Early detection of stripe rust infection in wheat using light-induced fluorescence spectroscopy.

In the current study, the application of fluorescence spectroscopy along with the advanced statistical technique and confocal microscopy was investigated for the early detection of stripe rust infection in wheat grown under field conditions. The indigenously developed Fluorosensor fitted with LED, emitting monochromatic light was used that covered comparatively larger leaf area for recording fluorescence data thus presenting more reliable current status of the leaf. The examined leaf samples covered the entire range of stripe rust disease infection from no visible symptoms to the complete disease prevalence. The molecular changes were also assessed in the leaves as the disease progresses. The emission spectra mainly produce two fluorescence emission classes, namely the blue-green fluorescence (400-600 nm range) and chlorophyll fluorescence (650-800 nm range). The chlorophyll fluorescence region showed lower chlorophyll bands both at 685 and 735 nm in the asymptomatic (early diseased) and symptomatic (diseased) leaf samples than the healthy ones as a result of partial deactivation of PSII reaction centers. The 735 nm chlorophyll fluorescence band was either slight or completely absent in the leaf samples with lower to higher disease incidence and thus differentiate between the healthy and the infected leaf samples. The Hydroxycinnamic acids (caffeic and sinapic acids) showed decreasing trend, whereas the ferulic acid increased with the rise in disease infection. Peak broadening/shifting has been observed in case of ferulic acid and carotenes/carotenoids, with the increase in the disease intensity. While using the LEDs (365 nm), the peak broadening and the decline in the chlorophyll fluorescence bands could be used for the early prediction of stripe rust disease in wheat crop. The PLSR statistical techniques discriminated well between the healthy and the diseased samples, thus showed promise in early disease detection. Confocal microscopy confirmed the early prevalence of stripe rust disease infection in a susceptible variety at a stage when the disease is not detectable visually. It is inferred that fluorescence emission spectroscopy along with the chemometrics aided in the effective and timely diagnosis of plant diseases and the detected signatures provide the basis for remote sensing.

Anatomical variations in living donors for liver transplantation-prevalence and relationship.

PURPOSE: Living donor liver transplantation (LDLT) is a widely accepted option to address the lack of a deceased liver program for transplantation. Understanding vascular and biliary anatomy and their variants is crucial for successful and safe graft harvesting. Anatomic variations are common, particularly in the right hepatic lobe. To provide evidence for screening potential liver transplant donors, the presence of vascular and biliary anatomic variations in Pakistan's preoperative assessment of transplantation donor candidates was explored. METHODS: This retrospective cross-sectional study evaluated the hepatic artery, portal vein, hepatic vein, and biliary variations in living liver donors. The study included 400 living liver donors; data were collected from March 2019 to March 2023. We used a CT scan and MRCP to assess the anatomical variations. RESULTS: The study examined 400 liver donors aged 18 to 53 years. Conventional arterial anatomy was the most common (65.8%), followed by replaced right hepatic artery (16%) and replaced left hepatic artery (10.8%). Conventional type 1 biliary anatomy was seen in 65.8% of cases. The dominant right hepatic vein was found in 13.3% of donors. There was a significant association between the prevalence of variant portal venous anatomy with variant biliary anatomy. CONCLUSION: Variations of the hepatic arterial, portal venous, and biliary systems are frequent and should be carefully evaluated while selecting a suitable living donor. A strong relationship between variant portal venous and biliary anatomy was found. These findings can aid in selecting suitable candidates and improving surgical planning for liver transplantation.

Stimuli predicting high-calorie reward increase dopamine release and drive approach to food in the absence of homeostatic need.

Animals and humans are motivated to consume high-fat, high-calorie foods by cues predicting such foods. The neural mechanisms underlying this effect are not well understood.Objective: We tested the hypothesis that cues paired with a food reward, as compared to explicitly unpaired cues, increase rats' food-seeking behavior by potentiating dopamine release in the nucleus accumbens, and that this effect would be less evident under satiety.Methods: We used a simple discriminative stimulus task and electrochemical recordings of dopamine release in freely moving rats.Results: We found that both food-predictive cue and hunger increased conditioned approaches to the receptacle (food-seeking behavior indicated by movement to the food receptacle). In addition, we observed dopamine release when the food-predictive cue (but not the unpaired cue) was presented, independent of hunger or satiety. Finally, we found a positive correlation between dopamine release amplitude and the number of conditioned approaches to the food receptacle in the sated condition, but not in the hungry condition.Discussion: Our results suggest that dopamine could drive seeking behavior for calorie-dense food in absence of homeostatic need, a core aspect of binge eating disorders.

Effects of the bovine SLICK1 mutation in PRLR on sweat gland area, FOXA1 abundance, and global gene expression in skin.

The SLICK1 mutation in the prolactin receptor (PRLR) results in a short-hair coat and increased ability to regulate body temperature during heat stress. It is unclear whether the mutation affects capacity for sweating. The objective of this observational study was to evaluate whether the SLICK1 mutation in PRLR alters characteristics of skin related to sweat gland abundance or function. Skin biopsies from 31 Holstein heifers, including 14 wild-type (SL-/-) and 17 heterozygous slick (SL+/-), were subjected to histological analysis to determine the percent of the surface area of skin sections that are occupied by sweat glands. We detected no effect of genotype on this variable. Immunohistochemical analysis of the forkhead transcription factor A1 (FOXA1), a protein essential for sweating in mice, from 6 SL-/- and 6 SL+/- heifers indicated twice as much FOXA1 in sweat glandular epithelia of SL+/- heifers as in SL-/- heifers. Results from RNA sequencing of skin biopsies from 5 SL-/- and 7 SL+/- heifers revealed few genes that were differentially expressed and none that have been associated with sweat gland development or function. In conclusion, results do not support the idea that the SLICK1 mutation changes the abundance of sweat glands in skin, but do show that functional properties of sweat glands, as indicated by increased abundance of immunoreactive FOXA1, are modified by inheritance of the mutation in PRLR.

Paper currency harbours antibiotic-resistant coliform bacteria and integron integrase.

AIMS: This study was designed to analyse the prevalence of class 1 and class 2 integron integrase genes among antibiotic-resistant coliform bacteria isolated from paper currency circulating in Pakistan. METHODS AND RESULTS: A total of 500 individual currency notes were collected from different food vending sites at Lahore, Pakistan. Bacterial population were identified by biochemical and PCR techniques. Antimicrobial susceptibility testing was performed by disc diffusion assay. The highest bacterial population on currency was found from street vendors and butcher shops. Escherichia coli was found to be the most prevalent coliform bacteria followed by Klebsiella sp. and Enterobacter sp. PCR amplification of antimicrobial resistance gene showed the presence of ampC, blaTEM , blaNDM-1 , qnrA, tet(A) and tet(B) genes among coliform isolates. A total of 47 integron integrase bearing strains of coliform bacteria were analysed. Sequence analysis showed the presence of dfrA1-aadA1, dfrA1, dfrA5, dfrA7, aadA1, aadA4 cassette arrays in class 1 integron and dfrA1-sat2-aadA1 in class 2 integrase genes. CONCLUSION: Circulating currency was heavily contaminated with antimicrobial-resistant coliform bacteria bearing class 1 and class 2 integron integrase genes. SIGNIFICANCE AND IMPACT OF THE STUDY: This study describes a potential threat of severe bacterial infections due to improper hand hygiene and community sanitation when dealing with the currency notes.

Raman spectroscopy based characterization of cow, goat and buffalo fats.

In this study, Raman spectroscopy has been utilized to characterize buffalo, cow and goat fat samples by using laser wavelengths at 532 and 785 nm as excitation sources. It has been observed that Raman spectra of cow fats contain beta-carotene at 1006, 1156 and 1520 cm-1, which are absent in buffalo and goat fats. The Raman bands at 1060, 1080, 1127 and 1440 cm-1 represent the saturated fatty acids, and their concentration is found relatively higher in buffalo fats than cow and goat. Similarly, the Raman band at 1650 cm-1 represent conjugated linoleic acid (CLA) which shows its relatively higher concentration in goat fats than cow and buffalo. The Raman band at 1267 cm-1 represent unsaturated fatty acids, which shows its relatively higher concentration in goat fats than cow and buffalo. The Raman bands at 838, 870 and 1060 cm-1 depict relatively higher concentration of vitamin D in buffalo fats than cow and goat. Principal component analysis has been applied to highlight the differences among three fat types which based upon the concentration of fatty acids, CLA and vitamin D.

Laser-induced fluorescence spectroscopy for early disease detection in grapefruit plants.

Biotic and abiotic stress both cause a considerable decrease in the chlorophyll content in plant leaves, which provides a means for the early diagnosis of diseases in plants. The emergence of diseases affects the fluorescence of phenolic compounds and chlorophyll, which have emissions located at 530, 686 and 735 nm. Herein, it was found that the intensity of the emission band of phenolic compounds at 530 nm increased and that of chlorophyll at 735 nm decreased with the onset of diseases. Statistical analysis through principal component analysis (PCA) and partial least squares regression (PLSR) was performed, which differentiated between apparently healthy leaf sites and diseased leaves, providing a basis for the detection of diseases in the early stages. The PLSR model was validated through the coefficient of determination (R2), standard error of prediction (SEP) and standard error of calibration (SEC) with the values of 0.99, 0.394 and 0.0.401, respectively, which authenticated the model. The prediction accuracy of the model was evaluated through root mean square error in prediction (RMSEP), with a value of 0.14, by predicting 22 unknown emission spectra of different leaf sites. Both the PCA and PLSR models produced similar results, proving that fluorescence spectroscopy is an excellent tool for early disease detection in plants.

Fluorescence Spectroscopy Based Detection of Adulteration in Desi Ghee.

Desi ghee, obtained by buffalo and cow milk, is highly expensive because it contains valuable vitamins and conjugated linoleic acid (CLA). Its high demand and cost result in to its adulteration with inferior banaspati ghee. In this study, Fluorescence spectroscopy along with multivariate analysis has been utilised for the detection and quantification of adulteration. Spectroscopic analysis showed that buffalo ghee contains more vitamins and CLA than cow, whereas cow ghee is enriched with beta-carotene. For multivariate analysis, principle component analysis (PCA) and partial least square regression (PLSR) have been applied on the spectral data for the determination of adulteration. PLSR model was authenticated by predicting 23 unknown samples including 3 commercial brands of desi ghee. The root mean square error in prediction (RMSEP) of unknown samples was found to be 1.7 which is a reasonable value for quantitative prediction. Due to non-destructive and requiring no sample pre-treatment, this method can effectively be employed as on line characterization tool for the food safety assurance.

Role of low-level laser therapy in post-herpetic neuralgia: a pilot study.

The aim of the present study was to investigate the influence of low-level laser radiation at a wavelength of 650 nm for treating post-herpetic neuralgia, an extremely painful condition which frequently occurs severely in old age and may persist for years with no predictable course. In total, fifteen patients were included in the present study, out of which 8 were females and 7 were males aged between 42 and 82 years. All patients were treated through 16 sessions for 8 weeks, and pain scoring was done on a visual analogue scale and statistical analysis was made for comparison before and after treatments. The final pain score was 0 in 11 patients although their initial pain score was severe in 8 and moderate in 3 patients. In three patients, pain reduced to mild intensity (2-3), and in one, the final pain score was 4 on the visual analogue scale. Patients treated during the present study have not complained for recurrence of pain or any other abnormality even after many months since completion of the therapy. Overall, low-level laser therapy (LLLT) proved itself an excellent therapeutic modality for the relief of pain in post-herpetic neuralgia patients, which may replace pain management medicines in future.

Characterization of Desi Ghee Extracted by Different Methods Using Fluorescence Spectroscopy.

In the current study, the effect of ghee extraction methods (direct cream DC, milk butter MB and milk skin MS) on its molecular composition has been investigated using Fluorescence spectroscopy. The excitation wavelength of 300 nm was found the best to produce pronounced spectral signatures of beta-carotene, vitamins and conjugated linoleic acid (CLA) in both cow and buffalo ghee types. Principal component analysis (PCA) has been applied on the spectral data to visualize the classification among ghee samples extracted by three methods. Both cow and buffalo ghee contain spectral signatures of vitamin A, E, K, D and CLA which has been verified through plotting loading vectors. The analysis of loading plots has been suggested that for cow ghee, MS extraction method conserve relatively higher concentration of beta carotene while DC and MB methods are a good choice for preserving relatively more concentrations of vitamins D, E and K. Similarly, for buffalo ghee, MS extraction method appear with higher concentration of CLA, whereas DC extraction method looks to preserve relatively higher concentration of vitamin A while MB method retains relatively low concentration of CLA and vitamins as compared to other two methods.

Effectiveness of premedication protocol using intravenous fentanyl to reduce pain associated with femoral artery closure device placement.

AIM: To test the effectiveness of a premedication protocol using intravenous bolus of 100 µg fentanyl to reduce pain associated with femoral artery closure device placement for neuro-endovascular procedures. MATERIALS AND METHODS: The severity of pain associated with femoral artery closure device placement was analysed using a numerical rating scale score ranging from 0 (no pain) to 10 (most severe pain) in two cohorts of consecutive adult patients (n=118), those who were (n=64) or were not (n=54) treated with premedication protocol. The primary endpoints were the proportion of patients with excellent (score ≤1) and failed pain control (score ≥8). Stepwise logistic regression analysis was performed to identify the effect of premedication on pain control after adjustment for potential confounders. RESULTS: The median numerical pain rating score at femoral artery closure device placement was significantly lower in patients treated with premedication protocol compared with those who underwent closure without premedication (1 versus 5, p<0.001). There was a significantly higher rate of excellent (56.2% versus 14.8%, p<0.001) and good (68.7% versus 31.2%, p<0.001) pain control at closure device placement among patients treated with premedication protocol. None of the patients treated with premedication protocol reported failed pain control compared with 33.4% of those who underwent closure device placement without premedication. In the multivariate analysis, treatment with the premedication protocol was significantly associated with an increased rate of excellent pain control (odds ratio 2.3; 95% confidence interval 1.9-3.1). CONCLUSION: Premedication with intravenous fentanyl injection prior to femoral artery closure device placement can reduce the intensity of pain associated with closure.

Relationship between the Vineland Adaptive Behaviour Scales and the Wechsler Adult Intelligence Scale IV in adults with intellectual disabilities.

BACKGROUND: Diagnoses of intellectual disability (ID) are based on three criteria: significant impairments in intellectual functioning, concurrent deficits in adaptive behaviour, and both being acquired in the developmental period. Adaptive behaviour was formally incorporated into the diagnosis in 1959; the rationale being that IQ and adaptive behaviour were different constructs that independently contribute to the diagnosis. However, there are limited data on the relationship between IQ and adaptive behaviour and especially so for adults who have ID. The aim of this study was to investigate this relationship on two widely used assessment tools: the Wechsler Adult Intelligence Scale - fourth edition (WAIS-IV) and the Vineland Adaptive Behaviour Scales (VABS). METHOD: Data were extracted from the case files of 147 adults who had a formal diagnosis of ID based on the WAIS-IV and VABS. Internal consistency was computed and compared to general population data. Correlations between the WAIS-IV and the VABS were computed. RESULTS: Internal consistencies for the tests when used with adults who have ID were generally good. The correlations between the WAIS-IV and VABS composite and subdomain scores were all low and similar to those reported for the general population. CONCLUSION: These results suggest that the WAIS-IV and VABS are measuring different constructs that contribute to the diagnosis of ID. Unfortunately, by the time such data have been collected, tests are being revised. The Vineland has now been revised and is in its third edition, but no data on the relationship between IQ and the VABS were collected during test development. The WAIS-V is now in development, and so it is recommended that such work be incorporated into this process or shortly thereafter to ensure that the tools continue to access independent constructs.

Role of fungal-induced stress in biochemical and phytochemical profiling of Peganum harmala.

The current study was designed to evaluate bioactive compounds under the influence of biotic stress on seedlings of Peganum harmala. Biologically active compounds were determined by using different techniques. The HPLC and GC-MS analyses detected the significant amount of phenolic acids and active biological compound. Total protein content, activity of proteases, α-amylases, catalases and peroxidases were observed to be accelerated under fungal stress. The seedling extracts exhibited prominent antifungal and antimicrobial activity against selected strains. The present study showed that P. harmala is a good candidate to be used in natural therapies and medicine.

Prevalence of Degnala disease in bovine along with screening of toxigenic fungi isolated from contaminated rice straw.

Toxigenic potential of different candidate fungi, isolated from rice straw feed of Degnala disease affected bovines was analyzed along with species, age, gender and seasonal prevalence. Of 1,536 cases, 104 (6.77%) showed positive signs with a significant association (p less than 0.05) between this disease and rice straw feeding, in buffaloes, and bovine aged over 1 year in the winter season. Complete blood count showed a marked increase in erythrocyte sedimentation rate and all white blood cells numbers, except lymphocytes in positive cases. There was a significant increase (p less than 0.05) in alanine amino transferase, aspirate amino transferase and alkaline phosphatase in the liver function test. At the same time, an increased value of creatinine was noted in the renal function test. For isolation and screening of toxigenic fungi, rice straw samples (n=40) being fed to the positive cases were processed further, and 85 fungal isolates were found, mainly of Aspergillus (57), Penicillium (10), Fusarium (04), Zygomycetes (03), Curvularia (01) and unidentified (10). All isolated fungi were subjected for mycotoxin production and only 11 showed mycotoxin-producing capability (including Aspergillus, Penicillium and Fusarium isolates) analyzed by thin layer chromatography and quantified through high performance liquid chromatography. It is concluded that all the fungi contaminating rice straw feed of Degnala affected animals were not toxigenic. This work will help in establishing major mycotoxin-producing fungi leading to the probable cause of Degnala disease in bovine.

An analysis of genetic association in opioid dependence susceptibility.

WHAT IS KNOWN: Drug addiction is a novelty-seeking personality trait that is associated with the candidate genes OPRD1 (opioid delta receptors), OPRK1 (opioid kappa receptors) and PDYN (prodynorphin). However, associations between single nucleotide polymorphisms (SNPs) rs1042114 (80G>T) of the OPRD1 gene, rs702764 (843 A>G) of the OPRK1 gene, and rs910080 (3' UTR _743T>C), rs1997794 (5' UTR -381A>G) and rs1022563 (3' UTR) of the PDYN gene and novelty seeking remain controversial as reported results have not been reproducible. OBJECTIVE: The goal of this study was to determine the frequencies of SNPs rs1042114, rs702764, rs1997794, rs1022563 and rs910080 in the Malaysian population and to study their association with opioid dependence in Malaysian Malays. METHODS: A total of 459 Malay male with opioid dependence and 543 healthy male (controls) subjects were included in this study. SNPs were genotyped using the TaqMan SNP genotyping assay. Statistical analysis was performed using Golden Helix SVS software suite to identify the distribution of allele and genotype frequencies, and SNP-SNP interactions were also analysed in this study. RESULTS AND DISCUSSION: SNP rs1042114 in the OPRD1 gene is strongly associated with opiate addiction (P=.0001). In individuals homozygous for this risk allele, the likelihood of opiate addiction is increased by a factor 1.62 (95% confidence interval (CI) 1.412-1.875). Polymorphic alleles at SNP rs702764 of OPRK1 were not associated with opioid dependence. A significant association between opioid dependence and SNP rs910080 of PDYN (P=.0217) was detected, but there was no association for SNPs rs199774 and rs1022563. A significant interaction was also identified between homozygous wild-type genotype TT of rs702764 with the risk genotypes TG/GG of rs1042114 (odds ratio (OR)=2.111 (95% CI 1.227-3.631), P=.0069) and with the risk genotypes GA/AA of rs910080 (OR=1.415 (95% CI 1.04-1.912), P=.0239). WHAT IS NEW AND CONCLUSION: The results indicate that SNPs rs1042114 and rs910080 contribute to vulnerability to opioid dependence in the Malaysian Malay population. These results will help us to understand the effect of the SNPs and the SNP-SNP interaction on opioid dependence and may assist in efforts to screen vulnerable individuals and match them with individually tailored prevention and treatment strategies.

Germline BRCA1-associated protein 1 mutation presenting as BAP1 inactivated melanocytic nevi in a child of a father with fatal paraganglioma.

BRCA1-associated protein 1(BAP1) inactivated melanocytic nevi are pink to tan and dome-shaped in clinical appearance, resembling dermal nevi, but with distinct histologic features of two melanocytic subpopulations: larger atypical melanocytes and nests of smaller, blander nevoid melanocytes. Pedigrees with BAP1 mutations are at greater risk of various malignancies. We report the case of a 16-year-old boy with multiple benign-appearing nevi, all demonstrating loss of BAP1 on immunohistochemistry. History revealed that his father had died of paraganglioma, which is also associated with BAP1 mutations.

Limbic-motor integration by neural excitations and inhibitions in the nucleus accumbens.

The nucleus accumbens (NAc) has often been described as a "limbic-motor interface," implying that the NAc integrates the value of expected rewards with the motor planning required to obtain them. However, there is little direct evidence that the signaling of individual NAc neurons combines information about predicted reward and behavioral response. We report that cue-evoked neural responses in the NAc form a likely physiological substrate for its limbic-motor integration function. Across task contexts, individual NAc neurons in behaving rats robustly encode the reward-predictive qualities of a cue, as well as the probability of behavioral response to the cue, as coexisting components of the neural signal. In addition, cue-evoked activity encodes spatial and locomotor aspects of the behavioral response, including proximity to a reward-associated target and the latency and speed of approach to the target. Notably, there are important limits to the ability of NAc neurons to integrate motivational information into behavior: in particular, updating of predicted reward value appears to occur on a relatively long timescale, since NAc neurons fail to discriminate between cues with reward associations that change frequently. Overall, these findings suggest that NAc cue-evoked signals, including inhibition of firing (as noted here for the first time), provide a mechanism for linking reward prediction and other motivationally relevant factors, such as spatial proximity, to the probability and vigor of a reward-seeking behavioral response.NEW & NOTEWORTHY The nucleus accumbens (NAc) is thought to link expected rewards and action planning, but evidence for this idea remains sparse. We show that, across contexts, both excitatory and inhibitory cue-evoked activity in the NAc jointly encode reward prediction and probability of behavioral responding to the cue, as well as spatial and locomotor properties of the response. Interestingly, although spatial information in the NAc is updated quickly, fine-grained updating of reward value occurs over a longer timescale.

Genotoxic and cytotoxic potential of Alternanthera Bettzickiana, an important ethno-medicinal plant.

The present study was carried out to investigate the mutagenic and cytotoxic potential of n-hexane and aqueous-methanolic whole plant extracts of Alternanthera bettzickiana. Aqueous-methanolic and n-hexane extracts of Alternanthera bettzickiana extracts were assessed for the mutagenic potential with Salmonella tester strains TA-100 and TA-102 in the presence and absence of the rodent enzyme activation system and cytotoxic potential was assessed by MTT assay. Aqueous-methanolic extract showed the presence of saponins, tannins, terpenoids, flavonoids and glycosides. However n-hexane extract revealed the presence of tannins and terpenoids only. It was found that a concentration as low as 15mg/mL of both extracts was more mutagenic to the TA 102 tester strain than TA-100. Hexane whole plant extract of Altenanthera bettzickiana was more mutagenic than aqueous-methanolic extract considering revertant colonies of TA 100 strain. Aqueous-methanolic and n-hexane whole plant extracts of Altenanthera bettzickiana showed higher mutagenic potential in the presence of the enzyme activation system. Mutagenicity of aqueous-methanolic extract increased with an enzyme activation system in case of TA 100 whereas mutagenicity of n-hexane extract decreased in the presence of the enzyme activation system with TA 100 and TA 102 strains. Aqueous-methanolic and n-Hexane whole plant extracts of Alternanthera bettzickiana showed an IC-50 of 493 and 456 µg/mL in BHK-21 cells respectively. It can be concluded that Altenanthera bettzickiana exhibited mutagenic activity in a bacterial reverse mutation assay with and without enzyme activation systems. However, it showed limited cytotoxicity to BHK-21 cells.

Genetic characterization of canine parvovirus from dogs in Pakistan.

Canine parvoviruses (CPV) exist as antigenic variants with varying frequencies and genetic variabilities across the globe. Given the endemicity and high prevalence in Pakistan, we characterized the CPVs originating from dogs-population to elucidate viral diversity and evolution. Fecal samples from clinically diseased pups (n = 17) of different breeds and age (2-6 months) were processed for hemagglutination assay (HA), and later for partial amplification of VP2 gene sequence and amino acid analysis. A total of 11 samples (64.71%) were found positive both in hemagglutination and PCR assays. Phylogenetic and evolutionary analysis demonstrated higher genetic heterogeneity in studied strains and constituted seven clusters within the CPV-2a group, however, they shared high level of identity with Chinese strains. Further studies are necessary to elucidate genetic analysis and epidemiology of CPV variants across a wide geographical area of the country.

Reassessing wanting and liking in the study of mesolimbic influence on food intake.

Humans and animals such as rats and mice tend to overconsume calorie-dense foods, a phenomenon that likely contributes to obesity. One often-advanced explanation for why we preferentially consume sweet and fatty foods is that they are more "rewarding" than low-calorie foods. "Reward" has been subdivided into three interdependent psychological processes: hedonia (liking a food), reinforcement (formation of associations among stimuli, actions, and/or the food), and motivation (wanting the food). Research into these processes has focused on the mesolimbic system, which comprises both dopamine neurons in the ventral tegmental area and neurons in their major projection target, the nucleus accumbens. The mesolimbic system and closely connected structures are commonly referred to as the brain's "reward circuit." Implicit in this title is the assumption that "rewarding" experiences are generally the result of activity in this circuit. In this review, I argue that food intake and the preference for calorie-dense foods can be explained without reference to subjective emotions. Furthermore, the contribution of mesolimbic dopamine to food intake and preference may not be a general one of promoting or coordinating behaviors that result in the most reward or caloric intake but may instead be limited to the facilitation of a specific form of neural computation that results in conditioned approach behavior. Studies on the neural mechanisms of caloric intake regulation must address how sensory information about calorie intake affects not just the mesolimbic system but also many other forms of computation that govern other types of food-seeking and food-oriented behaviors.