Expected survival compared with survival of peptic ulcer patients

In analyses of patient survival it is often desirable to compare observed survival curves with expected survival curves based on information obtained from the general population. However, current methods of calculating expected survival curves are difficult to interpret and are often poorly documented. We discuss an alternative formulation of the so-called direct method which we recommend for general use. By simulation, we show that the expected survival curve obtained from this method represents the expectation of a Kaplan-Meier curve for a set of random population controls. Thus, the term expected survival does not refer to the expectation of patient survival, but rather to the expected survival curve for a random set of controls. The alternative methods are discussed, and we illustrate the methods in an analysis of long time survival of a population-based sample of peptic ulcer patients.     

Differential responses of estrogen target tissues in rats including bone to clomiphene, enclomiphene, and zuclomiphene

The substituted triphenylethylene antiestrogen clomiphene (CLO) prevents cancellous bone loss in ovariectomized (OVX'd) rats. However, CLO is a mixture of two stereoisomers, enclomiphene (ENC) and zuclomiphene (ZUC), which have distinctly different activities on reproductive tissues and tumor cells. The purpose of the present dose response study was to determine the effects of ENC and ZUC on nonreproductive estrogen target tissues. These studies were performed in 7-month-old female rats with moderate cancellous osteopenia that was established by ovariectomizing rats 1 month before initiating treatment. OVX resulted in increases in body weight, serum cholesterol, endocortical resorption, and indices of cancellous bone turnover, as well as decreases in uterine weight, uterine epithelial cell height, bone mineral density, bone strength, and cancellous bone area. Estrogen treatment for 3 months restored body weight, uterine histology, dynamic bone measurements, and osteoblast and osteoclast surfaces in OVX'd rats to the levels found in the age-matched sham-operated rats. In contrast, estrogen only partially restored cancellous bone volume and uterine weight, and it reduced serum cholesterol to subnormal values. CLO was a weak estrogen agonist on uterine measurements and a much more potent agonist on body weight, serum cholesterol, and dynamic bone measurements. CLO increased trabecular thickness in osteopenic rats and was the most effective treatment in improving cancellous bone volume and architecture. ZUC was a potent estrogen agonist on all tissues investigated and had dose-dependent effects. In contrast, ENC had dose-dependent effects on most measurements similar to CLO and decreased the uterotrophic effects of ZUC. It is concluded that ENC antagonizes the estrogenic effects of ZUC on the uterus but that the beneficial effects of CLO on nonreproductive tissues in OVX'd rats is conferred by both isomers. Furthermore, the combined actions of the two isomers on bone volume and architecture were more beneficial than either isomer given alone.     

Effect of hypohydration on gastric emptying and intestinal absorption during exercise

Dehydration and hyperthermia may impair gastric emptying (GE) during exercise; the effect of these alterations on intestinal water flux (WF) is unknown. Thus the purpose of this study was to determine the effect of hypohydration ( approximately 2.7% body weight) on GE and WF of a water placebo (WP) during cycling exercise (85 min, 65% maximal oxygen uptake) in a cool environment (22 degrees C) and to also compare GE and WF of three carbohydrate-electrolyte solutions (CES) while the subjects were hypohydrated. GE and WF were determined simultaneously by a nasogastric tube placed in the gastric antrum and via a multilumen tube that spanned the duodenum and the first 25 cm of jejunum. Hypohydration was attained 12-16 h before experiments by low-intensity exercise in a hot (45 degrees C), humid (relative humidity 50%) environment. Seven healthy subjects (age 26.7 +/- 1.7 yr, maximal oxygen uptake 55.9 +/- 8.2 ml . kg-1 . min-1) ingested either WP or a 6% (330 mosmol), 8% (400 mosmol), or a 9% (590 mosmol) CES the morning following hypohydration. For comparison, subjects ingested WP after a euhydration protocol. Solutions ( approximately 2.0 liters total) were ingested as a large bolus (4.6 ml/kg body wt) 5 min before exercise and as small serial feedings (2.3 ml/kg body wt) every 10 min of exercise. Average GE rates were not different among conditions (P > 0.05). Mean (+/-SE) values for WF were also similar (P > 0.05) for the euhydration (15.3 +/- 1.7 ml . cm-1 . h-1) and hypohydration (18.3 +/- 2.6 ml . cm-1 . h-1) experiments. During exercise after hypohydration, water absorption was greater (P < 0.05) with ingestion of WP (18.3 +/- 2. 6) and the 6% CES (16.5 +/- 3.7), compared with the 8% CES (6.9 +/- 1.5) and the 9% CES (1.8 +/- 1.7). Mean values for final core temperature (38.6 +/- 0.1 degrees C), heart rate (152 +/- 1 beats/min), and change in plasma volume (-5.7 +/- 0.7%) were similar among experimental trials. We conclude that 1) hypohydration to approximately 3% body weight does not impair GE or fluid absorption during moderate exercise when ingesting WP, and 2) hyperosmolality (>400 mosmol) reduced WF in the proximal intestine.     

Surgical control of clinically localized prostate carcinoma is equivalent in African-American and white males

BACKGROUND: Few studies have compared the outcome of radical prostatectomy between African-American males (AAM) and white males, and the results of the few studies that have are conflicting. Therefore, the authors examined the impact of radical surgery on localized prostate carcinoma in both patient populations, and assessed whether stratification by pathologic extent of local disease would yield an equivalent outcome. METHODS: Prostate specific antigen (PSA) failure and carcinoma-associated death rates were assessed in 1319 patients (115 AAM and 1204 white males), 872 of whom had a pretreatment serum PSA level taken. The percent of prostate involved by tumor, tumor wet weight, and DNA ploidy status were available in 755, 522, and 638 patients, respectively. RESULTS: AAM were diagnosed at an earlier age than white males (62.8 years vs. 65.4 years; P = 0.0001). The distribution of pathologic extent of local disease was similar in both races, and AAM had a statistically higher rate of tumors with a Gleason sum of 7-10 at surgery than white males (64% vs. 46%). Race did not play a role in the outcome of patients with organ-confined or specimen-confined tumors. However, in patients with positive surgical margins, the median time to PSA failure and the median carcinoma-associated survival were less in AAM compared with white males. Tumor volume was significantly larger in AAM compared with white males. After multivariate adjustment for the pathologic extent of local disease, tumor grade at surgery, preoperative PSA, tumor volume, and age, African-American race was not a significant prognostic indicator for carcinoma-associated death and PSA failure (P = 0.17 and 0.14, respectively). CONCLUSIONS: The outcome of radical prostatectomy was similar in both racial groups, although AAM with positive surgical margins tended to fail earlier than white males, suggesting greater biologic aggressiveness of residual disease. Because local extent of disease impacts on PSA failure and survival, and because the disease appears to present earlier in AAM, the AAM population may benefit from early detection programs.     

The role of maternal thyroid hormones on the development of the brushtail possum, Trichosurus vulpecula

Thyroxine (T4) is a vital hormone for the development of mammals. To determine the role of maternal thyroid hormones on organ development, methimazole, an inhibitor of T4, was first administered via a minipump to 13 mothers with pouch young between days 10 and 80 post partum for 28 days. Three young survived and 10 of the young died at 104.0 +/- 10.8 days post partum (mean, SEM). Methimazole was then administered for 28 days to 6 lactating adult possums with pouch young at day 20 post partum. The effects of this treatment on the maternal plasma concentrations of T4 were monitored and the development of the lung, kidney and brain of the young were examined at day 90 post partum. There was no difference in the morphology of the lung, kidney and brain of pouch young at day 90 post partum whose mothers were treated with methimazole or saline. Thus methimazole administered to lactating possums for a short period early in lactation can cause the demise of the young about day 100 post partum although the cause of death is unknown. It is possible that the development of the central nervous system or some other vital organ has been inhibited, this altered state not being apparent morphologically. Nevertheless the marsupial appears to be similar to the eutherian in its requirement for thyroxine for normal development. However whereas this requirement is apparent during fetal development and around the time of birth in eutherians thyroxine is of importance during pouch development in marsupials.     

Reported changes in sexual behavior in response to AIDS in the United States

BACKGROUND: The AIDS epidemic has profoundly affected public health policy and everyday choices of individuals. Understanding the self-protective strategies adopted by the general population is crucial to designing appropriate and more effective primary AIDS prevention strategies. METHODS: A probability sample of the U.S. adult population in 1992, the National Health and Social Life Survey (n = 3,159), addressed detailed aspects of sexual behavior. How respondents changed their sexual behavior due to AIDS was recorded verbatim and categorized for analysis. RESULTS: Twenty-nine percent of U.S. adults reported some sexual behavior change, primarily, reducing numbers of partners (12%), using condoms more frequently (9%), selecting partners more carefully (7%), changing attitude toward sex (4%), and abstinence (3%). Individuals most at risk show the greatest propensity to change although the actual risk-reduction strategies and the meanings assigned to those strategies vary considerably. Strategies are not all compatible with each other nor equally likely to be adopted by individuals with different lifestyles. CONCLUSIONS: Self-protective strategies to avoid AIDS are widespread, but primary prevention efforts should be targeted to particular circumstances and the self-protective propensities of each individual.     

The changing mole. Additional warning signs of malignant melanoma

The causal involvement of bovine viral diarrhoea virus (BVDV) and border disease virus (BDV) infection in bovine and ovine abortion and perinatal mortality remain unclear. From 1992 until 1994, 213 bovine and 31 ovine foetuses as well as 36 calves and 25 lambs which had died perinatally were investigated. Tissue samples were tested for the presence of pestiviruses and serum or fluid from the body cavities were analysed for the presence of pestivirus antibodies. Detection of pestiviruses was performed by (i) cell culture isolation, (ii) antigen ELISA and (iii) immunohistochemical staining for viral antigen. For antibody-testing an indirect ELISA was used. In nine bovine foetuses and in two calves BVDV was isolated. Pestiviruses, most likely BDV were detected in one ovine foetus and three lambs. In 6% of the bovine and 11% of the ovine foetuses anti-pestivirus antibodies were detected. However, clinical features and history of bovine cases did not show a correlation with the diagnostic results, In contrast, the presence of central nervous system signs in neonatal lambs and the detection of BDV was correlated.