28-hour Period Research Articles

Abstract 2306: A deep learning framework for automated segmentation and analysis of 3D breast cancer spheroid invasion dynamics

Abstract Invasion of neighboring tissues is a cardinal feature of malignancy, notably observed in aggressive cancers like breast cancer, where it can lead to significant morbidity. To explore cancer invasion dynamics, the implementation of a three-dimensional (3D) tumor spheroid invasion assay offers a swift approach to mimicking a tumor micro-region or micro-metastasis. Differential Interference Contrast (DIC) time-lapse imaging was chosen for its fluorescence-free and non-destructive advantages in capturing live spheroid movement. However, the subsequent analysis posed challenges, including out-of-focus cells and a voluminous dataset with diverse microscope planes and time points. Our study introduces a segmentation framework featuring in-focus spatial stacking algorithm and novel training architecture that enabling in-depth automated analysis of 3D spheroid invasion behaviors within a microenvironment. Firstly, the MDA-MB-231 breast cancer spheroids were cultured in a microwell dish and then incorporated into a collagen type I matrix for the 3D spheroid invasion assay. Capturing spheroid invasion dynamics involved acquiring 15 z-plane images (spaced at 20 µm intervals) per timepoint for each spheroid using DIC microscopy at 15-minute intervals over a 28-hour period, employing a 20X objective lens. We refined the Focus Stacking framework into Multiple Slices Blurry Stacking (MSB-Stack) by pre-filtering blurred areas before stacking images. This process produced 6390 slices consolidated into 426 labeled stacked images, highlighting Invasive area, Spheroid core, and Invasive cells post-invasion. We then enhanced Mask R-CNN (Region based-Convolutional Neural Networks) with a weak-to-strong augmentation mechanism, leveraging well-segmented samples from MSB-Stack for training on both fully stacked and blurred images. Blurry Consistency Mask R-CNN (BCMask R-CNN) demonstrates overall improvement across feature extractors, outperforming Mask R-CNN. Using Mean average precision (mAP) as the main metric for instance segmentation and detection, our proposed model achieves 73.0% and 65.2% on mAP @[0.5, 0.95], showcasing robustness. Notably, our best results for mAP @0.5 reach 96.6% and 96.7% on both tasks, underscoring the effectiveness of consistency training in mitigating unclear boundary issues during preprocessing. In conclusion, our proposed method, MSB-Stack, effectively addresses the challenge of unclear boundaries in 3D breast cancer cell DIC microscopy datasets. The integration of weak-to-strong consistency training in our model, BCMask R-CNN, not only mitigates biases but also enhances performance across different backbones, setting the stage for future advancements in cell-tracking tasks and broader migratory analyses. Citation Format: Thi Kim Ngan Ngo, Thanh-Huy Nguyen, Fang-Yu Lin, Ting-Yuan Tu. A deep learning framework for automated segmentation and analysis of 3D breast cancer spheroid invasion dynamics [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2306.

Calving controlled by melt-under-cutting: detailed calving styles revealed through time-lapse observations

AbstractWe present a highly detailed study of calving dynamics at Tunabreen, a tidewater glacier in Svalbard. A time-lapse camera was trained on the terminus and programmed to capture images every 3 seconds over a 28-hour period in August 2015, producing a highly detailed record of 34 117 images from which 358 individual calving events were distinguished. Calving activity is characterised by frequent events (12.8 events h−1) that are small relative to the spectrum of calving events observed, demonstrating the prevalence of small-scale calving mechanisms. Five calving styles were observed, with a high proportion of calving events (82%) originating at, or above, the waterline. The tidal cycle plays a key role in the timing of calving events, with 68% occurring on the falling limb of the tide. Calving activity is concentrated where meltwater plumes surface at the glacier front, and a ~ 5 m undercut at the base of the glacier suggests that meltwater plumes encourage melt-under-cutting. We conclude that frontal ablation at Tunabreen may be paced by submarine melt rates, as suggested from similar observations at glaciers in Svalbard and Alaska. Using submarine melt rate to calculate frontal ablation would greatly simplify estimations of tidewater glacier losses in prognostic models.

Microstructure of frontoparietal connections predicts individual resistance to sleep deprivation

Sleep deprivation (SD) can degrade cognitive functioning, but growing evidence suggests that there are large individual differences in the vulnerability to this effect. Some evidence suggests that baseline differences in the responsiveness of a fronto-parietal attention system that is activated during working memory (WM) tasks may be associated with the ability to sustain vigilance during sleep deprivation. However, the neurocircuitry underlying this network remains virtually unexplored. In this study, we employed diffusion tensor imaging (DTI) to investigate the association between the microstructure of the axonal pathway connecting the frontal and parietal regions—i.e., the superior longitudinal fasciculus (SLF)—and individual resistance to SD. Thirty healthy participants (15 males) aged 20–43years underwent functional magnetic resonance imaging (fMRI) and diffusion tensor imaging (DTI) at rested wakefulness prior to a 28-hour period of SD. Task-related fronto-parietal fMRI activation clusters during a Sternberg WM Task were localized and used as seed regions for probabilistic fiber tractography. DTI metrics, including fractional anisotropy, mean diffusivity, axial and radial diffusivity were measured in the SLF. The psychomotor vigilance test (PVT) was used to evaluate resistance to SD. We found that activation in the left inferior parietal lobule (IPL) and dorsolateral prefrontal cortex (DLPFC) positively correlated with resistance. Higher fractional anisotropy of the left SLF comprising the primary axons connecting IPL and DLPFC was also associated with better resistance. These findings suggest that individual differences in resistance to SD are associated with the functional responsiveness of a fronto-parietal attention system and the microstructural properties of the axonal interconnections.

Ontogenetic Variation in Food Consumption of Rusty Crayfish (Orconectes rusticus) in a Central New York Stream

ABSTRACT We examined feeding periodicity of three size groups of the rusty crayfish (Orconectes rusticus) at four-hour intervals over a 28-hour period during July in a headwater stream of the Susquehanna River drainage in central New York. Feeding activity was expressed as the ratio of stomach weight divided by the crayfish wet weight. The diel food consumption patterns of all three size groups of rusty crayfish (i.e., ≤ 10 mm, 11–20 mm, and > 20 mm carapace length) were significantly different. Peak feeding of the smallest crayfish occurred during crepuscular periods. Food consumption of the intermediate size crayfish was highest at 2000 h, and feeding of large crayfish was consistently high from 1200 h to 0400 h. Feeding intensity of both small and intermediate size crayfish was highest when feeding intensity of large crayfsh was lowest. Ontogenetic differences in feeding periodicity may be associated with predation pressure from large rusty crayfish on smaller individuals.

CLINICAL STUDY: Quantification of breath carbon disulphide and acetone following a single dose of disulfiram (Antabuse) using selected ion flow tube mass spectrometry (SIFT‐MS)

Selected ion flow tube mass spectrometry (SIFT-MS) has been used to measure simultaneously the concentrations of both carbon disulphide and acetone in exhaled breath following the ingestion of a single dose of disulfiram (Antabuse). Carbon disulphide is a product of the metabolism of disulfiram and is excreted mainly through the lungs. Acetone is a product of normal metabolism and appears in the breath of all individuals. These breath analyses were performed in single exhalations and the results were available in real time. The levels of breath acetone and carbon disulphide were compared with levels obtained from a control subject who had not ingested disulfiram. Breath carbon disulphide was seen to increase from 15 p.p.b. to 618 p.p.b. over a 28-hour period, in the single individual tested, following ingestion of disulfiram, while acetone levels increased from 300 p.p.b. (normal) to over 4000 p.p.b. (greatly elevated). No such increases were seen in the breath of the control subject over the same period. An obvious positive correlation between breath carbon disulphide and acetone concentrations following disulfiram ingestion is seen and discussed.

High-Fat Diet May Affect Absorption Of Once-Daily ADHD Medications

Back to table of contents Previous article Next article Clinical & Research NewsFull AccessHigh-Fat Diet May Affect Absorption Of Once-Daily ADHD MedicationsJim RosackJim RosackSearch for more papers by this authorPublished Online:2 Aug 2002https://doi.org/10.1176/pn.37.15.0019aThe absorption of the two long-acting medications used to treat symptoms of attention-deficit/hyperactivity disorder (ADHD) is differentially affected by the presence of food in the stomach, especially if that food is high in fat, according to a new study.The data, reported in the July issue of Current Medical Research and Opinion, indicate that serum levels of methylphenidate in individuals taking the long-acting medication Concerta are not substantially different when the medication is taken with food or on an empty stomach.In contrast, individuals in the study who took Adderall XR, an extended-release formulation of mixed amphetamine salts, displayed drastically lower early blood levels when taking the medication with food compared with taking it on an empty stomach.The study was conducted by researchers at McNeil Consumer and Specialty Pharmaceuticals, which markets Concerta. Adderall is marketed by Shire Pharmaceuticals Group.The study compared the effect of eating a high-fat breakfast on the absorption and distribution of a typical morning dose of each medication (36 mg of Concerta or 20 mg of Adderall) in 36 healthy adults. Breakfast consisted of eggs, buttered bread, bacon, hash-brown potatoes, and eight ounces of whole milk. Blood samples were taken 18 times over the ensuing 28-hour period. Subjects received either Concerta or Adderall following either an overnight fast or 15 minutes after eating the high-fat breakfast.Blood levels of methylphenidate in subjects who received Concerta varied only about 3 percent between the fasting and post high-fat-meal dosings. Subjects who took Adderall after the high-fat meal, however, had on average a 55 percent decrease in their blood levels of amphetamine during the first four hours following dosing, compared with those who took Adderall after fasting.When a drug’s absorption is significantly affected by food intake, its label usually says it is best taken either one hour before or two hours after a meal. The current approved labeling for Adderall does not address any need to take the medication on an empty stomach.Requests by Psychiatric News for comment about the data from Shire Pharmaceuticals Group were not answered by press time. ▪ ISSUES NewArchived

Diltiazem Enhances Potassium Disposal in Subjects With End-Stage Renal Disease

Seven subjects with end-stage renal disease (ESRD) who were anuric and dialysis-dependent were studied during a 28-hour interdialytic period to assess changes in plasma potassium. Plasma potassium, glucose, magnesium, aldosterone, and cortisol were measured every 4 hours. Eight normal subjects were similarly treated. Subjects with ESRD had a progressive increase in plasma potassium, in contrast to normal subjects who exhibited a characteristic diurnal variation. In ESRD, diltiazem significantly reduced the rate of increase in plasma potassium compared with placebo and resulted in a significantly lower net increase in potassium over the entire 28-hour period. Diltiazem did not affect plasma potassium in normal subjects. Diltiazem did not affect plasma aldosterone, cortisol, glucose, or magnesium. In conclusion, diltiazem reduced the rate of increase of plasma potassium during a 28-hour interdialytic period.

Diel variation in the vertical distribution of some common zooplankton species off the west coast of South Africa

The vertical distribution and the diel variation of seven species of copepods and the euphausiid Euphausia lucens were examined over a 28-hour period covering 20—21 May 1978 in an area approximately 65 km north-west of Cape Columbine. The majority of the copepod species remained within the sampling depth (0—85 m) and showed no marked diel movement. Those that did migrate (Nannocalanus minor and Metridia lucens) showed evidence of reverse migratory behaviour. There was ontogenetic layering in the vertical range of Euphausia lucens. While the calyptopis larvae remained near the surface and did not migrate, the older stages did, with the juvenile and adults moving through a greater depth range than the younger furcilia stages. The data are discussed with reference to previous depth records from work carried out mainly in the Atlantic Ocean, and specifically to records from local waters.

Neuroleptic‐induced acute dystonic reactions may be due to enhanced dopamine release on to supersensitive postsynaptic receptors

Oral administration of butaperazine (40 mg per kilogram) to rats increased dopamine turnover, as measured by elevation of striatal and mesolimbic concentrations of homovanillic acid and 3,4-dihydroxyphen-ylacetic acid, for 24 to 48 hours. Initially, this dose of butaperazine inhibited stereotyped behavior in response to subcutaneous administration of apomorphine, but this effect was reversed at 12 hours. Later, animals had normal or exaggerated responses to apomorphine. The data suggest that at the critical 20- to 28-hour period after butaperazine administration, when most human acute dystonic reactions occur, normal or supersensitive cerebral dopamine receptors are exposed to an excessive synaptic release of dopamine. This may be responsible for the drug-induced dystonia.

Neuroleptic-induced acute dystonic reactions may be due to enhanced dopamine release on to supersensitive postsynaptic receptors.

Oral administration of butaperazine (40 mg per kilogram) to rats increased dopamine turnover, as measured by elevation of striatal and mesolimbic concentrations of homovanillic acid and 3,4-dihydroxyphenylacetic acid, for 24 to 48 hours. Initially, this dose of butaperazine inhibited stereotyped behavior in response to subcutaneous administration of apomorphine, but this effect was reversed at 12 hours. Later, animals had normal or exaggerated responses to apomorphine. The data suggest that the critical 20- to 28-hour period after butaperazine administration, when most human acute dystonic reactions occur, normal or supersensitive cerebral dopamine receptors are exposed to an excessive synaptic release of dopamine. This may be responsible for the drug-induced dystonia.

Gametogenesis in Chlamydomonas eugametos

Male and female mating types of Chlamydomonas eugametos Moewus show an absolute light requirement for gametogenesis. Increasing light intensity from 0.3 to 1.2 mw cm(-2) during nitrogen starvation (a precondition for gametogenesis) caused an increase in gametogenesis throughout a 28-hour period. Gametogenesis was measured by determining the percentage of paired cells after a 1-hour mixing period. Light requirements for the male and female differed. There was a 9-hour lag period in gametogenesis in the male, but no lag in the female. Gametogenesis was reduced 50% in the female and 90% in the male when 6.0 mum 3-(3,4-dichlorophenyl)-1, 1-dimethyl-urea was in the N-starvation medium. Sodium acetate, 1.8 mm, in the N-starvation medium increased gametogenesis in both mating types and eliminated the 9-hour lag in the male for cells irradiated for 3, 6, 9, 12, 15, 18, or 23 hours during the last part of a 23-hour N-starvation period. Sodium acetate concentrations higher than 1.8 mm inhibited the mating process. 3-(3,4-Dichlorophenyl)-1, 1-dimethylurea inhibition of gametogenesis was decreased in the male but increased in the female, when sodium acetate was added to the N-starvation medium. These results indicate a nonphotosynthetic as well as a photosynthetic role for light in the gametogenesis of both mating types. Also, the male will not undergo gametogenesis unless a required amount of energy is provided either in the medium or through photosynthesis.

Vegetative Nuclear Division in Neurospora

A re-examination of the mode of vegetative nuclear division in Neurospora crassa was facilitated by the availability of the mutant “clock” which produces definite growth bands. Since the growth rhythm is correlated with nuclear divisions, stained mycelial mats of this mutant prepared at intervals from the beginning of a growth period provided a sequence of stages of division. In a 28-hour period the following broad features of nuclear behavior were observed: In the early part of the period during rapid mycelial growth, dividing elongated nuclei predominated. At the end of the period the mycelium contained mostly rounded resting nuclei. In the middle of a growth period nuclear forms of various degrees of annularity occurred along with elongated and rounded nuclei. Elongated and rounded nuclei completed division cycles without change in form, although the corresponding stages of the two types were similar. Elongated nuclei assumed a spiral form at the beginning of division. As division proceeded, relaxation of the nuclear gyres was accompanied by a visible duplication of the chromatin thread and the appearance of chromomere-like bodies on the daughter threads. One of the chromomere-like bodies became displaced and was interpreted to be a chromosome or a segment of a chromosome that acts as a mitotic center. All the chromosomes were found to be interconnected and to act as a unit throughout the division cycle. Only after the separation of the daughter chromatin threads could seven chromosomes be counted. Electron microscopic studies complemented the observations with the light microscope. On the basis of the evidence it was concluded that the vegetative nuclear division in Neurospora differs from the classical mitotic pattern in the following respects: (1) absence of visible centrioles, (2) the presence of interconnected chromosomes, (3) the comparatively late appearance of countable chromosomes, and (4) the frequent presence of interzonal connections between separating chromatin threads.

Liver regeneration in rats exposed to simulated changes in gravity.

SummaryPartial hepatectomies were performed on 7-week-old male Sprague-Dawley rats that were subsequently centrifuged at 2.5 g or 4.7 g and sacrificed at various postoperative time intervals. No liver regeneration as measured by the mitotic index was noted in rats centrifuged at 2.5 g, 24 hours after operation; at this time period the control rats at normal gravity showed initiation of mitotic activity. At the 28-hour period, regeneration at 2.5 g was noted but the value was significantly lower than that of controls. The initiation of mitosis was delayed even longer in the group of animals that was centrifuged at 4.7 g.To study the effects on liver regeneration of a decrease in gravity, 3-week-old weanling rats were centrifuged for 4 weeks at 4.7 g, removed from the centrifuge, hepatectomized, and sacrificed 24, 28, and 36 hours after partial hepatectomy. Greater mitotic activity was observed in the 4.7 g-conditioned rats than in the rats not exposed to centrifugation during all 3 postoperative time perio...