Parameter sensitivity of a model of viral epidemics simulated with Monte Carlo techniques. I. Illness attack rates

This is the first of a series of papers concerning sensitivity analyses of stochastic micropopulation models. A model of epidemic spread of viral infection is used in this series to illustrate the principles and performance of the sensitivity analysis system. For these studies the analysis system now known as SENSEN was redesigned and extended to use the principles and modules of the SUMMERS simulation shell. The latter was used in the implementation of the epidemic model as well as a number of others. The SENSEN system can be used with any of these. The advantages of sensitivity analysis for stochastic micropopulation models are discussed. Its general form and operation are illustrated by a comparison of illness attack rates with infection attack rates.

Evaluation of the anti-inflammatory and liver-protective effects of anoectochilus formosanus, ganoderma lucidum and gynostemma pentaphyllum in rats

The pharmacological effects of Anoectochilus formosanus, Ganoderma lucidum and Gynostemma pentaphyllum were studied against carrageenan-induced paw edema and CC1(4)-induced hepatotoxicity in rats. The water extracts of G. pentaphyllum and G. lucidum were found to possess significant anti-inflammatory activity against carrageenan induced edema. The administration of Gynostemma pentaphyllum displayed an activity even more potent than indomethacin. In contrast, Anoectochilus formosanus showed a delayed onset of anti-inflammatory activity starting from 4 hrs post carrageenan administration. However, A. formosanus significantly decreased the acute increase in serum GOT and GPT level caused by CC1(4). Histological changes such as necrosis, fatty change, ballooning degeneration, inflammatory infiltration of lymphocytes and Kupffer cells around the central vein were simultaneously improved by the treatment of A. formosanus.

[Acute purulent pericarditis: clinical experience with primary pericardiectomy plus continuous pericardium lavage]

106 patients with acute purulent pericarditis were treated surgically with three different methods without operative mortality. The pericardiectomy plus continuous pericardial lavage was more effective than pericardiectomy without irrigation or simple pericardial drainage in several aspects, such as recovery of body temperature, elimination of infectious-toxic symptoms and cutting short hospitalization days. Besides, cardiac tamponade or late constriction of the pericardium could be avoided.

Pathologic findings associated with interleukin-2-based immunotherapy for cancer: a postmortem study of 19 patients

The use of interleukin-2 (IL-2), either alone or in combination with lymphokine-activated killer cells, tumor infiltrating lymphocytes, or other immunotherapeutic agents has added a new list of alternatives to conventional antineoplastic regimens. Little information is available about the pathologic changes occurring in patients treated with these agents. In this study, we reviewed the necropsy materials from 19 patients, 12 men and 7 women, with a variety of malignancies including melanoma, renal cell carcinoma, gastrointestinal and pulmonary adenocarcinoma, and metastatic gastrinoma, who died after receiving IL-2-based immunotherapy. Death occurred at intervals ranging from less than 1 hour to 143 days following the last dose of therapy. All patients dying at or less than 43 days following cessation of therapy had lymphoid infiltrates of varying intensity in residual tumor. At necropsy, the major cause of death unrelated to the presence of metastatic tumor was bacterial sepsis. In addition, we found evidence of significant cardiac and pulmonary toxicity: two patients with acute myocardial infarction, one with and one without significant coronary artery disease, two cases of unexplained lymphocytic myocarditis, and one case of fatal pulmonary capillary plugging following an infusion of lymphokine-activated killer cells. Thus, not unlike other forms of therapy for cancer, IL-2-based immunotherapy does not appear to be without significant toxicity.

Primary renovascular effects of erythromycin in the rat: relationship to cyclosporine nephrotoxicity

Erythromycin is known to exacerbate cyclosporine nephrotoxicity. This has been attributed to the potential of erythromycin to reduce the hepatic microsomal metabolism and clearance of cyclosporine. Erythromycin may also be nephrotoxic. We tested the hypothesis that erythromycin may have direct effects on the renal vasculature which are additive or synergistic with the effects of cyclosporine. Sprague-Dawley rats were administered graded doses of either erythromycin, 2.5, 5, 7.5, and 10 mg/kg BW/min i.v. over consecutive 10-min intervals; cyclosporine, 1, 2, 3, and 4 mg/kg BW/min i.v. over consecutive 10-min intervals; or both drugs simultaneously. In separate experiments, identical doses of erythromycin or cyclosporine were infused intravenously following acute unilateral renal denervation. Infusion of erythromycin led to an initial decline in arterial blood pressure whereas infusion of cyclosporine resulted in a dose-related increase in arterial blood pressure. Despite these different systemic effects, each drug alone produced a striking decrease in renal blood flow. This effect was more pronounced when the drugs were infused concomitantly. The reduction in renal blood flow occurred in an additive manner as a direct consequence of increased renal vascular resistance. Prior renal denervation did not modify the response to either erythromycin or cyclosporine. These results demonstrate that cyclosporine-induced vasoconstriction is exacerbated by erythromycin and suggest that the decline in renal function observed in patients coadministered these drugs may be due in part to additive renovascular toxicity.

LINKERS: a simulation programming system for generating populations with genetic structure

Significant features are described of a Monte Carlo simulation system, LINKERS, that generates nuclear family data conforming to one locus and two loci genetic models. Software engineering techniques help to produce a user friendly environment for studies of genetic ascertainment. LINKERS' 39 code modules are maintained and optimized using VAXset. Within a VAX/VMS workstation environment LINKERS generates a useful population of 10,000 families in 1 min. An example is presented to illustrate the use of LINKERS. Generated data were analysed using the segregation program POINTER. Likelihood ratio tests showed the effects of multiple alleles, gene frequency and incorrect specification of disease prevalence.

Functional and psychosocial effects of multimodality limb-sparing therapy in patients with soft tissue sarcomas

We have documented functional and psychosocial changes in patients with extremity soft tissue sarcomas who have undergone multimodality limb-sparing treatments. In 88 patients, parameters related to economic status, sexual activity, pain, limb function, and global quality of life (QOL) were recorded prior to surgery and every 6 months postoperatively. Changes from the preoperative assessment for every parameter were analyzed in each patient. Six months after surgery, there was a decrease in employment status, sexual activity, and in limb function in a significant number of patients. At 12 months, these decreases were still evident. Despite these changes, global QOL measured by a standardized test showed at least some improvement in a significant proportion of patients at 12 months. These findings highlight the difficulty in defining QOL. It could not be ascertained if radiation therapy and/or chemotherapy were causative factors in specific changes because of the small numbers of patients in each subgroup. However, among 60 patients with high-grade sarcomas, significant wound problems developed in 10 of 33 who received postoperative radiation therapy in combination with adjuvant doxorubicin and cyclophosphamide chemotherapy compared with one of 27 patients who received adjuvant chemotherapy alone (P = .016). Also, among high-grade sarcoma patients with 12-month follow-up, six of 19 patients who received radiation therapy and chemotherapy developed joint contractures compared with zero of 15 patients who received chemotherapy alone (P less than .04). The combination of postoperative radiation therapy and chemotherapy appeared to be associated with significantly more tissue-related injury in patients with high-grade sarcomas compared with chemotherapy alone.

Pre- and postoperative sequential study on the immunosuppressive activity of serum and cell-free skin bleb fluid of patients with lung cancer and esophageal cancer

Serial changes of immunosuppressive activity of serum and cell-free skin bleb fluid that can suppress the activity of acid a-naphthyl acetate esterase (ANAE) of lymphocytes and phagocytosis of macrophages were detected by immunoregulatory tests in vitro in 50 lung cancer and 42 esophageal cancer patients. In comparing these tests with those of 53 cases of noncancerous thoracic lesion and 69 normal adults, the immunosuppressive activity of serum and skin bleb fluid from cancer patients is significantly higher than that of noncancerous thoracic lesions and normal individuals (P less than .01). The activity is related to the stages of cancer, the size of primary tumor, the presence of lymph node metastasis, and tumor resect-ability, but not to histological classification, sex, and age. The immunosuppressive activity of serum and skin bleb fluid decreased gradually after the removal of the tumor and was eliminated on the 30th postoperative day. These results suggest that serum and skin bleb fluid from cancer patients may contain immunosuppressive factors that can suppress the immune responsive functions of lymphocytes and macrophages in vitro in a manner similar to that seen in vivo. Therefore, complete surgical removal of cancer is likely the most effective immunotherapy.

[Surgical treatment of primary pulmonary cryptococcal granuloma--report of 4 cases]

Primary pulmonary cryptococcal granuloma is not common in Sichuan. The diagnosis of this disease is difficult to make because the patient has no characteristic symptoms and the chest X-ray findings of the mass are not easily differentiated from carcinoma of the lung. The incidence of this disease is apparently increasing. Pulmonary cryptococcosis may be disseminated hematogenously to the meninges and cryptococcal meningitis is very difficult to treat. If the pulmonary lesion is localized, the patient's general condition is good with no evidence of systemic lupus erythematosis, diabetes, leukemia or lymphoma, partial resection of the lung is indicated. But, if the patient has a history of recent cryptococcal meningitis, surgery must be deferred. Four cases of primary pulmonary cryptococcal granuloma have been treated surgically supplemented with medical therapy in the First Affiliated Hospital from 1986 to 1987. Follow-up of more than one year showed good results in each case.

Order of response surfaces for representation of a Monte Carlo epidemic model

Response hypersurfaces for two selected outcomes and for 6 model features were generated for Latin Hypercube (LH) samples of the parameter space of a discrete, micro-population, Monte Carlo model of an epidemic of an infectious disease agent. SAS stepwise, multivariate regression routines were used to generate response hypersurfaces of first, second and third order in the model features for each outcome. These are used as illustrative examples to examine the appropriateness of the order of the polynomial describing the response hypersurface. The response hypersurfaces are very dependent on the model outcomes and also on the selected ranges of the model features. Results indicate that there is little reason to prefer any particular order for the response hypersurfaces. Further, it is suggested that apparent interaction terms found when using quadratic and cubic response hypersurfaces may represent artifacts of the choice of a particular order for the response hypersurface. Nonetheless, the comparison of the 3 orders of response hypersurfaces can, under some circumstances, reveal basic characteristics of the sensitivity of the outcome to the model features.