Neonatal immune challenge influences the microbiota and behaviour in a sexually dimorphic manner.

There is comorbidity between anxiety disorders and gastrointestinal disorders, with both linked to adverse early life events. The microbiome gut-brain-axis, a bidirectional communication system, is plastic throughout the neonatal period and is a possible mediator of this relationship. Here, we used a well-established neonatal rodent immune activation model to investigate the long-term effect of neonatal lipopolysaccharide (LPS) exposure on adult behaviour and the relationship to microbiome composition. Wistar rats were injected with LPS (0.05 mg/kg) or saline (equivolume) on postnatal days 3 and 5. In adulthood, behavioural tests were performed to assess anxiety-like behaviour, and microbiota sequencing was performed on stool samples. There were distinctly different behavioural phenotypes for LPS-exposed males and females. LPS-exposed males displayed typical anxiety-like behaviours with significantly decreased social interaction (F(1,22) = 7.576, p = 0.009) and increased defecation relative to saline controls (F(1,23) = 8.623, p = 0.005). LPS-exposed females displayed a different behavioural phenotype with significantly increased social interaction (F(1,22) = 6.094, p = 0.018), and exploration (F(1,24) = 6.359, p = 0.015), compared to saline controls. With respect to microbiota profiling data, Bacteroidota was significantly increased for LPS-exposed females (F(1,14) = 4.931p = 0.035) and Proteobacteria was decreased for LPS-exposed rats of both sexes versus controls (F(1,30) = 4.923p = 0.035). Furthermore, alterations in predicted functional pathways for neurotransmitters in faeces were observed with a decrease in the relative abundance of D-glutamine and D-glutamate metabolism in LPS exposed females compared to control females (p < 0.05). This suggests that neonatal immune activation alters both later life behaviour and adult gut microbiota in sex-specific ways. These findings highlight the importance of sex in determining the impact of neonatal immune activation on social behaviour and the gut microbiota.

Maternal Obesity during Pregnancy is Associated with Lower Cortical Thickness in the Neonate Brain.

BACKGROUND AND PURPOSE: Recent studies have suggested that maternal obesity during pregnancy is associated with differences in neurodevelopmental outcomes in children. In this study, we aimed to investigate the relationships between maternal obesity during pregnancy and neonatal brain cortical development. MATERIALS AND METHODS: Forty-four healthy women (28 normal-weight, 16 obese) were prospectively recruited at <10 weeks' gestation, and their healthy full-term neonates (23 boys, 21 girls) underwent brain MR imaging. All pregnant women had their body composition (fat mass percentage) measured at ∼12 weeks of pregnancy. All neonates were scanned at ∼2 weeks of age during natural sleep without sedation, and their 3D T1-weighted images were postprocessed by the new iBEAT2.0 software. Brain MR imaging segmentation and cortical surface reconstruction and parcellation were completed using age-appropriate templates. Mean cortical thickness for 34 regions in each brain hemisphere defined by the UNC Neonatal Cortical Surface Atlas was measured, compared between groups, and correlated with maternal body fat mass percentage, controlled for neonate sex and race, postmenstrual age at MR imaging, maternal age at pregnancy, and the maternal intelligence quotient and education. RESULTS: Neonates born to obese mothers showed significantly lower (P ≤ .05, false discovery rate-corrected) cortical thickness in the left pars opercularis gyrus, left pars triangularis gyrus, and left rostral middle frontal gyrus. Mean cortical thickness in these frontal lobe regions negatively correlated (R = -0.34, P = .04; R = -0.50, P = .001; and R = -0.42, P = .01; respectively) with the maternal body fat mass percentage measured at early pregnancy. CONCLUSIONS: Maternal obesity during pregnancy is associated with lower neonate brain cortical thickness in several frontal lobe regions important for language and executive functions.

Avoiding COVID-19 complications with diabetic patients could be achieved by multi-dose Bacillus Calmette-Guérin vaccine: a case study of beta cells regeneration.

Diabetes mellitus (DM) is one of the major risk factors for COVID-19 complications as it is one of the chronic immune-compromising conditions especially if patients have uncontrolled diabetes, poor HbA1c and/or irregular blood glucose levels. Diabetic patients' mortality rates with COVID-19 are higher than those of cardiovascular or cancer patients. Recently, Bacillus Calmette-Guérin (BCG) vaccine has shown successful results in reversing diabetes in both rats and clinical trials based on different mechanisms from aerobic glycolysis to beta cells regeneration. BCG is a multi-face vaccine that has been used extensively in protection from tuberculosis (TB) and leprosy and has been repositioned for treatment of bladder cancer, diabetes and multiple sclerosis. Recently, COVID-19 epidemiological studies confirmed that universal BCG vaccination reduced morbidity and mortality in certain geographical areas. Countries without universal policies of BCG vaccination (Italy, Nederland, USA) have been more severely affected compared to countries with universal and long-standing BCG policies that have shown low numbers of reported COVID-19 cases. Some countries have started clinical trials that included a single dose BCG vaccine as prophylaxis from COVID-19 or an attempt to minimize its side effects. This proposed research aims to use BCG vaccine as a double-edged weapon countering both COVID-19 and diabetes, not only as protection but also as therapeutic vaccination. The work includes a case study of regenerated pancreatic beta cells based on improved C-peptide and PCPRI laboratory findings after BCG vaccination for a 9 year old patient. The patient was re-vaccinated based on a negative tuberculin test and no scar at the site of injection of the 1st BCG vaccination at birth. The authors suggest and invite the scientific community to take into consideration the concept of direct BCG re-vaccination (after 4 weeks) because of the reported gene expressions and exaggerated innate immunity consequently. As the diabetic MODY-5 patient (mutation of HNF1B, Val2Leu) was on low dose Riomet® while eliminating insulin gradually, a simple analytical method for metformin assay was recommended to ensure its concentration before use as it is not approved yet by the Egyptian QC labs.

Effect of lead on the physiological, biochemical and ultrastructural properties of Leucaena leucocephala.

Heavy metals are characterised by a relatively high density and cause genotoxic, cytotoxic and mutagenic effects on plants, animals and humans. Lead (Pb) is one of the heavy metals that causes toxicity to plants and animals. This experiment was conducted using a hydroponic technique to study the effects of Pb(NO3 )2 on physiological, biochemical and ultrastructural characteristics in Leucaena leucocephala seedlings. Plants were grown in a growth chamber for 21 days in Hoagland's solution supplemented with 0 (control), 25, 50, 100, 300, 500 and 700 µm Pb(NO3 )2 . Shoot heights as well as root lengths decreased significantly in Pb-treated plants with 300, 500 and 700 µm. In Pb-treated plants with high Pb concentrations, photosynthesis rate (PN ), stomatal conductance (gs ) and transpiration rate (E) decreased. Total protein and carbohydrate content in Pb-treated plants with 300, 500 and 700 µm increased significantly in leaves. Moreover, in Pb-treated plants with 300, 500 and 700 µm Pb(NO3 )2 , mesophyll cells had enlarged chloroplasts with disrupted thylakoid membranes associated with large starch grains. In contrast, Pb treatments with 25, 50 µm and 100 µm were not toxic to the plants. Thick sections of roots of Pb-treated plants with 300, 500 and 700 µm Pb showed distinct changes in structure of epidermal and cortical cells. Moreover, thin sections of roots of Pb-treated plants with 300, 500 and 700 µm Pb had thickened walls of xylem cells. These results will shed more light in understanding the effects of heavy metal stress on plants.

Efficacy of artemisinin-naphthoquine phosphate against Schistosoma haematobium adult flukes: dose-effect relationship and tegumental alterations.

Schistosoma haematobium and Schistosoma mansoni infections have broadly overlapping geographical distributions. Praziquantel is the only treatment for human schistosomiasis, so drug tolerance and/or resistance are major concerns. Artemisinin-naphthoquine phosphate (CO-ArNp), an artemisinin-based combination therapy endorsed by the World Health Organization as a gold standard therapy for malaria, has also been identified as a promising treatment for S. mansoni. In this in vitro study, we tested the effect of 1-40 µg/ml CO-ArNp on S. haematobium worms, and inspected tegumental changes by using scanning electron microscopy (SEM), aiming to determine if this combination therapy has a broad-spectrum antischistosomal activity. Incubation of S. haematobium adults with 20 or 30 µg/ml CO-ArNp caused 100% mortality of worms within 72 or 48 h, respectively. SEM examination showed extensive tegumental alterations such as oedema, constriction, shortening and loss of spines, fissuring, sloughing and perforation, resulting in exposure of the underlying basal lamina, mainly in treated male schistosomes. Besides the well-established potent efficacy, bioavailability, tolerability and safety of the antimalarial artemisinin-naphthoquine phosphate combined therapy, these results may also suggest its possible utilization as a new broad-spectrum antischistosomal agent.

The first record of Centrocestus formosanus (Nishigori, 1924) (Digenea: Heterophyidae) in Egypt.

The life cycle of Centrocestus formosanus (Digenea: Heterophyidae) was to be successfully completed in the laboratory in the present study. Hundreds of the thiarid snail, Melanoides tuberculata, were collected from the main water course Mansouriya Canal, Giza Governorate, Egypt. The snails were individually exposed to artificial light to determine possible infection with trematode larvae. Fifteen snails were found infected with opthalmopleurolophocercous cercariae (infection index of 1.97). These opthalmopleurolophocercous cercariae shedded from snails were collected and placed in an aquarium with fish intermediate host, Gambusia affinis, to obtain metacercariae encysted in the gills. The gills with metacercariae were fed to albino rats, Rattus norvegicus, to obtain the adult worms. Adult worms were recovered in the small intestine of rats at 7 days after infection and they were identified as Centrocestus formosanus based on the morphological characteristics and the comparison with the previous descriptions in the literature. They were small, 518 × 324 µm in average size and had characteristic 32 circumoral spines around the oral sucker. The morphological characteristics of the developmental stages, from cercariae to adults, of this heterophyid fluke were given here. Therefore, the presence of this fluke is to be confirmed for the first time in Egypt by the present study.

Anti-acetylcholinesterase potential and metabolome classification of 4 Ocimum species as determined via UPLC/qTOF/MS and chemometric tools.

Ocimum (sweet basil) is a plant of considerable commercial importance in traditional medicine worldwide as well as for the flavor and food industry. The goal of this study was to examine Ocimum extracts anti-acetylcholinesterase activity and to correlate the activity with their secondary metabolites profiles via a metabolome based ultraperformance liquid chromatography-mass spectrometry (UPLC-MS) approach coupled to chemometrics. The metabolomic differences in phenolics from leaves derived from 4 Ocimum species: Ocimum basilicum, Ocimum africanum, Ocimum americanum and Ocimum minimum were assessed. Under optimized conditions, 81 metabolites were identified including 21 hydroxy cinnamic acids, 4 benzoic acid conjugates, 14C/O flavonoid conjugates, 2 alcohols, 5 acyl sugars, 4 triterpenes and 12 fatty acids. Several salviolanic acid derivatives including salviolanic acid A, B, C & I found in Salvia, were found in Ocimum herein for the first time. Unsupervised principal component analysis (PCA) and supervised orthogonal projection to latent structures-discriminant analysis (OPLS-DA) were further used for comparing and classification of samples. A clear separation among the four investigated Ocimum species was revealed, with O. africanum samples found most enriched in hydroxy cinnamates conjugates (HC) and flavonoids. To the best of our knowledge, this is the first report for compositional differences among Ocimum leaves via a metabolomic approach revealing that among examined species O. africanum leaves present a better source of Ocimum bioactive metabolites. The anticholinesrase activity of examined species was further assessed with a potent IC50 values for O. americanum, O. africanum, O. basilicum ranging from 2.5 to 6.6mg/ml, whereas O. minimum was least active with IC50 of 31.4mg/ml. Furthermore, major HC i.e., caftaric, chlorogenic and rosmarinic acids identified in extracts via UPLC-MS analysis exhibited IC50 values of 24, 0.5 and 7.9mg/ml respectively, suggesting that HCs are likely to mediate for the anticholinesterase effect in Ocimum extracts.

Intrinsic excitability differs between murine hypoglossal and spinal motoneurons.

Motoneurons differ in the behaviors they control and their vulnerability to disease and aging. For example, brain stem motoneurons such as hypoglossal motoneurons (HMs) are involved in licking, suckling, swallowing, respiration, and vocalization. In contrast, spinal motoneurons (SMs) innervating the limbs are involved in postural and locomotor tasks requiring higher loads and lower movement velocities. Surprisingly, the properties of these two motoneuron pools have not been directly compared, even though studies on HMs predominate in the literature compared with SMs, especially for adult animals. Here we used whole cell patch-clamp recording to compare the electrophysiological properties of HMs and SMs in age-matched neonatal mice (P7-P10). Passive membrane properties were remarkably similar in HMs and SMs, and afterhyperpolarization properties did not differ markedly between the two populations. HMs had narrower action potentials (APs) and a faster upstroke on their APs compared with SMs. Furthermore, HMs discharged APs at higher frequencies in response to both step and ramp current injection than SMs. Therefore, while HMs and SMs have similar passive properties, they differ in their response to similar levels of depolarizing current. This suggests that each population possesses differing suites of ion channels that allow them to discharge at rates matched to the different mechanical properties of the muscle fibers that drive their distinct motor functions.

Electrical maturation of spinal neurons in the human fetus: comparison of ventral and dorsal horn.

The spinal cord is critical for modifying and relaying sensory information to, and motor commands from, higher centers in the central nervous system to initiate and maintain contextually relevant locomotor responses. Our understanding of how spinal sensorimotor circuits are established during in utero development is based largely on studies in rodents. In contrast, there is little functional data on the development of sensory and motor systems in humans. Here, we use patch-clamp electrophysiology to examine the development of neuronal excitability in human fetal spinal cords (10-18 wk gestation; WG). Transverse spinal cord slices (300 µm thick) were prepared, and recordings were made, from visualized neurons in either the ventral (VH) or dorsal horn (DH) at 32°C. Action potentials (APs) could be elicited in VH neurons throughout the period examined, but only after 16 WG in DH neurons. At this age, VH neurons discharged multiple APs, whereas most DH neurons discharged single APs. In addition, at 16-18 WG, VH neurons also displayed larger AP and after-hyperpolarization amplitudes than DH neurons. Between 10 and 18 WG, the intrinsic properties of VH neurons changed markedly, with input resistance decreasing and AP and after-hyperpolarization amplitudes increasing. These findings are consistent with the hypothesis that VH motor circuitry matures more rapidly than the DH circuits that are involved in processing tactile and nociceptive information.

Intrinsic and synaptic homeostatic plasticity in motoneurons from mice with glycine receptor mutations.

Inhibitory synaptic inputs to hypoglossal motoneurons (HMs) are important for modulating excitability in brainstem circuits. Here we ask whether reduced inhibition, as occurs in three murine mutants with distinct naturally occurring mutations in the glycine receptor (GlyR), leads to intrinsic and/or synaptic homeostatic plasticity. Whole cell recordings were obtained from HMs in transverse brainstem slices from wild-type (wt), spasmodic (spd), spastic (spa), and oscillator (ot) mice (C57Bl/6, approximately postnatal day 21). Passive and action potential (AP) properties in spd and ot HMs were similar to wt. In contrast, spa HMs had lower input resistances, more depolarized resting membrane potentials, higher rheobase currents, smaller AP amplitudes, and slower afterhyperpolarization current decay times. The excitability of HMs, assessed by "gain" in injected current/firing-frequency plots, was similar in all strains whereas the incidence of rebound spiking was increased in spd. The difference between recruitment and derecruitment current (i.e., ΔI) for AP discharge during ramp current injection was more negative in spa and ot. GABAA miniature inhibitory postsynaptic current (mIPSC) amplitude was increased in spa and ot but not spd, suggesting diminished glycinergic drive leads to compensatory adjustments in the other major fast inhibitory synaptic transmitter system in these mutants. Overall, our data suggest long-term reduction in glycinergic drive to HMs results in changes in intrinsic and synaptic properties that are consistent with homeostatic plasticity in spa and ot but not in spd. We propose such plasticity is an attempt to stabilize HM output, which succeeds in spa but fails in ot.

Are all spinal segments equal: intrinsic membrane properties of superficial dorsal horn neurons in the developing and mature mouse spinal cord.

Neurons in the superficial dorsal horn (SDH; laminae I-II) of the spinal cord process nociceptive information from skin, muscle, joints and viscera. Most of what we know about the intrinsic properties of SDH neurons comes from studies in lumbar segments of the cord even though clinical evidence suggests nociceptive signals from viscera and head and neck tissues are processed differently. This 'lumbar-centric' view of spinal pain processing mechanisms also applies to developing SDH neurons. Here we ask whether the intrinsic membrane properties of SDH neurons differ across spinal cord segments in both the developing and mature spinal cord. Whole cell recordings were made from SDH neurons in slices of upper cervical (C2-4), thoracic (T8-10) and lumbar (L3-5) segments in neonatal (P0-5) and adult (P24-45) mice. Neuronal input resistance (R(IN)), resting membrane potential, AP amplitude, half-width and AHP amplitude were similar across spinal cord regions in both neonates and adults (∼100 neurons for each region and age). In contrast, these intrinsic membrane properties differed dramatically between neonates and adults. Five types of AP discharge were observed during depolarizing current injection. In neonates, single spiking dominated (∼40%) and the proportions of each discharge category did not differ across spinal regions. In adults, initial bursting dominated in each spinal region, but was significantly more prevalent in rostral segments (49% of neurons in C2-4 vs. 29% in L3-5). During development the dominant AP discharge pattern changed from single spiking to initial bursting. The rapid A-type potassium current (I(Ar)) dominated in neonates and adults, but its prevalence decreased (∼80% vs. ∼50% of neurons) in all regions during development. I(Ar) steady state inactivation and activation also changed in upper cervical and lumbar regions during development. Together, our data show the intrinsic properties of SDH neurons are generally conserved in the three spinal cord regions examined in both neonate and adult mice. We propose the conserved intrinsic membrane properties of SDH neurons along the length of the spinal cord cannot explain the marked differences in pain experienced in the limbs, viscera, and head and neck.

The expression and localization of the human placental prorenin/renin-angiotensin system throughout pregnancy: roles in trophoblast invasion and angiogenesis?

The renin-angiotensin system (RAS) is thought to regulate placentation, however, the expression and localization of RAS pathways in early gestation human placenta is not known. Here we describe the expression of prorenin (REN), (pro)renin receptor (ATP6AP2), angiotensinogen (AGT), angiotensin-converting enzyme 1 and 2 (ACE; ACE2), angiotensin II type 1 and 2 receptors (AGTR1; AGTR2) and angiotensin 1-7 receptor (MAS1), as well as the angiogenic factor, vascular endothelial growth factor (VEGF), and transforming growth factor-ß1 (TGF-ß1), in early gestation (6-16 weeks) and term (>37 weeks) human placentae. We also describe the location of all of the key RAS proteins in the early gestation placentae. The highest levels of REN, ATP6AP2, AGT, AGTR1 and ACE2 mRNAs were found in early gestation, whereas ACE1 mRNA was highest at term. AGTR2 and MAS1 mRNA expression were low to undetectable in all samples. REN, ATP6AP2 and AGTR1 mRNA levels were correlated with VEGF expression, but not with TGF-ß1 mRNA. In early gestation placentae, prorenin, (pro)renin receptor and the angiotensin II type 1 receptor (AT(1)R) were localized to extravillous trophoblast cells, suggesting they play a key role in trophoblast migration. ACE2 in syncytiotrophoblasts could regulate release of Ang 1-7 into the maternal circulation contributing to the vasodilation of the maternal vasculature. ACE was only found in fetal vascular endothelium and may specifically target the growing fetal placental vessels. Because REN, ATP6AP2 and AGTR1 show strong correlations with expression of VEGF this pathway is likely to be important in placental angiogenesis.

Probing glycine receptor stoichiometry in superficial dorsal horn neurones using the spasmodic mouse.

Inhibitory glycine receptors (GlyRs) are pentameric ligand gated ion channels composed of α and ß subunits assembled in a 2:3 stoichiometry. The α1/ßheteromer is considered the dominant GlyR isoform at 'native' adult synapses in the spinal cord and brainstem. However, the α3 GlyR subunit is concentrated in the superficial dorsal horn (SDH: laminae I-II), a spinal cord region important for processing nociceptive signals from skin, muscle and viscera. Here we use the spasmodic mouse, which has a naturally occurring mutation (A52S) in the α1 subunit of the GlyR, to examine the effect of the mutation on inhibitory synaptic transmission and homeostatic plasticity, and to probe for the presence of various GlyR subunits in the SDH.We usedwhole cell recording (at 22-24◦C) in lumbar spinal cord slices obtained from ketamine-anaesthetized (100 mg kg⁻¹, I.P.) spasmodic and wild-type mice (mean age P27 and P29, respectively, both sexes). The amplitude and decay time constants of GlyR mediated mIPSCs in spasmodic micewere reduced by 25% and 50%, respectively (42.0 ± 3.6 pA vs. 31.0 ± 1.8 pA, P <0.05 and 7.4 ± 0.5 ms vs. 5.0 ± 0.4 ms, P <0.05; means ± SEM, n =34 and 31, respectively). Examination of mIPSC amplitude versus rise time and decay time relationships showed these differences were not due to electrotonic effects. Analysis of GABAAergic mIPSCs and A-type potassium currents revealed altered GlyR mediated neurotransmission was not accompanied by the synaptic or intrinsic homeostatic plasticity previously demonstrated in another GlyR mutant, spastic. Application of glycine to excised outside-out patches from SDH neurones showed glycine sensitivity was reduced more than twofold in spasmodic GlyRs (EC50 =130 ± 20 µM vs. 64 ± 11 µM, respectively; n =8 and 15, respectively). Differential agonist sensitivity and mIPSC decay times were subsequently used to probe for the presence of α1-containing GlyRs in SDHneurones.Glycine sensitivity, based on the response to 1-3 µM glycine, was reduced in>75% of neurones tested and decay times were faster in the spasmodic sample. Together, our data suggest most GlyRs and glycinergic synapses in the SDH contain α1 subunits and few are composed exclusively of α3 subunits. Therefore, future efforts to design therapies that target the α3 subunit must consider the potential interaction between α1 and α3 subunits in the GlyR.

Molluscicidal and schistosomicidal activities of a steroidal saponin containing fraction from Dracaena fragrans (L.).

The steroidal saponin-containing fraction from methanolic extract of Dracaena fragrans (Family: Agavaceae) was tested for molluscicidal and ovicidal activities against Biomphalaria alexandrina and Bulinus truncatus, the snail vectors of Schistosoma mansoni and S. haematobium in Egypt, respectively. It was also tested for schistosemicidal activity in vitro on adult S. mansoni and against the free-living miracidia and cercariae of the parasite. The homogenated soft body of B. alexandrina was used to determine the effect of the saponin fraction on total protein, albumen, aminotransferase enzymes and acetylcholin esterase. The results showed that the saponin fraction had considerable molluscicidal activity; LC50 & LC90 were 2.7 ppm & 3.7 ppm for B. alexandrina and 2 ppm & 2.5 ppm for B. truncatus, respectively. Snail eggs did not hatch in concentration as low as half molluscicidal LC50 (1.35 ppm). The LC50 killed all miracidia and cercariae in 30 seconds and after 22 & 40 minutes at a very low concentration (0.165 ppm) respectively, and had in vitro lethal effect on adults with LC50 18.4 microg/ml 4 days post-exposure. The snail tissue homogenate showed significant increase in total protein content & albumen, in aminotransferases and acetylcholinesterase activities.

Sucrose stearate-based proniosome-derived niosomes for the nebulisable delivery of cromolyn sodium.

A Novel approach was developed for the preparation of controlled release proniosome-derived niosomes, using sucrose stearates as non-ionic biocompatible surfactants for the nebulisable delivery of cromolyn sodium. Conventional niosomes were prepared by a reverse phase evaporation method followed by the preparation of proniosomes by spraying the optimized surfactant-lipid mixture of sucrose stearate, cholesterol and stearylamine in 7:3:0.3 molar ratio onto the surface of spray dried lactose powder. Proniosome-derived niosomes were obtained by hydrating proniosomes with 0.9% saline at 50 degrees C and mixing for approximately 2 min. All vesicles were evaluated for their particle size, morphological characteristics, entrapment efficiency, in vitro drug release, nebulisation efficiency and physical stability at 2-8 degrees C. In addition, coating carrier surface with the surfactant-lipid mixture, during preparation of proniosomes, resulted in smaller, free flowing, homogenous and smooth vesicles with high drug entrapment efficiency. Compared to a standard drug solution, a successful retardation of the drug release rate was achieved with the proniosome-derived niosomes, where the t50% value of the release profile was 18.1h compared to 1.8h. Moreover, high nebulisation efficiency percentage and good physical stability were also achieved. The results are very encouraging and offer an alternative approach to minimize the problems associated with conventional niosomes like degradation, sedimentation, aggregation and fusion.

A case of unusual substance abuse causing myeloneuropathy.

STUDY DESIGN: Case report. OBJECTIVES: Examine an unusual drug related case of myeloneuropathy as well as the pathophysiology of nitrous oxide induced subacute combined degeneration. SETTING: Major metropolitan teaching hospital - Princess Alexandra Hospital, Queensland, Australia. METHODS: Review case notes, investigations, relevant medical literature and epidemiological data. RESULTS: A 23-year-old female developed a myeloneuropathy and encephalopathy after an 8-month history of nitrous oxide abuse. Her presentation was complicated by acute renal failure, deep vein thrombosis (DVT) and pulmonary embolism (PE) as well as severe cognitive deficits. After eight months of multidisciplinary rehabilitation the patient is able to walk short distances with mobility aids and is able to manage self cares. However, she still requires a wheelchair for long distances and will have significant residual neurological deficits. CONCLUSION: The abuse of nitrous oxide has potentially serious outcomes that require discussion of issues related to harm minimisation and health promotion.

Phosphorylation of LHI beta during membrane synthesis in the photosynthetic bacterium Rhodovulum sulfidophilum.

Cells of Rhv. sulfidophilum were grown under different conditions in the presence of 32P-phosphate and the corresponding H and L membrane fractions obtained and fractionated by SDS-PAGE. Both membranes showed almost identical polypeptide composition. The bacteriochlorophyll (Bchl) specific content in H was always lower that in L. As described before, oxygen did not regulate gene expression. Under high light, an almost two- to threefold decrease of the cellular specific Bchl content was observed. Pulse and chase experiments showed that transitions from aerobiosis to light-anaerobiosis did not quantitatively affect the Bchl content of the membranes, although a turnover of the 32P-phosphate and 35S-methionine was observed. LHI beta was the only polypeptidic subunit of the Bchl-binding polypeptides that was phosphorylated in vivo, and phosphotyrosine was the only phosphorylated amino acid detectable. The phosphorylated LHI beta was determined to be insoluble in the organic solvent mixture of (vol/vol) 1:1 chloroform-methanol containing ammonium acetate (0.1 m final concentration). Treatment with a chaotropic agent such as Na2CO3 solubilized the phosphorylated LHI beta, indicating that part of this posttranslationally modified polypeptide was not inserted in a transmembrane position. These results were used to speculate about the regulatory properties of this posttranslational modification of LHI beta on membrane differentiation.