Nmethyl-N-nitrosourea (MNU) induces papillary thyroid tumours which lack ras gene mutations in the hermaphroditic fish Rivulus marmoratus

To investigate the patterns of alkylating agent-induced tumour formation, 40 fish (Rivulus marmoratus) were exposed to N-methyl-N-nitrosourea (MNU) at 50 ppm in 10 mM Hepes-buffered synthetic seawater for 2 h. Tumour incidence 4 months after exposure was approximately 95%, and mainly papillary thyroid tumours were induced. For elucidating the molecular event in Rivulus papillary thyroid carcinogenesis, we first analysed for ras gene mutations based on the known ability of MNU to induce point mutations. The amplified R. Marmoratus Ha-and Ki-ras gene exon 1 and 2 regions were checked along with confirming the presence and expression patterns of the DNA repair gene O(6)-methylguanine alkyltransferase (O(6)-MT) and other oncogenes (c-src, c-fos, and c-myc). Ha- and Ki-ras genes from 38 tumour samples were tested for point mutations with direct sequencing but were not found to contain mutations. In this report, based on the lack of Ha- and Ki-ras gene mutations in papillary thyroid tumour induction in R. Marmoratus, we suggest that Ha- and Ki-ras gene-independent pathways such as ret/PTC rearrangements and other activations are involved in Rivulus papillary thyroid carcinogenesis. Teratogenesis Carcinog. Mutagen. 20:1-9, 2000.     

Regulation of CD27 expression in the course of germinal center B cell differentiation: the pivotal role of IL-10

The molecules of the TNF superfamily and their receptors play crucial roles in the humoral immune response. In view of the powerful effects on germinal center (GC) B cell differentiation, the expression of these molecules should be tightly regulated. In this study, we have undertaken a detailed analysis of the regulation of CD27 expression following the differentiation of GC B cells supported by a follicular dendritic cell line. We show that CD27 is differentially expressed on B cell subpopulations at different stages of differentiation. Naive B cells are virtually negative but plasma cells generated in vivo are strongly positive for CD27 expression. GC B cells that exhibit a moderate expression of CD27 remarkably up-regulate the expression levels of this molecule when they differentiate into plasma cells, which is induced by IL-10. The up-regulation of CD27 expression correlates with that of CD38. Therefore, high expression of CD27 molecules emerges as a specific marker for plasma cells. Our results suggest an important role for CD27 in the differentiation of GC B cells into plasma cells. Evaluation of CD27 expression levels may be of a clinical significance in assessment of B cell maturation in immunocompromised patients.     

Helicobacter pylori infection with iron deficiency anaemia and subnormal growth at puberty

The purpose of this study was to determine whether Helicobacter pylori infection can contribute to growth deficit, especially in pubescent children who need large amounts of iron for growth. A structured questionnaire was sent to the parents of 532 healthy children aged 10 to 15 years (mean 12.9) to obtain demographic information on the parents and the environment. Of the 532 questionnaires sent out, 375 (70.5%; 170 girls and 205 boys) were returned. After collecting blood samples from participants, haemoglobin, serum iron, total iron binding capacity, serum ferritin, and serum IgG antibodies to H pylori were measured. The effects of risk factors such as H pylori infection, iron deficiency anaemia, sex, socioeconomic status, type of house, and crowding index on growth were analysed using multiple regression analysis. Of 63 H pylori positive children, 18 (28.6%) were below the 25th centile values for height, compared with 63 of 312 (20.2%) H pylori negative children. The prevalence rate of H pylori infection was 15.5% (53 of 343) in children without iron deficiency anaemia and 31.3% (10 of 32) in those affected. The relative risk of short stature was 2.2 (95% confidence interval (CI), 1.0 to 4.8) for iron deficiency anaemia, and 1.4 (95% CI, 0.8 to 2.4) for H pylori infection. The mean height was significantly lower in the group having both H pylori infection and iron deficiency anaemia. Therefore, H pylori infection accompanied by iron deficiency anaemia, rather than H pylori infection per se, might delay pubertal growth.     

Sedative tolerance accompanies tolerance to the analgesic effects of fentanyl in infant rats

Iatrogenic tolerance and physical dependence have been documented in human neonates and infants infused with fentanyl or morphine i.v. to maintain continuous analgesia and sedation during extracorporeal membrane oxygenation (ECMO) and mechanical ventilation for the treatment of life-threatening pulmonary diseases. Using postnatal d 17 infant rats, the hypothesis was tested that sedative tolerance accompanies tolerance to fentanyl analgesia in the tail-flick test. Postnatal d 14 infant rats remained naive or received osmotic minipumps infusing saline (1 microL/h) or fentanyl citrate (60 microg x kg(-1) h(-1)). Seventy-two hours later, fentanyl's antinociceptive potency was reduced 3.1-fold in fentanyl-infused rats. Conscious sedation and deep sedation were examined with the cliff-avoidance and the righting-reflex procedures, respectively. Fentanyl-infused infants were tolerant to both the conscious and deep sedative effects of fentanyl. Another hypothesis tested was that very high receptor intrinsic activity opioids are less likely to produce tolerance, or to be cross-tolerant to other opioids. Dihydroetorphine is 5,000 to 10,000 times more potent than morphine. However, fentanyl-infused infant rats were cross-tolerant to the analgesic and sedative effects of dihydroetorphine. Interestingly, dihydroetorphine's analgesic efficacy was significantly reduced to a maximum analgesic efficacy (Emax) value of 40% maximum possible effect (MPE). Another concern was whether fentanyl tolerance would generalize to another class of sedatives, the benzodiazepines. This was especially relevant considering the widespread use of benzodiazepines like midazolam in ECMO and mechanical ventilation. Midazolam elicited no analgesia in the tail-flick test. Furthermore, fentanyl-tolerant rats were not cross-tolerant to the conscious or deep sedative effects of midazolam.     

The Use of High-Resolution Computed Tomography in the Evaluation of Pulmonary Hemodynamics in Patients with Congenital Heart Disease: In Pulmonary Vessels Larger Than 1 mm in Diameter

High-resolution computed tomography (HRCT) was carried out in 36 patients with congenital left-to-right shunt disease and 10 normal control subjects to assess the feasibility of CT in the evaluation of pulmonary hemodynamics. The patients had a left-to-right or a bidirectional shunt and the hemodynamic data obtained by cardiac catheterization in these patients were compared to the information obtained by CT imaging. The pulmonary/systemic blood flow (Q _p/Q _s) ratio and pulmonic/systemic resistance (R _p/R _s) ratio had a significant correlation with the pulmonary artery/bronchus (PA/Br) ratio (r= 0.54 and r=−0.37, respectively) and pulmonary vein/bronchus (PV/Br) ratio (r= 0.66 and r=−0.66, respectively), and the R _p/R _s and mean PA pressure also showed a significant correlation with the PA/PV ratio (r= 0.53 and r=−0.61, respectively) in the mid-lung field when accompanying bronchi were 4.0–5.9 mm in diameter. There was no correlation between the hemodynamic data and the size of the central and hilar PA or with the rate of PA tapering. With HRCT, it is possible to evaluate pulmonary hemodynamics in patients with congenital heart disease with a left-to-right or bidirectional shunt, particularly R _p/R _s and mean PA pressure, which have been very difficult to obtain noninvasively. The small-sized pulmonary vessel/Br ratio or the small-sized PA/PV ratio could offer very useful information, but the dimension of the central PA provided the least useful information.     

Mechanistic understanding of time-dependent oral absorption based on gastric motor activity in humans.

The relationship of gastric motor activity and gastric emptying of 0.7mm caffeine pellets with their absorption was investigated in the fed state in healthy human subjects by simultaneous monitoring of antral motility and plasma concentrations. A kinetic model for gastric emptying-dependent absorption yielded multiple phases of gastric emptying and rate constants (k(g)) with large inter-individual differences and large variability in onset of gastric emptying (50-175min). The model suggests that 50% of the dose is emptied in 1-2h and over 90% emptied by 3.5h following dosing, in all subjects. The maximum values of k(g) (k(g)(max)) were much greater than those reported for emptying of liquids in the fasted state and were comparable to k(g) values in the late Phase II/III of the migrating motor complex (MMC). The model described the observed irregular absorption rate-time and plasma concentration-time profiles adequately but not in detail. The model was more successful at simulating double-peak phenomena in absorption rate profiles and onset of caffeine absorption. The results suggest that gastric emptying regulates drug absorption of small particles in the fed state. Further, estimates of k(a) derived using the time-dependent absorption model were closer to the intrinsic absorption rate constant for caffeine.     

Development and application of evaluation indices for hospital infection surveillance and control programs in the Republic of Korea.

OBJECTIVE: To develop new evaluation indices of infection control and to use them to evaluate Korean infection surveillance and control programs (ISCPs). DESIGN: We performed a questionnaire-based survey to 164 acute care general hospitals throughout the Republic of Korea that had more than 300 beds. Study methods were based completely on those of the Study on the Efficacy of Nosocomial Infection Control (SENIC). Four SENIC indices (hospital epidemiologist index, infection control nurse index, surveillance index, and control index) and 4 newly developed indices (healthcare worker index, quality improvement index, resource index, and hand hygiene facilities index) were used to evaluate Korean ISCPs. Data were collected by questionnaire from June 17 to October 11, 2003. SETTING: One hundred sixty-four general hospitals with more than 300 beds in the Republic of Korea. RESULTS: Personnel from 85 general hospitals responded to the study questionnaire. The reliability and validity of the evaluation indices were statistically significant (P<.05). The 8 evaluation indices were categorized into 2 factor groups: personnel factors (hospital epidemiologist index and infection control nurse index) and activity factors (the remaining 6 indices). Korean ISCPs showed a major weakness in surveillance. The scores for the newly developed evaluation indices were better than those for the SENIC evaluation indices. However, most Korean hospitals were estimated to have had only slight reductions in nosocomial infection rates. The evaluation indices were influenced significantly by the number of beds in the hospital, whether the hospital was located in the Seoul-Gyonggi region, the presence of full-time infection control nurses at the hospital, the education level of the infection control nurses, and the nurses' experience in infection control (P<.05). CONCLUSIONS: The reliability and validity of the SENIC evaluation indices and the newly developed evaluation indices were satisfactory in evaluating Korean ISCPs. However, surveillance should be improved to increase the efficacy of Korean ISCPs.     

Long-term cardiac gene expression using a coxsackieviral vector

Efficient myocardial gene transfer in the intact adult heart is difficult using conventional transfer vectors. Since coxsackievirus B3 (CVB3) is cardiotropic, it may be possible to exploit its cardiotropic characteristics to design a vector for gene transfer to the intact heart. We generated a recombinant CVB3 cDNA by inserting a green fluorescent protein (GFP) gene immediately upstream from the VP0 capsid protein of CVB3. The infectious virus (rCVB3-GFP) was recovered from the supernatants of the transfected Cos-7 cells, and was grown in HeLa cells to titers of 10(11) pfu/ml. In the rCVB3-GFP infected HeLa cells and neonatal rat cardiac myocytes, GFP protein expression was documented by immunoblot and by fluorescent microscopy. GFP expression was maintained after five passages in HeLa cells. To test in vivo expression of GFP, we infected 8-week-old inbred female Balb/C mice with 10(6) pfu of rCVB3-GFP, intraperitoneally. GFP was present in up to 30% of cardiac myocytes over the 8 weeks post infection (p.i.) and it was co-localized with CVB3 infection. Surprisingly, in spite of detection of GFP up to at least 8 weeks after infection, there was no mortality in the mice. It is possible to express exogenous proteins in the intact heart after an intraperitoneal (i.p.) injection of recombinant coxsackievirus. The duration of expression persisted for at least 8 weeks with little immune response nor mortality. These results demonstrated that the cardiac tropism of CVB3 could be used to design vectors for efficient gene expression in the intact heart.