Factor analysis shows that female rat behaviour is characterized primarily by activity, male rats are driven by sex and anxiety

This experiment explored sex differences in behaviour using factor analysis to describe the relationship between different behavioral variables. A principal component solution with an orthogonal rotation of the factor matrix was used, ensuring that the extracted factors are independent of one another, and thus reflect separate processes. In the elevated plus-maze test of anxiety, in male rats factor 1 accounted for 75% of the variance and reflected anxiety, factor 2 represented activity, and accounted for 24% of the variance. This contrasted with the finding in female rats in which factor 1 was activity, accounting for 57% of the variance, with the anxiety factor accounting for only 34% of the variance. When behaviour in both the plus-maze and holeboard were analysed, a similar sex difference was found with anxiety emerging as factor 1 in males and holeboard activity as factor 1 in females. Locomotor activity in the inner portion of the holeboard loaded on the anxiety factor for males, but on activity for females. When behaviours in the plus-maze and sexual orientation tests were analysed, anxiety emerged as factor 1 in males, sexual preferences factor 2, and activity factor 3. In females, activity was factor 1, sexual preference factor 2, anxiety factor 3, and social interest factor 4. These results suggest caution should be exercised in interpreting the results from female rats in tests validated on males because the primary controlling factor may be different.

Beneficial effects of glycine (bioglycin) on memory and attention in young and middle-aged adults

The N-methyl D-aspartate receptor complex is involved in the mechanism of long-term potentiation, which is thought to be the biological basis of learning and memory. This complex can be manipulated in a number of ways, one of which is through the strychnine-insensitive glycine receptor coagonist site. The effects of Bioglycin(Konapharma, Pratteln, Switzerland), a biologically active form of the amino acid glycine, were therefore studied in healthy students (mean age, 20.7 years) and middle-aged men (mean age, 58.9 years) with tests that measured attention, memory and mood, using a double-blind, randomized, crossover design. Compared with the young group, the middle-aged group had significantly poorer verbal episodic memory, focused, divided, and sustained attention; they also differed in their subjective responses at the end of testing. Bioglycin significantly improved retrieval from episodic memory in both the young and the middle-aged groups, but it did not affect focused or divided attention. However, the middle-aged men significantly benefited from Bioglycin in the sustained-attention task. The effects of Bioglycin differed from those of other cognitive enhancers in that it was without stimulant properties or significant effects on mood, and it primarily improved memory rather than attention. It is likely to be of benefit in young or older people in situations where high retrieval of information is needed or when performance is impaired by jet lag, shift work, or disrupted sleep. It may also benefit the impaired retrieval shown in patients with schizophrenia, Parkinson's disease, and Huntington's disease.

The effect of treatment regimen on the development of tolerance to the sedative and anxiolytic effects of diazepam

RATIONALE

Chronic treatment with benzodiazepines results in tolerance to their sedative and anxiolytic effects and there is considerable evidence that different mechanisms underlie the development of tolerance to different behavioural effects.

OBJECTIVE

The purpose of the present experiment was to compare the behavioural effects of chronic treatment with diazepam (15 mg/kg per day) given as daily subcutaneous injections or by osmotic minipump. Both regimens resulted in continual receptor occupancy, but the daily injections also provided a period of higher brain concentrations.

METHODS

Rats were tested in the holeboard, which provides measures of exploration and locomotor activity, and in the elevated plus-maze and social interaction tests of anxiety. For those in the subcutaneous injection group the tests were 2 h after injection, when brain concentrations were highest.

RESULTS

Despite a higher brain concentration in the injected group, both groups showed tolerance to diazepam's sedative effects, after 7 days of treatment. In contrast, in the elevated plus-maze, there was tolerance to the anxiolytic effects in the pump group after 14 days, but a persisting anxiolytic effect in the injected group at 14 and 28 days. Whilst higher brain concentrations could explain this result in the plus-maze, they cannot account for the pattern observed in the social interaction test, where the injection group showed a significant anxiogenic effect at 28 days.

CONCLUSIONS

Whereas the mechanism underlying tolerance to the sedative effects of diazepam was insensitive to the different treatment regimens, the results suggest that different adaptive mechanisms were triggered in the two tests of anxiety with a differential sensitivity to the treatment regimen. The adaptive mechanism predominating in the social interaction test was favoured by the injection regimen which produced intermittent peak concentrations. This mechanism seems to be an oppositional one, leading to an anxiogenic response, which was manifest despite high brain concentrations of diazepam at the time of testing.

Mechanisms of Na+-K+ pump regulation in cardiac myocytes during hyposmolar swelling

We have previously demonstrated that the sarcolemmal Na+-K+ pump current (Ip) in cardiac myocytes is stimulated by cell swelling induced by exposure to hyposmolar solutions. However, the underlying mechanism has not been examined. Because cell swelling activates stretch-sensitive ion channels and intracellular messenger pathways, we examined their role in mediating Ip stimulation during exposure of rabbit ventricular myocytes to a hyposmolar solution. Ip was measured by the whole cell patch-clamp technique. Swelling-induced pump stimulation altered the voltage dependence of Ip. Pump stimulation persisted in the absence of extracellular Na+ and under conditions designed to minimize changes in intracellular Ca2+, excluding an indirect influence on Ip mediated via fluxes through stretch-activated channels. Pump stimulation was protein kinase C independent. The tyrosine kinase inhibitor tyrphostin A25, the phosphatidylinositol 3-kinase inhibitor LY-294002, and the protein phosphatase-1 and -2A inhibitor okadaic acid abolished Ip stimulation. Our findings suggest that swelling-induced pump stimulation involves the activation of tyrosine kinase, phosphatidylinositol 3-kinase, and a serine/threonine protein phosphatase. Activation of this messenger cascade may cause activation by the dephosphorylation of pump units.

Blue rubber bleb naevus: case report and literature review

Blue rubber bleb naevus syndrome is a rare cutaneous-digestive angiomatosis, described first by William Bean in 1958. Today, there are more than 200 cases published. The dangers of this syndrome include angiomata in the brain, kidneys or lungs (due to vasculature obliteration by in situ thrombosis). Patients are scanned with technetium-labelled red blood cells in order to identify the affected organs. Multiple techniques are used to treat the lesions by gastrointestinal endoscopy.

Dizocilpine does not prevent the development of tolerance to the anxiolytic effects of diazepam in rats

The non-competitive NMDA receptor antagonist, dizocilpine (0.25 mg/kg), has previously been shown to block the development of tolerance to the sedative effects of diazepam (2 mg/kg). Since there is considerable evidence that different mechanisms underlie the development of tolerance to the sedative and anxiolytic effects of diazepam, the present experiment examined whether dizocilpine would block the development of tolerance to diazepam's anxiolytic effects. Rats tested after an acute dose of diazepam (2 mg/kg) showed an anxiolytic effect, measured by an increase in the time spent in social interaction, whereas those tested after 21 days of treatment had scores equal to the control group. This development of tolerance was not blocked by concomitant administration of dizocilpine (0.25 mg/kg). Thus, these results provide further evidence that the mechanism underlying tolerance to the anxiolytic effects of diazepam is different from that underlying tolerance to the sedative effects.

Synchronic signet ring carcinoma and adenocarcinoma complicating extensive and long-standing ulcerative colitis

We report the case of a 38 year-old woman with extensive ulcerative colitis (UC) for 9 years that had consistently been under close endoscopic surveillance. She had had two previous severe attacks requiring hospital admission, with good response to intravenous steroids. In the last relapse, a total colonoscopy demonstrated extensive lesions of UC throughout the entire colon. Multiple biopsies taken every 3 cm revealed only low-grade dysplasia and lesions characteristic of UC. Due to medical therapy failure, the patient was submitted for proctocolectomy. Pathological examination of the resected specimen showed a signet ring carcinoma and a synchronic adenocarcinoma in the sigmoid colon, both undetected by colonoscopy and biopsies. The issue of surveillance in patients with extensive and long-standing UC is discussed.

Cancer cluster among young Indian adults living near power transmission lines in Bom Jesus do Tocantins, Pará, brazil

A case study was carried out to explore the occurrence of a cancer cluster in 1992 among young indian adults adults living in an Amazonian village near two 500 kV power transmission lines that began operating a decade ago. Current blood levels of DDT and organophosphorus pesticides and metal levels in hair samples were measured. Extremely low magnetic field exposure was determined during current daily activities carried out by the Indian villagers. Taking into account the cancer incidence rates in different Brazilian cities, the probability of the occurrence of this cluster by chance was considered remote (p< 0.003, Poisson distribution). High blood levels of p,p'-DDT (median levels ranging from 26 to 58 ppb) were observed. As a whole, this community showed a pattern of low exposure to organophosphorus pesticides, and high recent exposure was only observed in a few blood samples. Continuous exposure to extremely low electromagnetic fields originated in the power transmission lines (which reached 95.0 mG under the lines) was observed on several opportunities during daily activities carried out by Indian villagers. Further observational studies should evaluate the interaction between exposure to extremely low electromagnetic fields and prior exposure to tumor initiators in cancer development.

The influence of alcoholism and cirrhosis on benzodiazepine receptor function

In a previous study we reported that the affinity of the platelet benzodiazepine receptor was greater in alcoholic cirrhotic patients compared with normal controls and that there were detectable ligands for the neuronal benzodiazepine receptor in plasma from both alcoholic and nonalcoholic cirrhotic patients. The aim of the present study was to assess the separate contributions of alcoholism and cirrhosis to the presence of ligands in plasma for the neuronal and peripheral benzodiazepine receptors and to changes in peripheral benzodiazepine receptor binding in platelets. These parameters were measured in 10 alcoholic cirrhotics, 9 nonalcoholic cirrhotics, 7 alcoholics with a normal liver function, and 15 nonalcoholic subjects and normal liver function. Both groups of alcoholics had been abstinent for several months and the nonalcoholic groups had abstained for 24 h before the study. The concentration of ligands for the peripheral benzodiazepine receptor were significantly higher in both cirrhotic groups compared with the other two groups, suggesting that cirrhosis was responsible for this accumulation. Furthermore, the cirrhotic patients with detectable concentrations of these ligands had significantly poorer episodic memory than those without ligands. However, the presence of ligands for the peripheral benzodiazepine receptor did not correlate with the change in receptor affinity, which was increased in the alcoholic cirrhotic group compared with all other groups. Neither cirrhosis nor alcoholism altered the peripheral benzodiazepine receptor number. The cirrhotic patients with detectable ligands for the neuronal benzodiazepine receptor showed psychomotor slowing and executive dysfunction. The results suggest that the ligands for the peripheral benzodiazepine receptor may contribute to some of the cognitive deficits seen in hepatic encephalopathy, but are not responsible for the receptor affinity change seen in the alcoholic cirrhotics. This affinity change is not solely due to the effects of alcohol and could possibly serve as a marker for those at risk for developing alcoholic cirrhosis.

[Service delivery and quality of hospital care in the State of Rio de Janeiro, Brazil--1992 to 1995]

INTRODUCTION

Recent trends in hospital care in the State of Rio de Janeiro, Brazil, are analysed. The data are taken from the Unified Health Care System (SUS) and cover monthly observations between January 1992 and October 1995 for the public, teaching and private hospital subsectors.

METHODOLOGY

The data entries are based on hospital declarations on the AIH form, processed by the National Inpatient Information System (SIH-SUS). When comparing the three subsectors, production of services and outcome were examined particularly closely. Comparisons are made using structural models for time series based on the break-down of a time series into components of interest, such as trend, seasonal variation and irregularity.

RESULTS

The analysis shows a significant downward trend in the frequency of hospital admissions in the State of Rio de Janeiro, probably reflecting the deliberate withdraw of financial investments in this sector, which began in 1993. This reduction was selective with regard to age group distribution--being greater in the adult and elderly groups. The analysis has also shown that the teaching sector has steadily raised its admissions. The quality of care was analysed through the sentinel event approach. For the State of Rio de Janeiro as a whole, the occurrence of avoidable deaths during the hospital admission process shows a weak overall tendency to decline as detected by the reduction of this kind of death in the private sub-sector. In public and teaching hospitals the frequency of avoidable deaths has remained stable. The frequency of maternal deaths has remained high and stable, while the number of caesarean sections shows a significant increase, despite the high figures observed at the beginning of the period.

CONCLUSIONS

The results of this study indicate an overall decline in the quality of health care offered by the SUS within the Rio de Janeiro State. Regardless of the existing limitations in SIH-SUS, this study has shown this to be a useful instrument for monitoring hospital care services.

Decreased 5-HT1A and increased 5-HT2A receptor binding after chronic corticosterone associated with a behavioural indication of depression but not anxiety

The effects of chronic corticosterone treatment (100 mg pellet implanted for 1 week) were assessed in animal tests of anxiety, exploration and motor activity, and changes in binding to 5-HT1A and 5-HT2A receptors, and the 5-HT transporter, were measured. At the end of the week's treatment, the corticosterone concentration was significantly elevated and there were significant decreases in adrenal, thymus and body weights. However, there were no changes in the measures of anxiety in the social interaction test or on trials 1 and 2 of the elevated plus-maze. Also supporting a dissociation between anxiety and elevated corticosterone concentrations are previous findings that benzodiazepine withdrawal causes increased anxiety but no change in corticosteroid concentrations. Therefore these two situations provide a double dissociation between anxiety and elevated corticosteroids. Decreased 5-HT1A receptor binding in the dentate gyrus and increased 5-HT2A receptor binding in the parietal cortex was found following chronic corticosterone treatment. This reciprocal relationship between 5-HT1A and 5-HT2A receptors has been proposed to be important in mediating depression. The significant decreases in motor activity observed in all the test situations would be compatible with this proposal. Thus the constellation of behavioural and biochemical changes detected after chronic corticosterone treatment is more pertinent to depression than anxiety. One week after removal of the pellets, the behavioural and neurochemical changes had disappeared and the only differences to remain were decreased adrenal, thymus and body weights in the animals that had been treated chronically with corticosterone.

Technetium-99m labelling of the IOR CEA 1 monoclonal antibody: evaluation of different methods

AIM

The aim of this study was to investigate the in vivo and in vitro properties of 99mTc labelled monoclonal antibody, IOR CEA 1 when radiolabelled by different methods.

METHODS

To achieve that purpose IOR CEA was directly radiolabelled via 2-mercaptoethanol (2-Me) and stannous ion (SnCl2) reduction and indirectly via the 2-iminothiolane (2-Im) conjugation. The resulting 99mTc-MoAbs were analysed for number of free sulfhydryl groups, chemical and radiochemical purity (checked by HPLC and SDS PAGE), immunoreactivity and biological distribution in mice.

RESULTS

Experimental results indicated a similar radiochemical purity and immunoreactivity for direct labelling methods and a decrease of both for 2-Im method. 2-Me antibody reduction led to a high antibody fragmentation as indicated by non-denaturing SDS PAGE analysis. Nevertheless SnCl2 and 2-Im labels revealed lower in vivo stability.

CONCLUSION

99mTc-(2-Me) IOR CEA presented favorable in vitro and in vivo properties. Therefore this label was compared to 99mTc-monoclonal antibody BW 431/26. Similar characteristics were found. Clinical studies also revealed identical biodistribution profile.

Evidence that the median raphé nucleus--dorsal hippocampal pathway mediates diazepam withdrawal-induced anxiety

On the basis of our previous series of experiments we had postulated that the increased anxiety that occurred during diazepam withdrawal was mediated by increased 5-HT release in the hippocampus. The present series of experiments provide evidence for a major role of the median raphé nucleus (MRN) dorsal hippocampal pathway. Rats were treated once daily for 21 days with diazepam (2 mg/kg IP) and then tested after 24 h withdrawal in the social interaction test of anxiety. Relative to chronically vehicle treated animals, those withdrawn from diazepam were significantly more anxious and had significantly greater K(+)-evoked release of [3H]-5-hydroxytryptamine (5-HT) from slices of dorsal and of ventral regions of the hippocampus. Estimation of extracellular concentrations of 5-HT within the dorsal hippocampus, using in-vivo microdialysis, showed doubling in the levels of 5-HT in the rats withdrawn from chronic diazepam treatment. This just failed to reach significance, but 33% of the rats showed dramatic increases (650%). It was not possible to test these animals in the social interaction test, but it is proposed that only the diazepam-withdrawn rats with raised extracellular levels of 5-HT would have displayed increased anxiety. 5-HT1A receptor agonists injected into the MRN decrease the MRN firing rate, and hence the release of 5-HT in the dorsal hippocampus. As a further test of our hypothesis, we examined the effects of MRN injection of the 5-HT1A receptor agonist, 8-OH DPAT, on animals withdrawn from diazepam and tested in the low light familiar condition of the social interaction test. 8-OH DPAT (50-200 ng) dose-dependently reversed the anxiogenic effect of diazepam withdrawal, while having no effects in chronic vehicle-treated animals. These results provide clear evidence that the MRN-dorsal hippocampal 5-HT pathway is at least one of the pathways playing an important role in mediating diazepam withdrawal-induced anxiety.

Evidence against oppositional and pharmacokinetic mechanisms of tolerance to diazepam's sedative effects

Acute administration of diazepam (2 mg/kg i.p.) to rats decreased the number of head-dips, locomotor activity and the number of rears made in the holeboard apparatus, indicating sedative effects. After daily treatment for 7 days with diazepam (2 mg/kg) tolerance developed to all these behavioural effects, despite serum concentrations of diazepam and N-desmethyldiazepam significantly higher than those following acute treatment. After 7 drug-free recovery days the rats were quite unresponsive to a probe dose of diazepam (2 mg/kg) and although there was a gradual recovery of responsiveness to diazepam, the reduction in rears still did not reach the level of the acute group even after 21 drug-free days. There was evidence for pharmacokinetic changes when probe doses of diazepam were given after 7, 14 or 21 recovery days. Lower levels of diazepam and higher levels of N-desmethyldiazepam than following an acute dose to the drug-naïve group were detected, indicating that the chronic treatment had resulted in a persistently enhanced rate of N-demethylation. It is argued that these changes do not fully account for the reduced responsiveness to the probe doses, and nor can they account for the gradual return of response over the 3-week recovery period. There were no detectable scrum concentrations of either compound 24 h after the end of the chronic treatment. However, no rebound increases in behavioural responses were detected at any time-point in withdrawal. Thus, the mechanism underlying this behavioural tolerance was not oppositional in nature. It is suggested that a situation-independent learned behavioural strategy is the most likely mechanism for the observed tolerance.

Cognitive impairments of alcoholic cirrhotic patients: correlation with endogenous benzodiazepine receptor ligands and increased affinity of platelet receptors

OBJECTIVES

To determine whether differences in cognitive function between alcoholic and non-alcoholic cirrhotic patients relate to differences in endogenous ligands for the benzodiazepine receptor and/or benzodiazepine binding.

METHODS

Seventeen grade-I hepatic encephalopathic patients (nine alcoholic, eight non-alcoholic) were compared with 10 matched controls on plasma concentrations of endogenous ligands for the neuronal benzodiazepine receptor, benzodiazepine binding in platelets, and performance on tests of cognitive function.

RESULTS

Both groups of patients were impaired on verbal recall and on reaction time tasks compared with controls; alcoholic patients were also impaired on Reitan's trails test and digit cancellation. Four of the 17 patients had detectable concentrations of endogenous benzodiazepine ligands and they were more impaired than other patients on trails and cancellation tests. The groups did not differ in the density of benzodiazepine platelet receptors, but receptor affinity was higher in alcoholic patients than in controls; furthermore, receptor affinity correlated with the time to complete the cancellation task and with reaction time.

CONCLUSION

Alcoholic cirrhotic patients may have enhanced concentrations of ligands for neuronal and peripheral benzodiazepine receptors and these may contribute to cognitive impairments in these patients.

The influence of open arm ledges and maze experience in the elevated plus-maze

In Experiment 1, rats were tested in a plus-maze, with or without small ledges on the open arms, after injection with vehicle or chlordiazepoxide (7.5 mg/kg). They were scored either on their first or second exposure to the maze; those scored on trail 2 had received a 5-min undrugged exposure to the maze 24 h earlier. This dose of chlordiazepoxide had a significant anxiolytic effect on trial 1 only in the maze without ledges, and on trial 2 only in the maze with ledges; thus, the presence of ledges differentially affected anxiolytic sensitivity on trials 1 and 2. The results of a factor analysis study (Experiment 2) confirmed that ledges had a differential effect when rats were repeatedly exposed to the maze. Thus, in the maze without ledges, the scores reflecting anxiolytic activity on trial 1 loaded on one factor, whereas the scores from trials 2 and 3 loaded on another independent factor. In the maze with ledges, the scores reflecting anxiolytic activity on trials 1, 2, and 3 loaded on three independent factors. Considering the published evidence and the results of the present study, we suggest that both types of plus-maze may be measuring the same type of anxiety with different sensitivities on trial 1 (e.g., generalised anxiety or fear of open spaces); different types of anxiety on trial 2 (without ledges--phobia/fear of heights; with ledges--not known), and trial 3 in the maze with ledges, yet another type of anxiety. The factor analysis results are also presented for ethological measures on the plus-maze, and for activity and exploration in the holeboard. Based on the factor loadings, a composite measure of anxiety on trial 1 is presented which will increase the sensitivity of the plus-maze to anxiolytic treatments. The measures of motor activity in the plus-maze load on a different factor from those derived from the holeboard, thus cautioning against considering all measures of motor activity as interchangeable.

Electrocardiographic measurement of infarct size after thrombolytic therapy

OBJECTIVES

We examined the utility of the 32-point QRS score from the 12-lead electrocardiogram (ECG) for measurement of the ischemic risk region and infarct size in patients receiving thrombolytic therapy.

BACKGROUND

The QRS score offers a means of evaluating the therapeutic benefit of thrombolytic therapy by comparing final infarct size with the initial extent of ischemic myocardium.

METHODS

The study included 38 patients (34 men, 4 women; mean [+/-SD] age 54 +/- 10 years) with a first infarction (18 anterior, 20 inferior). The maximal potential QRS score (QRS0) was assigned to all leads with >/= 100-microV ST elevation on the initial ECG. The QRS scores were calculated at 7 and 30 days after infarction. Left ventricular ejection fraction was measured by radionuclide ventriculography at 1 month. Twenty-eight patients had thallium (Tl)-201 and technetium (Tc)-99m pyrophosphate tomographic measurement of the ischemic region and infarct size.

RESULTS

The QRS0 was 10.3 +/- 3.1 (mean +/- SD) for anterior and 10.4 +/- 3.5 for inferior infarcts. The QRS scores were similar at 7 and 30 days for both anterior (5.6 +/- 3.4 vs. 5.5 +/- 3.4) and inferior infarcts (3.7 +/- 2.6 vs. 2.9 +/- 2.2). The day 7 QRS score and ejection fraction at 1 month were inversely correlated (r = -0.74, p < 0.01). The Tl-201 perfusion defect was 34 +/- 11% of the left ventricle for anterior and 32 +/- 7% for inferior infarcts. Subsequent Tc-99m pyrophosphate infarct size was 15 +/- 9% of the left ventricle for anterior and 17 +/- 9% for inferior infarcts. The QRS0 was correlated with the extent of the Tl-201 perfusion defect (r = 0.79, p < 0.001), and the day 7 QRS score was correlated with Tc-99m pyrophosphate infarct size (r = 0.79, p < 0.005).

CONCLUSIONS

The 32-point QRS score can provide useful immediate measurements of the ischemic risk region and subsequent infarct size.

Flumazenil-precipitated panic and dysphoria in patients dependent on benzodiazepines: a possible aid to abstinence

Ten long-term users of benzodiazepines (average daily dose, 20 mg of diazepam or equivalent) who had experienced problems in withdrawing from the drugs were given an i.v. challenge with either the benzodiazepine antagonist flumazenil (1 mg injected over 30 s) or placebo (vehicle solution) in a randomized double-blind design. There were no 'pseudo withdrawal' responses to either single-blind or double-blind placebo injections, whereas flumazenil produced dramatic panic reactions in all four subjects tested, followed by characteristic benzodiazepine withdrawal symptoms. There were also small but significant rises in pulse rate and blood pressure, but no change in serum cortisol. Flumazenil-induced panic could not be entirely accounted for by a past or present diagnosis of panic disorder, and did not seem to be related to previous withdrawal problems, present benzodiazepine dosage, or to the severity of withdrawal symptoms precipitated by flumazenil in the same challenge test. Attempts to reduce benzodiazepine intake over the next 3 weeks tended to be more successful in the flumazenil group. The results are discussed with reference to possible changes in the GABA-benzodiazepine system in long-term benzodiazepine users.

Relation between ischemia time, infarct size, and left ventricular function in humans

BACKGROUND

Experimental studies indicate that duration of ischemia is a major determinant of myocardial infarct size, but only limited information is available about the relation between ischemia time and infarct size in individual patients. This prospective study sought to document the role of ischemia time as a determinant of infarct size in humans.

METHODS AND RESULTS

We studied 61 patients (50 men, 11 women) 57 +/- 11 years old admitted with a first infarct (31 anterior, 30 inferior) who underwent continuous 12-lead ECG monitoring to document ischemia time. Infarct size (32-point QRS score on day 7) and changes in regional myocardial wall motion (echocardiography) during the following month were related to ischemia time. Among patients with < 3 hours of ischemia (n = 16), mean infarct size on day 7 was 21 +/- 13% of potential infarct size; in patients with 3 to 6 hours of ischemia (n = 23), infarct size was 38 +/- 18% of potential (P < .05 versus 0 to 3 hours of ischemia); and in patients with 6 to 9 hours of ischemia (n = 10), infarct size was 66 +/- 14% of potential (P < .05 versus 3 to 6 hours). In contrast, the 12 patients with an ischemia time > 9 hours had a final infarct size of 77 +/- 10% of potential (P < .01 versus 3 to 6 hours). Multivariate regression identified size of risk region, duration of ischemia, and degree of initial ST-segment elevation as independent predictors of infarct size, of which the most important variable was ischemia time. The regression models accurately predicted both individual absolute infarct size (R2 = .83) and individual infarct/risk ratio (R2 = .74). Patients with < 6 hours of ischemia exhibited significant recovery of myocardial wall motion by day 7 (wall motion score, 2.1 +/- 1.4 versus 5.7 +/- 3.2 on day 1, P < .01). Patients with 6 to 9 hours of ischemia had some recovery by 1 month (score, 6.3 +/- 4.4 versus 10.9 +/- 3.8 on day 1, P < .01), but patients with > 9 hours of ischemia had little recovery of wall motion by 1 month (score, 10.3 +/- 4.5 versus 12.8 +/- 3.1 on day 1, P < .05).

CONCLUSIONS

Measurement of ischemia time allows improved prediction of infarct size in humans. Significant myocardial salvage and functional recovery may be achieved by reperfusion up to 9 hours after coronary occlusion. Continuous ST-segment monitoring should be used to measure ischemia time and guide interventions to reperfuse the infarct artery.

Diazepam withdrawal increases [3H]-5-HT release from rat amygdaloid slices

The release of [3H]-5-HT and [14C]-GABA from hippocampal and amygdaloid slices was studied in a group of rats in which an anxiogenic response had been found on withdrawal of chronic diazepam treatment (2 mg/kg/day for 21 days). Basal release and uptake of [3H]-5-HT and [14C]-GABA and K(+)-evoked release of [14C]-GABA were not significantly changed in either brain region following diazepam withdrawal. However, there was a significant increase in K(+)-evoked [3H]-5-HT release from the amygdala, but not from the hippocampal, slices. These results demonstrate that increased 5-HT release from the hippocampus is not necessary to mediate the anxiogenic withdrawal response, and that raised 5-HT release in the amygdala may be sufficient to mediate this response. The results are discussed with respect to conditions, such as noise during diazepam treatment, that might produce regionally specific changes in 5-HT tone and hence modify the pattern of changes found during diazepam withdrawal.

Dose related promoter effect of metanil yellow on the development of hepatic pre-neoplastic lesions induced by N-nitrosodiethylamine in rats

The dose-dependent effect of mentanil yellow (MY) on the development of preneoplastic hepatic lesions during N-nitrosodiethylamine (DEN) induced hepatocarcinogenesis was studied in comparison with phenobarbitone (PB), in male Wistar (WR) rats. Rats were administered 200 ppm DEN through drinking water for a period of 1 month. After an interval of 2 wk, the animals were administered MY at concentrations of 0.1, 0.5 and 1.0 per cent in the diet for a period of 7 months. PB at 500 ppm served as the standard tumour promoter. The dose-dependent tumour promoter effects of MY were monitored on the basis of morphological appearance of the livers, liver weight profile, histological pattern, appearance of gamma-glutamyl transpeptidase (GGT) positive foci, total GGT activity and the induction of glycogen-deficient islands. All the three doses of MY were found to enhance liver carcinogenesis when compared with either the corresponding controls or only the DEN treated animals. MY at 0.1 per cent was found to be more effective as an enhancer of DEN-induced carcinogenesis than 0.5 and 1.0 per cent. In the present study a dose-related enhancing effect of MY on DEN-induced hepatic preneoplasia in rats has been demonstrated.

Dizocilpine prevents the development of tolerance to the sedative effects of diazepam in rats

Acute treatment with diazepam (2 mg/kg) decreased locomotor activity, rearing, and the number of head dips made in a holeboard. After 3 days of diazepam treatment, tolerance developed to the decreases in locomotor activity and the number of head dips, and there was an emergence of an increased time spent head dipping, compared with controls. Two days of concomitant treatment with the noncompetitive NMDA receptor antagonist, dizocilpine (0.25 mg/kg) blocked the development of tolerance and the increased time spent head dipping. In some respects, the effects of dizocilpine resembled those of holeboard experience. Thus, the rats tested daily in the holeboard after diazepam treatment showed significantly less tolerance to the decrease in locomotor activity and did not show enhanced time spent head dipping after 3 days of treatment. Possible similarities between changes induced by experience and those occurring during the development of tolerance are discussed.

Noise stress and the development of benzodiazepine dependence in the rat

Rats housed in conditions of noise stress were given daily injections of diazepam (4 mg/kg). Significant tolerance developed to the sedative effects within 5 days of treatment, as measured by head dipping and motor activity in the holeboard and by the number of closed arm entries in the plus-maze. These results are in agreement with other reports of rapid tolerance to sedative effects. However, in contrast to the usual finding of tolerance to anxiolytic actions after 2-3 weeks of treatment, in this study no tolerance developed after 23 days of treatment to diazepam's anxiolytic effects in the plus-maze. On withdrawal from the 23 days of diazepam treatment, there was no anxiogenic response in the plus-maze. Therefore, it seems that when chronic administration of diazepam is accompanied by chronic stress, tolerance does not occur to the anxiolytic effects, although it does develop to the sedative effects.

Beware the builders: construction noise changes [14C]GABA release and uptake from amygdaloid and hippocampal slices in the rat

The effects of exposure to chronic noise and vibration, produced by construction work, on the release and uptake of [3H]5-hydroxytryptamine ([3H]5-HT) and [14C]gamma-aminobutyric acid ([14C]GABA) from rat amygdaloid and hippocampal slices were investigated. Noise-exposure resulted in increased release, with no significant change in uptake, of [14C]GABA from amygdaloid slices. In hippocampal slices, [14C]GABA release was also increased, but the changes in release were dependent upon the marked decrease in uptake of [14C]GABA into these slices. There was an increase in peak K(+)-evoked release of [3H]5-HT from hippocampal slices, but no other changes in [3H]5-HT release or uptake in either region were observed following noise-exposure. These findings may have important practical implications for the research carried out in laboratories exposed to construction noise and vibrations.

Morphological transformation of Syrian hamster embryo cells in primary culture by malachite green correlates well with the evidence for formation of reactive free radicals

Malachite green (MG) (green crystals with metallic luster and very soluble in water) is highly cytotoxic to mammalian cells and also acts as a liver tumor promoter. In view of its industrial importance and possible exposure to individuals, MG poses a potential environmental health hazard. We have studied the effect of MG on the formation of morphologically transformed colonies using Syrian hamster embryo (SHE) cell transformation assay. MG induced a dose-related increase in the formation of transformed foci, the optimum concentration being 0.05 micrograms/ml. Electron spin resonance (ESR) analysis using 5,5-dimethyl-1-pyrroline N-oxide (DMPO) as a spin-trapping agent showed the formation of reactive free radicals during the in vitro metabolism of MG. The present study suggests a close relationship between the morphological transformation of SHE cells by MG and the possible involvement of reactive free radical formation.

The cytotoxic properties of malachite green are associated with the increased demethylase, aryl hydrocarbon hydroxylase and lipid peroxidation in primary cultures of Syrian hamster embryo cells

Malachite green (MG), an industrial compound and potential environmental health hazard, is highly cytotoxic to mammalian cells in culture. In an attempt to define the biochemical basis, we have compared the cytotoxic effects and morphological alterations shown by MG in Syrian hamster embryo (SHE) cells with the levels of lipid peroxidation and the activities of aryl hydrocarbon hydroxylase, aminopyrine-N-demethylase, superoxide dismutase and catalase. Treatment of SHE cells with MG results into an induction of the mono-oxygenase system, lipid peroxidation and catalase in a dose-dependent way, indicating the formation of reactive free radicals. Accordingly, the possible involvement of reactive free radicals especially hydroxymethyl radicals in the observed high cytotoxicity due to exposure to MG is postulated.

Effect of negative ion atmospheric loading on cognitive performance in human volunteers

Negative ion atmospheric loading has been reported to affect a range of psychological functions, from alertness to circadian rhythms, and has been suggested to benefit a variety of medical conditions, from allergies to migraine. In a double-blind study planned to assess the effect of negative ions on cognitive performance in human volunteers, 65 female graduate course students were randomized into ionized atmosphere (n = 34) and control (n = 31) groups. The following cognitive tasks were administered: Digit Symbol Substitution Test, Addition Test, Visual Memory (Complex Figure) Test, Verbal Memeory (Complex Passage) Test, Ideational Fluency Test and Clerical Speed and Accuracy test. On all but the last two tests, the negative ion groupperfonned significantly better (to a 15-40% extent) than controls. It is concluded that negative ionization of the atmosphere by artificial means may be of benefit in certain common, practical situation in which depletion of these ions occurs.

Enhanced expression of low molecular weight keratins during progressive diethylnitrosamine-induced hepatocarcinogenesis in rats is associated with the presence of high levels of gamma-glutamyl transpeptidase and glycogen-deficient islands

The sequential expression of keratin proteins as a function of tumour progression was studied in the rat liver and compared with several tumour markers like histochemical gamma-glutamyl transpeptidase (GGT)-positive foci, quantitative GGT activity and glycogen deficient islands at corresponding stages using diethylnitrosamine (DEN) as a carcinogen. The enhanced expression of low molecular weight keratins indicating undifferentiated nature of the tumour is associated with the increased levels of tumour markers. The findings are discussed in relation to cytoskeletal alterations during progressive hepatocarcinogenesis in rats.

Enhancing effect of malachite green on the development of hepatic pre-neoplastic lesions induced by N-nitrosodiethylamine in rats

The effects of malachite green (MG) and phenobarbitone (PB) were compared on the development of pre-neoplastic lesions during N-nitrosodiethylamine(DEN)-induced hepatocarcinogenesis in male Wistar rats. Rats were administered 200 p.p.m. DEN in drinking water for a period of 1 month. After an interval of 2 weeks the animals were given either MG (25 p.p.m.) or PB (500 p.p.m.) in drinking water for 2.5 months. The effects were monitored on the basis of the morphological appearance of the liver, histological pattern, gamma-glutamyltranspeptidase (GGT)-positive foci, total GGT activity and the induction of glycogen-deficient islands. Both MG and PB were found to enhance liver carcinogenesis to a significant extent when compared with either their corresponding controls or animals given DEN alone. The enhancing effect of MG at 25 p.p.m. is comparable with PB at 500 p.p.m. An enhancing effect of MG on DEN-induced hepatocarcinogenesis in the rats was demonstrated.

Transpyloric feeding in small preterm infants

Wolfsdorf, J., Makarawa, S., Fernandes, C., Fenner, A. (1975). Archives of Disease in Childhood, 50, 723. Transpyloric feeding in small preterm infants. In 20 preterm infants, birthweight ranging from 775 to 1540 g, transpyloric feeding was carried out using expressed human milk as the sole nutrient (study group). 10 further infants, birthweight range 910-1500 g, were also fed with human milk via nasogastric tube (control group). The group fed transpylorically had higher fluid intakes during the early days of life. Body weight loss after birth was similar in both groups, but subsequent weight gain was more rapid in the study group. Thus transpyloric feeding is considered to offer the following advantages in comparison with nasogastric feeding. (1) No danger of aspiration after vomiting. (2) More rapid weight gain.