The 9L rat brain tumor model for pre-clinical investigation of radiation-chemotherapy interactions

Summary The rat 9L gliosarcoma brain tumor model has been used for more than thirty years to investigate a variety of potential therapeutic agents, combinations, schedules, and approaches that might be applicable to the management of high-grade malignant brain tumors in man. When tumor cells are implanted intracerebrally, a solid tumor grows until its mass results in the death of the animal, typically between 20 and 30 days post-inoculation. Radiation therapy (either single or fractionated doses) is effective at prolonging survival in a dose-dependent manner. Numerous cancer chemotherapeutic agents, by a variety of doses, schedules, and routes of delivery, have demonstrated therapeutic efficacy in the 9L model. The combination of radiation and agents such as AZQ, BCNU, bleomycin, and cis-platinum has resulted in prolongation of survival that is significantly better than either agent used alone, without exceeding the tolerance of critical normal tissues. These pre-clinical data suggest that combining standard fractionated radiation therapy with appropriate concomitant cytotoxic chemotherapeutic agents might benefit patients with high-grade brain tumors.     

The accountability of clinical education: its definition and assessment

BACKGROUND: Medical education is not exempt from increasing societal expectations of accountability. Competition for financial resources requires medical educators to demonstrate cost-effective educational practice; health care practitioners, the products of medical education programmes, must meet increasing standards of professionalism; the culture of evidence-based medicine demands an evaluation of the effect educational programmes have on health care and service delivery. Educators cannot demonstrate that graduates possess the required attributes, or that their programmes have the desired impact on health care without appropriate assessment tools and measures of outcome. OBJECTIVE: To determine to what extent currently available assessment approaches can measure potentially relevant medical education outcomes addressing practitioner performance, health care delivery and population health, in order to highlight areas in need of research and development. METHODS: Illustrative publications about desirable professional behaviour were synthesized to obtain examples of required competencies and health outcomes. A MEDLINE search for available assessment tools and measures of health outcome was performed. RESULTS: There are extensive tools for assessing clinical skills and knowledge. Some work has been done on the use of professional judgement for assessing professional behaviours; scholarship; and multiprofessional team working; but much more is needed. Very little literature exists on assessing group attributes of professionals, such as clinical governance, evidence-based practice and workforce allocation, and even less on examining individual patient or population health indices. CONCLUSIONS: The challenge facing medical educators is to develop new tools, many of which will rely on professional judgement, for assessing these broader competencies and outcomes.     

Cesarean versus vaginal delivery in abruptio placentae associated with live fetuses

In order to test the relative effectiveness of cesarean section and vaginal delivery in mild abruptio placentae associated with live fetuses, 23 consecutive patients were delivered vaginally and 18 by cesarean section over an 18-month period at the University of Ife Hospital in Nigeria. The perinatal mortality of the vaginal delivery group (52.2%) was significantly greater than that of those delivered by cesarean section (16.7%) (P greater than 0.02; less than 0.05; chi 2 test). The 1-min Apgar score test was also significantly greater than that of those delivered by cesarean section (P greater than 0.001). These differences have been attributed to the admission-to-delivery interval, which was significantly longer in the vaginal delivery group (12 h vs. 2 h). It is concluded that cesarean section is clearly superior to vaginal delivery in the management of abruptio placentae associated with live fetuses.     

Group B streptococci colonization among Saudi women in labor and neonatal acquisition

Rates of high vaginal Group B Streptococcus colonization and the perinatal transmission were determined in 260 Saudi women admitted for delivery to the Obstetrical Unit of the King Fahd Hospital of the University, Al-Khobar. Of these women, 24 mothers in labour had vaginal colonization (9.2%). Three neonates acquired Group B Streptococci soon after birth on more than one body site and the perinatal transmission rate was 12.5%. Implication of these findings are reviewed.     

Effects of maternal oxygen administration on fetal oxygenation during reductions in umbilical blood flow in fetal lambs

In 11 chronically catheterized fetal lambs (123 +/- 6, mean +/- SD, days of gestation; term = 147 days), we measured fetal oxygen delivery and oxygen consumption before and during reductions in umbilical blood flow (Qumb). Qumb was reduced by inflation of a balloon occluder located just proximal to the origin of the common umbilical artery. Measurements were made while the unanesthetized maternal sheep received either room air or 100% oxygen to breathe. In oxygen-treated fetuses, oxygen concentrations in umbilical venous blood (Cuvo2) and arterial blood (Cao2) were increased over a wide range of Qumb when compared with those of room air-treated fetuses. Because of these responses, fetal oxygen delivery (Do2 = Qumb X Cuvo2) and oxygen consumption [Vo2 = Qumb(Cuvo2-Cao2)] were greater in oxygen-treated fetuses than in room air-treated fetuses during episodes of reduced Qumb. In oxygen-treated fetuses, Vo2 decreased from normal levels only when Qumb was less than or equal to 75 ml/min/kg of fetus, whereas in room air-treated fetuses Vo2 decreased at Qumb less than or equal to 150 ml/min/kg. Our data indicate that oxygen administration to the pregnant sheep increases oxygen delivery to the fetus during times of reduced umbilical perfusion and that this supplemental oxygen supply provides an oxygen reserve with which the fetus can maintain oxidative metabolism. These data may be relevant to those clinical conditions, such as umbilical cord compression in labor, that are associated with reductions in umbilical blood flow.     

缓慢释放孕酮宫内节育器的体内释药研究及对垂体—卵巢轴影响的探讨

本文依据雌性家兔及人体内使用9%乙烯醋酸乙烯(9%Ethylene Vinyl Acetate,简称EVA)共聚物作为释药系统,含一定量孕酮的宫内节育器,经过使用不同时间后分别取出测定剩余的孕酮量,观察本释药系统在体内的药物释放情况。测定结果证明家兔体内释放符合零级动力学,即恒速释放,释放速度为46.6μg/cm~2/天。在人体内也达到恒速释放,释药速度为29μg/cm~2/天。此外对四名育龄妇女进行上环前一个周期及上环后九个月至一年的基础体温、宫颈粘液、阴道脱落细胞成熟指数及血清促黄体生成激素、促卵泡激素、雌二醇和孕酮的放射免疫测定的系统纵向观察,结果证明受试者上环后每个周期均有排卵,释放孕酮量为29μg/cm~2/天的宫内节育器对机体垂体-卵巢轴无显著影响。     

Technical aspects of multifocal ERG recording

There are a wide range of variables which can influence the quality of the multifocal response. It is possible to place these variables into one of four categories. First, the method of stimulus delivery will determine the field of view, interference levels and the duration of on-state stimulation. Second, data acquisition variables such as electrode type and placement, amplifier specifications and filter bandwidth settings will have a direct impact on waveform shape and on the topographic distribution of signal amplitudes. Third, patient variables such as fixation, pupil dilation and refractive error will also contribute to the multifocal response. Fourth, there are many measurements that can be taken from multifocal recordings. In addition to standard amplitude and implicit time measures (the implicit time measure in the multifocal response is becoming increasingly important particularly in early stages of disease processes), the scalar product measure provides information on waveform shape. The conventional impulse and higher order responses will be different for different modes of stimulation such as Cathode Ray Tube (CRT) and Liquid Crystal Display (LCD) systems and latency shifts will be introduced if not corrected in software. Procedures which could lead to misleading interpretation include artefact rejection, averaging with neighbours and summing of responses. These procedures should be handled with caution. This revised version was published online in July 2006 with corrections to the Cover Date.     

Possible Etiological Factors in Extensive Periventricular Leukomalacia of Preterm Infants

ABSTRACT. During a twelve-month period five cases of extensive periventricular leukomalacia (PVL) in preterm infants with a gestational age of 31–32 weeks were diagnosed by routine ultrasound screening of preterm infants. The perinatal courses and later development of these infants were compared with 12 other infants with a comparable gestational age born during the same time period. PVL babies were delivered more often by the vaginal route ( p =0.0034), and their mean highest serum total bilirubin value was significantly higher ( p =0.0054) than that of the control infants. The mean value of the highest blood pH during the first 72 hours of life was also significantly higher ( p =0.0311) in PVL babies than in control babies. On the basis of these results we speculate that in addition to ischaemia in the periventricular area, bilirubin toxicity may play an additional role in the severe damage seen in extensive periventricular leukomalacia.     

VASOPRESSIN, ACTH AND NEONATAL HAEMODYNAMICS

Pohjavuori, M. and Fyhrquist, F. (Department of Paediatric Cardiology, Children's Hospital, University of Helsinki, and The Minerva Institute for Medical Research, Helsinki, Finland). Vasopressin, ACTH and neonatal haemodynamics. Acta Paediatr Scand, Suppl. 305: 79–83, 1983.—In 21 normal deliveries, high concentrations of AVP and ACTH in cord blood were associated with higher blood pressure and lower skin temperature, indicating peripheral vasoconstriction. Following Caesarean section after the onset of labour ( n =8), cord AVP concentrations and blood pressures were lower than after normal delivery but higher than after elective Caesarean section ( n =9). Maternal AVP concentrations at delivery were normal, as were plasma AVP concentrations in all infants 3 days after delivery. The relationship between vasopressin, a potential ACTH releasing factor, and ACTH was interesting. We conclude that the massive release of vasopressin is associated with normal delivery, elevated ACTH values and with peripheral vasoconstriction. These findings reflect favourable adaptation to hypoxia and stress of delivery, intended to redistribute cardiac output to vital organs and may provide for physiological adjustments necessary for extrauterine life.     

Deliveries after cesarean birth in two Asian university hospitals

The task force of the consensus conference on cesarean birth of the National Institutes of Health, USA, has recommended substituting a trial of labor and vaginal delivery for elective repeat cesarean section in selected women. This paper assesses the benefits and risks associated with that recommendation using data from two Asian teaching hospitals, one in Jakarta, Indonesia and the other in Colombo, Sri Lanka. Data recorded on the Maternity Record Form designed by the International Fertility Research Program and the International Federation of Gynecology and Obstetrics were used for analysis. Consistent findings were derived from the two hospitals, in spite of the different medical care delivery systems in their countries. No significant increase in maternal and infant mortality and morbidity were associated with women having vaginal delivery subsequent to cesarean birth as compared to those with repeat cesarean section. Savings in medical cost were considerable in the former group.