Identification of a specific binding site for the anabolic steroid stanozolol in male rat liver microsomes

Male rat liver microsomes contain a [3H]dexamethasone binding site, capable of binding glucocorticoids and progesterone. We have shown previously that the 17 alpha-alkylated androgen, stanozolol, can inhibit the [3H]dexamethasone binding to microsomes through a negative allosteric mechanism, which gives rise to the possibility of its interaction with a different binding site. In this study, the existence of a single-saturating binding site, capable of binding the radioactive steroid with a maximum number of the specific binding site of 49 +/- 2 pmol/mg of protein and a Kd of 37 +/- 1.3 nM was demonstrated by using [3H]stanozolol. In competition experiments, only stanozolol and danazol were able to compete with [3H]stanozolol for its binding to microsomes, among more than 60 steroids and other compounds tested. The binding of [3H]stanozolol was depressed after protease treatment of the microsomes, or after the administration of cycloheximide to adult male rats for 24 hr, which suggest its proteic nature. The [3H]stanozolol binding site was detected in many tissues of the rat, with the highest concentrations being found in the liver. It was detected from birth, increasing afterward in concentration and reaching a peak at 2 to 3 months of age. This is the first experimental verification of the existence in liver microsomes of a specific binding site for some 17 alpha-alkylate androgens, such as stanozolol and danazol, different from the androgen receptor or the [3H]dexamethasone binding site.     

Ewing's sarcoma of the pelvis: changes over 25 years in treatment and results

The pelvic localisations of Ewing's sarcoma have the worst prognosis due to large size at diagnosis, frequent distant metastases, radiosensitive organs next to the tumour and difficult surgery. The purpose of the present study was to analyse treatment results over a period of 25 years and to investigate the impact of newer chemotherapy schedules, improved radiotherapy techniques and newer surgical methods on the prognosis. 35 children and young adults were identified from 1967 to 1994 for whom diagnosis, presentation, performed treatment and outcome were available. Tumour size, as measured from CT scans, response to chemotherapy and radiotherapy target volume, could be reviewed in the later years. Actuarial 5-year survival for the whole group was 31% and for the 24 non-metastatic patients 40%, with a disease-free interval of 19%. Tumour size could be measured in 27 patients and ranged from 36 to 1540 cm3. There were 12 local recurrences, 1 in the 4 patients treated with surgery. After 1983, 9 out of 17 irradiated patients developed local failure. 3 patients had adequate fields and one a close field which did not cover completely the prechemotherapy extent and 3 of these recurred. All 4 patients with stable disease after neoadjuvant CT failed locally, not withstanding high-dose radiotherapy. The mean length of neoadjuvant CT tended to be shorter in patients without local relapse. There was no significant difference in survival before and after 1983.     

Tracing the spread of methicillin-resistant Staphylococcus aureus by Southern blot hybridization using gene-specific probes of mec and Tn554

In a community hospital in Brooklyn, New York, over a 3-year period, 79 methicillin-resistant Staphylococcus aureus (MRSA) isolates from five different case clusters were subtyped by Southern blot hybridization with two previously characterized gene probes, mec and Tn554. Together, the genotyping enabled the hospital infection control team to differentiate simultaneous MRSA clusters in the surgical intensive care unit (type I:A) and the open heart unit (type II:J), document the spread of one strain (type I:A) between roommates, identify an endemic strain (type II:J) from cardiac monitors and medical personnel, and identify an unrelated outbreak strain (type II:NH) in the labor and delivery unit. On the basis of this investigation it is clear that the routine DNA fingerprinting of MRSA in health care facilities, to monitor their spread and identify cases of nosocomial infections, is an important infection control measure.     

Prevention of deep-vein thrombosis after total hip arthroplasty. Comparison of warfarin and dalteparin

The effectiveness and safety of warfarin were compared with those of a low-molecular-weight heparin (dalteparin) for the prevention of deep-vein thrombosis after total hip arthroplasty in a prospective, randomized, multi-institutional trial. Patients who were older than eighteen years of age and were scheduled to have an elective primary or revision total hip arthroplasty were eligible; 580 patients were randomized, 550 had the operation and received prophylaxis, and 382 had evaluable venograms. Prophylaxis was provided either with warfarin beginning the night before the operation or with dalteparin beginning two hours before the operation and was continued until venography was performed. Bleeding was assessed on the basis of intraoperative blood loss, transfusion requirements, a decrease in hematocrit, and clinically identified bleeding complications. The prevalence of deep-vein thrombosis was found to be significantly lower in the patients who had received dalteparin than in those who had received warfarin (twenty-eight [15 per cent] of 192 patients compared with forty-nine [26 per cent] of 190 patients; p = 0.006). Deep-vein thrombosis occurred in the calf veins of twenty-one patients (11 per cent) who had received dalteparin and of forty-three patients (23 per cent) who had received warfarin; this difference was significant (p = 0.003). Proximal deep-vein thrombosis occurred in ten patients (5 per cent) who had received dalteparin and in sixteen patients (8 per cent) who had received warfarin; however, with the numbers available, no significant difference could be detected (p = 0.185). We also could not detect a significant difference with regard to the intraoperative and postoperative blood loss, the decrease in hematocrit, and the prevalence of major bleeding complications between the two groups; however, the patients who had received dalteparin had a significantly higher prevalence of bleeding complications involving the operative site (p = 0.03), and a significantly greater percentage required postoperative transfusions (p = 0.001). We concluded that preoperative prophylaxis with dalteparin is significantly more effective than that with warfarin in preventing deep-vein thrombosis after total hip arthroplasty. The greater effectiveness of dalteparin must be considered, however, in light of an increased need for postoperative transfusions and an increase in the prevalence of wound-related bleeding complications.     

Connexin43 immunoreactivity in the catfish retina

Tyrosine hydroxylase (TH) mRNA levels in the rat substantia nigra (SN), ventral tegmental area (VTA) and locus coeruleus (LC) were measured by in situ hybridization histochemistry 1, 4, 6 and 24 h after a single injection of methamphetamine (MAP, 4 mg/kg, i.p.) or an equivalent volume of saline. TH mRNA levels in LC were transiently increased (130% of control saline group, P < 0.05) at 1 h after MAP injection, and returned to basal levels within 4 h. In contrast, acute MAP administration did not significantly affect TH mRNA levels in SN and VTA. These findings are the first to demonstrate TH mRNA expression in the different responses of catecholaminergic neurons to acute MAP administration.     

Apoptosis of late-stage erythroblasts in megaloblastic anemia: association with DNA damage and macrocyte production

An in vitro model of folate-deficient erythropoiesis has been developed using proerythroblasts isolated from the spleens of Friend virus-infected mice fed an amino acid-based, folate-free diet. Control proerythroblasts were obtained from Friend virus-infected mice fed the same diet plus 2 mg folic acid/kg diet. Our previous studies showed that, after 20 to 32 hours of culture in folate-deficient medium with 4 U/mL of erythropoietin, the folate-deficient proerythroblasts underwent apoptosis, whereas control erythroblasts survived and differentiated into reticulocytes over a period of 48 hours. The addition of folic acid or thymidine to the folate-deficient medium prevented the apoptosis of the folate-deficient erythroblasts, thereby implicating decreased thymidylate synthesis as the main cause of apoptosis in the folate-deficient erythroblasts. In the study reported here, we examined intracellular folate levels, uracil misincorporation into DNA, p53 and p21 proteins, and reticulocyte formation in erythroblasts cultured in folate-deficient or control medium. In all experiments, the folate-deficient erythroblasts cultured in folate-deficient medium gave results that varied significantly from folate-deficient erythroblasts cultured in control medium or control erythroblasts cultured in either folate-deficient or control media. Folate-deficient erythroblasts cultured in folate-deficient medium had marked decreases in all coenzyme forms of folate that persisted throughout culture, increased uracil misincorporation into DNA, persistent accumulations of p53 and p21, and decreased reticulocyte production but increased size of individual reticulocytes. A model of folate-deficient erythropoiesis based on apoptosis of late stage erythroblasts is presented. This model provides explanations for the clinical findings in megaloblastic anemia.     

Is the hippocampus involved in temporal discrimination and the memory of short intervals?

Rats with lesions to the hippocampus proper and the subiculum were tested for timing behavior and temporal memory. Using the peak procedure, they were trained to discriminate a 40 s interval and a retention gap tested the memory for time. Results were interpreted within the theoretical framework of the internal clock and with respect to current theories on hippocampal function. Timing behavior was unaffected by either lesion and no shifts in the temporal discrimination functions were observed. The lesions also failed to show a deficit in the memory for temporal events. For all groups, the retention gap increased the mean peak time by the time of the gap. This indicated that all rats used the stop rule which required the use of working memory. Thus, it was concluded that the hippocampus is neither necessary for accurate timing behavior nor for the memory of temporal events.