's method and Beck's method. Finally these two new methods are compared to each other.

Follow-up study of 582 liver cirrhosis patients for 26 years in Japan.

A long-term follow-up study of liver cirrhosis (LC) was performed in 582 patients diagnosed by peritoneoscopy and liver biopsy in the 26 years from 1958 to 1984. The etiology of LC consisted of hepatitis B virus (HBV) in 21%, alcoholic in 39% and cryptogenic in 39%. Fifty-nine percent of patients had died. Causes of death were hepatocellular carcinoma (HCC 44%), liver failure (30%), rupture of esophageal varices (14%), gastrointestinal bleeding (4%) and non-liver-related causes (8%). HCC accounted for increasing percentages (68%) since 1980. In all groups classified by the etiology, the causes of death had the same order in incidence. The age of onset of LC increased by 10 years from 42 to 52 years old and the age of death by 15 years from 43 to 58 in the 26-year period. The cumulative survival rate improved over the period. The 50% survival year was 7.9 in total patients, and 7.0, 8.5 and 10.0 in the three periods 1958-64, 1965-74 and 1975-84, respectively. It was 9.5, 6.3 and 9.8 in HBV, alcoholic and cryptogenic, respectively. LC patients survived 40-44% of the life expectancy of the general population in Japan in all age groups. Cox's multiregression life-table method selected three important prognostic factors from 7 parameters: a poor prognosis with a history of heavy alcohol consumption and old age at onset, and a better prognosis with recent onset.

Survival with primary cutaneous malignant melanoma, evaluated from 2012 cases. A multivariate regression analysis.

Cox's multivariate regression model for survival data was applied to 2,012 patients with primary cutaneous melanoma in order to evaluate the relative prognostic value of numerous clinical and histological variables and to establish their prognostically most efficient combination. The material was divided into 4 groups according to the size of resection margin of the primary lesion (less than 2.0 cm, 2.0 cm, 2.1-4.9 cm, and greater than or equal to 5.0 cm). Data were analysed separately in these 4 groups and equivalent results were obtained. The risk factors were clinical stage, site of tumour, tumour thickness, level of invasion, mitotic activity, ulceration, lymphocytic reaction, predominant type of invasive tumour cell and partial regression. When accounting for these factors, histological type, nuclear pleomorphism, nucleolar size, vascular invasion, pigmentation, verrucous growth pattern, and dermal elastosis were without prognostic influence. The effect of sex and age of patient was uncertain and both variables, therefore, were retained in the model. By using Cox's method it is possible to make a qualified estimate of the survival for the individual patient.

Standard computer programs in statistical analysis of survival in childhood lymphoblastic leukemia.

A material comprising all children in Sweden with acute lymphoblastic leukemia diagnosed in the years 1973-80 was analysed statistically. The total number of children was 505. Studies were made of 38 different variables, using frequency tables, cross tables, life table studies (1) and linear regression analysis according to Cox's method (2,4). Chi-square tests and log rank tests were included in the methods. The combination of life-table studies and linear regression analysis proved to be of value in assessing the significance of different parameters and treatment programs with regard to prognosis. The aim of this paper is to present a method for analysis of a patient material with use of standard computer programs. The results of the total analysis will be published elsewhere (3).

Size and Power Assessments of Tests of Hypotheses on Survival Parameters

Abstract Assuming the time-dependent component of Cox's form of the hazard function to be specified by the constant, Weibull, and Gompertz, produces three failure density models. Using simulation techniques, size and power comparisons between tests of hypotheses (concerning the regression parameters) arising from Cox's nonparametric method and tests arising from the three parametric models are made. The test statistics arise from the likelihood ratio criterion and the asymptotic normality property of maximum likelihood estimators.

Size and Power Assessments of Tests of Hypotheses on Survival Parameters

Abstract Assuming the time-dependent component of Cox's form of the hazard function to be specified by the constant, Weibull, and Gompertz, produces three failure density models. Using simulation techniques, size and power comparisons between tests of hypotheses (concerning the regression parameters) arising from Cox's nonparametric method and tests arising from the three parametric models are made. The test statistics arise from the likelihood ratio criterion and the asymptotic normality property of maximum likelihood estimators.

The Efficiency of Cox's Likelihood Function for Censored Data

Abstract D.R. Cox has suggested a simple method for the regression analysis of censored data. We carry out an information calculation which shows that Cox's method has full asymptotic efficiency under conditions which are likely to be satisfied in many realistic situations. The connection of Cox's method with the Kaplan-Meier estimator of a survival curve is made explicit.

The Efficiency of Cox's Likelihood Function for Censored Data

Abstract D.R. Cox has suggested a simple method for the regression analysis of censored data. We carry out an information calculation which shows that Cox's method has full asymptotic efficiency under conditions which are likely to be satisfied in many realistic situations. The connection of Cox's method with the Kaplan-Meier estimator of a survival curve is made explicit.

Discussion: “Multiple Jet Correlations for Gas Turbine Engine Combustor Design” (Cox, Jr., G. B., 1976, ASME J. Eng. Power, 98, pp. 265–272)

As the comparisons between predicted and experimental profiles in his present paper and the JANNAF paper (reference [9]) show, Cox's correlation method does very well in predicting the temperature distributions. However, the form in which some of the correlations are presented makes it very difficult to see the relative importance of the several independent variables. This is especially true of the jet temperature center-line correlation. The expression of this correlation as a base correlation with correction factors is misleading, since the corrections are not equal to one at the base condition. This correlation is more revealing when written in the following equivalent form, Y

An evaluation of the method of Cox for the rapid analysis of pregnanediol in urine by gas-liquid chromatography.

SUMMARY Cox's method for the analysis of pregnanediol in human urine by gas—liquid chromatography (GLC) of the free steroid on neopentyl glycol adipate in conjunction with a semi-automatic extractor for processing the urine was evaluated. Without automation of the GLC, one worker could complete 24 assays/day. The reliability of Cox's method was confirmed. Results obtained throughout the menstrual cycle in 15 women, during the pregnancies of 480 patients, in 18 postmenopausal women and in 20 men are presented.

Virilizing tumors of the adrenal cortex.

FUNCTIONING neoplasms of the adrenal cortex are clinically manifested by virilization, Cushing's syndrome, feminization, or hyperaldosteronism. In the present report, seven patients with virilizing adrenal tumors are described. In one case, virilization was present from birth. This is a unique instance of in utero virilization attributable to a tumor. Other unusual clinical, pathological, and laboratory findings are being reported. <h3>Methods</h3> The method used for 17-ketosteroid (17-KS) measurements was a modification of that of Callow et al.¹The procedure of Allen et al²was used for dehydroisoandrosterone (DHA). Pregnanetriol was measured at the BioScience Laboratories, Los Angeles, by Cox's method.³The 17-hydroxycorticosteroids (17-OHCS) were measured by a modification⁴of the method of Glenn and Nelson.⁵Aldosterone was estimated in patient 1 by a modification of the procedure of Neher and Wettstein.⁶Cathecholamines were measured by the method of Jacobs et al,⁷and vanillyl mandelic acid as described

Urinary Excretion of Acetaldehydogenic Corticoids in Normal Subjects and Patients with Various Diseases

Daily urinary excretion of total (free and conjugated) acetaldehydogenic corticoids (ACS) was measured by modified Cox's method in patients with various diseases as well as normal subjects, and the following results were obtained.1. The mean urinary excretion of ACS for normal men, with 95% confidence limit, was 3.0 ±0.5mg /day, and the mean for normal women was 2.0 ±0.5mg/day.2. Most of the diseases investigated were observed to affect the urinary excretion of ACS, 17-hydroxycorticosteroids (17-OH·CS) and formaldehydogenic corticosteroids in the same way, that is, the excretion of all the three groups of substances seemed to increase or decrease together according as the disease involved produced enhancement or suppression of the function of the pituitary-adrenal system. It was observed, however, that the ACS-forming activity of the adrenal gland did not always keep steps with its adrenocortical-hormone-forming activity, either of the two being sometimes very vigorous while the other remained low. Marked decrease of the ACS excretion was observed in one case each of liver cirrhosis, tetany, pituitary anorexia and Simond's disease as well as two cases of Addison's disease. On the other hand, striking increase was observed in a number of patients with high fever, another who had received transplantation of a bovine pituitary gland and two others who had been surgically operated. This is worthy of notice, as it is contrary to the generally accepted view that such elevated ACS excretion is characteristic of patients with certain adrenocortical tumours. In patients with Cushing's syndrome or Basedow's disease, it was observed that the urinary 17-OH-CS excretion increased while the ACS excretion remained normal or decreased. This may be explained by adopting the view that Cushing's syndrome accompanies elevated production of adrenocortical hormones alone and Basedow's disease belongs to the kind of disorder in which the reduction of hydrocortisone alone is accelerated.3. All the subjects except those with extremely disordered adrenal gland function, e.g., advanced Addison's disease, responded to administration of ACTH with increased ACS excretion. This suggests that ACS production is promoted by ACTH.4. Administration of adrenocortical hormones brought about hardly any increase of ACS excretion either in the normal subjects or the patients, but even some decrease in a few cases.5. Administration of Fowler's solution, adrenochrome-monosemicarbazon or pyrogen had almost no effect on the ACS excretion.From these results it may be reasonably concluded that the ACS appearing in the urine is directly derived from some substances produced in the adrenal gland such as 17,20-dihydroxy-20-methylsteroids and that the process of formation is promoted by ACTH, probably prior to their conversion to progesterone.Under conditions accompanying increased progesterone production, such as pregnancy, augmentation of the ACS excretion was observed. Can 17-hydroxylation take place in the placenta, ovaries etc. ? Nobody has produced conclusive evidence to decide this issuer either way. If 17-hydroxylation of progesterone takes place only in the adrenal gland, the amount of ACS excreted will indirectly indicate the level of the adrenocortical activity.

Research Items

Preparation of Epidemic Typhus Vaccine A. P. BERKOWITZ (S. Afric. J. Med. Sci., 9, 109; 1944) has investigated the suitability of duck and turkey eggs for the large-scale preparation of epidemic typhus vaccine. Duck embryos live longer (8–9 days) after inoculation than chick embryo do (6–7 days). The growth of rickettsiæ in the yolk sac of the duck egg is far more prolific than in the yolk sac of the hen's egg; and the duck egg's yolk sac at the stage used (15–16 days old) is about twice as big as that of a 13–14 day hen's egg. Duck eggs inoculated by Cox's method gave, on the 7–8th day after inoculation with a South African strain of epidemic typhus, an average yield of 100–200 c.c. of vaccine, which is about five times the yield of hen's eggs. Stained smears show, in a high percentage of yolk sacs, an almost confluent sheet of rickettsiæ, "quite beyond anything seen even in the most heavily infected hen's eggs". Because the yield per yolk sac is so high, the residual proteins are correspondingly diluted, so that processing is easier. Preliminary protection tests in guinea pigs have indicated that the protective value of the duck egg vaccine is at least equal to that of the hen egg vaccine. A Middle East strain of epidemic typhus gave a similar extremely prolific growth in duck eggs. In turkey eggs the growth was just as prolific, and the yield of vaccine as great. It was found that the best conditions for primary incubation of duck eggs were a temperature of 102° F. in a completely humid atmosphere.

Methods of rendering Golgi-sublimate Preparations permanent by Platinum Substitution

All histologists who have worked with the silver and sublimate methods of Golgi have experienced the great inconvenience arising from the facts that the preparations are not durable, and that in mounting them a cover-glass cannot be employed in the ordinary way. Preparations by the silver method generally remain in good condition for a somewhat longer period than those by the sublimate method; Golgi has indeed stated he has some which have remained unaltered for nine years. The sublimate method is now most commonly employed in the form of the modification of Cox, in which only one fluid is required instead of two. In preparing sections of tissues that have been kept for the necessary time in this fluid, it is practically essential to blacken the originally steel-grey deposit by one or other of the several methods by which this may now be done. Such preparations, when new, are probably unsurpassed by those obtained by any other Golgi-method; but, unfortunately, when mounted in the orthodox manner without a cover-glass, and in spite of the most careful attention to various other technical details that have been recommended for the purpose of increasing their durability, they almost constantly show disintegration of the black deposit in from four to six months, and are certainly absolutely useless within a year. Ever since Golgi's methods came into use, histologists have been endeavouring to find some means of overcoming this great disadvantage of want of durability of the preparations. The only measure of success that has so far been achieved is that obtained by means of various processes of gold toning. All gold methods are, however, notoriously uncertain in their results. This, of course, simply means that in carrying them out it is necessary to fulfil certain very precise conditions, and that these conditions are as yet imperfectly understood. Certainly the gold toning processes that have been recommended for rendering Golgipreparations permanent are no exception to this rule. Our own observations and experiments have been made chiefly upon sections of tissues preserved in Cox's solution, because we are convinced that Cox's method is for various reasons the most trustworthy process of this class that has yet been devised, and therefore the one most likely to be of service in studying pathological changes. We have tried the methods of Obregia and Golgi for toning sublimate sections with gold. With that of the former we have not had any success. On the other hand, with that of the latter (as briefly described in Jack's translation of Pollack's Methods of Staining the Nervous System) we have obtained some very beautiful purple-black preparations, which have now remained unchanged under a cover-glass for considerably over a year. In the great majority of instances, however, the results have been unsatisfactory, the deposit rapidly undergoing disintegration.

The Structure of Nerve Cells

THE Spanish histologist, Dr. S. R. Cajal, on p. 9 of his book “Les nouvelles idees sur la structure du Systeme nerveux,” translated into French by Dr. L. Azoulay, makes the following assertion:—“Les cellules nerveuses sont des unites independantes, ne s'anastomosant jamais ni par leurs rameaux protoplasmiques, ni par leurs expansions nerveuses ou cylindres axes.” (The italics are mine.) I venture to bring this statement forward because recently I have discovered that it is not universally correct; in sections of the medulla oblongata of a young snake, Tropidonotus natrix, prepared according to Cox's modification of Golgi's corrosive sublimate process, I have found a pair of cells on the ventral edge distinctly united together by a protoplasmic process, or, as I would propose to term it, a dendrite. Cox's mercurial method is so far better than the chrom-osmium-silver method, inasmuch as the preparations made by it keep much longer.