Excess thymidine induces folate sensitive fragile sites

Folate sensitive fragile sites on human chromosomes have been found to be inducible in cultured lymphocytes by high levels of thymidine but not by high levels of BrdU. The biochemical interpretation of events leading to fragile site expression has been revised since it is now clear that low levels of either thymidylate or deoxycytidine triphosphate will result in this phenomenon. A model for the DNA at a fragile site, composed of alternating repeating polypurine/polypyrimidine sequences is proposed.

Iron chelation by pyridoxal isonicotinoyl hydrazone and analogues in hepatocytes in culture

Pyridoxal isonicotinoyl hydrazone (PIH) and several analogues were synthesized and assessed in the rat hepatocyte culture for their potential in iron chelation therapy. Pyridoxal isonicotinoyl hydrazone and pyridoxal benzoyl hydrazone were as effective as desferrioxamine (DFO) in reducing both net uptake of rat transferrin-59Fe and incorporation into ferritin by hepatocytes. Dialysis studies showed that this was due to a cellular action and not to the extracellular chelation of transferrin-bound 59Fe. The analogues of PIH were more effective in mobilization studies than PIH and DFO, releasing more 59Fe from ferritin as well as from the stroma-mitochondrial membranes in hepatocytes prelabelled using transferrin-59Fe. Chelator action was dependent on incubation time, concentration, temperature and lipophilicity. Pyridoxal benzoyl hydrazone, the most effective iron chelator, was also the most lipophilic, suggesting that access to cellular iron compartments as well as iron-binding affinity is important in effective iron chelation.

Cerebral amyloid angiopathy associated with massive intracerebral hemorrhage

Characteristic computed tomographic, clinical and pathologic features are discussed in two patients with cerebral amyloid angiopathy (CAA) associated with massive intracerebral hemorrhage. Amyloid angiopathy should be considered in any elderly patient in whom intracerebral hemorrhage occurs at an atypical site. Cortical involvement, multiplicity of hemorrhages, bilaterality, and repeated episodes should further arouse diagnostic suspicion. Clinical management is confined to prevention of systemic hypertension.

New classes of common fragile sites induced by 5-azacytidine and bromodeoxyuridine

Two new classes of common fragile site seen in chromosomes from blood lymphocyte cultures are reported. The first class is induced in bands 1q42 and 19q13 by 5-azacytidine (5-AZA). Maximum induction of these fragile sites occurs when the 5-AZA is added 5-8h prior to harvest. The second class is induced in bands 6q13, 9p21, and 10q21 by bromodeoxyuridine (BrdU). In this instance maximum induction occurred if the BrdU was added 4-6h prior to harvest. The known fragile sites, both rare and common, are summarised.

The prognostic value of age for patients with common epithelial ovarian cancer

For 230 patients with common epithelial ovarian cancer, the prognostic impact of age was examined. Statistical analysis was done using proportional hazard models, 3- and 5-year survival rates and median survival of stratified groups, and the Kaplan-Meier mean. Taking the age-adjusted mortality into account, the prognosis of the older patients was significantly worse. This effect depended primarily on early mortality (survival time less than 2 months). A comparative analysis was made of the prognostic factors age, grade, and stage, taking into account the correlation between factors. This analysis showed that, for our series, age was of lesser prognostic significance than grading, and both of these were of much less prognostic importance than staging.

Transferrin and iron release from rat hepatocytes in culture

The regulation of transferrin and iron release from the liver was studied using adult rat hepatocytes in primary monolayer culture. The cells were prelabeled by incubation with rat transferrin doubly labeled with iodine-125 and iron-59. Approximately 50% of the 125I-transferrin but only 10% of the iron-59 taken up by the cells was released during reincubation for 24 h. Less than 10% of the refluxed transferrin was catabolized as indicated by the protein-free iodine-125 values. These results suggest that at least part of iron uptake by hepatocytes is mediated by the reversible binding of transferrin in a manner comparable with erythroid cells and placenta. However, several iron chelators mobilized hepatic iron, in contrast to erythroid cells. Apotransferrin and desferrioxamine released a maximum of about 20% iron-59 with little effect on transferrin binding. A greater proportion of the iron-59 was available for chelation after shorter uptake times (1-2 h) than longer times. Hence, there are at least three iron compartments in hepatocytes in culture: rapidly refluxing iron that may be transferrin bound, a fixed pool, and a chelatable pool that may represent iron in transit between plasma transferrin and ferritin.

[Grading of epithelial ovarian cancers]

Tissue slides of 230 epithelial ovarian cancers were examined by two different pathologic teams to determine the following details: histological pattern, grade of polymorphy, mitotic index, density of chromatin, presence of nuclei and macronuclei, lymphocytic infiltration, psammoma bodies, and necrosis. For statistical evaluations the data were presented together with stage, age and survival times in form of an information vector for each of the 230 patients and analysed using hazard-models (Cox 1972, Carter 1983) and contingency tables.

RESULTS

The agreement between the 2 pathologic teams was good. There were many interrelated histological concomitants, such as polymorphy and chromatin density, and as nuclei and macronuclei. Necrosis was relatively independent. Significant effects on prognosis could be demonstrated for polymorphy, chromatin density, mitotic index, histologic pattern, (macro)nuclei. Polymorphy was the best histological prognostic indicator and, together with necrosis, produced the best prognostic grading system.

Prevention of alcohol misuse through the development of personal and social competence: a pilot study

Seventh graders (N = 239) from two New York City junior high schools were involved in a 9-month study testing the efficacy of a broad-spectrum approach to prevention of alcohol misuse. The two schools were randomly assigned to experimental and control conditions. The seventh graders in the treatment school received a 20-session program targeted at the major cognitive, attitudinal, social and personality factors believed to promote the early stages of alcohol misuse. The program contained material on decision making, coping with anxiety, general social skills and assertiveness (including techniques for resisting peer pressure to drink) as well as information about the short- and long-term consequences of alcohol misuse. Complete pretest, posttest 1 and posttest 2 data were collected from 167 students (89 women). A significantly greater proportion of the students in the experimental group reported less frequent drinking (p less than .02), less drinking per occasion (p less than .04), and less frequent episodes of drunkenness (p less than .01) than the students in the control group.

Self-control behavior in hyperactive and nonhyperactive children

This study was aimed at evaluating the self-control behaviors of hyperactive (HA) and nonhyperactive ( NHA ) first-grade pupils under conditions of repeated failure on a previously learned concept formation task. Subjects were divided into HA and NHA groups on the basis of their scores on the Conners (1969) Teacher Rating Scale. During the training stage of the experiment the children learned a concept formation task under a schedule of contingent positive reinforcement. In the test stage they performed the same task but under a negative noncontingent reinforcement schedule. The results revealed no differences in initial rate of learning the task between the groups. After the introduction of the negative noncontingent reinforcement schedule, however, the HA group showed a marked decrease in the use of effective problem-solving strategies. The HA children's performance on the concept formation task was accompanied by the emission of negative self-evaluations and solution-irrelevant statements. The NHA group used significantly more statements showing useful goal-directed cognitive mediations than the HA children. The results suggested that HA children may have deficits in self-control skills.

Transferrin and iron uptake by rat hepatocytes in culture

Hepatic iron and transferrin metabolism was studied using rat transferrin doubly labeled with 59Fe and 125I and adult rat hepatocytes in primary monolayer culture. Iron uptake was linear for 48 h while transferrin uptake was biphasic. Total transferrin and iron uptake increased in a linear manner as the transferrin concentration was raised up to at least 130 microM. This indicates that transferrin and iron are taken up primarily by nonspecific processes, possibly by endocytosis (absorptive or fluid) and by the action of iron chelators. However, some evidence indicated the presence of receptors for diferric transferrin on hepatocytes: the molar ratio of iron to transferrin accumulation increased with incubation time, transferrin and iron uptake was proportional to the iron saturation of the transferrin, apotransferrin displaced bound apotransferrin but had no effect on the binding of diferric transferrin, and the molar ratio of iron to transferrin uptake decreased with increasing transferrin concentrations.

Vitamin content of some normal human brain segments

Nicotinates, pantothenates, riboflavin, vitamins B6 and B12' free (acetyl) and total (free and bound) choline, biopterin, thiamin, biotin, methylated and nonmethylated folates in frontal, temporal, precentral, postcentral, and occipital cortex, thalamus, cerebellum, pons, basal ganglia, and substantia nigra were estimated. Nicotinates are significantly more concentrated in basal ganglia and thalamus than pons. Nonmethylated folate content is not significantly varied in brain segments; the pons contains more methylated folate. Riboflavin content is higher in the basal ganglia and temporal cortex than frontal cortex. Biotin is concentrated in pons and basal ganglia. Thiamin concentration is less in the postcentral cortex than the thalamus and substantia nigra. Biopterin is significantly higher in substantia nigra and basal ganglia than the other brain segments. Total choline content is high in substantia nigra, pons, and thalamus; free (acetyl) choline is significantly elevated in basal ganglia. B12 content is less concentrated in the cortex segments. B6 is highly concentrated in the basal ganglia. Pantothenate content is elevated in pons when compared to the various cortex segments and cerebellum.

A cognitive-behavioral approach to substance abuse prevention

The effectiveness of a 20 session cognitive-behavioral approach to substance abuse prevention was tested on seventh grade students (n = 1,311) from 10 suburban New York junior high schools. The prevention strategy attempted to reduce intrapersonal pressure to smoke, drink excessively, or use marijuana by fostering the development of general life skills as well as teaching students tactics for resisting direct interpersonal pressure to use these substances. Additionally, this study was designed to compare the relative effectiveness of this type of prevention program when implemented by either older peer leaders or regular classroom teachers. Results indicated that the prevention program had a significant impact on cigarette smoking, excessive drinking, and marijuana use when implemented by peer leaders. Furthermore, significant changes were also evident with respect to selected cognitive, attitudinal, and personality predisposing variables in a direction consistent with non-substance use. These results provide further support for the efficacy of a broad-spectrum smoking prevention strategy and tentative support for its applicability to the prevention of other forms of substance abuse.

The effects of scheduling format and booster sessions on a broad-spectrum psychosocial approach to smoking prevention

The effectiveness of a fifteen session psychosocial smoking prevention strategy was tested on 902 seventh graders from seven junior high schools in suburban New York over 2 years. The prevention program was implemented by regular classroom teachers and consisted of a cognitive component dealing with the immediate consequences of cigarette smoking, a decision-making component, a relaxation-training component, a social skills training component, and a self-improvement component. In addition to testing the overall effectiveness of this approach, the relative efficacy of two different scheduling formats was compared and the extent to which "booster" sessions conducted during the year after completion of the program helped to maintain reductions in new smoking was also examined. Results indicated that the prevention program was able to reduce new cigarette smoking by 50% at the end of the first year and by 55% at the end of the second year for the intensive format condition. New regular cigarette smoking was reduced by 87% in the second year for the students in the booster condition. Significant changes consistent with nonsmoking were also evident on several cognitive, attitudinal, and personality variables.

Developmental changes in attitudes toward cigarette smokers during early adolescence

Attitudes of 104 sixth, 137 seventh, and 110 eighth graders concerning the social image of cigarette smoking were examined to identify potential developmental differences. Significant differences were found between the attitudes of sixth, seventh, and eighth graders; sixth graders had the least positive attitudes and the eighth graders the most positive attitudes. A significant interaction of sex × grade was also evident; the sixth grade boys had the least favorable attitudes toward smokers. No significant differences were evident between students who had friends who smoke and those who did not. These findings suggest that, in addition to the many other developmental changes occurring during early adolescence, there is a shift toward a more positive social image of cigarette smoking that is unrelated to the smoking status of friends.

Transcatheter occlusion of a Blalock-Taussig shunt with a detachable balloon in a child

A case of transcatheter occlusion of a Blalock-Taussig shunt with a detachable silicone filled balloon is described. This 11 year old boy had previously had a repair of tetralogy of Fallot together with ligation of a large Blalock-Taussig shunt. Though there was a good surgical result, the shunt proved to be incompletely closed leaving a significant left to right shunt. As an alternative to a further operation a silicone filled balloon was detached in the Blalock-Taussig shunt and this successfully closed the fistula.

Distribution of transferrin and transferrin receptors in the rabbit placenta

The quantity and distribution of transferrin and transferrin-binding sites in the placenta were investigated in rabbits on the 28th-29th days of pregnancy. The animals were injected intravenously with a mixture of 59Fe-125I-labelled rabbit diferric transferrin and 131I-labelled rabbit albumin. The binding of transferrin to placentas removed 3-75 min later was determined by using the 131I-labelled albumin values to correct for tissue content of plasma. Mean values for transferrin binding of 1460 and 560 micrograms/g tissue were obtained 3-15 and 45-75 min after injection, respectively. Gel filtration of placental extracts prepared with the non-ionic detergent, Teric 12A9, showed that the 125I-labelled transferrin bound to a large molecular weight component which had the properties of a specific receptor. The receptor had a higher affinity for diferric transferrin than for apotransferrin. The subcellular distribution of transferrin binding sites was determined by differential centrifugation of placental homogenates and by electron microscope autoradiography. The results with the former method indicated that the transferrin was bound to the microsomal fraction of the cells. Autoradiography showed that the majority of the transferrin molecules were at intracellular sites, mainly on the membrane of intracellular vesicles. It is concluded that iron-containing transferrin molecules enter the trophoblast cells by endocytosis or via a canalicular system after binding to cell membrane receptors. The higher affinity of the receptors for diferric transferrin than for apotransferrin explains the difference in amount of transferrin binding found within 15 min of injecting labelled diferric transferrin and that found 45-75 min later when much of the iron had been removed from the transferrin.

SCE, X-radiation sensitivity and mutation rate in multiple sclerosis

In order to detect any underlying DNA abnormality that may be present in multiple sclerosis (MS), the incidence of SCE, X-radiation sensitivity and the frequency of 6-thioguanine-resistant cells were determined in the lymphocytes of 34 MS patients. As a group, MS patients showed an increase in the SCE rate compared to control. However, there was no increase in X-radiation sensitivity. The frequency of 6-thioguanine-resistant mutant cells was also normal.

Heritable fragile sites on human chromosomes. X. New folate-sensitive fragile sites: 6p23, 9p21, 9q32, and 11q23

Four new folate-sensitive fragile sites are documented at 6p23, 9p21, 9q32, and 11q23. These have all been shown to be heritable except for the one at 9p21, which has been seen only in a single individual. As with the other autosomal fragile sites, these appear to be innocuous in heterozygotes.

Genetic length of a human chromosomal segment measured by recombination between two fragile sites

Two families were studied in which the same homolog of chromosome pair 10 expressed both the fragile sites on the long (q) arm at 10q23 and 10q25. Recombination between the fragile sites was observed in 3 of the 27 offspring in whom it could occur. The genetic length of chromosome between the fragile sites was 11 female centimorgans within a 95 percent probability interval of 4 to 28 centimorgans. This estimate of genetic length is comparable to those obtained with other methods.

Sister-chromatid exchange (SCE) analysis in mothers exposed to DNA-damaging agents and their newborn infants

The incidence of SCE in the lymphocytes of mothers and their newborn infants was determined. A detailed antenatal history of parental habits such as smoking, alcohol consumption and possible exposure to DNA-damaging agents was documented. The results showed that the SCE rate in the newborn is significantly less than that of their mothers. Mothers who consumed alcohol, but not cigarette smokers, had a significantly increased SCE rate compared to control mothers. However, these maternal habits did not affect the SCE rate of their infants. Neonates with neural tube defects showed a significantly increased SCE rate compared to normal babies.

Effect of iron saturation on transferrin uptake by reticulocytes. A morphological study

The presence of iron on the transferrin molecule increases its affinity for and sojourn time on the reticulocyte. This could be due to selective internalization of iron-containing transferrin molecules. This possibility was investigated by electron microscopic autoradiography. Rabbit reticulocytes were incubated with rabbit transferrin at 6, 33, and 72% iron saturations, and the distribution of transferrin molecules at membrane and intracellular locations was assessed by grain counting. The results showed that (1) both apotransferrin and iron transferrin enter the cell interior and (2) the amount of intracellular transferrin was primarily controlled by the concentration of membrane-bound transferrin and not by its iron saturation.

Iron release from isolated hepatocytes

The isolated hepatocyte suspension was evaluated as an experimental procedure for investigating liver iron metabolism. Following prelabelling in vivo with transferrin-59Fe, isolated hepatocytes released radioactive iron in vitro by a temperature dependent process, without change in cell viability. Iron mobilization was increased by serum, apotransferrin and a range of iron chelators, of which the most effective were citrate, desferrioxamine and the ionophore A 23187. The rate of iron release was inversely related to oxygen levels, indicating that a ferric-ferrous reduction was involved in iron mobilization. The uncoupler TTFB, DTPA, and hypercapnia caused a reduction in iron release, but the metabolites cysteine, NADH and ascorbic acid had no effect. It was concluded that isolated hepatocytes are a useful experimental model for studying iron metabolism and for further evaluation of iron chelators.

Sister chromatid exchange in aplastic anemia

The incidence of sister chromatid exchanges (SCE) in the lymphocytes of patients with aplastic anemia (AA) was determined before and after exposure to mitomycin C (MMC). The "baseline" SCE rate was significantly higher in AA, but MMC-induced SCE rate was not different compared to controls. It is suggested that some patients with AA may have an underlying DNA damage.

The regulation of iron release from the perfused rat liver

Factors affecting iron efflux from the isolated perfused rat liver were studied following the intravenous administration of transferrin-(59)Fe or transferrin-(55)Fe administered to the rat from 1.5 h to 3.5 d before perfusion of the liver. The liver was perfused with rat red cells suspended either in rat plasma or Eagle's Basal Medium (EBM). The mean rate of efflux into a plasma pool containing normal iron and transferrin concentrations was 0.9% of the initial hepatic radioactive iron pool per hour. In EBM the average rate of efflux was 0.1%/h and this could be increased to the rate observed with plasma by the addition of apotransferrin. The rate of iron release from the liver in the presence of apotransferrin or other chelators was inversely proportional to the time of prelabelling. Maximal release rates were observed in livers perfused within 5 h of administering transferrin-(59)Fe to the rat. The effect of apotransferrin on efflux into EBM was concentration dependent. However, the maximum release of liver iron by apotransferrin occurred at physiological apotransferrin concentrations and addition of apotransferrin to plasma produced no increase in the rate of iron efflux. The stimulation of iron release in EBM caused by apotransferrin could be reversed by reducing the unsaturated iron binding capacity of the perfusate, either by addition of iron or removal of apotransferrin. However, increasing the iron concentration in the perfusate by the addition of iron-saturated transferrin without any reduction in the unsaturated iron binding capacity additionally increased iron release into plasma and EBM. This presumably reflects the exchange of plasma transferrin-(56)Fe for liver (59)Fe. Hence iron release measured in these studies represent the sum of two processes-net release of (59)Fe induced by apotransferrin and iron exchange between plasma and liver iron pools. Apotransferrin and desferrioxamine were equally effective, per unit iron binding capacity, in mobilizing liver iron, and may compete for the same parenchymal iron pool. This suggests that mobilization of iron by apotransferrin may depend solely on its ability to chelate ferric iron and not on a more specific ferroxidase activity or interaction with membrane receptors.

Heritable fragile sites on human chromosomes. V. A new class of fragile site requiring BrdU for expression

A new fragile site at 10q25 is described, representing a new class of fragile site that requires bromodeoxyuridine (BrdU) in the culture medium for expression. This new fragile site is present in approximately one in 30 of the Australian population; it has only been observed in heterozygotes.

Effect of thirty-two per cent dextran 70 on peritoneal adhesion formation and re-formation after lysis

Thirty-two per cent dextran 70 in dextrose (Hyskon) has been reported effective in limiting adhesion formation following a peritoneal injury when employed in doses larger than that known to be safe for intraperitoneal use in humans. The effectiveness of a lower dosage believed to be safe for human use was investigated. Female rabbits received a standardized injury to their uterine horns and proximal fallopian tubes. Following the injury, Hyskon (2.5 ml/kg of body weight) was dripped over the sites of injury in the treatment group. Animals were reoperated upon 2 weeks later, and adhesions were scored. Hyskon significantly reduced adhesion formation. In a second experiment the effect of Hyskon on adhesion re-formation was evaluated. Adhesions were induced in the same manner. Two weeks later, the animals were reoperated upon, and adhesions were scored and lysed. Hyskon was instilled in the treatment group as in the first experiment. No significant difference was noted between adhesion scores in control and treatment groups after adhesion induction or when re-evaluated 2 weeks after lysis.

Liposome entrapped desferrioxamine and iron transporting ionophores: a new approach to iron chelation therapy

Liposome-entrapped desferrioxamine was administered to iron-over-loaded 59Fe lavelled mice. When given orally or intraperitoneally entrapment did not enhance the effect of the chelator, but given intravenously liposomal desferrioxamine doubled the 59Fe excretion for a given dose of the drug, and excretion after a single dose continued for up to 3 d. In addition, liposomes containing ionophore A23187 administered concurrently with DTPA caused an excretion of 59Fe, whereas DTPA alone had no effect.

Placental iron transfer in the cat

1. The transfer of iron from maternal plasma to the foetus was studied in the cat using cat transferrin labelled with (59)Fe and radioiodine.2. Pregnancy was accompanied by a fall in maternal haematocrit, a rise in serum total iron-binding capacity and iron stores, but no change in serum iron concentration or plasma iron turnover.3. Near-term foetal haematocrit and serum iron concentration were higher and iron binding capacity lower than in the pregnant animals.4. The uptake of (59)Fe from maternal plasma by the placenta and transfer to the foetuses were slow and small in amount. The daily transfer of iron to the foetuses calculated from these data was only 5 mug.5. There was a small, transient uptake of (59)Fe from the plasma by the foetal membranes.6. Small amounts of plasma transferrin and albumin were slowly taken up by the placenta.7. It was concluded that the maternal endothelium of the placenta of the cat acts as a barrier for the uptake of plasma transferrin-bound iron. As a result the rate of iron transfer to the foetuses from maternal plasma is inadequate to account for their rate of iron accumulation, and another source, such as maternal erythrocytes, must supply most of the iron to the foetuses.