Biophysical and biochemical features' feedback associated with a flood episode in a tropical river basin model

Global climate change scenarios such as frequent and extreme floods disturb the river basins by destructing the vegetation resulting in rehabilitation procedures being more costly. Thus, understanding the recovery and regeneration of vegetation followed by extreme flood events is critical for a successful rehabilitation process. Spatial and temporal variation of biochemical and biophysical features derived from remote sensing technology in vegetation can be incorporated to understand the recovery and regeneration of vegetation. The present study explores the flood impact on vegetation caused by major river basins in Sri Lanka (a model tropical river basin) by comparing pre-flood and post-flood cases. The study utilized enhanced vegetation index (EVI), normalized difference vegetation index (NDVI), the fraction of photosynthetically active radiation (FPAR), and gross primary productivity (GPP) of the Moderate Resolution Imaging Spectroradiometer (MODIS) platform. A remarkable decline in EVI, LAI, FPAR, GPP, and vegetation condition index was observed in the post-flood case. Notably, coupled GPP-EVI and GPP-LAI portrayed dependency of features and showed a significant impact triggered by the flood episode by narrowing the feature in post-flood events. EVI depicted the highest regeneration (0.333) while GPP presented the lowest regeneration (0.093) after the flood event. Further, it was revealed that 1.18 years have been on the regeneration. The regeneration of GPP and LAI remained low comparatively justifying the magnitude and impact of the flood event. The study revealed successful implications of vegetation indices on flood basin management of small to large tropical river basins.

Female infertility and diet, is there a role for a personalized nutritional approach in assisted reproductive technologies? A Narrative Review

Female infertility is a major public health concern and a global challenge. It is a disorder of the reproductive system, defined as the inability to achieve a clinical pregnancy. Nutrition and other environmental factors are found to impact reproductive health in women as well as the outcome of assisted reproductive technologies (ART). Dietary factors, such as polyunsaturated fatty acids (PUFA), fiber as well as the intake of Mediterranean diet appear to exert beneficial effects on female reproductive outcomes. The exact mechanisms associating diet to female fertility are yet to be identified, although genomic, epigenomic, and microbial pathways may be implicated. This review aims to summarize the current knowledge on the impact of dietary components on female reproduction and ART outcomes, and to discuss the relevant interplay of diet with genome, epigenome and microbial composition.

The efficacy of aerobic training on the pulmonary functions of hemophilic A patients: a randomized controlled trial

OBJECTIVE

The present study investigated the efficacy of a program of aerobic exercise on pulmonary functions in adult males with hemophilia A (HA).

PATIENTS AND METHODS

40 patients with HA who met the eligibility criteria (40 HA; age range: 20-39 years) were invited to participate in the study. The patients were divided into two groups, 20 per each. Participants in the study group (A) underwent selected physical therapy program, along with aerobic training sessions on a cycle ergometer (50-60% heart rate reserve, moderate intensity), while the control group (B) underwent a selected physical therapy program only. The pulmonary functions (FVC, FEV1, FEV1/FVC, PEF, PIF, and MVV) were measured before and after treatment program.

RESULTS

There were noteworthy statistical differences between pre- and post-measurements in the study group in all measured variables (p < 0.05). There were also significant statistical differences between the study and control groups in all measured variables post treatment (p < 0.05).

CONCLUSIONS

This study has demonstrated that hemophilic A patients' pulmonary functions have improved significantly following aerobic exercise training. As a result, aerobic exercise can be used in addition to medical treatment for hemophilic A patients.

Choosing between cocaine and sucrose under the influence: testing the effect of cocaine tolerance

RATIONALE

Cocaine use not only depends on the reinforcing properties of the drug, but also on its pharmacological effects on alternative nondrug activities. In animal models investigating choice between cocaine and alternative sweet rewards, the latter influence can have a dramatic impact on choice outcomes. When choosing under cocaine influence is prevented by imposing sufficiently long intervals between choice trials, animals typically prefer the sweet reward. However, when choosing under the drug influence is permitted, animals shift their preference in favor of cocaine.

OBJECTIVES

We previously hypothesized that this preference shift is mainly due to a direct suppression of responding for sweet reward by cocaine pharmacological effects. Here we tested this hypothesis by making rats tolerant to this drug-induced behavioral suppression.

RESULTS

Contrary to our expectation, tolerance did not prevent rats from shifting their preference to cocaine when choosing under the influence.

CONCLUSION

Thus, other mechanisms must be invoked to explain the influence of cocaine intoxication on choice outcomes.

Metal vs fibre posts - which is clinically superior for the restoration of endodontically treated teeth?

Data sources Medline/PubMed, Web of Science, Scopus and Cochrane Library databases. Grey literature searches (OpenGrey, ProQuest databases), hand searches in the reference list of eligible studies and relevant journals.Study selection Randomised controlled trials (RCTs) and prospective clinical trials (PCTs) with direct comparisons between metal posts (MPs) and fibre posts (FPs). Trials contained a minimum of ten patients and endodontically treated permanent teeth that had received either single crowns or fixed partial dentures (bridges) and followed up for a minimum of one year. The primary outcome compared the difference in failure rates between FPs and MPs, with subgroup analysis comparing location (anterior/posterior), type of MP (cast post core/preformed MP) and most frequent modes of failure (debond/root fracture).Data extraction and synthesis Study selection, data collection and risk of bias assessments were completed independently by two reviewers. Disagreements were discussed with a third reviewer to reach a consensus. The risk of bias was evaluated using the Cochrane risk of bias tool (RCTs) or the ROBINS-I tool (PCTs). The quality of responses was assessed using the Grading of Recommendations Assessment, Development And Evaluation (GRADE) approach. The meta-analysis (MA) was performed using the Mantel-Haenszel method. Trial heterogeneity was assessed using random- and fixed-effects models. Inter-examiner agreement during the database search and study selection process was checked using the kappa statistic.Results After duplicates were removed, 1,026 articles were assessed and screened by title and abstract. Of these, 21 articles underwent full-text evaluation, with ten articles meeting the eligibility criteria. Eligible studies included six RCTs and four PCTs. A total of 844 endodontically treated teeth (ETT) were restored with intra-radicular posts in 704 participants. Four hundred and fifty-three ETT were restored with FPs and 391 with MPs. The mean age of participants was 42.7 (33.95-55.45) years, with a mean follow-up period of 50.95 (12-154) months. Most studies reported failures during the follow-up period, but the MA revealed no significant difference between FPs and MPs in terms of failure rates (P = 0.39; RR: 0.82 mm; CI: 0.52-1.29). Sub-analysis showed no difference in failure rates between anterior and posterior regions and no difference when comparing FPs to cast post and core vs prefabricated MPs. Root fractures and post debondings were the most common modes of failure, but within these failures, no difference was observed between FPs and MPs.Conclusions No evidence was identified for a difference in failure rates between FPs and MPs. This was independent of the type of MP and position within the arch. Reporting of RCTs and PCTs was variable and further high-quality studies are needed.

Habit, choice, and addiction

Addiction was suggested to emerge from the progressive dominance of habits over goal-directed behaviors. However, it is generally assumed that habits do not persist in choice settings. Therefore, it is unclear how drug habits may persist in real-world scenarios where this factor predominates. Here, we discuss the poor translational validity of the habit construct, which impedes our ability to determine its role in addiction. New evidence of habitual behavior in a drug choice setting are then described and discussed. Interestingly, habitual preference did not promote drug choice but instead favored abstinence. Here, we propose several clues to reconcile these unexpected results with the habit theory of addiction, and we highlight the need in experimental research to face the complexity of drug addicts' decision-making environments by investigating drug habits in the context of choice and in the presence of cues. On a theoretical level, we need to consider more complex frameworks, taking into account continuous interactions between goal-directed and habitual systems, and alternative decision-making models more representative of real-world conditions.

Clinical and metabolic characteristics of the Diabetes Intervention Accentuating Diet and Enhancing Metabolism (DIADEM-I) randomised clinical trial cohort

OBJECTIVES

Diabetes Intervention Accentuating Diet and Enhancing Metabolism-I (DIADEM-I) is the first randomised controlled trial (RCT) in the Middle East and North Africa (MENA) region testing the effectiveness of an intensive lifestyle intervention (ILI) for weight loss and diabetes remission. We report on the recruitment process and baseline characteristics of the DIADEM-I cohort based on origin (Middle East vs North Africa), and waist circumference.

DESIGN

DIADEM-I is an open-label randomised, controlled, parallel group RCT recruiting young individuals (18-50 years) with early type 2 diabetes (≤3 years since diagnosis) originating from MENA. Individuals from primary care were randomised to usual medical care or ILI (total dietary replacement phase using meal replacement products, followed by staged food reintroduction and physical activity support). The primary outcome is weight loss at 12 months. Other outcomes are glycaemic control and diabetes remission.

SETTING

Primary care, Qatar.

PARTICIPANTS

147 (73% men) randomised within DIADEM-I who were included in the final trial data analysis.

OUTCOME MEASURES

Recruitment metrics, and baseline clinical and metabolic characteristics.

RESULTS

Of 1498 people prescreened, 267 (18%) were invited for screening and 209 (78%) consented. 173 (83%) were eligible. 15 (7%) withdrew before randomisation and the remaining 158 were randomised. Mean age was 42.1 (SD 5.6) years and mean body mass index was: 36.3 (5.5) kg/m² (women) and 34.4 (5.4) kg/m² (men). Mean diabetes duration was 1.8 (1.0) years and mean glycosylated haemoglobin (HbA1c) was 7.0% (1.30) (52.5 mmol/mol (SD 14.3)). Participants originated from 13 countries. Those from North Africa reported greater physical activity and had lower family history of diabetes. 90% of subjects were taking diabetes medications and 31% antihypertensives. Those with greater waist circumference had significantly higher insulin resistance and lower quality of life.

CONCLUSION

Recruitment of participants originating from the MENA region into the RCT was successful, and study participation was readily accepted. While DIADEM-I participants originated from 13 countries, there were few baseline differences amongst participants from Middle East versus North Africa, supporting generalisability of RCT results.

TRIAL REGISTRATION NUMBER

ISRCTN20754766; NCT03225339.

Effect of intensive lifestyle intervention on bodyweight and glycaemia in early type 2 diabetes (DIADEM-I): an open-label, parallel-group, randomised controlled trial

BACKGROUND

Type 2 diabetes is affecting people at an increasingly younger age, particularly in the Middle East and in north Africa. We aimed to assess whether an intensive lifestyle intervention would lead to significant weight loss and improved glycaemia in young individuals with early diabetes.

METHODS

This open-label, parallel-group, randomised controlled trial (DIADEM-I), done in primary care and community settings in Qatar, compared the effects of an intensive lifestyle intervention with usual medical care on weight loss and glycaemic outcomes in individuals with type 2 diabetes, aged 18-50 years, with a short diabetes duration (≤3 years), had a BMI of 27·0 kg/m² or more, and who were from the Middle East and north Africa region. Participants were randomly allocated (1:1) either to the intensive lifestyle intervention group or the usual medical care control group by a computer-generated sequence and an online randomisation service. The intensive lifestyle intervention comprised a total diet replacement phase, in which participants were given formula low-energy diet meal replacement products followed by gradual food reintroduction combined with physical activity support, and a weight-loss maintenance phase, involving structured lifestyle support. Participants in the control group received usual diabetes care, which was based on clinical guidelines. The primary outcome was weight loss at 12 months after receiving the assigned intervention. Our analysis was based on the intention-to-treat principle. Key secondary outcomes included diabetes control and remission. The trial was registered with the ISRCTN registry, ISRCTN20754766, and ClinicalTrials.gov, NCT03225339.

FINDINGS

Between July 16, 2017, and Sept 30, 2018, we enrolled and randomly assigned 158 participants (n=79 in each group) to the study. 147 participants (70 in the intervention group and 77 in the control group) were included in the final intention-to-treat analysis population. Between baseline and 12 months, the mean bodyweight of participants in the intervention group reduced by 11·98 kg (95% CI 9·72 to 14·23) compared with 3·98 kg (2·78 to 5·18) in the control group (adjusted mean difference -6·08 kg [95% CI -8·37 to -3·79], p<0·0001). In the intervention group, 21% of participants achieved more than 15% weight loss between baseline and 12 months compared with 1% of participants in the control group (p<0·0001). Diabetes remission occurred in 61% of participants in the intervention group compared with 12% of those in the control group (odds ratio [OR] 12·03 [95% CI 5·17 to 28·03], p<0·0001). 33% of participants in the intervention group had normoglycaemia compared with 4% of participants in the control group (OR 12·07 [3·43 to 42·45], p<0·0001). Five serious adverse events were reported in four participants in the control group; four admissions to hospital because of unanticipated events (supraventricular tachycardia, abdominal pain, pneumonia, and epididymo-orchitis), and one admission to hospital for an anticipanted event (hyperglycaemia).

INTERPRETATION

Our findings show that the intensive lifestyle intervention led to significant weight loss at 12 months, and was associated with diabetes remission in over 60% of participants and normoglycaemia in over 30% of participants. The provision of this lifestyle intervention could allow a large proportion of young individuals with early diabetes to achieve improvements in key cardiometabolic outcomes, with potential long-term benefits for health and wellbeing.

FUNDING

Qatar National Research Fund.

Effects of stock, sex, and muscle type on carcass characteristics and meat quality attributes of parent broiler breeders and broiler chickens

This study aimed to investigate the effect of using breeder parents (434-days-old) and broiler chickens (37 D of age) from Ross 308 on meat quality parameters and carcass characteristics; sex and muscle type were also estimated. Carcass assessment involved hot carcass weight, carcass yield, and cuts (breast, legs, wings, back, and shoulder). A total of 120 birds were divided into 2 groups (60 birds from each stock), each stock contain equal number of sexes (30 males and 30 females), and further divided into 6 replicates, so that there were 5 birds in each replicate. The birds were fed ad libitum. A sample of 30 birds (male, n = 15 and female, n = 15) from each group was slaughtered for assessing carcass and physical characteristics. Sensory analysis was carried out on each group after boiling or roasting the bird. Live weight, carcass weight and yield, breast weight, legs, wings, and back weights and yield were higher (P < 0.001) for breeder parents when compared to broilers, with the exception of breast percentage. Moreover, better carcass characteristics were observed in males than in females. Parent stock had better water-holding capacity and myofibrillar fragmentation whereas broilers had more tender meat than breeders. Moreover, cooking loss and other sensory characters were not significant between the two groups; however, females had more tender pectoral muscles and more myofibrillar fragmentation than males. We concluded that parent breeders had better carcass characteristics than broiler chickens. The broiler chickens of Ross 308 and female birds had better meat quality than parent breeders.

Growth, carcass characteristics, and meat quality of broilers fed a low-energy diet supplemented with a multienzyme preparation

The effect of a low-ME diet with a multienzyme (Kemzyme Plus, Kemin, Des Moines, IA) blend on performance, meat quality, and carcass traits was evaluated in Hubbard broiler chicks. A total of 120 Hubbard broiler chicks were allocated to the following 4 experimental groups and every group was separated into 6 replicates, with 5 birds per replicate: control (3,180 kcal/kg of ME), control + 0.50 g/kg diet of enzyme (Cont-Enz), low-ME diet (3,080 kcal/kg), and low-ME + 0.50 g/kg diet of enzyme (low-ME-Enz). The trail lasted for 16 D (32 to 48 D of age). No significant differences in growth parameters or carcass traits were observed among treatments. However, liver weight increased with the low-ME-Enz diet (P = 0.038). The low-ME diet recorded the highest weight for the bursa (P = 0.043) and thymus (P = 0.019). Dietary treatments had significant impacts on the length of duodenum, ileum, and cecum, as well as the weight of duodenum. The length of duodenum, ileum, and cecum increased with enzyme supplementation. The myofibril fragmentation index was lower with the Cont-Enz, low-ME, and low-ME-Enz diets than with the control diet (P = 0.043). The shear force increased with the low-ME-Enz diet (P = 0.022) than the control diet. Dietary treatments influenced breast meat yellowness (P = 0.019), whereas the low-ME diet had the lowest yellowness at the slaughtering age. The dietary treatments affected the breast meat pH (P = 0.001), with the control diet having the highest pH value after 24 hours. Thus, there was no effect of low-ME or enzyme supplementation to the control or low-ME diet on growth performance or carcass yield. However, feeding a low-ME diet or Cont-Enz preparation influenced organ and small intestine weights and meat characteristics.

Diabetes Intervention Accentuating Diet and Enhancing Metabolism (DIADEM-I): a randomised controlled trial to examine the impact of an intensive lifestyle intervention consisting of a low-energy diet and physical activity on body weight and metabolism in early type 2 diabetes mellitus: study protocol for a randomized controlled trial

Background

Type 2 diabetes mellitus (T2DM) and obesity are syndemic and will have a significant impact on affected individuals and healthcare services worldwide. Evidence shows that T2DM remission can be achieved with significant weight loss in those who are younger with early diabetes and requiring fewer medications for glycaemic control. DIADEM-I aims to examine the impact of an intensive lifestyle intervention (ILI) using a low-energy diet (LED) meal replacement approach combined with physical activity in younger individuals with early T2DM.

Methods

The planned study is an ongoing, non-blinded, pragmatic, randomised controlled, parallel-group trial examining the impact of an LED-based ILI on body weight and diabetes remission in younger (18–50 years) T2DM individuals with early diabetes (≤ 3-year duration). The ILI will be compared to usual medical care (UMC). The primary outcome will be weight loss at 12 months. Other key outcomes of interest include diabetes remission, glycaemic control, diabetes complications, cardiovascular health, physical activity, mental health, and quality of life. It is planned for the study to include 138 subjects for assessment of the primary outcome. Safety will be assessed throughout.

Discussion

If DIADEM-I demonstrates a clinically significant effect for younger individuals with early T2DM, it will inform clinical guidelines and services of the future for management of T2DM.

Trial registration

ISRCTN: ISRCTN20754766 (date assigned: 7 June 2017); ClinicalTrials.gov, ID: NCT03225339 Registered on 26 June 2017.

Electronic supplementary material

The online version of this article (10.1186/s13063-018-2660-1) contains supplementary material, which is available to authorized users.

Effect of subchronic intake of green tea extract on liver of albino rat histomorphometric, ultrastructural and biochemical study

BACKGROUND

There are conflicting reports on the effect of green tea extract (GTE) on the liver of animals. Some studies failed to show any adverse hepatic effects following administration of GTE to mice, rats, and dogs. Others reported severe hepatic necrosis, resulting in death in female Swiss-Webster mice following its administration. The aim of the study was to examine the subchronic toxicity of GTE on the liver of the adult male albino rats.

MATERIALS AND METHODS

Forty male adult Wistar albino rats were used in the study. The rats were divided into four groups; group I (control), group II (low-dose green tea), group III (medium-dose green tea) and group IV (high-dose green tea). Histological, biochemical and histomorphometric analyses were done.

RESULTS

Mild hepatic affections were observed in group II. The affections were severe in groups III and IV. The central veins and hepatic sinusoids were congested. The hepatocytes were degenerated. Hypertrophy of the hepatic arteries, dilation of the bile ducts and cellular infiltration were clearly observed in the last two groups. Mild degenerative changes were observed in the hepatocytes in rat's group II; the cytoplasm was rarefied and vacuolated. Some mitochondria were ruptured. The blood sinusoids were congested. The rough endoplasmic retinaculum was fragmented in group III. More degenerative changes were observed in group IV; the hepatic architectures were lost with disruption of cell membranes. Most of the cell organelles were degenerated and most of mitochondria were ballooned. As compared to that of the control groups: the total serum protein values in groups II, III and IV showed a statistically significant decrease (12%, 20% and 21%, respectively), the mean area per cent of collagen fibres in groups III and IV increased 5 and 7 folds.

CONCLUSIONS

Subchronic administration of GTE resulted in structural and functional affection of the rats' liver. The dose of 250 mg/kg/day seemed to be safe, while the doses of 500 mg/kg/day and 1000 mg/kg/day had deleterious effect being more evident in the latter dose.

Potentiality of uranium biosorption from nitric acid solutions using shrimp shells

Biosorption has gained important credibility during recent years because of its good performance and low cost. This work is concerned with studying the potentiality of the chitin component of the shrimp shells for uranium biosorption from nitric acid liquid solutions. The structural characteristics of the working chitin have been determined via Fourier Transform Infrared Spectroscopy (FTIR). The surface morphology was examined using Scanning Electron Microscopy (SEM). The adsorption capacity of biomass was investigated experimentally. The influence of contact time, pH, metal ion concentration, solution volume to mass ratio and temperature were evaluated and the results were fitted using adsorption isotherm models. The kinetic of uranium biosorption was also investigated as well as biosorption thermodynamic.

Morphological and radiometrical study of the human intervertebral foramina of the cervical spine

BACKGROUND

Degenerative changes of the cervical spine are an inevitable response to certain occupational status and aging processes. Compression of cervical nerve roots may result from disc degeneration, disc herniation or intervertebral foraminal stenosis. The precise and detailed anatomical knowledge of the intervertebral foramen of the cervical spine is essential for the diagnosis and management of cervical radiculopathy. The significance of the observations and findings of the present study was to elucidate the correlation between the morphology and disorders of the cervical intervertebral foramina in normal and pathological conditions especially at the level of C3-C4 to C6-C7 on both sides and in both sexes. Moreover, it will help greatly in the planning of both surgical and conservative strategies.

MATERIALS AND METHODS

In the present study, 5 formalin-fixed adult cadavers and radiological specimens of the cervical region of the vertebral column of 28 normal and 209 subjects suffering from cervical disorder from both sexes and different age groups. They subjected for morphological and radiometrical analysis.

RESULTS

All measurements of the present study of the cervical disorders in females were found to be 6% less than in males in all age groups, which is statistically significant (p < 0.01) as compared with the control group (2%). The mean intervertebral foraminal areas in the control group of C5-C6 and C6-C7 are significantly greater than those of C3-C4 and C4-C5.

CONCLUSIONS

The mean intervertebral foraminal area was greater in the lower cervical region than the upper in normal adult individuals. In pathological condition the affection of C3-C4 and C4-C5 intervertebral foramina was more due to narrower surface area. The pathology of cervical spine affecting the intervertebral foramina of female which complaint earlier than male due to narrower foramina.

Study of methyl transferase (G9aMT) and methylated histone (H3-K9) expressions in unexplained recurrent spontaneous abortion (URSA) and normal early pregnancy

We investigated the expression of methyl transferase G9a and methylated histone H3-K9 in fresh human decidual/endometrial tissue of 12 normal early pregnancies and 15 unexplained recurrent spontaneous abortions (URSA). The samples were obtained through dilatation and curettage and collected as per strict inclusion-exclusion criteria. The tissue was subjected to immunohistochemical analysis (IHC), western blotting (WB) and RT-PCR analysis. The results demonstrated methyl transferase G9a to have a lower expression in abortions when compared with that in normal pregnancy (P < 0.05). The sensitivity of RT-PCR, IHC and WB were respectively 66.67, 75 and 71.43%, while specificity of the same were 66.67, 60 and 78.92%, respectively. Methylated histone H3-K9 was significantly lower (P < 0.0001) in URSA tissues than in controls. This study suggests that methylation may cause URSA and indicates the need for further work to explore the role of methylation in URSA and its possible prevention through locally acting methylating/demethylating agents.

Extraction and phytochemical investigation of Calotropis procera: effect of plant extracts on the activity of diverse muscles

CONTEXT

Calotropis procera (Ait.) R.Br. (Asclepiadaceae) is a shrub or small tree that grows wild in Egypt. Calotropis acts as a purgative, anthelmintic, anticoagulant, palliative (in problems with respiration, blood pressure), antipyretic, and analgesic, and induces neuromuscular blocking activity. Little research has been done to study the electrophysiological effects of this plant's extracts on cardiac, smooth, and skeletal muscle activities.

OBJECTIVE

The present study was conducted to determine the phytochemical composition and the effect of the total alcohol extract of the shoot of the plant, which contains almost all of C. procera's cardiac glycosides, flavonoids, and saponins. Also, this study attempted to throw more light on the electrophysiological effects of the plant extracts on cardiac, smooth, and skeletal muscle activities and to clarify the mechanism(s) of their observed action(s).

MATERIALS AND METHODS

The aerial parts of the plant were air dried and their ethanol extracts partitioned with successive solvents. Cardiac, smooth, and skeletal muscles were used in this study to investigate the physiological and pharmacological effects of the plant extracts from different solvents. The data were analyzed by paired t-test.

RESULTS

The phytochemical investigation of Calotropis procera revealed the presence of cardenolides, flavonoids, and saponins. The effects of ethanol, n-butanol, and ethyl acetate (EtOAc) extracts were each evaluated on isolated toad heart and their mechanisms of action determined. Perfusion with 2 μg/mL ethanol, 0.2 μg/mL butanol, and 0.2 μg/mL EtOAc extracts caused a significant decrease in heart rate (bradycardia), significant increase in the force of ventricular contraction, and increase in T-wave amplitude. In addition, the effects of different extracts of the studied plant on smooth muscle and skeletal muscle were investigated in this study. The different extracts and latex of C. procera induced a negative chronotropic effect and decreased the heart rate (HR) of isolated toad heart. The different extracts increased the power of contraction of the duodenum (trace a). Pretreatment with atropine sulfate as a muscarinic receptor blocker abolished the stimulatory effect of the different plant extracts and latex of C. procera (trace b).

DISCUSSION

The present data suggest that ethanol, butanol, and EtOAc extracts of Calotropis procera have negative chronotropism and positive inotropism. Verapamil could abolish the inotropic effect of ethanol as well as that of butanol and EtOAc extracts. Meanwhile, atropine did not abolish the observed negative chronotropic effect. The ethanol extract increased the power of contraction of rabbit duodenum, but atropine abolished this effect. It also decreased the skeletal muscle contraction; this effect could be through blocking of the nicotinic receptors. Butanol and EtOAc extract data for smooth and skeletal muscles are very close to those for the corresponding ethanol extract of the studied plant. The present data for C. procera indicate its direct action on the myocardium, its increase of smooth muscle motility, and its relaxation of skeletal muscle contraction. The chemical constituents could directly affect the cell membrane probably through receptors coupling to G proteins. They regulate the ion channel physiology as in the myocardium.

CONCLUSION

The present data on the extracts of C. procera indicate a direct action on the myocardium, stimulatory effect on smooth muscle motility, and relaxant action on skeletal muscle contraction. Chemical constituents could directly affect the cell membrane probably through receptors coupling to G proteins. They regulate the ion channel physiology as in the myocardium.

Computational approaches to the neurobiology of drug addiction

To increase our understanding of drug addiction--notably its pharmacological and neurobiological determinants--researchers have begun to formulate computational models of drug self-administration. Currently, one can roughly distinguish between three classes of models which all have in common to attribute to brain dopamine signaling a key role in addiction. The first class of models contains quantitative pharmacological models that describe the influence of pharmacokinetic and pharmacodynamic factors on drug self-administration. These models fail, however, to explain how the drug self-administration behavior is acquired and how it eventually becomes rigid and compulsive with extended drug use. Models belonging to the second class circumvent some of these limitations by modeling how drug use usurps the function of dopamine in reinforcement learning and action selection. However, despite their behavioral plausibility, these latter models lack neurobiological plausibility and ignore the potential role of opponent processes in addiction. The third class of models attempts to surmount these pitfalls by providing a more realistic picture of the midbrain dopamine circuitry and of the complex action of drugs of abuse in the output of this circuitry. Here we provide a brief overview of these different models to illustrate the potential contribution of mathematical modeling to our understanding of the neurobiology of drug addiction.

A non-invasive gating device for continuous drug delivery that allows control over the timing and duration of spontaneous opiate withdrawal

Opiate dependence in laboratory animals is commonly induced by two methods: (1) subcutaneous (s.c.) insertion of morphine pellets, and (2) daily injections of increasing doses of opiates. While both of these methods reliably induce opiate dependence, they do not allow one to discontinue, and subsequently reestablish steady state opiate plasma levels with minimal invasive procedures. We developed an "ON-OFF" gating device for repeatedly and non-invasively turning ON or OFF opiate delivery by standard osmotic minipumps. The reliability of this "device" was tested utilizing naloxone (NAL)-precipitated somatic signs of withdrawal, and body mass index (BMI) as measures of withdrawal. Rats were implanted with osmotic minipumps equipped with the gating device, containing heroin (2.66 mg per day). Three days after surgery, somatic signs of withdrawal were precipitated every 48 h by NAL (0.3mg/kg), with minipumps gated ON or OFF. For BMI, spontaneous withdrawal was repeatedly (three times) induced by turning OFF and ON the gating devices every 48 h. Body weights were measured every 4h from 06:00 to 22:00 h daily. Results show that NAL precipitated intense somatic signs of withdrawal when gating devices were ON. This effect was almost abolished when gating devices were OFF. BMI rapidly decreased after the gating devices were turned OFF with maximum weight loss occuring 12 h post-OFF position, and gradually returning to baseline values after gating devices were turned back ON. These results demonstrate the validity of the "ON-OFF" gating device for non-invasively and repeatedly inducing physical dependence to opiates over a prolonged time.

Role of thoracic surgery in patients suffering from Acquired Immune Deficiency Syndrome

BACKGROUND AND PURPOSE

To study the role of thoracic surgery in patients suffering from Acquired Immune Deficiency Syndrome (AIDS) in a South Bronx community with a high incidence of the disease.

METHODS

A retrospective analysis of medical records of patients who underwent thoracic surgery at Bronx-Lebanon hospital, New York, over a three year period between 1996-1998.

RESULTS

The thoracic surgeons at Bronx-Lebanon Hospital in New York operated upon a total of 210 patients. Of these, 39 were operated upon for AIDS-related illnesses, comprising 17% of the operative workload. The indications of surgery in these patients were variable, ranging from infections to tumours. Fifteen patients were operated on for pericardial effusion. Ten were operated on for empyema, which had failed to resolve with thoracostomy alone and necessitated decortication. Tumours also formed a significant portion of the surgical workload. Three patients had Kaposi's sarcoma of the lung and three had a primary lymphoma in the lung. The mortality rate was high (46%).

CONCLUSION

The data suggest that surgical intervention in AIDS-related chest diseases is unable to alter the course of the disease. Earlier detection and intervention of these complications may improve outcome in some patients.

Amyloid beta peptide-induced cerebral endothelial cell death involves mitochondrial dysfunction and caspase activation

Amyloid beta peptide (A beta), a 39 to 43 amino acid fragment of the beta-amyloid precursor protein (betaAPP), forms insoluble fibrillar accumulation in neurofibrillary tangles and vascular plaques. A beta has been implicated in neuronal and vascular degeneration in brain regions susceptible to plaque formation because of its cytotoxic effect on neurons and endothelial cells (ECs). The authors used a murine cerebral endothelial cell (CEC) line and primary cultures of bovine CECs to explore the cytotoxic mechanism of A beta. A beta 1-40 and A beta 25-35 peptides caused cell death in a dose-dependent and time-dependent manner. Exposure to either A beta 25-35 or A beta 1-40 at 10 micromol/L for 48 hours caused at least 40% cell death. Cerebral endothelial cell death was characterized by nuclear condensation, mitochondrial dysfunction, and nuclear and mitochondrial DNA damage. A beta 25-35 activated both caspase-8 and caspase-3 in murine CECs. zVAD-fmk, a broad-spectrum caspase inhibitor, prevented A beta 25-35-induced increase in caspase-3 activity and CEC death. N-acetyl-cysteine, an antioxidant, also prevented A beta-induced cell death. Together, these findings indicate that A beta-mediated CEC death is an apoptotic process that is characterized by increased oxidative stress, caspase activation, mitochondrial dysfunction, and nuclear and mitochondrial DNA damage.

iNOS and nitrotyrosine expression after spinal cord injury

Secondary tissue damage after spinal cord injury (SCI) may be due to inflammatory mediators. After SCI, the nuclear factor-kappaB (NF-kappaB) transcription factor can activate many pro-inflammatory genes, one of which is inducible nitric oxide synthase (iNOS). iNOS catalyzes the synthesis of nitric oxide (NO), a key inflammatory mediator, which in turn reacts with superoxide to generate peroxynitrite. Peroxynitrite is a strong oxidant that can damage cellular enzymes, membranes, and subcellular organelles through the nitration of tyrosine residues on proteins. The presence of nitrotyrosine (NT) is an indirect chemical indicator of toxic NO and peroxynitrite-induced cellular damage. Using a New York University (NYU) impactor to induce SCI in adult rats, we examined the temporal and cellular expression of iNOS and NT. We observed a progressive increase in iNOS expression in the injured cord starting at day 1 with maximal expression occurring at day 7, as determined by Western blot analysis. iNOS expression corresponded temporally to an increase in iNOS enzyme activity after SCI. In parallel with the progressive increase in iNOS activity, NT expression also increased with time after SCI. The iNOS and NT immunoreactivity was localized in neurons, astrocytes, endothelial cells and ependymal cells at the epicenter and adjacent to the region of spinal cord impact and injury. Results from the present study suggest that increased iNOS and peroxynitrite anion, as reflected by the progressive accumulation of NT in the injured impacted spinal cord, may contribute to the secondary injury process after SCI.

Prevalence and possible risk factors of Helicobacter pylori infection among children attending Damanhour Teaching Hospital

Helicobacter pylori (H. pylori) is a major cause of gastrointestinal disease in children. The factors influencing the acquisition and prevalence of H. pylori infection remain incompletely understood. In the present study, the prevalence and possible risk factors of H. pylori infection were studied among children aged 1.5-16 years who were attending the pediatric outpatient clinic of Damanhour Teaching Hospital. Blood samples were drawn and IgG seroprevalence of H. pylori among the studied children was determined using ELISA kits. A specially designed questionnaire inquired about personal, socioeconomic, household characteristics, feeding history during infancy and the child's health data was completed for every child. Results revealed that the overall seroprevalence of H. pylori infection was 50.5 %. The prevalence was widely age dependent: it was 60.6% among those age > or = 5 years and only 25.9% among those < 5 years (OR = 4.4; 95% CI = 1.6-11.9). Increased crowding in bed was also an associated factor; the prevalence among children where > or = 3 share a bed was 59.7% compared to only 26.9% among those where < 3 persons share a bed (OR = 4.1; 95% CI = 1.5-10.9). The prevalence among children who were breast fed for < 1 year was 64.7% compared to only 42.4% among those who were fed for > or =1 year (OR = 2.5; 95% CI = 1.1-5.9). After controlling for possible confounding in a Stepwise Multiple Logistic Regression model, independent predictors for H. pylori infection were: increasing age (> or = 5 years), overcrowding in bed (> or = 3/ bed) and shorter duration of breast-feeding (< 1 year) during infancy. It could be concluded that, H. pylori was highly prevalent among the sampled children and the possible risk factors are related to the community. So, there is a need to early diagnose, treat and eradicate infection during childhood to prevent its complications during adulthood.

Glucocorticoid receptor-mediated suppression of activator protein-1 activation and matrix metalloproteinase expression after spinal cord injury

Post-traumatic inflammatory reaction may contribute to progressive tissue damage after spinal cord injury (SCI). Two key transcription factors, nuclear factor kappaB (NF-kappaB) and activator protein-1 (AP-1), are activated in inflammation. An increase in NF-kappaB binding activity has been shown in the injured spinal cord. We report activation of AP-1 after SCI. Electrophoretic mobility shift assay showed that AP-1 binding activity increased after SCI, starting at 1 hr, peaking at 8 hr, and declining to basal levels by 7 d. Methylprednisolone (MP) is the only therapeutic agent approved by the Food and Drug Administration for treating patients with acute traumatic SCI. MP reduced post-traumatic AP-1 activation. RU486, a glucocorticoid receptor (GR) antagonist, reversed MP inhibition of AP-1 activation. Immunostaining showed an increase in the expression of the Fos-B and c-Jun components of AP-1 in the injured cord. A c-fos antisense oligodeoxynucleotide (ODN) inhibited AP-1, but not NF-kappaB, activation after SCI. AP-1 and NF-kappaB can transactivate genes encoding matrix metalloproteinase-1 (MMP-1) and MMP-9. Western blotting and immunostaining show increased expression of MMP-1 and MMP-9 in the injured cord. MP inhibited MMP-1 and MMP-9 expression after SCI. RU486 reversed this MP effect. The c-fos antisense ODN, however, failed to suppress MMP-1 or MMP-9 expression. These findings demonstrate that MP may suppress post-traumatic inflammatory reaction by inhibiting both the AP-1 and NF-kappaB transcription cascades via a GR mechanism. Expression of inflammatory genes such as MMP-1 and MMP-9 that are transactivated jointly by AP-1 and NF-kappaB may not be suppressed by inhibiting only AP-1 activity.

Amyloid-beta peptides are cytotoxic to oligodendrocytes

Alzheimer's disease (AD) is a neurodegenerative disease characterized by progressive dementia. Amyloid-beta peptide (Abeta), a 39-43 amino acid peptide derived from beta-amyloid precursor protein, forms insoluble fibrillar aggregates that have been linked to neuronal and vascular degeneration in AD and cerebral amyloid angiopathy. Here we demonstrate that Abeta 1-40 and a truncated fragment, Abeta 25-35, induced death of oligodendrocytes (OLGs) in vitro in a dose-dependent manner with similar potencies. Abeta-induced OLG death was accompanied by nuclear DNA fragmentation, mitochondrial dysfunction, and cytoskeletal disintegration. Abeta activation of redox-sensitive transcription factors NF-kappaB and AP-1 and antioxidant prevention of Abeta-mediated OLG death suggest that oxidative injury contributes to Abeta cytotoxicity in OLGs. Recent demonstration of Abeta deposition and white matter abnormalities in AD implies a potential pathophysiological role for Abeta-mediated cytotoxicity of OLGs in this neurodegenerative disease.

The therapeutic time window—Theoretical and practical considerations

The length of time during which neuroprotectants can be expected to be effective is likely to vary from drug to drug and depends on an individual drug's specific mechanism of action. Glutamate-induced toxicity is a very early event during the acute phase of ischemic stroke, which means that glutamate antagonists are likely to be effective as neuroprotectants for only a short time (perhaps as little as 1 to 2 hours). Neurotrophic growth factors, however, begin to appear a few hours after the onset of ischemia, and their production may continue for weeks. Drugs aimed at protecting neurons against reperfusion injury, however, may need to be given for 1 to 2 days. Similarly, caspases, the key enzymes in apoptosis, reach a peak 1 to 2 days after the onset of ischemia. Consequently, caspase inhibitors would need to be given for at least 2 days. Drugs with very short therapeutic time windows will be difficult to examine in phase III clinical trials because of the difficulty in completing the formalities for entry to the trial. There is also a potential problem in achieving adequate concentrations of the drug in the brain if the time window is short, especially if the drug enters the central nervous system slowly. One factor that determines the way in which the drug will be used is the slope of the dose-response curve. If the curve is steep, it is easy to undershoot or overshoot the target plasma concentration. Another practical consideration is controlling physiologic and biochemical parameters. The effects of drugs that alter blood pressure or blood glucose, for example, will need to be taken into account in developing treatment regimens. Short durations of treatment are simpler to administer. Drugs or regimens that increase the level of nursing care will require changes to management practices-for example, checking that an infusion is running properly or that a large fluid load has not triggered congestive heart failure. If a treatment requires the patient to be immobile for a prolonged period, the risk of venous thrombosis, for example, will increase. Such risks will have to be balanced against the benefit the drug provides. In general, the magnitude of benefit will tend to diminish with time after the onset of stroke, whereas the risk of adverse phenomena increases with time. The utility of the drug will therefore change with the length of time the treatment needs to be given.

Oxygen-glucose deprivation induces inducible nitric oxide synthase and nitrotyrosine expression in cerebral endothelial cells

BACKGROUND AND PURPOSE

The cerebral endothelial cells (ECs) are a primary target of hypoxic or ischemic brain insults. EC damage may contribute to postischemic secondary injury. Massive production of NO after inducible NO synthase (iNOS) expression has been implicated in cell death. This study aimed to characterize bovine cerebral EC death in relation to iNOS expression after oxygen-glucose deprivation (OGD) in vitro.

METHODS

OGD in bovine cerebral ECs in culture was induced by deleting glucose in the medium and by incubating the cells in a temperature-controlled anaerobic chamber. The extent of cell death was assessed by trypan blue exclusion, MTT assay, and LDH release. ELISA, gel electrophoresis, and staining by terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling were used to examine DNA fragmentation. The expression of iNOS mRNA and protein was detected by reverse transcription-polymerase chain reaction and Western blotting, respectively. Nitrotyrosine expression was confirmed with Western blot analysis and immunostaining.

RESULTS

Bovine cerebral EC death was dependent on the duration of OGD and showed selected biochemical, morphological, and pharmacological features suggestive of apoptosis. OGD also induced the expression of iNOS mRNA and protein in bovine cerebral ECs. Increased expression of nitrotyrosine, the product formed by peroxynitrite reaction with proteins, was also detected after OGD. The involvement of iNOS in EC death was suggested by partial reduction of cell death by NO synthase inhibitors, including L-N(G)-(1-iminoethyl)ornithine and nitro-L-arginine, and an NO scavenger, the Fe(2+)-N-methyl-D-glucamine dithiocarbamate complex.

CONCLUSIONS

OGD-induced bovine cerebral EC death involves an apoptotic process. Induction of iNOS with subsequent peroxynitrite formation may contribute to bovine cerebral EC death caused by OGD.

Persistent increase in the motivation to take heroin in rats with a history of drug escalation

The transition from stable to escalated levels of cocaine self-administration has been shown to depend upon drug availability. The generality of this phenomenon is assessed here by studying the effects of availability on heroin self-administration. Two groups of rats were trained on a 1-h continuous schedule of self-administration, after which, access to heroin (40 microg/injection) was increased to 11 h in one group (long access or LgA rats) or kept to 1 h in the other group (short access or ShA rats). After 18 sessions on this regimen, both ShA and LgA rats were tested for extinction and stress-induced reinstatement of heroin-seeking behavior. In LgA rats, both total and first hour intake gradually escalated over time. After escalation, LgA rats were slower to extinguish heroin-seeking behavior and responded more to the reinstating effect of stress after extinction. These findings show that: (1) the escalation process in drug consumption is common to both opiate and stimulant self-administration; (2) escalation in heroin consumption is associated with a persistent increase in the motivation for taking heroin.

What animal models have taught us about the treatment of acute stroke and brain protection

Stroke research has progressed in leaps and bounds in the past decades. A driving force is the increasing availability of new research tools in this field (eg, animal stroke models). Animal stroke models have been extensively applied to advance our understanding of the mechanisms of ischemic brain injury and to develop novel therapeutic strategies for reducing brain damage after a stroke. Animal stroke models have been useful in characterizing the molecular cascades of injury processes. These "injury pathways" are also the targets of therapeutic interventions. The major achievements made in the past 2 decades applying animal stroke models include 1) the identification of the mediator role of excitotoxin and oxygen free radicals in ischemic brain injury; 2) the confirmation of apoptosis as a major mechanism of ischemic cell death; 3) the characterization of postischemic gene expression; 4) the delineation of postischemic inflammatory reaction; 5) the application of transgenic mice to confirm the roles of purported mediators in ischemic brain injury; 6) development of novel magnetic resonance imaging sequences for early noninvasive detection of ischemic brain lesions; and, 7) the development of novel therapeutic strategies based on preclinical findings derived from animal stroke models.

Microinjections of an opiate receptor antagonist into the bed nucleus of the stria terminalis suppress heroin self-administration in dependent rats

Recent anatomical evidence suggests that the shell of the nucleus accumbens, the bed nucleus of the stria terminalis, and the central nucleus of the amygdala, together referred to as the extended amygdala, may play a role in opiate dependence. The bed nucleus of the stria terminalis and the shell of the nucleus accumbens have a moderately high density of opiate receptors, which allows for manipulation of opiate neurotransmission with receptor antagonists. The goal of this study was to determine the role these regions play in opiate reinforcement, and whether dependence alters the reinforcing effects of opiates by examining the effect of local administration of the opiate receptor antagonist methylnaloxonium on heroin self-administration in dependent and nondependent rats. Previous studies revealed that blockade of the reinforcing effects of opiates with systemic administration of opiate receptor antagonists results in an increase in heroin self-administration in nondependent rats, and a greater increase in dependent rats. In the present study, methylnaloxonium dose-dependently suppressed heroin intake when injected into the bed nucleus of the stria terminalis and shell of the nucleus accumbens of dependent rats, and had no effect in nondependent rats. These results demonstrate that opiate receptors in parts of the extended amygdala may be responsible for the reinforcing effects of opiates in dependent animals and suggest that activity in this system may be recruited during the development of dependence.

Effects of lipopolysaccharide priming on acute ischemic brain injury

BACKGROUND AND PURPOSE

Infection has been implicated as a stroke risk factor. Activation and infiltration of polymorphonuclear neutrophils (PMNs) after cerebral ischemia may contribute to ischemic brain injury. This study was conducted to investigate how enhanced postischemic PMN infiltration by lipopolysaccharide (LPS) altered the acute ischemic outcomes.

METHODS

LPS (0.05 mg/kg SC) or vehicle was given to Long-Evans male rats 24 hours before ischemia. Focal cerebral ischemia was induced by temporary ligation of the right middle cerebral artery and both common carotid arteries for 45 minutes. Animals were killed 6 and 24 hours after reperfusion to determine the extent of PMN infiltration (myeloperoxidase assay), brain edema (wet-dry weight method), and vascular injury (fluorescein isothiocyanate-conjugated dextran extravasation). The infarct volumes were measured on the basis of TTC stain 24 hours after ischemia.

RESULTS

LPS had little effect on body temperature or peripheral white count but substantially enhanced PMN infiltration into the ischemic right middle cerebral artery cortex on the basis of myeloperoxidase activity (6 hours: control, 0 U/g; LPS, 0.186+/-0. 025 U/g; 24 hours: control, 0.185+/-0.025 U/g; LPS, 0.290+/-0.040 U/g; P<0.001) and morphological studies. The extent of vascular injury defined by the extravasation of fluorescein isothiocyanate-conjugated dextran into the ischemic tissue (6 hours: control, 3.11+/-0.41 microliter/mg protein; LPS, 0.48+/-0.16 microliter/mg protein; 24 hours: control, 1.77+/-0.23 microliter/mg protein; LPS, 0. 90+/-0.19 microliter/mg protein; P<0.001) and brain edema determined by the brain water content (6 hours: control, 84.77+/-1.63%; LPS, 82. 09+/-1.25%; 24 hours: control, 89.40+/-0.43%; LPS, 87.88+/-0.58%; P<0.01) were paradoxically reduced by LPS priming. LPS-primed rats also had smaller infarct volumes (control, 135+/-5 mm(3); LPS, 108+/-12 mm(3); P<0.05).

CONCLUSIONS

Enhanced postischemic PMN infiltration is anticipated to facilitate ischemic brain injury. Contrary to this expectation, results from the present study suggest that an increase in postischemic PMN infiltration after LPS priming was not detrimental. These findings challenge the notion that postischemic PMN infiltration is uniformly deleterious.

Chronic morphine treatment alters NMDA receptor-mediated synaptic transmission in the nucleus accumbens

In a study of a possible substrate underlying morphine addiction, we examined NMDA receptor-mediated synaptic transmission of core nucleus accumbens neurons after chronic morphine treatment, using intracellular recording in a slice preparation of rat. We evoked pharmacologically isolated NMDA EPSCs by local stimulation and elicited inward currents by NMDA superfusion. In control slices, Mg(2+) and phorbol 12,13-diacetate (PDAc), a protein kinase C activator, strongly inhibited and increased, respectively, NMDA EPSC amplitudes. The PDAc effects were likely postsynaptic because PDAc enhanced the currents evoked by superfused NMDA to the same extent that it did the NMDA EPSCs. Chronic morphine treatment significantly decreased NMDA EPSC amplitudes and the sensitivity of NMDA EPSCs to Mg(2+) and PDAc, as well as the kinetics of the decay (inactivation rate) of the EPSCs (from 97 +/- 2.5 msec in untreated rats to 78.7 +/- 1.8 msec in slices from treated rats). One week after withdrawal, the Mg(2+) and PDAc effects were still significantly less than those in control slices. Interestingly, 1 week of withdrawal led to an increased NMDA EPSC inactivation rate compared with controls. These data demonstrate that chronic morphine treatment significantly alters NMDA receptor-mediated synaptic transmission in the accumbens, and these effects persist 1 week after withdrawal. These long-term effects may represent an important neuroadaptation in opiate dependence.

Long-lasting increase in the set point for cocaine self-administration after escalation in rats

RATIONALE

When access time to a continuous schedule of drug self-administration is restricted, animals tend to limit intake to a certain level over time and across doses. This observation suggests an endogenous constraint or set point that determines the individual's preferred level of pharmacological effects.

OBJECTIVES

To assess whether the transition to increased levels of drug intake is associated with a change in set point.

METHODS

Two groups of rats were trained on a 1-h continuous schedule of cocaine self-administration (250 microg/injection), after which access to cocaine was increased to 6 h in one group (Long Access or LgA rats) or kept to 1 h in the other group (Short Access or ShA rats). After 22 sessions on this regimen, different doses of cocaine were tested (31.25, 62.5, 125, and 250 microg/injection). For each dose, the post-response time-out period was reduced to 4 s to reduce any temporal limitations on self-injections and subjects were tested several times.

RESULTS

In LgA rats, the first hour intake escalated over time and eventually reached a level 200% greater than that of ShA rats. Though all rats maintained relatively constant intake across doses, LgA rats took nearly two times as much cocaine than ShA rats. When access to cocaine for LgA rats was reduced to 1 h, intake returned very slowly toward pre-escalation levels but was still elevated even after 2 months of reduced availability.

CONCLUSIONS

These data suggest that the transition to escalated levels of intake is associated with a long-lasting change in cocaine set point.

Amphetamine-induced conditioned activity is insensitive to perturbations known to affect pavlovian conditioned responses in rats

Psychostimulant-induced conditioned activity is characterized by the presence of a hyperactivity in drug-free rats exposed to an environment previously paired with the effects of a psychostimulant. This phenomenon is thought to result from a Pavlovian conditioning process. This hypothesis predicts that conditioned activity will be sensitive to perturbations known to affect classical conditioned responses. In direct contrast with this prediction, the authors report here that conditioned activity is insensitive to (a) the temporal order between the stimulant injection and the exposure to the environment, (b) unsignaled stimulant injections between drug-environment pairings, and (c) drug preexposures before the start of drug-environment pairings. It is concluded that the stimulant effects responsible for the establishment of conditioned activity may not be amenable to a Pavlovian associative process.

Transition from moderate to excessive drug intake: change in hedonic set point

Differential access to cocaine self-administration produced two patterns of drug intake in rats. With 1 hour of access per session, drug intake remained low and stable. In contrast, with 6 hours of access, drug intake gradually escalated over days. After escalation, drug consumption was characterized by an increased early drug loading and an upward shift in the cocaine dose-response function, suggesting an increase in hedonic set point. After 1 month of abstinence, escalation of cocaine intake was reinstated to a higher level than before. These findings may provide an animal model for studying the development of excessive drug intake and the basis of addiction.

Acute reversible renal failure in a patient with paroxysmal nocturnal hemoglobinuria

We present the case of a young male with 2-month history of intermittent upper abdominal pain who developed diarrhea, anorexia, tea-color urine, and decreased urine output. He was found to be in severe acute renal failure requiring hemodialysis, four sessions in 10-day period. By the end of the second week of hospitalization renal function gradually improved with total recovery of function to a baseline creatinine of 1.1 mg/dl 25 days after the diagnosis of acute renal failure. His workup included Ham's test, water sugar test, and RBC fragility test which confirmed the diagnosis of paroxysmal nocturnal hemoglobinuria.

Amphetamine-induced conditioned activity is insensitive to perturbations known to affect pavlovian conditioned responses in rats

Psychostimulant-induced conditioned activity is characterized by the presence of a hyperactivity in drug-free rats exposed to an environment previously paired with the effects of a psychostimulant. This phenomenon is thought to result from a Pavlovian conditioning process. This hypothesis predicts that conditioned activity will be sensitive to perturbations known to affect classical conditioned responses. In direct contrast with this prediction, the authors report here that conditioned activity is insensitive to (a) the temporal order between the stimulant injection and the exposure to the environment, (b) unsignaled stimulant injections between drug-environment pairings, and (c) drug preexposures before the start of drug-environment pairings. It is concluded that the stimulant effects responsible for the establishment of conditioned activity may not be amenable to a Pavlovian associative process.

Cocaine- but not food-seeking behavior is reinstated by stress after extinction

Reinstatement of drug-seeking behavior after extinction constitutes a potential animal model of relapse to drug abuse. In a typical reinstatement experiment, previously drug-trained rats undergo extinction during which responding is no longer followed by drug delivery. After significant extinction is observed, rats are then exposed to an event expected to reinstate drug-seeking behavior. Using this procedure, it has been recently reported that footshock stress leads to reinstatement of drug-seeking in heroin-trained, presently drug-free rats. The purpose of the present study was to assess the generality of this effect of stress. Here we report that 15 min of intermittent footshock (0.86 mA; 0.5 s on, with a mean off period of 40 s) reinstated selectively cocaine-seeking behavior after 14 extinction sessions (rats were previously trained on a FR1 TO 20 s to obtain cocaine at a dose of 0.25 mg/infusion). In contrast, under similar experimental conditions, the same stressor did not reinstate food-seeking in food-trained rats after seven extinction sessions (rats were previously trained on a FR1 TO 20 s to obtain six food pellets). Rather, when the basal level of responding was sufficiently high, footshock stress induced a significant suppression of the instrumental performance. These data are discussed in light of several behavioral mechanisms which may explain the specificity of stress in reinstating drug-seeking behavior and not food-seeking behavior.

Amphetamine-induced conditioned activity does not result from a failure of rats to habituate to novelty

Psychostimulant-induced conditioned activity is characterized by the presence of a hyperactivity in drug-free rats exposed to an environment previously paired with the effects of a psychostimulant. According to the habituation hypothesis, conditioned activity arises not through a Pavlovian conditioning process but rather because rats under the effects of the psychostimulant would be unable to habituate normally to the environment paired with these effects. This hypothesis predicts that conditioned activity should not develop in a previously habituated environment. This prediction was tested using a within-subject design. In this design, conditioned activity is evidenced when a group of rats, following a vehicle injection, was more active in a previously amphetamine-paired environment than in a previously vehicle-paired environment. The drug-environment pairing involved administering rats with d-amphetamine (1.25 mg/kg; SC) immediately prior to their placement in one of two distinctive environments. On alternate days, the rats received the vehicle and were placed in the other environment. With this design, it was found that: a) conditioned activity developed in a previously habituated environment; b) its magnitude was independent of the number of amphetamine-environment pairings (two, four or eight pairings); c) this development of conditioned activity did not result from a forgetting of the habituated environment due to a state-dependent retention of the habituation. Taken together, these results do not support the habituation hypothesis of psychostimulant-induced conditioned activity.

Amphetamine-induced conditioned activity in rats: comparison with novelty-induced activity and role of the basolateral amygdala

A within-subject design was used to investigate the behavioral and neural basis of the conditioned activity induced by amphetamine in male Wistar rats. In this design, conditioned activity was inferred when the activity of a given rat following a vehicle injection was greater in its amphetamine-paired environment (CS+) than in its vehicle-paired environment (CS-). Conditioned activity (a) did not change in magnitude with the number of conditioning sessions, (b) did not differ from the level of activity recorded during the first exposure to the CS- (novelty), (c) had an extinction rate that was similar to the rate of habituation to the CS-, and (d) was not impaired by a bilateral excitotoxic lesion of the basolateral amygdala. Results are discussed in light of the incentive conditioning and habituation theories of conditioned activity.

Amphetamine-induced conditioned activity in rats: comparison with novelty-induced activity and role of the basolateral amygdala

A within-subject design was used to investigate the behavioral and neural basis of the conditioned activity induced by amphetamine in male Wistar rats. In this design, conditioned activity was inferred when the activity of a given rat following a vehicle injection was greater in its amphetamine-paired environment (CS+) than in its vehicle-paired environment (CS-). Conditioned activity (a) did not change in magnitude with the number of conditioning sessions, (b) did not differ from the level of activity recorded during the first exposure to the CS- (novelty), (c) had an extinction rate that was similar to the rate of habituation to the CS-, and (d) was not impaired by a bilateral excitotoxic lesion of the basolateral amygdala. Results are discussed in light of the incentive conditioning and habituation theories of conditioned activity.

Social deprivation enhances the vulnerability of male Wistar rats to stressor- and amphetamine-induced behavioral sensitization

The aim of the present study was to assess the influence of experiential factors on the vulnerability of rats to develop amphetamine (AMPH)- and stressor-induced behavioral sensitization. Young male Wistar rats with previous social experience were isolated from their peers for 2 weeks. 1) The effect of this short-lasting social deprivation were: a) a reduced tendency to explore a fearful environment; b) a prolonged exploratory activity in response to a novel but little fearful environment; and c) a dose-dependent increase in the psychomotor stimulation induced by systemic AMPH injection. 2) After repeated AMPH injections (injection every other day for 10 days), isolated rats exhibited behavioral sensitization at lower doses (0.5 and 0.75 mg/kg) than those required for group-housed rats (1 mg/kg). 3) After being submitted to a repeated stressor (3, 7 or 14 footshock sessions, with 2 days between sessions), the isolated rats exhibited a greater increase in the behavioral responsivity to a subsequent AMPH challenge (1 mg/kg) than did the group-housed rats regardless of the number of stress sessions. In conclusion, these results suggest that experiential factors such as privation of contact with peers (social isolation) may make rats more vulnerable to the long-term repercussions of chronic environmental and pharmacological challenges.

Corticotropin-releasing factor induces a place aversion independent of its neuroendocrine role

The purpose of the present experiment was to test the hypothesis that corticotropin-releasing factor (CRF), a polypeptide of 41 amino acids, when administered either intracerebroventricularly (i.c.v.) or subcutaneously (s.c.), has aversive properties in the conditioned place-preference paradigm. Five doses of CRF (0, 0.005, 0.05, 0.5, 5 micrograms) were tested. i.c.v. CRF induced a specific dose-dependent reduction of the amount of time spent in the environment previously paired with the administration of CRF. Furthermore, this CRF-induced place aversion was prevented by pretreatment with alpha-helical-CRF(9-41), a specific CRF antagonist, administered i.c.v. In order to test whether the aversive effects induced by i.c.v. CRF could result from the stimulation of the HPA axis accompanying i.c.v. CRF injection, the reinforcing properties of s.c. CRF were studied using the same dose range. Only the higher s.c. dose was effective in producing a place aversion suggesting that the aversive effects of CRF could not be due solely to the stimulation of the pituitary-adrenocortical system, measured by plasmatic levels of adrenocorticotropic hormone (ACTH) and corticosterone, because the lower doses consistently activate the pituitary-adrenocortical system without producing any behavioral changes. Altogether, these data indicate that the non-neurosecretory CRF neurons may mediate the aversive state occurring during stress.

Assessment of "insight" understanding of mental illness in developing countries

'Insight', which is an indication of patient's understanding about his/her illness, needs particularly sensitive measures for its assessment. A questionnaire regarding insight, and brief psychosocial profile of the patients was applied to 103 cases. The cases were categorized according to the diagnosis and initial understanding of mental illness and 'insight' by the patients in our culture. The study did not support the popular belief that neurotics have and psychotics do not have insight.

Early experience with fluoxetine

A new antidepressant Fluoxetine, a serotonin re-uptake inhibitor, was tried on 26 resistant depressed patients. There were four drop out due to severe side effects. Improvement was noticeable soon after the first week and was maximum within 3 weeks of medication in 14 (63.6%) patients while in 8 (36.4%) patients it was as late as 6-12 weeks. The decline in improvement after three weeks in 7(31.8%) patients, needs attention in future studies. Bradycardia in 2 patients above the age of sixty indicate that the drug should be used with caution in elderly. GIT disturbance, insomnia, anorexia, restlessness and lethargy were common side effects. A well planned double blind study is recommended before its place is assigned in our patient population.