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L R Muenz

Publications and source records attributed to L R Muenz.

54 records · Page 3Linked to original sources
PubMed1985

Markov models for covariate dependence of binary sequences.

Suppose that a heterogeneous group of individuals is followed over time and that each individual can be in state 0 or state 1 at each time point. The sequence of states is assumed to follow a binary Markov chain. In this paper we model the transition probabilities for the 0 to 0 and 1 to 0 transitions by two logistic regressions, thus showing how the covariates relate to changes in state. With p covariates, there are 2(p + 1) parameters including intercepts, which we estimate by maximum likelihood. We show how to use transition probability estimates to test hypotheses about the probability of occupying state 0 at time i (i = 2, ..., T) and the equilibrium probability of state 0. These probabilities depend on the covariates. A recursive algorithm is suggested to estimate regression coefficients when some responses are missing. Extensions of the basic model which allow time-dependent covariates and nonstationary or second-order Markov chains are presented. An example shows the model applied to a study of the psychological impact of breast cancer in which women did or did not manifest distress at four time points in the year following surgery.

Analysis of Variance↗
PubMed1984

Hormone receptors in rapidly progressing breast cancer.

Biopsy specimens from 85 Tunisian breast cancer patients were compared with those of 95 American breast cancer patients for estrogen receptor (ER) and progesterone receptor (PR) levels. Tunisian patients with rapidly progressing breast cancer (RPBC) had lower ER levels than American patients or Tunisian patients without evidence of RPBC. Lower ER levels in the earliest stage of RPBC, which presents without inflammatory signs, supported epidemiologic and pathologic studies indicating that rapid growth as reported by the patient is an important aspect of RPBC. Low ER levels were generally found in young, premenopausal Tunisian women with advanced RPBC; multivariate analyses suggest that age was the most important correlating factor. In the Tunisian patients, ER levels showed a direct correlation with response to therapy. No consistent relationship between American and Tunisian patients or subgroups was observed for PR levels. These results indicate the need for reevaluating the routine use of oophorectomy in RPBC.

Age Factors↗
PubMed1984

Effect of treatment on the evolution of renal abnormalities in lupus nephritis.

We retrospectively studied the evolution of histopathologic features in successive renal biopsies in patients with lupus nephritis, to evaluate the effects of various treatment regimens. Repeat renal biopsies had been performed in 62 patients after more than 18 months of observation (median interval, 44 months) in randomized therapeutic trials comparing prednisone with cytotoxic drugs. Renal histopathologic features were graded individually, and a composite score reflecting the number and severity of irreversible lesions was defined as a chronicity index. The chronicity index for patients treated with conventional high-dose prednisone increased linearly with the interval between biopsies, whereas the index in the group receiving cytotoxic-drug treatments did not increase over time. After statistical adjustment for important prognostic factors (age and initial chronicity index) identified by multiple linear regression, the difference in the slopes between the group receiving prednisone and the group receiving cytotoxic drugs was significant (P less than 0.0001). We conclude that cytotoxic-drug treatment reduces the likelihood of progressive renal scarring in lupus nephritis.

Adult↗
PubMed1984

A retrospective study of personality variables associated with fibrocystic disease and breast cancer.

Women with breast cancer were compared to women with fibrocystic disease and healthy women to determine differences in self-perceptions of personality characteristics. Four standardized personality instruments were analyzed using analysis of covariance. An Adjective Check List was analyzed using logistic regression. Women with breast cancer were found to be more depressed, less aggressive and less demonstrative than women in the other two groups. Women with fibrocystic disease and with breast cancer were found to have higher needs for neatness and order and were found to be less curious and analytical than women in the healthy group. Women in the healthy group described themselves as calm, relaxed, outgoing and able to express anger. Women in the fibrocystic group described themselves as tense, restless, outgoing and expressing anger. Women in the breast cancer group described themselves as timid, non-assertive, non-competitive, calm, easy going and as keeping anger inside.

Adult↗
PubMed1984

Diffuse proliferative lupus nephritis: identification of specific pathologic features affecting renal outcome.

Prerandomization renal biopsy specimens were examined in 102 patients upon entry into prospective therapeutic trials of lupus nephritis in an attempt to identify early predictors of renal failure outcome. All 11 renal failures occurred among the 72 individuals with diffuse proliferative or membranoproliferative glomerulonephritis (DPGN/MPGN); thus, these patients were at modestly, but significantly, increased risk of endstage renal disease compared to those with focal proliferative, membranous, or mesangial glomerulonephritis. Considering the low incidence of endstage renal disease among patients with DPGN/MPGN, we sought to refine the prognostic information obtained from renal morphology by semiquantitative scoring of individual histologic features and by derivation of composite histologic scores specified by Activity (AI) and Chronicity (CI) Indices. Among the 72 patients with DPGN/MPGN, the composite AI was more strongly predictive of renal failure than were the individual active histologic features; cellular crescents and extensive fibrinoid necrosis yielded positive associations, while endocapillary proliferation, leucocytic exudation, and hyaline thrombi in glomeruli and interstitial inflammation by themselves did not emerge as useful prognostic indicators. However, chronicity items (glomerular sclerosis, fibrous crescents, tubular atrophy, and interstitial fibrosis) considered individually, as well as in the composite CI, were highly predictive of renal failure outcome. Particularly striking was the prognostic value of tubular atrophy; all 11 renal failures were among the 43 patients with tubular atrophy on prerandomization renal biopsy. While no single pathologic variable improved outcome predictions among those with tubular atrophy, examination for interactions among variables revealed that glomerular sclerosis and cellular crescents had a synergistic effect which augmented the prognostic information derived from analysis of tubular atrophy alone.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1983

Prognostic factors in lupus nephritis. Contribution of renal histologic data.

The predictive value of laboratory results and renal histologic data was examined in 102 patients upon entry into prospective, randomized, therapeutic trials of lupus nephritis. Three clinical features at the time of entry into the study were individually associated with increased rates of renal failure: age less than 24 years, male gender, and an elevated serum creatinine level. Subjects with diffuse proliferative or membranoproliferative glomerulonephritis were at a modest but significantly increased risk for the development of end-stage renal disease compared with patients with other classes of lupus nephritis. Semiquantitative scores of histologic features (specified by activity and chronicity indexes) identified subgroups of patients with comparatively high renal failure rates. To address the controversial issue of whether renal histologic data significantly improve the outcome predictions in patients with lupus nephritis, multivariate survival models were generated, permitting simultaneous consideration of multiple prognostic factors. Outcome predictions based on the strongest clinical predictors (age, sex, and serum creatinine level) were significantly enhanced by the addition of activity and chronicity indexes. Only age and chronicity index contributed significantly to the five-variable model and together constituted a two-variable model, the predictions of which were similar to observed outcomes. In the context of the highly significant prognostic indicators (age and chronicity index), immunosuppressive agents appeared to provide a slight therapeutic advantage over oral corticosteroids alone.

Adolescent↗
PubMed1982

Preliminary results of primary systemic chemotherapy in association with surgery or radiotherapy in rapidly progressing breast cancer.

112 Tunisian patients with rapidly progressing breast cancer (RPBC) were entered into a clinical trial evaluating combination chemotherapy as a primary form of treatment before surgery or radiotherapy. Three cycles of cyclophosphamide, methotrexate, and 5-fluorouracil (CMF) were administered at monthly intervals; patients were then randomized to surgery or radiotherapy to control the primary tumour, and 12 more cycles of CMF followed local/regional therapy. RPBC was sensitive to CMF; after only 3 cycles, 11% of evaluable patients showed complete remission and 78% had at least 25% diminution in tumour size. The disease-free interval (DFI) was substantially greater in this series than in a previously reported series treated by surgery and/or radiotherapy alone. No difference in DFI was found between patients randomized to receive surgery and those randomized to receive radiotherapy. Postmenopausal patients responded to CMF as well as premenopausal patients. Combination chemotherapy appears to play an important role in the control of RPBC, an aggressive malignancy often resembling inflammatory breast cancer.

Adult↗
PubMed1980

Epidemiologic features of rapidly progressing breast cancer in Tunisia.

A form of breast cancer characterized by rapid disease progression, inflammation, and edema is found in approximately 55% of the breast cancer patients presenting at the Institute Salah Azaiz, Tunis (Tunisia). In 581 patients seen between January 1, 1969, and December 31, 1974, we examined age, place of residence, reproductive history, delay in seeking treatment, and blood gropu as potential risk factors to determine the distinction between the rapidly progressing disease and the less aggressive form. Rural residence, blood type A, and recent pregnancy are risk factors among premenopausal women, but older age, rural residence, blood type A, late menarche, and delay in diagnosis are associated with postmenopausal rapidly progressing breast cancer. The most significant risk factors were rural residence and blood type A. Rapidly progressing breast cancer was diagnosed in two of every three breast cancer patients coming from a rural environment. Forty-three percent of 203 patients with rapid disease progression were blood type A, a significantly higher percentage than the 33% found in the general Tunisian population and the breast cancer patients without evidence of rapidly progressive disease. We observed that the risk factors for disease progression were quite different from those reported to influence the incidence of breast cancer.

Adult↗
PubMed1977

Applications of the Mantel-Haenszel statistic to the comparison of survival distributions.

In comparing two survival distributions, a Mantel-Haenszel statistic can be computed after each death as a non-linear two-sample rank statistic. The distributions of both the maximum and terminal statistics in such a sequence are studied numerically, in the absence of censoring, and appropriate critical values are determined. The maximum statistic is applied to simultaneous inference, and both the maximum and terminal statistics are used as the basis for early stopping procedures (especially in the pseudo-sequential context). Procedures based on the two statistics are compared for power and for early decision properties such as stopping index and (for exponential distributions) stopping time.

Biometry↗
PubMed1975

Results of hyperthermic perfusion for melanoma of the extremities.

Our studies show that the malignant melanoma cell in human beings is more sensitive to the lethal effect of heat than its normal counterpart, the melanocyte. Malignant melanoma of the extremities presents unique problems; at times, local control can be extremely difficult. The addition of heat to regional perfusion with melphalan has dramatically improved the objective response of melanoma. Complications rise as the tempreature and duration of perfusion increase. These risks must be weighed carefully against the volume and extent of tumor. One hundred and eighty-five hyperthermic perfusions have been perfomed on 165 patients. When done with meticulous attention to details, this procedure is accompanied by minimal morbidity and mortality. Hyperthermic perfusion is currently the best treatment for recurrent melanoma of the extremities and has almost eliminated the necessity for amputation. Perfusion is recommended as a prophylactic measure for the more deeply invasive primary lesions. It reduces the incidence of regional recurrence. A retrospective statistical analysis of survival rates of patients treated with nonheated and heated perfusion for recurrent melanoma, State IIIA, was conducted. If the experience of the heated group continues, which from a clinical standpoint appears likely, then a striking advantage of heated perfusion over nonheated perfusion will be demonstrated. This superiority in survival rates for the heated group is now three to one or 300 per cent. The most reasonable explanation for the improvement in survival time of patients in State IIIA is stimulation of the immune response. As a result of our experience with heated perfusion of limbs, we are investigating the possibility that systemic hyperthermia may enhance the antitumor effects of various chemotherapeutic agents on melanoma.

Acute Kidney Injury↗
PubMedDate not supplied

Alterations of cerebral metabolism in probable Alzheimer's disease: a preliminary study.

Previous in vitro and in vivo 31P MRS studies of Alzheimer's disease patients have revealed alterations in membrane phospholipid metabolism and PET studies have shown alterations in glucose and oxidative metabolism. This study of probable Alzheimer's disease patients demonstrates severity dependent alterations in measures of both high-energy phosphate and membrane phospholipid metabolism. Mildly demented Alzheimer's patients compared to the controls, have increases in the levels of phosphomonoesters, decreases in the levels of phosphocreatine and probably adenosine diphosphate, and an increased oxidative metabolic rate. As the dementia worsens, the levels of phosphocreatine and adenosine diphosphate increase, the levels of phosphomonoesters decrease, and the oxidative metabolic rate decreases. The phosphomonoester findings replicate previous findings and provide a new dimension to the molecular pathology of Alzheimer's disease, implicating basic defects in membrane metabolism. The changes in oxidative metabolic rate suggest the AD brain is under energetic stress. The changes in energy metabolites with increasing dementia could be a consequence of nerve terminal degeneration and are consistent with previous PET findings. 31P MRS provides new diagnostic and metabolic insights into this disease and would be a noninvasive method to follow the progression of the disease and the metabolic response to therapeutic interventions.

Adenosine Diphosphate↗
PubMedDate not supplied

Twelve-month test-retest reliability of the structured clinical interview for DSM-III-R personality disorders in cocaine-dependent patients.

This study examined 12-month test-retest reliability of the Structured Clinical Interview for DSM-III-R Personality Disorders (SCID-II) in cocaine-dependent patients. Thirty-one patients completed the SCID-II during the second week of hospitalization for cocaine dependence, and again 12 months later. In both interviews, patients were asked to answer questions about their personality during the several years preceding admission to the hospital. Test-retest reliability, as measured by kappa, was relatively poor at .46. However, reliability of negative diagnoses (the absence of a disorder at both time points) was higher than reliability of positive diagnoses (the presence of a disorder at both time points). Reasons for the difficulty in attaining long-term test-retest reliability of axis II diagnoses in cocaine-dependent patients are discussed.

Adult↗