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Single-use plastics in packaging and service ware contribute the most to plastic pollution which leads to global accumulation of non-degradable wastes. A promising solution to this issue should be favorably banana plastic, a lightweight, durable, and biodegradable alternative to high-density polyethylene (HDPE) and polystyrene plastic. In this study, the application of banana plastic as a packaging material was examined with modifications to the synthesis process for further efficiency and industrial viability. Banana plastic was synthesized by grinding banana peels and using the chemical processes of acidification for HCl hydrolysis, glycerin plasticization, and NaOH neutralization, followed by a 72 hour dry and modified heat treatment at 65°C in a dehumidifier. Sodium metabisulfite was used to control the degree of biodegradability of the banana plastic. Using Onshape and Flashforge 3D printing software, the optimal packaging mold with the least shrinkage and maximum printing efficiency was created and used for producing the packaging materials. Data suggested that a concentration of 0.1 M Na2S2O5 created the sustainable and durable packing materials. A percent weight decrease of 64.95% was recorded over 12 weeks in degradability monitoring at a 37°C incubator, demonstrating the compostable characters of the banana plastic. Because of the bioplastic’s unique chemical and physical qualities, banana plastic created with a concentration of 0.1 M Na2S2O5 could be a sustainable alternative to industrial packing materials.

Translating ribosomes accompany co-translational regulation of nascent polypeptide chains, including subcellular targeting, protein folding, and covalent modifications. Ribosome-associated quality control (RQC) is a co-translational surveillance mechanism triggered by ribosomal collisions, an indication of atypical translation. The ribosome-associated E3 ligase ZNF598 ubiquitinates small subunit proteins at the stalled ribosomes. A series of RQC factors are then recruited to dissociate and triage aberrant translation intermediates. Regulatory ribosomal stalling may occur on endogenous transcripts for quality gene expression, whereas ribosomal collisions are more globally induced by ribotoxic stressors such as translation inhibitors, ribotoxins, and UV radiation. The latter are sensed by ribosome-associated kinases GCN2 and ZAKα, activating integrated stress response (ISR) and ribotoxic stress response (RSR), respectively. Hierarchical crosstalks among RQC, ISR, and RSR pathways are readily detectable since the collided ribosome is their common substrate for activation. Given the strong implications of RQC factors in neuronal physiology and neurological disorders, the interplay between RQC and ribosome-associated stress signaling may sustain proteostasis, adaptively determine cell fate, and contribute to neural pathogenesis. The elucidation of underlying molecular principles in relevant human diseases should thus provide unexplored therapeutic opportunities. [BMB Reports 2021; 54(9): 439-450].

C9ORF72-derived dipeptide repeat proteins have emerged as the pathogenic cause of neurodegeneration in amyotrophic lateral sclerosis and frontotemporal dementia (C9-ALS/FTD). However, the mechanisms underlying their expression are not fully understood. Here, we demonstrate that ZNF598, the rate-limiting factor for ribosome-associated quality control (RQC), co-translationally titrates the expression of C9ORF72-derived poly(GR) protein. A Drosophila genetic screen identified key RQC factors as potent modifiers of poly(GR)-induced neurodegeneration. ZNF598 overexpression in human neuroblastoma cells inhibited the nuclear accumulation of poly(GR) protein and decreased its cytotoxicity, whereas ZNF598 deletion had opposing effects. Poly(GR)-encoding sequences in the reporter RNAs caused translational stalling and generated ribosome-associated translation products, sharing molecular signatures with canonical RQC substrates. Furthermore, ZNF598 and listerin 1, the RQC E3 ubiquitin-protein ligase, promoted poly(GR) degradation via the ubiquitin-proteasome pathway. An ALS-relevant ZNF598R69C mutant displayed loss-of-function effects on poly(GR) expression, as well as on general RQC. Moreover, RQC function was impaired in C9-ALS patient-derived neurons, whereas lentiviral overexpression of ZNF598 lowered their poly(GR) expression and suppressed proapoptotic caspase-3 activation. Taken together, we propose that an adaptive nature of the RQC-relevant ZNF598 activity allows the co-translational surveillance to cope with the atypical expression of pathogenic poly(GR) protein, thereby acquiring a neuroprotective function in C9-ALS/FTD.

Significance In animals, the control of daily sleep–wake rhythms is mediated by discrete circadian clock neurons via their rhythmic activity–dependent release of neuropeptides and neurotransmitters. Here, we describe a gene, Tango10, critical for daily behavioral rhythms. TANGO10 functions as an adaptor with its partner, the E3 ubiquitin ligase CULLIN 3, to regulate protein ubiquitination, neuronal excitability via voltage-gated potassium channels, and neuropeptide accumulation. These studies define a mechanism for control of neuronal excitability and daily rhythmicity., Circadian transcriptional timekeepers in pacemaker neurons drive profound daily rhythms in sleep and wake. Here we reveal a molecular pathway that links core transcriptional oscillators to neuronal and behavioral rhythms. Using two independent genetic screens, we identified mutants of Transport and Golgi organization 10 (Tango10) with poor behavioral rhythmicity. Tango10 expression in pacemaker neurons expressing the neuropeptide PIGMENT-DISPERSING FACTOR (PDF) is required for robust rhythms. Loss of Tango10 results in elevated PDF accumulation in nerve terminals even in mutants lacking a functional core clock. TANGO10 protein itself is rhythmically expressed in PDF terminals. Mass spectrometry of TANGO10 complexes reveals interactions with the E3 ubiquitin ligase CULLIN 3 (CUL3). CUL3 depletion phenocopies Tango10 mutant effects on PDF even in the absence of the core clock gene timeless. Patch clamp electrophysiology in Tango10 mutant neurons demonstrates elevated spontaneous firing potentially due to reduced voltage-gated Shaker-like potassium currents. We propose that Tango10/Cul3 transduces molecular oscillations from the core clock to neuropeptide release important for behavioral rhythms.

Sleep behaviors are observed even in nematodes and arthropods, yet little is known about how sleep-regulatory mechanisms have emerged during evolution. Here, we report a sleep-like state in the cnidarian Hydra vulgaris with a primitive nervous organization. Hydra sleep was shaped by homeostasis and necessary for cell proliferation, but it lacked free-running circadian rhythms. Instead, we detected 4-hour rhythms that might be generated by ultradian oscillators underlying Hydra sleep. Microarray analysis in sleep-deprived Hydra revealed sleep-dependent expression of 212 genes, including cGMP-dependent protein kinase 1 (PRKG1) and ornithine aminotransferase. Sleep-promoting effects of melatonin, GABA, and PRKG1 were conserved in Hydra However, arousing dopamine unexpectedly induced Hydra sleep. Opposing effects of ornithine metabolism on sleep were also evident between Hydra and Drosophila, suggesting the evolutionary switch of their sleep-regulatory functions. Thus, sleep-relevant physiology and sleep-regulatory components may have already been acquired at molecular levels in a brain-less metazoan phylum and reprogrammed accordingly.

The brain-less freshwater polyp Hydra controls sleep-wake cycles by mechanisms conserved or reprogrammed among animal species., Sleep behaviors are observed even in nematodes and arthropods, yet little is known about how sleep-regulatory mechanisms have emerged during evolution. Here, we report a sleep-like state in the cnidarian Hydra vulgaris with a primitive nervous organization. Hydra sleep was shaped by homeostasis and necessary for cell proliferation, but it lacked free-running circadian rhythms. Instead, we detected 4-hour rhythms that might be generated by ultradian oscillators underlying Hydra sleep. Microarray analysis in sleep-deprived Hydra revealed sleep-dependent expression of 212 genes, including cGMP-dependent protein kinase 1 (PRKG1) and ornithine aminotransferase. Sleep-promoting effects of melatonin, GABA, and PRKG1 were conserved in Hydra. However, arousing dopamine unexpectedly induced Hydra sleep. Opposing effects of ornithine metabolism on sleep were also evident between Hydra and Drosophila, suggesting the evolutionary switch of their sleep-regulatory functions. Thus, sleep-relevant physiology and sleep-regulatory components may have already been acquired at molecular levels in a brain-less metazoan phylum and reprogrammed accordingly.

Sleep and metabolism are physiologically and behaviorally intertwined; however, the molecular basis for their interaction remains poorly understood. Here, we identified a serine metabolic pathway as a key mediator for starvation-induced sleep suppression. Transcriptome analyses revealed that enzymes involved in serine biosynthesis were induced upon starvation in Drosophila melanogaster brains. Genetic mutants of astray (aay), a fly homolog of the rate-limiting phosphoserine phosphatase in serine biosynthesis, displayed reduced starvation-induced sleep suppression. In contrast, a hypomorphic mutation in a serine/threonine-metabolizing enzyme, serine/threonine dehydratase (stdh), exaggerated starvation-induced sleep suppression. Analyses of double mutants indicated that aay and stdh act on the same genetic pathway to titrate serine levels in the head as well as to adjust starvation-induced sleep behaviors. RNA interference-mediated depletion of aay expression in neurons, using cholinergic Gal4 drivers, phenocopied aay mutants, while a nicotinic acetylcholine receptor antagonist selectively rescued the exaggerated starvation-induced sleep suppression in stdh mutants. Taken together, these data demonstrate that neural serine metabolism controls sleep during starvation, possibly via cholinergic signaling. We propose that animals have evolved a sleep-regulatory mechanism that reprograms amino acid metabolism for adaptive sleep behaviors in response to metabolic needs.

Post-translational control is a crucial mechanism for circadian timekeeping. Evolutionarily conserved kinases and phosphatases have been implicated in circadian phosphorylation and the degradation of clock-relevant proteins, which sustain high-amplitude rhythms with 24-hr periodicity in animal behaviors and physiology. Here, we report a novel clock function of the heterodimeric Ca2+/calmodulin-dependent phosphatase calcineurin and its regulator sarah (sra) in Drosophila. Genomic deletion of the sra locus dampened circadian locomotor activity rhythms in free-running constant dark after entrainment in light–dark cycles. Poor rhythms in sra mutant behaviors were accompanied by lower expression of two oscillating clock proteins, PERIOD (PER) and TIMELESS (TIM), at the post-transcriptional level. RNA interference-mediated sra depletion in circadian pacemaker neurons was sufficient to phenocopy loss-of-function mutation in sra. On the other hand, a constitutively active form of the catalytic calcineurin subunit, Pp2B-14DACT, shortened circadian periodicity in locomotor behaviors and phase-advanced PER and TIM rhythms when overexpressed in clock neurons. Heterozygous sra deletion induced behavioral arrhythmicity in Pp2B-14DACT flies, whereas sra overexpression rescued short periods in these animals. Finally, pharmacological inhibition of calcineurin in either wild-type flies or clock-less S2 cells decreased the levels of PER and TIM, likely by facilitating their proteasomal degradation. Taken together, these data suggest that sra negatively regulates calcineurin by cell-autonomously titrating calcineurin-dependent stabilization of PER and TIM proteins, thereby sustaining high-amplitude behavioral rhythms in Drosophila.

Many phytochemical compounds have been claimed to induce beneficial effects to human health because of high antioxidants and other flavonoid molecules. Some of these products claim to work like a panacea that can treat multiple chronic diseases such as cancer, hypertension, diabetes and weak immunity. Despite of so many unproven claims, there has not been a reliable bioassay that can verify these claims from any aspect. Compared to the seriousness on the reality of verifying the benefits from most antioxidant products, almost no method has been found for this unique method that was devised and tested as an experimental modality. Daphnia was chosen for the ease of hearbeat evaluation with relatively low-level magnification under an optical microscopy. It assumed that the cardiac stress might induce the perturbation in heartbeat rate and its body system should require increased ATPs to keep their heartbeat constant. The increased ATPs should be generated in mitochondrial structures, where possibly more oxidants should be generated. And, our antioxidant products might reduce the oxidant burden so to make the hearbeat to normal faster. This study was performed to find a proof of concept as a bioassay using an invertebrate model, assumably though not directly related to the effects on humans. The ability of antioxidants to restore once-stressed cardiac activity was studied by monitoring heartbeat change. Three popular antioxidant materials were chosen to investigate: propolis, acai berry, and ginseng extract. The materials we chose were expected to restore the heartbeat of daphnia fast after its heartbeat varied under the acute incubation in alcohol solutions and culturing water at low pH, or low temperature. Result indicated that mean restoration rates were 2.0 ~ 3.0 times greater in the solutions of antioxidant materials, compared to that in culturing water. A similar trend was found for the different conditions of stress such as alcohol solution, culturing water in low pH, or cold temperature. The study concluded that the antioxidant solutions expedited the heartbeat stabilization with some beneficial effects to the cardiac functions of daphnia. The study might find a useful tool of applying the physiology of daphnia for verifying the beneficial effects of various dietary supplements.

Sleep and metabolism are physiologically and behaviorally intertwined; however, the molecular basis for their interaction remains poorly understood. Here, we identified a serine metabolic pathway as a key mediator for starvation-induced sleep suppression. Transcriptome analyses revealed that enzymes involved in serine biosynthesis were induced upon starvation in

Post-translational control is a crucial mechanism for circadian timekeeping. Evolutionarily conserved kinases and phosphatases have been implicated in circadian phosphorylation and the degradation of clock-relevant proteins, which sustain high-amplitude rhythms with 24-hr periodicity in animal behaviors and physiology. Here, we report a novel clock function of the heterodimeric Ca(2+)/calmodulin-dependent phosphatase calcineurin and its regulator sarah (sra) in Drosophila. Genomic deletion of the sra locus dampened circadian locomotor activity rhythms in free-running constant dark after entrainment in light–dark cycles. Poor rhythms in sra mutant behaviors were accompanied by lower expression of two oscillating clock proteins, PERIOD (PER) and TIMELESS (TIM), at the post-transcriptional level. RNA interference-mediated sra depletion in circadian pacemaker neurons was sufficient to phenocopy loss-of-function mutation in sra. On the other hand, a constitutively active form of the catalytic calcineurin subunit, Pp2B-14D(ACT), shortened circadian periodicity in locomotor behaviors and phase-advanced PER and TIM rhythms when overexpressed in clock neurons. Heterozygous sra deletion induced behavioral arrhythmicity in Pp2B-14D(ACT) flies, whereas sra overexpression rescued short periods in these animals. Finally, pharmacological inhibition of calcineurin in either wild-type flies or clock-less S2 cells decreased the levels of PER and TIM, likely by facilitating their proteasomal degradation. Taken together, these data suggest that sra negatively regulates calcineurin by cell-autonomously titrating calcineurin-dependent stabilization of PER and TIM proteins, thereby sustaining high-amplitude behavioral rhythms in Drosophila.

The field of medication has advanced in a rapid way. Most attention has been directed towards the treatment of global scale diseases like cancer, diabetes, and AIDS. However, the treatment of non-transmittant illnesses, such as burn injuries, has not received enough attention. Burn injury is one of the leading causes of morbidity in the world. Globally, thousands suffer from long-term consequences due to the lack of effective first-aid treatment burn injury. Many commercial burn creams available today have been found to be ineffective in providing the needs that must be fulfilled to treat a burn wound effectively. This research of formulating a therapeutic cream has been motivated as a way to alleviate the pains of burn patients. The cream has been formulated, considering on the three essential elements: antibacterial strength, moisturizing capability, blister reduction ability, and anesthetic effect. Spirulina Plantensis extract and gold nanoparticles have been synersized for maximum antibacterial strength. Glycerine for moisturization and sodium dodecyl sulfate for blister reduction were enforced. Lidocaine has been added to provide anesthetic effect to the cream. Various tests have been conducted and verified the effectiveness of our burn injury cream.

Kohlschutter-Tönz syndrome (KTS) is a rare genetic disorder with neurological dysfunctions including seizure and intellectual impairment. Mutations at the Rogdi locus have been linked to development of KTS, yet the underlying mechanisms remain elusive. Here we demonstrate that a Drosophila homolog of Rogdi acts as a novel sleep-promoting factor by supporting a specific subset of gamma-aminobutyric acid (GABA) transmission. Rogdi mutant flies displayed insomnia-like behaviors accompanied by sleep fragmentation and delay in sleep initiation. The sleep suppression phenotypes were rescued by sustaining GABAergic transmission primarily via metabotropic GABA receptors or by blocking wake-promoting dopaminergic pathways. Transgenic rescue further mapped GABAergic neurons as a cell-autonomous locus important for Rogdi-dependent sleep, implying metabotropic GABA transmission upstream of the dopaminergic inhibition of sleep. Consistently, an agonist specific to metabotropic but not ionotropic GABA receptors titrated the wake-promoting effects of dopaminergic neuron excitation. Taken together, these data provide the first genetic evidence that implicates Rogdi in sleep regulation via GABAergic control of dopaminergic signaling. Given the strong relevance of GABA to epilepsy, we propose that similar mechanisms might underlie the neural pathogenesis of Rogdi-associated KTS.

Gene expression in multicellular organisms fluctuates in line with the day/night cycle, resulting in differential behaviours throughout the day. These changes in expression have been widely studied at the transcriptional and post-translational levels. A further type of circadian-influenced regulation has now been identified in the fruitfly Drosophila. A gene termed twenty-four (twf) is shown to have a role in an under-appreciated aspect of the clock pathway, the translation of a clock component from RNA to protein. The twenty-four protein associates with the mRNA of the clock protein PER, enhancing its translation. Gene expression fluctuates in concert with the day/night cycle, and this results in differential behaviours throughout the day. These changes in expression have been studied at the transcriptional and post-translational levels. Here, another type of circadian-influenced regulation that occurs at the post-transcriptional level is defined. The twenty-four (TYF) protein associates with the mRNA of the clock protein PER, enhancing its translation. Daily oscillations of gene expression underlie circadian behaviours in multicellular organisms1. While attention has been focused on transcriptional and post-translational mechanisms1,2,3, other post-transcriptional modes have been less clearly delineated. Here we report mutants of a novel Drosophila gene twenty-four (tyf) that show weak behavioural rhythms. Weak rhythms are accompanied by marked reductions in the levels of the clock protein Period (PER) as well as more modest effects on Timeless (TIM). Nonetheless, PER induction in pacemaker neurons can rescue tyf mutant rhythms. TYF associates with a 5′-cap-binding complex, poly(A)-binding protein (PABP), as well as per and tim transcripts. Furthermore, TYF activates reporter expression when tethered to reporter messenger RNA even in vitro. Taken together, these data indicate that TYF potently activates PER translation in pacemaker neurons to sustain robust rhythms, revealing a new and important role for translational control in the Drosophila circadian clock.

vrille and Par domain protein 1 (Pdp1) epsilon constitute the second transcriptional feedback loop in Drosophila circadian clock system. Their rhythmic expression is controlled by Drosophila Clock (dClk) gene, and they feed back to negatively and positively, respectively, regulate the oscillating transcription from dClk gene. In this study, we characterized the functional domains of PDP1epsilonin vitro using a panel of deletion mutants and showed that PDP1epsilon basic leucine zipper domain can act as a dominant-negative (DN) mutant of wild-type PDP1epsilon. In transgenic flies, the inhibition of PDP1epsilon activity by PDP1(DN) expression or PDP1 knock-down resulted in arrhythmic circadian behavior with altered dorsal projections from small ventral lateral neurons. We propose that one of PDP1-target genes may be involved in the formation of neural connection between the pacemaker cells and their targets for maintaining the rhythmicity of adult locomotor activity under free-running condition.

Rhythmic histone acetylation underlies the oscillating expression of clock genes in the mammalian circadian clock system. Cellular factors that contain histone acetyltransferase and histone deacetylase activity have been implicated in these processes by direct interactions with clock genes, but their functional relevance remains to be assessed by use of appropriate animal models. Here, using transgenic fly models, we show that CREB-binding protein (CBP) participates in the transcriptional regulation of the Drosophila CLOCK/CYCLE (dCLK/CYC) heterodimer. CBP knockdown in pigment dispersing factor-expressing cells lengthens the period of adult locomotor rhythm with the prolonged expression of period and timeless genes, while CBP overexpression in timeless-expressing cells causes arrhythmic circadian behaviors with the impaired expression of these dCLK/CYC-induced clock genes. In contrast to the mammalian circadian clock system, CBP overexpression attenuates the transcriptional activity of the dCLK/CYC heterodimer in cultured cells, possibly by targeting the PER-ARNT-SIM domain of dCLK. Our data suggest that the Drosophila circadian clock system has evolved a distinct mechanism to tightly regulate the robust transcriptional potency of the dCLK/CYC heterodimer.

Summary Gene transcription is a central timekeeping process in animal clocks. In Drosophila , the basic helix-loop helix (bHLH)-PAS transcription-factor heterodimer, CLOCK/CYCLE (CLK/CYC), transcriptionally activates the clock components period ( per ), timeless ( tim ), Par domain protein 1 ( Pdp1 ), and vrille ( vri ), which feed back and regulate distinct features of CLK/CYC function [1]. Microarray studies have identified numerous rhythmically expressed transcripts [2–7], some of which are potential direct CLK targets [7]. Here we demonstrate a circadian function for one such target, a bHLH-Orange repressor, CG17100/CLOCKWORK ORANGE (CWO). cwo is rhythmically expressed, and levels are reduced in Clk mutants, suggesting that cwo is CLK activated in vivo. cwo mutants display reduced-amplitude molecular and behavioral rhythms with lengthened periods. Molecular analysis suggests that CWO acts, in part, by repressing CLK target genes. We propose that CWO acts as a transcriptional and behavioral rhythm amplifier.

Reversible phosphorylation of clock proteins plays an important role in circadian timekeeping as it is a key post-translational mechanism that regulates the activity, stability and subcellular localization of core clock proteins. The kinase DOUBLETIME (DBT), a Drosophila ortholog of mammalian casein kinase Iepsilon, regulates circadian phosphorylation of two essential clock proteins, PERIOD and dCLOCK. We present evidence that Par Domain Protein 1epsilon (PDP1epsilon), a transcription factor and mediator of clock output in Drosophila, is phosphorylated in vivo and in cultured cells by DBT activity. We also demonstrate that DBT interacts with PDP1epsilon and promotes its degradation by the ubiquitin-proteasome pathway in cultured cells. In addition, PDP1epsilon nuclear localization is decreased by dbt RNA interference in S2 cell system. These results suggest that DBT regulates phosphorylation, stability and localization of PDP1epsilon, and that it has multiple targets in the Drosophila circadian system.

This paper presents findings from uptake studies to evaluate the ability of an “artificial lymphatic system” (ALS) to enhance large and small molecular weight drug transport into solid tumors and the therapeutic effect of the additional drug on their growth. These studies also served to test the effectiveness of an implantable multidrain ALS. Walker 256, Neuroblastoma, and Sarcoma dual-tumor models were used to evaluate the effect of ALS aspiration on the uptake of 3F8 monoclonal antibody, and doxorubicin. A tumor shrinkage experiment using Walker 256 dual tumors was used to evaluate the efficacy of an implantable ALS with cyclophosphamide chemotherapy. Drug uptake significantly increased in all aspirated tumors; 3F8 uptake was enhanced 37.4% in the Walker and 93.1% in the Neuroblastoma tumor lines (p < 0.05). Doxorubicin uptake increased 23.2%; in Sarcoma tumor (p < 0.05). The shrinkage study demonstrated that one-drain aspirated tumors shrank 90% faster (p < 0.01) than control tumors, while three-drain aspirated tumors shrank 123% faster than control tumors (p < 0.01). © 2000 Biomedical Engineering Society.

The growth, interstitial fluid pressure (IFP) and interstitial fluid velocity (IFV) profiles of a human neuroblastoma propagated in the flank of an immune suppressed rat were characterized. IFP was measured in the tumor center as a function of size, while radial distributions of IFP and IFV were measured in 2-cm tumors. IFP and IFV were measured using the wick-in-needle and clearance of locally generated hydrogen techniques, respectively. These techniques have a high spatial resolution, permit repetitive measurements, and are minimally invasive. We observed that IFP in the neuroblastoma increased as the tumor grew. Furthermore, IFP increased and its IFV decreased from the periphery toward the center of the tumor. Measured IFP and IFV values were compared to theoretical expectations calculated from the Baxter and Jain mathematical model. The predictions were highly correlated to the measured IFP and IFV profiles with the transport impedence parameter α 2 = 24.4. From our measurement data and the Baxter-Jain equations, we computed the interstitium hydraulic conductivity for neuroblastoma to be 7.11 × 10 -6 cm 2 /mm Hg-sec.

Lazaroid belongs to a novel group of compounds — aminosteroids (AS) which are potent inhibitors of central nervous system tissue lipid peroxidation, and are devoid of classical glucocorticoid and mineralocorticoid activities. Recent studies have shown that aminosteroids possess cerebral-protective properties and are efficacious in attenuating damage to the CNS imparted by trauma, ischemia, and vasospasm. The purpose of this study was to determine the effect of AS on (a) brain elastance, a measure of the protective volumetric buffering capacity of the brain, and (b) on cerebral perilesional edema. We used the cryogenic brain injury rat model, the constant rate and continuous infusion method to study brain elastance, and the gravitometric method to determine brain edema.

In this paper we introduce and characterize pycnometry, a method used to measure fluid density, for determining a tissue's specific gravity. It uses a 2-ml glass pycnometer filled with distilled water to determine a tissue sample's displacement volume. The tissue's density is determined when it's weight is divided by this volume and specific gravity is computed by dividing the tissue density by the density of water. Pycnometry was validated using pre-calibrated glass, specific gravity standards over the range 1.03-1.26, and compared to the density gradient method using rat brain tissue. We observed that the specific gravity values obtained using pycnometry were highly correlated with the specific gravity standards (slope = 1.0107, r = 0.996) and with the density gradient column when tissue volumes larger than 0.120 ml were used with the pycnometer (slope = 1.0707, r = 0.9826). Good correlation was also observed between percent water content values computed using the Nelson equation with pycnometry or density gradient specific gravity values versus the measured percent water content values obtained with the wet weight/dry weight method. Pycnometry is an accurate, reproducible technique to measure tissue specific gravity and brain edema and is best suited for use in a laboratory that engages sporadically in brain edema measurement.

A novel method to measure specific gravity (SG) of tissues, pycnometry (PYC), is described. This method utilizes a 2 ml glass pycnometer filled with distilled H2O to determine the displacement volume of a tissue sample and an equation to compute SG from the sample’s weight and the pycnometer’s weight before and after adding the sample. The PYC method was validated using glass SG standards over the range 1.02–1.26, and against the column density gradient (DG) method using brain tissue from 250–300 g male rats. Factors which affect PYC accuracy, i.e. sample size, were also evaluated. Our results indicate that PYC SG values are highly correlated with the glass SG standards (slope = 1.0107, r = 0.9955, p < 0.001), and highly correlated with DG when ~0.120 ml tissue samples are used in the pycnometer. The DG method was preferable to the PYC method, however, when small tissue samples, i.e. 0.60 ml or less, were used.

U-78517G belongs to a novel group of compounds-aminosteroids (AS) wich are potent inhibitors of central nervous system tissue lipid peroxidation and are devoid of classical glucocorticoid and mineralocorticoid activities. The AS have been found to possess cerebral protective properties against ischaemia, ischaemic oedema, trauma to the cerebrum and spinal cord and in sub-arachnoid hemorrhage. The possible efficacy of U-78517G in attenuating peritumoural oedema was examined in rats harbouring cerebral 9L gliosarcomas. 19 Sprague-Dawley rats were implanted intracranially with 9L gliosarcoma cells. On day 14 post implantation rats were randomized to control (no treatment n = 10) and AS treated animals (n = 9). On day 20 animals were sacrificed and six brain samples per rat were examined for the percentage of water content. Oedema was assessed with the wet/dry weight technique. The AS treated animals were found to have a significant increase in peritumoural oedema (+ 1.38%, P