Immunomodulatory role of thyroid hormones: effect on humoral immune response to Salmonella typhi O antigen

Effect of long term administration of thyroid hormones and the removal of thyroid on humoral antibody response to S. typhi O antigen was studied in male albino rats of HM strain. Humoral antibody response to S. typhi O antigen was enhanced in animals pretreated with T3 or T4 at a dose of 10 micrograms daily for 15 days. Administration of thyroid hormones simultaneously along with antigen, resulted in suppression of antibody response. In thyroidectomized animals, the antibody titer to S. typhi O antigen was decreased; this decrease in antibody titer was restored to normal level following hormone supplementation. Thyroidectomy significantly depressed TLC as well. Total leucocyte count and absolute lymphocyte count were increased following hormone treatment. Present findings, thus show the lymphoproliferative response of thyroid hormones and their effect on antibody response suggesting the immunomodulatory role of thyroid hormones.     

Effect of thyroid hormones on delayed type hypersensitivity reaction

The effect of long term administration of thyroid hormones and its deprivation on delayed type hypersensitivity (DTH) reaction to 2-4 dinitrochlorobenzene (DNCB) was studied. Animals were either pre-treated with thyroid hormones (T3 or T4) for 15 days and then subjected to DNCB skin test or the animals received thyroid hormones and simultaneously subjected to DNCB skin test. In both the cases DTH reaction was found to be increased significantly. When DNCB skin test was performed in the thyroidectomized animals, DNCB skin reaction was significantly decreased and the reaction was restored to normal following supplementation of thyroid hormones to the thyroidectomized animals. TLC and ALC were increased significantly following hormone treatment and thyroidectomized animals. TLC hand, induced significant depression in the count which was restored by hormone administration to the thyroidectomized animals.     

In vitro clonal multiplication of turmeric (Curcuma spp.) and ginger (Zingiber officinale Rosc.)

Rhizome buds, excised from threeCurcuma spp., and ginger, inoculated aseptically on MS medium with varying levels of BAP and kinetin, produced multiple shoots. For shoot multiplication, a concentration of 3.0 mg/l BAP was found to be optimum for all the species.In vitro plants were successfully established in the field and were morphologically uniform. A simple method to extend the subculture interval was used and its relevance to germplasm conservation is discussed.Abbreviations BAP 6-benzylaminopurine - kinetin 6-furfurylaminopurine - MS Murashige and Skoog (1962)     

ISOLATED NERVE ENDINGS (NEUROSECRETOSOMES) FROM THE POSTERIOR PITUITARY : Partial Separation of Vasopressin and Oxytocin and the Isolation of Microvesicles

Subcellular fractions of the bovine posterior pituitary, including one composed almost exclusively of pinched-off nerve endings (neurosecretosomes), were characterized electron microscopically, hormonally, and enzymically. 15% of the nerve terminals in the gland were isolated as neurosecretosomes, as estimated from determinations of lactic dehydrogenase, a soluble, cytoplasmic enzyme. Neurosecretosomes were subdivided into three fractions by density-gradient centrifugation. The three subfractions, each shown to be nearly homogeneous populations of neurosecretosomes by means of electron microscopic and enzymic criteria, differed from each other in their vasopressin/oxytocin (VP/OT) ratios. The VP/OT ratio increased from the lightest to the densest fraction, indicating that VP is localized to denser and OT to lighter neurosecretosomes; similar results have been obtained previously for subfractions of neurosecretory granules (NSG). No morphological differences were apparent in neurosecretosomes among the three subfractions. Although complete separation of VP and OT was not achieved, the findings suggest that VP and OT are each stored in a different species of nerve ending and support the hypothesis that a given neurosecretory cell synthesizes, stores, and secretes only one of the peptide hormones. Microvesicles, 40–80 mµ diameter and contained in typical neurosecretory cell terminals, are believed to be degradation products of membrane ghosts of depleted NSG; electron micrographs indicative of this transformation are presented. A fraction rich in microvesicles, but containing some NSG membranes, was prepared by density-gradient centrifugation of an osmolysate of neurosecretosomes. Smaller, apparently nonneurosecretory nerve endings, lacking NSG but filled with small vesicles, are occasionally seen in sections from whole gland. The vesicles in these atypical posterior pituitary nerve endings may be true neurohumor-containing, "synaptic" vesicles.     

Role of Ca2+ in induction and secretion of dengue virus-induced cytokines

The present study was undertaken to investigate the role of calcium ions (Ca₂₊) in the induction and secretion of the dengue type 2 virus induced cytotoxic factor and the cytotoxin. This was done by using calcium channel blocking drugs such as verapamil, nifedipine or diltiazem hydrochloride. The production of cytotoxic factor was significantly reduced by treatment of dengue type 2 virus infected mice with verapamil. Similarly, a dosedependent inhibition of the secretion of cytotoxic factor was observed, when spleen cells of the virus-primed mice were treatedin vitro with the 3 calcium channel blockers. The production of cytotoxin by macrophages was abrogated by pretreatment with calcium channel blockers but had little effect on its secretion as shown by treatment of macrophages with verapamil at 1 h after the induction to later periods up to 18 h. The findings thus show that in the induction of both the cytokines Ca₂₊ plays a critical role; on the other hand it is required for the secretion of the cytotoxic factor but not for that of the cytotoxin.     

Plant regeneration via somatic embryogenesis in ginger

Embryogenic callus cultures of ginger were induced from young leaf segments taken from in vitro shoot cultures. Among the four auxins tested in Murashige & Skoog medium, dicamba at 2.7 M was most effective in inducing and maintaining embryogenic cultures. Efficient plant regeneration was achieved when embryogenic cultures were transferred to Murashige & Skoog medium containing 8.9 M benzyladenine. Histological studies revealed various stages of somatic embryogenesis characteristic of the monocot system. The in vitro-raised plants have been established in soil.Abbreviations BA benzyladenine - 2,4-d 2,4-dichlorophenoxyacetic acid - IAA indole-3-acetic acid - MS Murashige and Skoog - NAA naphthaleneacetic acid     

Cyclic dipeptide-based small molecules modulate zinc-mediated liquid–liquid phase separation of tau

Liquid–liquid phase separation (LLPS) is a complex physicochemical phenomenon mediated by multivalent transient weak interactions among macromolecules like polymers, proteins, and nucleic acids. It has implications in cellular physiology and disease conditions like cancer and neurodegenerative disorders. Many proteins associated with neurodegenerative disorders like RNA binding protein FUS (FUsed in Sarcoma), alpha-synuclein (α-Syn), TAR DNA binding protein 43 (TDP-43), and tau are shown to undergo LLPS. Recently, the tau protein responsible for Alzheimer's disease (AD) and other tauopathies is shown to phase separate into condensates in vitro and in vivo. The diverse noncovalent interactions among the biomolecules dictate the complex LLPS phenomenon. There are limited chemical tools to modulate protein LLPS which has therapeutic potential for neurodegenerative disorders. We have rationally designed cyclic dipeptide (CDP)-based small-molecule modulators (SMMs) by integrating multiple chemical groups that offer diverse chemical interactions to modulate tau LLPS. Among them, compound 1c effectively inhibits and dissolves Zn-mediated tau LLPS condensates. The SMM also inhibits tau condensate-to-fibril transition (tau aggregation through LLPS). This approach of designing SMMs of LLPS establishes a novel platform that has potential implication for the development of therapeutics for neurodegenerative disorders.     

Computer calculation-based quantitative structure-activity relationships for the oxidation of phenol derivatives horseradish peroxidase compound II

 The second-order rate constants for the oxidation of a series of phenol derivatives by horseradish peroxidase compound II were compared to computer-calculated chemical parameters characteristic for this reaction step. The phenol derivatives studied were phenol, 4-chlorophenol, 3-hydroxyphenol, 3-methylphenol, 4-methylphenol, 4-hydroxybenzoate, 4-methoxyphenol and 4-hydroxybenzaldehyde. Assuming a reaction of the phenolic substrates in their non-dissociated, uncharged forms, clear correlations (r = 0.977 and r = 0.905) were obtained between the natural logarithm of the second-order rate constants (ln k _app and ln k ₂ respectively) for their oxidation by compound II and their calculated ionisation potential, i.e. minus the energy of their highest occupied molecular orbital [E(HOMO)]. In addition to this first approach in which the quantitative structure-activity relationship (QSAR) was based on a calculated frontier orbital parameter of the substrate, in a second and third approach the relative heat of formation (ΔΔHF) calculated for the process of one-electron abstraction and H^• abstraction from the phenol derivatives was used as a parameter. Plots of the natural logarithms of the second-order rate constants (k _app and k ₂) for the reaction and the calculated ΔΔHF values for the process of one-electron abstraction also provide clear QSARs with correlation coefficients of –0.968 and –0.926 respectively. Plots of the natural logarithms of the second-order rate constants (k _app and k ₂) for the reaction and the calculated ΔΔHF values for the process of H^• abstraction provide QSARs with correlation coefficients of –0.989 and –0.922 respectively. Since both mechanisms considered, i.e. initial electron abstraction versus initial H^• abstraction, provided clear QSARs, the results could not be used to discriminate between these two possible mechanisms for phenol oxidation by horseradish peroxidase compound II. The computer calculation-based QSARs thus obtained for the oxidation of the various phenol derivatives by compound II from horseradish peroxidase indicate the validity of the approaches investigated, i.e. both the frontier orbital approach and the approach in which the process is described by calculated relative heats of formation. The results also indicate that outcomes from computer calculations on relatively unrelated phenol derivatives can be reliably compared to one another. Furthermore, as the actual oxidation of peroxidase substrates by compound II is known to be the rate-limiting step in the overall catalysis by horseradish peroxidase, the QSARs of the present study may have implications for the differences in the overall rate of substrate oxidation of the phenol derivatives by horseradish peroxidase. Received: 29 March 1996 / Accepted: 17 July 1996     

Nerve Growth Factor Administration Attenuates Cognitive but Not Neurobehavioral Motor Dysfunction or Hippocampal Cell Loss Following Fluid-Percussion Brain Injury in Rats

Abstract: Lateral fluid-percussion brain injury in rats results in cognitive deficits, motor dysfunction, and selective hippocampal cell loss. Neurotrophic factors have been shown to have potential therapeutic applications in neurodegenerative diseases, and nerve growth factor (NGF) has been shown to be neuroprotective in models of excitotoxicity. This study evaluated the neuroprotective efficacy of intracerebral NGF infusion after traumatic brain injury. Male Sprague-Dawley rats received lateral fluid-percussion brain injury of moderate severity (2.1–2.3 atm). A miniosmotic pump was implanted 24 h after injury to infuse NGF (n = 34) or vehicle (n = 16) directly into the region of maximal cortical injury. Infusions of NGF continued until the animal was killed at 72 h, 1 week, or 2 weeks after injury. Animals were evaluated for cognitive dysfunction (Morris Water Maze) and regional neuronal cell loss (Nissl staining) at each of the three time points. Animals surviving for 1 or 2 weeks were also evaluated for neurobehavioral motor function. Although an improvement in memory scores was not observed at 72 h after injury, animals receiving NGF infusions showed significantly improved memory scores when tested at 1 or 2 weeks after injury compared with injured animals receiving vehicle infusions ( p < 0.05). Motor scores and CA3 hippocampal cell loss were not significantly different in any group of NGF-treated animals when compared with controls. These data suggest that NGF administration, in the acute, posttraumatic period following fluid-percussion brain injury, may have potential in improving post-traumatic cognitive deficits.