Relative Brain Volume of Carnivorans Has Evolved in Correlation with Environmental and Dietary Variables Differentially among Clades

Carnivorans possess relatively large brains compared to most other mammalian clades. Factors like environmental complexity (Cognitive Buffer Hypothesis) and diet quality (Expensive-Tissue Hypothesis) have been proposed as mechanisms for encephalization in other large-brained clades. We examine whether the Cognitive Buffer and Expensive-Tissue Hypotheses account for brain size variation within Carnivora. Under these hypotheses, we predict a positive correlation between brain size and environmental complexity or protein consumption. Relative endocranial volume (phylogenetic generalized least-squares residual from species' mean body mass) and 9 environmental and dietary variables were collected from the literature for 148 species of terrestrial and marine carnivorans. We found that the correlation between relative brain volume and environment and diet differed among clades, a trend consistent with other larger brained vertebrates (i.e., Primates, Aves). Mustelidae and Procyonidae demonstrate larger brains in species with higher-quality diets, consistent with the Expensive-Tissue Hypothesis, while in Herpestidae, correlations between relative brain size and environment are consistent with the Cognitive Buffer Hypothesis. Our results indicate that carnivorans may have evolved relatively larger brains under similar selective pressures as primates despite the considerable differences in life history and behavior between these two clades.

Medial femoral trochlea flap reconstruction versus proximal row carpectomy for Kienböck's disease: a morphometric comparison

Surgical options for advanced Kienböck's disease include proximal row carpectomy or lunate reconstruction with a medial femoral trochlea osteochondral flap. This study compares morphology of the proximal capitate and the medial femoral trochlear surfaces to the proximal lunate using three-dimensional geometric morphometric analysis. Virtual articular surfaces were extracted from MRI studies of ten healthy volunteers. Distances between corresponding points on the proximal lunate and proximal capitate or medial femoral trochlear surfaces were measured. In seven subjects, mean inter-surface distance for the medial femoral trochlea-proximal lunate pair was significantly lower than the proximal capitate-proximal lunate pairing. In three subjects, mean proximal capitate-proximal lunate distance was significantly lower. We conclude that the medial femoral trochlear flap was anatomically closer to the shape of the proximal lunate in the majority of the examined subjects. However, we found that in three out of ten cases, the proximal capitate was a better match.

Use of an adeno-associated virus serotype Anc80 to provide durable cure of phenylketonuria in a mouse model

Phenylketonuria (PKU) is the most common inborn error of metabolism of the liver, and results from mutations of both alleles of the phenylalanine hydroxylase gene (PAH). As such, it is a suitable target for gene therapy via gene delivery with a recombinant adeno-associated virus (AAV) vector. Here we use the synthetic AAV vector Anc80 via systemic administration to deliver a functional copy of a codon-optimized human PAH gene, with or without an intron spacer, to the Pah^enu2 mouse model of PKU. Dose-dependent transduction of the liver and expression of PAH mRNA were present with both vectors, resulting in significant and durable reduction of circulating phenylalanine, reaching near control levels in males. Coat color of treated Pah^enu2 mice reflected an increase in pigmentation from brown to the black color of control animals, further indicating functional restoration of phenylalanine metabolism and its byproduct melanin. There were no adverse effects associated with administration of AAV up to 5 × 10¹² VG/kg, the highest dose tested. Only minor and/or transient variations in some liver enzymes were observed in some of the AAV-dosed animals which were not associated with pathology findings in the liver. Finally, there was no impact on cell turnover or apoptosis as evaluated by Ki-67 and TUNEL staining, further supporting the safety of this approach. This study demonstrates the therapeutic potential of AAV Anc80 to safely and durably cure PKU in a mouse model, supporting development for clinical consideration.

Early weight gain trajectories in first episode anorexia: predictors of outcome for emerging adults in outpatient treatment

BACKGROUND

Early response to treatment has been shown to be a predictor of later clinical outcomes in eating disorders (EDs). Specifically, early weight gain trajectories in anorexia nervosa (AN) have been shown to predict higher rates of later remission in inpatient treatment. However, no study has, as of yet, examined this phenomenon within outpatient treatment of first episode cases of AN or in emerging adults.

METHODS

One hundred seven patients with AN, all between the ages of 16 and 25 and with an illness duration of < 3 years, received treatment via the first episode rapid early intervention in eating disorders (FREED) service pathway. Weight was recorded routinely across early treatment sessions and recovery outcomes (BMI > 18.5 kg/m2 and eating psychopathology) were assessed up to 1 year later. Early weight gain across the first 12 treatment sessions was investigated using latent growth mixture modelling to determine distinct classes of change. Follow-up clinical outcomes and remission rates were compared between classes, and individual and clinical characteristics at baseline (treatment start) were tested as potential predictors.

RESULTS

Four classes of early treatment trajectory were identified. Three of these classes (n = 95), though differing in their early change trajectories, showed substantial improvement in clinical outcomes at final follow-up. One smaller class (n = 12), characterised by a 'higher' start BMI (> 17) and no early weight gain, showed negligible improvement 1 year later. Of the three treatment responding groups, levels of purging, depression, and patient reported carer expressed emotion (in the form of high expectations and low tolerance of the patient) determined class membership, although these findings were not significant after correcting for multiple testing. A higher BMI at treatment start was not sufficient to predict optimal clinical outcomes.

CONCLUSION

First episode cases of AN treated via FREED fit into four distinct early response trajectory classes. These may represent subtypes of first episode AN patients. Three of these four trajectories included patients with substantial improvements 1 year later. For those in the non-response trajectory class, treatment adjustments or augmentations could be considered earlier, i.e., at treatment session 12.

Development of a porcine model of phenylketonuria with a humanized R408W mutation for gene editing

Phenylketonuria (PKU) is a metabolic disorder whereby phenylalanine metabolism is deficient due to allelic variations in the gene for phenylalanine hydroxylase (PAH). There is no cure for PKU other than orthotopic liver transplantation, and the standard of care for patients is limited to dietary restrictions and key amino acid supplementation. Therefore, Pah was edited in pig fibroblasts for the generation of PKU clone piglets that harbor a common and severe human mutation, R408W. Additionally, the proximal region to the mutation was further humanized by introducing 5 single nucleotide polymorphisms (SNPs) to allow for development of gene editing machinery that could be translated directly from the pig model to human PKU patients that harbor at least one classic R408W allele. Resulting piglets were hypopigmented (a single Ossabaw piglet) and had low birthweight (all piglets). The piglets had similar levels of PAH expression, but no detectable enzymatic activity, consistent with the human phenotype. The piglets were fragile and required extensive neonatal care to prevent failure to thrive and early demise. Phenylalanine levels rose sharply when dietary Phe was unrestricted but could be rapidly reduced with a low Phe diet. Fibroblasts isolated from R408W piglets show susceptibility to correction using CRISPR or TALEN, with subsequent homology-directed recombination to correct Pah. This pig model of PKU provides a powerful new tool for development of all classes of therapeutic candidates to treat or cure PKU, as well as unique value for proof-of-concept studies for in vivo human gene editing platforms in the context of this humanized PKU allele.

Ex Vivo Cell Therapy by Ectopic Hepatocyte Transplantation Treats the Porcine Tyrosinemia Model of Acute Liver Failure

The effectiveness of cell-based therapies to treat liver failure is often limited by the diseased liver environment. Here, we provide preclinical proof of concept for hepatocyte transplantation into lymph nodes as a cure for liver failure in a large-animal model with hereditary tyrosinemia type 1 (HT1), a metabolic liver disease caused by deficiency of fumarylacetoacetate hydrolase (FAH) enzyme. Autologous porcine hepatocytes were transduced ex vivo with a lentiviral vector carrying the pig Fah gene and transplanted into mesenteric lymph nodes. Hepatocytes showed early (6 h) and durable (8 months) engraftment in lymph nodes, with reproduction of vascular and hepatic microarchitecture. Subsequently, hepatocytes migrated to and repopulated the native diseased liver. The corrected cells generated sufficient liver mass to clinically ameliorate the acute liver failure and HT1 disease as early as 97 days post-transplantation. Integration site analysis defined the corrected hepatocytes in the liver as a subpopulation of hepatocytes from lymph nodes, indicating that the lymph nodes served as a source for healthy hepatocytes to repopulate a diseased liver. Therefore, ectopic transplantation of healthy hepatocytes cures this pig model of liver failure and presents a promising approach for the development of cures for liver disease in patients.

Comparison of Gene Delivery to the Kidney by Adenovirus, Adeno-Associated Virus, and Lentiviral Vectors After Intravenous and Direct Kidney Injections

There are many kidney diseases that might be addressed by gene therapy. However, gene delivery to kidney cells is inefficient. This is due, in part, to the fact that the kidney excludes molecules above 50 kDa and that most gene delivery vectors are megaDaltons in mass. We compared the ability of adeno-associated virus (AAV), adenovirus (Ad), and lentiviral (LV) vectors to deliver genes to renal cells. When vectors were delivered by the intravenous (IV) route in mice, weak luciferase activity was observed in the kidney with substantially more in the liver. When gene delivery was observed in the kidney, expression was primarily in the glomerulus. To avoid these limitations, vectors were injected directly into the kidney by retrograde ureteral (RU) and subcapsular (SC) injections in mice. Small AAV vectors transduced the kidney, but also leaked from the organ and mediated higher levels of transduction in off-target tissues. Comparison of AAV2, 6.2, 8, and rh10 vectors by direct kidney injection demonstrated highest delivery by AAV6.2 and 8. Larger Ad and LV vectors transduced kidney cells and mediated less off-target tissue transduction. These data demonstrate the utility of direct kidney injections to circumvent the kidney size exclusion barrier. They also identify the effects of vector size on on-target and off-target transduction. This lays the foundation for the use of different vector platforms for gene therapy of diverse kidney diseases.

Ex Vivo Hepatocyte Reprograming Promotes Homology-Directed DNA Repair to Correct Metabolic Disease in Mice After Transplantation

Ex vivo CRISPR/Cas9-mediated gene editing in hepatocytes using homology-directed repair (HDR) is a potential alternative curative therapy to organ transplantation for metabolic liver disease. However, a major limitation of this approach in quiescent adult primary hepatocytes is that nonhomologous end-joining is the predominant DNA repair pathway for double-strand breaks (DSBs). This study explored the hypothesis that ex vivo hepatocyte culture could reprogram hepatocytes to favor HDR after CRISPR/Cas9-mediated DNA DSBs. Quantitative PCR (qPCR), RNA sequencing, and flow cytometry demonstrated that within 24 hours, primary mouse hepatocytes in ex vivo monolayer culture decreased metabolic functions and increased expression of genes related to mitosis progression and HDR. Despite the down-regulation of hepatocyte function genes, hepatocytes cultured for up to 72 hours could robustly engraft in vivo. To assess functionality long-term, primary hepatocytes from a mouse model of hereditary tyrosinemia type 1 bearing a single-point mutation were transduced ex vivo with two adeno-associated viral vectors to deliver the Cas9 nuclease, target guide RNAs, and a 1.2-kb homology template. Adeno-associated viral Cas9 induced robust cutting at the target locus, and, after delivery of the repair template, precise correction of the point mutation occurred by HDR. Edited hepatocytes were transplanted into recipient fumarylacetoacetate hydrolase knockout mice, resulting in engraftment, robust proliferation, and prevention of liver failure. Weight gain and biochemical assessment revealed normalization of metabolic function. Conclusion: The results of this study demonstrate the potential therapeutic effect of ex vivo hepatocyte-directed gene editing after reprogramming to cure metabolic disease in a preclinical model of hereditary tyrosinemia type 1.

Lentiviral Vector-mediated Gene Therapy of Hepatocytes Ex Vivo for Autologous Transplantation in Swine

Gene therapy is an ideal choice to cure many inborn errors of metabolism of the liver. Ex-vivo, lentiviral vectors have been used successfully in the treatment of many hematopoietic diseases in humans, as their use offers stable transgene expression due to the vector's ability to integrate into the host genome. This method demonstrates the application of ex vivo gene therapy of hepatocytes to a large animal model of hereditary tyrosinemia type I. This process consists of 1) isolation of primary hepatocytes from the autologous donor/recipient animal, 2) ex vivo gene delivery via hepatocyte transduction with a lentiviral vector, and 3) autologous transplant of corrected hepatocytes via portal vein injection. Success of the method generally relies upon efficient and sterile removal of the liver resection, careful handling of the excised specimen for isolation of viable hepatocytes sufficient for re-engrafting, high-percentage transduction of the isolated cells, and aseptic surgical procedures throughout to prevent infection. Technical failure at any of these steps will result in low yield of viable transduced hepatocytes for autologous transplant or infection of the donor/recipient animal. The pig model of human type 1 hereditary tyrosinemia (HT-1) chosen for this approach is uniquely amenable to such a method, as even a small percentage of engraftment of corrected cells will lead to repopulation of the liver with healthy cells based on a powerful selective advantage over native-diseased hepatocytes. Although this growth selection will not be true for all indications, this approach is a foundation for expansion into other indications and allows for manipulation of this environment to address additional diseases, both within the liver and beyond, while controlling for exposure to viral vector and opportunity for off-target toxicity and tumorigenicity.

Wear and its effects on dental topography measures in howling monkeys (Alouatta palliata)

OBJECTIVES

Three dental topography measurements: Dirichlet Normal Energy (DNE), Relief Index (RFI), and Orientation Patch Count Rotated (OPCR) are examined for their interaction with measures of wear, within and between upper and lower molars in Alouatta palliata. Potential inferences of the "dental sculpting" phenomenon are explored.

MATERIALS AND METHODS

Fifteen occluding pairs of howling monkey first molars (15 upper, 15 lower) opportunistically collected from La Pacifica, Costa Rica, were selected to sample wear stages ranging from unworn to heavily worn as measured by the Dentine Exposure Ratio (DER). DNE, RFI, and OPCR were measured from three-dimensional surface reconstructions (PLY files) derived from high-resolution CT scans. Relationships among the variables were tested with regression analyses.

RESULTS

Upper molars have more cutting edges, exhibiting significantly higher DNE, but have significantly lower RFI values. However, the relationships among the measures are concordant across both sets of molars. DER and EDJL are curvilinearly related. DER is positively correlated with DNE, negatively correlated with RFI, and uncorrelated with OPCR. EDJL is not correlated with DNE, or RFI, but is positively correlated with OPCR among lower molars only.

DISCUSSION

The relationships among these metrics suggest that howling monkey teeth adaptively engage macrowear. DNE increases with wear in this sample presumably improving food breakdown. RFI is initially high but declines with wear, suggesting that the initially high RFI safeguards against dental senescence. OPCR values in howling monkey teeth do not show a clear relationship with wear changes.

Dietary inference from upper and lower molar morphology in platyrrhine primates

The correlation between diet and dental topography is of importance to paleontologists seeking to diagnose ecological adaptations in extinct taxa. Although the subject is well represented in the literature, few studies directly compare methods or evaluate dietary signals conveyed by both upper and lower molars. Here, we address this gap in our knowledge by comparing the efficacy of three measures of functional morphology for classifying an ecologically diverse sample of thirteen medium- to large-bodied platyrrhines by diet category (e.g., folivore, frugivore, hard object feeder). We used Shearing Quotient (SQ), an index derived from linear measurements of molar cutting edges and two indices of crown surface topography, Occlusal Relief (OR) and Relief Index (RFI). Using SQ, OR, and RFI, individuals were then classified by dietary category using Discriminate Function Analysis. Both upper and lower molar variables produce high classification rates in assigning individuals to diet categories, but lower molars are consistently more successful. SQs yield the highest classification rates. RFI and OR generally perform above chance. Upper molar RFI has a success rate below the level of chance. Adding molar length enhances the discriminatory power for all variables. We conclude that upper molar SQs are useful for dietary reconstruction, especially when combined with body size information. Additionally, we find that among our sample of platyrrhines, SQ remains the strongest predictor of diet, while RFI is less useful at signaling dietary differences in absence of body size information. The study demonstrates new ways for inferring the diets of extinct platyrrhine primates when both upper and lower molars are available, or, for taxa known only from upper molars. The techniques are useful in reconstructing diet in stem representatives of anthropoid clade, who share key aspects of molar morphology with extant platyrrhines.

Dietary intake in population-based adolescents: support for a relationship between eating disorder symptoms, low fatty acid intake and depressive symptoms

BACKGROUND

Relatively little is known about the dietary intake and nutritional status of community-based individuals with eating disorders. This research aimed to: (i) describe the dietary intake of population-based adolescents with an eating disorder and (ii) examine associations between eating disorder symptoms, fatty acid intake and depressive symptoms in adolescents with and without an eating disorder.

METHODS

Data were drawn from the Western Australian Pregnancy Cohort (Raine) Study, a population-based cohort study that has followed participants from birth to young adulthood. This research utilised self-report data from the 17-year Raine Study assessment. Participants comprised 429 female adolescents who completed comprehensive questionnaire measures on dietary intake, eating disorder symptoms and depressive symptoms.

RESULTS

Adolescents with an eating disorder (n = 66) reported a significantly lower intake of total fat, saturated fat, omega-6 fatty acid, starch, vitamin A and vitamin E compared to adolescents without an eating disorder (n = 363). Adolescents with an eating disorder and pronounced depressive symptoms (n = 23) also reported a significantly lower intake of polyunsaturated fat and omega-3 and omega-6 fatty acid than adolescents with an eating disorder but no marked depression (n = 43). In the eating disorder sample but not the control sample, omega-3 and omega-6 fatty acid correlated significantly and negatively with eating disorder symptoms and with depressive symptoms.

CONCLUSIONS

Support is provided for a relationship between low omega-3 and omega-6 fatty acid intake and depressive symptoms in adolescents with eating disorders. Research is needed to examine the feasibility and effectiveness of fatty acid supplementation in this high-risk group.

Dietary quality and encephalization in platyrrhine primates

The high energetic costs of building and maintaining large brains are thought to constrain encephalization. The 'expensive-tissue hypothesis' (ETH) proposes that primates (especially humans) overcame this constraint through reduction of another metabolically expensive tissue, the gastrointestinal tract. Small guts characterize animals specializing on easily digestible diets. Thus, the hypothesis may be tested via the relationship between brain size and diet quality. Platyrrhine primates present an interesting test case, as they are more variably encephalized than other extant primate clades (excluding Hominoidea). We find a high degree of phylogenetic signal in the data for diet quality, endocranial volume and body size. Controlling for phylogenetic effects, we find no significant correlation between relative diet quality and relative endocranial volume. Thus, diet quality fails to account for differences in platyrrhine encephalization. One taxon, in particular, Brachyteles, violates predictions made by ETH in having a large brain and low-quality diet. Dietary reconstructions of stem platyrrhines further indicate that a relatively high-quality diet was probably in place prior to increases in encephalization. Therefore, it is unlikely that a shift in diet quality was a primary constraint release for encephalization in platyrrhines and, by extrapolation, humans.

Differential localization of gamma-aminobutyric acid type A and glycine receptor subunits and gephyrin in the human pons, medulla oblongata and uppermost cervical segment of the spinal cord: an immunohistochemical study

Gephyrin is a multifunctional protein responsible for the clustering of glycine receptors (GlyR) and gamma-aminobutyric acid type A receptors (GABA(A)R). GlyR and GABA(A)R are heteropentameric chloride ion channels that facilitate fast-response, inhibitory neurotransmission in the mammalian brain and spinal cord. We investigated the immunohistochemical distribution of gephyrin and the major GABA(A)R and GlyR subunits in the human light microscopically in the rostral and caudal one-thirds of the pons, in the middle and caudal one-thirds of the medulla oblongata, and in the first cervical segment of the spinal cord. The results demonstrate a widespread pattern of immunoreactivity for GlyR and GABA(A)R subunits throughout these regions, including the spinal trigeminal nucleus, abducens nucleus, facial nucleus, pontine reticular formation, dorsal motor nucleus of the vagus nerve, hypoglossal nucleus, lateral cuneate nucleus, and nucleus of the solitary tract. The GABA(A)R alpha(1) and GlyR alpha(1) and beta subunits show high levels of immunoreactivity in these nuclei. The GABA(A)R subunits alpha(2), alpha(3), beta(2,3), and gamma(2) present weaker levels of immunoreactivity. Exceptions are intense levels of GABA(A)R alpha(2) subunit immunoreactivity in the inferior olivary complex and high levels of GABA(A)R alpha(3) subunit immunoreactivity in the locus coeruleus and raphe nuclei. Gephyrin immunoreactivity is highest in the first segment of the cervical spinal cord and hypoglossal nucleus. Our results suggest that a variety of different inhibitory receptor subtypes is responsible for inhibitory functions in the human brainstem and cervical spinal cord and that gephyrin functions as a clustering molecule for major subtypes of these inhibitory neurotransmitter receptors.

Tremorgenic mycotoxins increase gastric smooth muscle activity of sheep reticulum and rumen in vitro

Reticulum and rumen strips (consisting of both muscle layers and the myenteric plexus) were superfused with Tyrode Ringer and their contractions recorded isometrically. The strips were subjected to exogenous acetylcholine and electrical field stimulation (EFS) resulting in contractions that could be blocked by atropine. Responses to the tremorgenic mycotoxin penitrem A and others thought to be involved in ryegrass staggers, paxilline and lolitrem B (10(-10)-10(-6)M), were compared with those of control vehicle (0.1% DMSO). The tremorgens were without effect on quiescent preparations. Penitrem A and paxilline enhanced spontaneously active preparations and the amplitude of contractions in response to EFS. Responses to paxilline had a shorter latency than to penitrem A. Responses of spontaneously active preparations were resistant to atropine. Penitrem A, but not paxilline, increased responses to exogenous acetylcholine. Lolitrem B (10(-6)M) increased responses to EFS, but many responses were equivocal, possibly due to the lower solubility of lolitrem B in aqueous solutions compared to the other tremorgens. The results show that these mycotoxins have peripheral excitatory effects on the reticulorumen and it is suggested that such activity in vivo may reflexly affect centrally derived cyclical contractions.

Acute stroke: usefulness of early CT findings before thrombolytic therapy

PURPOSE

To determine whether the extent of subtle parenchymal hypoattenuation detected on computed tomographic (CT) scans obtained within 6 hours of ischemic stroke is a factor in predicting patients' response to thrombolytic treatment.

MATERIALS AND METHODS

The baseline CT scans of 620 patients, who received either recombinant tissue plasminogen activator (rt-PA) or a placebo, in a double-blind, randomized multicenter trial were prospectively evaluated and assigned to one of three categories according to the extent of parenchymal hypoattenuation: none, 33% or less (small), or more than 33% (large) of the middle cerebral artery territory. The association between the extent of hypoattenuation on the baseline CT scans and the clinical outcome in the placebo-treated and the rt-PA-treated groups after 3 months was analyzed.

RESULTS

In 215 patients with a small hypoattenuating area, treatment increased the chance of good outcome. In 336 patients with a normal CT scan and in 52 patients with a large hypoattenuating area, rt-PA had no beneficial effect but increased the risk for fatal brain hemorrhage.

CONCLUSION

The response to rt-PA in patients with ischemic stroke can be predicted on the basis of initial CT findings of the extent of parenchymal hypoattenuation in the territory of the middle cerebral artery.

A hematopoietic cell L-selectin ligand exhibits sulfate-independent binding activity

L-selectin is a leukocyte cell-surface glycoprotein that mediates adhesive interactions between circulating cells and vascular endothelium. All endothelial ligands of L-selectin characterized to date are glycoproteins that require sulfation for activity and share reactivity with MECA 79, a monoclonal antibody that recognizes a sulfate-dependent epitope involved in L-selectin attachment. We have recently identified by functional assay a glycoprotein L-selectin ligand expressed on the human hematopoietic cell line KG1a. We report here that this ligand is not recognized by MECA 79 and that it retains binding activity after metabolic inhibition of sulfation by chlorate. A native membrane L-selectin ligand exhibiting sulfate-independent function has not been described previously. Identification of this novel ligand on a nonendothelial cell type suggests that structural determinants conferring L-selectin binding may vary in a cell- and tissue-specific manner.

The formation of desethyl-piperacillin from piperacillin by human liver S9 in vitro

Piperacillin (PIPC) has been used as one of the most useful beta-lactam antibiotics over the past 10 years. The metabolism of PIPC has been thoroughly investigated and it has been recognized that PIPC gives few metabolites in laboratory species or humans. Recently, an active metabolite, desethyl-piperacillin (DEt-PIPC), was detected in human plasma and urine after PIPC administration. In the current study, human tissues were obtained from organ donors (n = 3) and subcellular fractions (S9) were prepared. The time course of metabolism by S9 mix from liver, kidney cortex, and kidney medulla was then determined using 0.5 mM PIPC. For comparative purposes, rat liver S9 were also prepared and incubated with PIPC under the same conditions. DEt-PIPC was formed by human liver S9 mix from all three specimens studied, with the rate varying approximately eightfold. No DEt-PIPC was detected in any of the incubations with rat liver S9 mix (n = 3) and kidney S9 mix (n = 3) prepared from either the cortex or medulla. In summary, these data suggest that the formation of the unique human metabolite, DEt-PIPC, can be predicted by in vitro studies with human tissues and that this metabolite is formed predominantly by the liver.

Free radical oxidation of brain proteins in accelerated senescence and its modulation by N-tert-butyl-alpha-phenylnitrone

According to the free radical theory of aging, reactive oxygen species cause oxidative damage, proposed to be an underlying factor of the aging process. In the current study, we have used electron paramagnetic resonance spin labeling, measurements of protein carbonyl content, an index of protein oxidation, and determination of the activity of glutamine synthetase (an oxidatively sensitive enzyme) to report that cortical synaptosomal membranes from the senescence accelerated-prone (SAMP8) mouse showed structural characteristics of free radical oxidative stress relative to the senescence accelerated-resistant (SAMR1) mouse. The SAMP8 mouse exhibited a decrease in the relevant EPR parameter consistent with oxidative stress (P < 0.002), a decreased glutamine synthetase activity (P < 0.05), and an increased protein carbonyl content (P < 0.01) compared with these parameters in the SAMR1 mouse. Further, because free radical trapping compounds have been demonstrated to extend maximum life span and improve cognition in SAMP8 mice, we investigated the protective nature of the known free radical scavenger, N-tert-butyl-alpha-phenylnitrone (PBN), on the physical state of cortical synaptosomal membrane proteins. For 14 days, SAMR1 and SAMP8 mice were injected with 30 mg/kg PBN while the controls were injected with the corresponding volume of saline. Characteristic of less oxidized systems, cortical synaptosomal membranes from the PBN-injected SAMP8 mouse exhibited a return toward normal values of the relevant EPR parameter [the M1 = +1 low-field weakly immobilized line/M1 = +1 low-field strongly immobilized line (W/S) ratio of a protein-specific spin label] (P < 0.001) compared with that from saline-injected SAMP8 mice. In SAMR1 mice, in contrast to SAMP8, there was no significant change in the conformation of membrane proteins or protein carbonyl content of cortical synaptosomal membranes from the PBN-injected and saline-injected SAMR1 mice, showing that PBN itself did not induce conformational changes in cortical synaptosomal membrane proteins. The results are discussed with reference to the use of free radical scavengers as potential anti-aging agents.

Prevention of hyperoxia-induced alterations in synaptosomal membrane-associated proteins by N-tert-butyl-alpha-phenylnitrone and 4-hydroxy-2,2,6,6-tetramethylpiperidin-1-oxyl (Tempol)

Hyperoxia has been considered a model of free radical reactive oxygen species production in aging and age-related disorders. Previously, we studied the membrane protein alterations that occur during hyperoxia; we found that exposure of young animals to 24 h of hyperoxia provided the greatest degree of oxidation of cortical synaptosomal membrane proteins. We reasoned that free radical oxidation was involved in this protein oxidation. In accordance, in the current study we investigated the protective nature of two known free radical scavengers, N-tert-butyl-alpha-phenylnitrone (PBN) and 4-hydroxy-2,2,6,6-tetramethylpiperidin-1-oxyl (Tempol), against 24-h hyperoxia damage. The three techniques used in this study were electron paramagnetic resonance (EPR) protein-specific spin labeling, assay of the activity of the oxidatively sensitive enzyme glutamine synthetase (GS), and measurement of protein carbonyl content. Before hyperoxia, gerbils received intraperitoneal injections of varying concentrations of either of the two free radical scavengers. After 30 min, the gerbils were exposed to 90-100% O2 for 24 h. For the spin labeling experiments, cortical synaptosomes were isolated from gerbils. The membrane proteins were spin labeled with the thiol-specific label MAL-6 (2,2,6,6-tetramethyl-4-maleimidopiperidin-1-oxyl). As in our earlier study, the EPR spectral parameter of MAL-6-labeled membranes, the W/S ratio, decreased with hyperoxia (p < 0.00001). This effect was lessened significantly with administration of PBN (p < 0.0003) or Tempol (p < 0.00003). For the GS and protein carbonyl assays, cortical proteins were used. The activity of the GS decreased with hyperoxia (p < 0.000005), and this effect likewise was lessened with administration of PBN (p < 0.004) or Tempol (p < 0.002). The protein carbonyl content increased with hyperoxia (p < 0.0002), and there was a protective effect found with Tempol (p < 0.000001). The optimum doses for PBN and Tempol were 20 and 5 mg/kg, respectively. The results are discussed with reference to the use of free radical scavengers as potential antiaging agents.

The effect of gamma-irradiation on the antibacterial activity of honey

There is increasing usage of honey as a dressing on infected wounds, burns and ulcers, but there is some concern that there may be a risk of wound botulism from the clostridial spores sometimes found in honey. It is well-established that the antibacterial activity is heat-labile so would be destroyed if honey were sterilized by autoclaving, but the effect of gamma-irradiation on the antibacterial activity of honey is not known. Therefore an investigation was carried out to assess the effect on the antibacterial activity of honey when the honey was subjected to a commercial sterilization procedure using gamma-irradiation (25 kGy). Two honeys with antibacterial activity due to enzymically-generated hydrogen peroxide and three manuka honeys with non-peroxide antibacterial activity were investigated. The honeys were tested against Staphylococcus aureus in an agar well diffusion assay. There was no significant change found in either type of antibacterial activity resulting from this form of sterilization of honey, even when the radiation was doubled (to 50 kGy). Testing of honey seeded with spores of Clostridium perfringens and C. tetani (10000 and 1000 spores g-1 of honey, respectively) showed that 25 kGy of gamma-irradiation was sufficient to achieve sterility.

Effect of reperfusion following cerebral ischaemia on the activity of the mitochondrial respiratory chain in the gerbil brain

The effect of reperfusion following 30 min of cerebral ischaemia on brain mitochondrial respiratory chain activity has been studied in the gerbil. The state 3 respiration rates with both FAD- and NAD-linked substrates were reduced after ischaemia. After 5 min of reperfusion, state 3 respiration with FAD-linked substrates was restored, but levels of NAD-linked substrates did not return to control values until 30 min of reperfusion. By 120 min of reperfusion state 3 respiration decreased relative to control values with all substrates studied. Measurement of the individual respiratory chain complexes showed that complex I, complex II-III, and complex V activities were reduced after ischaemia. By 5 min of reperfusion complex II-III activity was restored, but the activities of complexes I and V did not return to control values until 30 min of reperfusion. In contrast, complex IV activity was unaffected by ischaemia or 5 and 30 min of reperfusion but was significantly reduced after 120 min of reperfusion, possibly owing to free radical production and lipid peroxidation.

Changes of respiratory chain activity in mitochondrial and synaptosomal fractions isolated from the gerbil brain after graded ischaemia

In this study we have examined (1) the integrated function of the mitochondrial respiratory chain by polarographic measurements and (2) the activities of the respiratory chain complexes I, II-III, and IV as well as the ATP synthase (complex V) in free mitochondria and synaptosomes isolated from gerbil brain, after a 30-min period of graded cerebral ischaemia. These data have been correlated with cerebral blood flow (CBF) values as measured by the hydrogen clearance technique. Integrated functioning of the mitochondrial respiratory chain, using both NAD-linked and FAD-linked substrates, was initially affected at CBF values of approximately 35 ml 100 g-1 min-1, and declined further as the CBF was reduced. The individual mitochondrial respiratory chain complexes, however, showed differences in sensitivity to graded cerebral ischaemia. Complex I activities decreased sharply at blood flows below approximately 30 ml 100 g-1 min-1 (mitochondria and synaptosomes) and complex II-III activities decreased at blood flows below 20 ml 100 g-1 min-1 (mitochondria) and 35-30 ml 100 g-1 min-1 (synaptosomes). Activities declined further as CBF was reduced below these levels. Complex V activity was significantly affected only when the blood flow was reduced below 15-10 ml 100 g-1 min-1 (mitochondria and synaptosomes). In contrast, complex IV activity was unaffected by graded cerebral ischaemia, even at very low CBF levels.

Identification of ethanolamine in rat and gerbil brain tissue extracts by NMR spectroscopy

Some NMR resonances which have previously been observed but not identified in mammalian brain tissue extracts have been shown to arise from ethanolamine. This conclusion is drawn from a systematic study of the perchloric acid extracts of rodent brain tissue in which several NMR experiments were used to assign the peaks unambiguously. The extraction procedure used in this work gave samples with highly reproducible spectra, and ethanolamine was observed in all our extract samples. A localized increase in the concentration of ethanolamine was seen in the spectra of extracts produced from a cerebral infarct induced by occlusion of the middle cerebral artery in the rat.

Early changes in cerebral sodium distribution following ischaemia monitored by 23Na magnetic resonance imaging

23Na magnetic resonance imaging has been used in this preliminary study to investigate early changes in brain sodium signal intensity during and after cerebral ischaemia in a gerbil model. The total sodium signal in selected brain regions decreased between 15 and 30% within 4 min of the onset of ischaemia, and then remained constant throughout the ischaemic period. The same pattern was observed in the eyes. On reperfusion, there was no significant change in the sodium signal over the first 4 min, but by 8 min the signal intensity had returned to or passed through control levels in all regions measured, with the exception of the eyes. These observations are consistent with the loss and resynthesis of ATP as seen in this model, and may be reflecting the redistribution of tissue sodium resulting from energy failure and recovery.

A sodium magnetic resonance imaging study of acute cerebral ischaemia in the gerbil

23Na magnetic resonance imaging has been used to investigate sodium changes during and after cerebral ischaemia in a gerbil model. The sodium signal decreased within 4 minutes of the onset of ischaemia, and subsequently increased between 4 and 8 minutes after the onset of reperfusion. These observations may be reflecting the redistribution of tissue sodium resulting from energy failure and recovery.

Controllable graded cerebral ischaemia in the gerbil: studies of cerebral blood flow and energy metabolism by hydrogen clearance and 31P NMR spectroscopy

A technique for remotely controlling the degree of carotid artery occlusion in the gerbil model of cerebral ischaemia has been developed. The technique relies on manually adjustable nylon snares around the carotid arteries, in conjunction with a computer-based monitoring system, to control the degree of occlusion. This has allowed us to determine the dependence of energy metabolism (as assessed by 31P NMR spectroscopy) on blood flow in greater detail than was possible in our previous studies. Data obtained show that energy changes first appear at flows of 25-30 mL/100 g/min, while at flows below 20 mL/100 g/min there is a major derangement of energy metabolism. The model was used to determine the sensitivity of cerebral energy metabolism to reduced cerebral blood flow under normothermic conditions and in mild hypothermia (30 degrees C). Hypothermia had a protective effect in that energy metabolites were maintained at flows significantly below the normothermic threshold.

Diffusion-weighted imaging studies of cerebral ischemia in gerbils. Potential relevance to energy failure

BACKGROUND AND PURPOSE

Diffusion-weighted magnetic resonance imaging has been shown to be particularly suited to the study of the acute phase of cerebral ischemia in animal models. The studies reported in this paper were undertaken to determine whether this technique is sensitive to the known ischemic thresholds for cerebral tissue energy failure and disturbance of membrane ion gradients.

METHODS

Diffusion-weighted images of the gerbil brain were acquired under two sets of experimental conditions: as a function of cerebral blood flow after controlled graded occlusion of the common carotid arteries (partial ischemia), as a function of time following complete bilateral carotid artery occlusion (severe global ischemia), and on deocclusion after 60 minutes of ischemia.

RESULTS

During partial cerebral ischemia, the diffusion-weighted images remained unchanged until the cerebral blood flow was reduced to 15-20 ml.100 g-1.min-1 and below, when image intensity increased as the cerebral blood flow was lowered further. This is similar to the critical flow threshold for maintenance of tissue high-energy metabolites and ion homeostasis. After the onset of severe global cerebral ischemia, diffusion-weighted image intensity increased gradually after a delay of approximately 2.5 minutes, consistent with complete loss of tissue adenosine triphosphate and with the time course of increase in extracellular potassium. This hyperintensity decreased on deocclusion following 60 minutes of ischemia.

CONCLUSIONS

The data suggest that diffusion-weighted imaging is sensitive to the disruption of tissue energy metabolism or a consequence of this disruption. This raises the possibility of imaging energy failure noninvasively. In humans, this could have potential in visualizing brain regions where energy metabolism is impaired, particularly during the acute phase following stroke.

A survey of the antibacterial activity of some New Zealand honeys

To assess the variation in antibacterial activity of honey a survey was carried out on 345 samples of unpasteurized honey obtained from commercial apiarists throughout New Zealand. Most of the honeys were considered to be monofloral, from 26 different floral sources. The honeys were tested against Staphylococcus aureus in an agar well diffusion assay, with reference to phenol as a standard. Antibacterial activity was found to range from the equivalent of less than 2% (w/v) phenol to 58% (w/v) phenol, with a median of 13.6 and a standard deviation of 12.5. Neither the age of the honey samples nor whether they had been processed by the apiarist was associated with lower activity. However, the difference between floral sources in the antibacterial activity was very highly significant. Kanuka (Kunzea ericoides (A. Rich.) J. Thompson. Family: Myrtaceae), manuka (Leptospermum scoparium J. R. et G. Forst. Family: Myrtaceae), ling heather (Calluna vulgaris (L.) Hull. Family: Ericaceae) and kamahi (Weinmannia racemosa Linn. f. Family: Cunoniaceae) were shown to be sources likely to give honey with high antibacterial activity. When antibacterial activity was assayed with catalase added to remove hydrogen peroxide, most of the honeys showed no detectable antibacterial activity. Only manuka and vipers bugloss (Echium vulgare L. Family: Boraginaceae) honeys showed this type of activity in a significant proportion of the samples. The high antibacterial activity of manuka honey was in many cases due entirely to this non-peroxide component.

Residues flanking the COOH-terminal C-region of a model eukaryotic signal peptide influence the site of its cleavage by signal peptidase and the extent of coupling of its co-translational translocation and proteolytic processing in vitro

The polar, COOH-terminal c-region of signal peptides has been considered to be most important for influencing the efficiency and fidelity of signal peptidase cleavage while the hydrophobic core or h-region appears indispensable for initiating translocation. To identify structural features of residues flanking the c-region that influence the fidelity and efficiency of signal peptidase cleavage as well as co-translational translocation, we introduced six amino acid substitutions into the COOH terminus of the hydrophobic core and seven substitutions at the NH2 terminus of the mature region (the +1 position) of a model eukaryotic preprotein-human pre(delta pro)apoA-II. This preprotein contains several potential sites for signal peptidase cleavage. The functional consequences of these mutations were assayed using an in vitro co-translational translocation/processing system and by post-translational cleavage with purified, detergent-solubilized, hen oviduct signal peptidase. The efficiency of translocation could be correlated with the hydrophobic character of the residue introduced at the COOH terminus of the h-region. Some h/c boundary mutants underwent co-translational translocation across the microsomal membrane with only minimal cleavage yet they were cleaved post-translationally by hen oviduct signal peptidase more efficiently than other mutants which exhibited a high degree of coupling of co-translational translocation and cleavage. These data suggest that features at the COOH terminus of the h-domain can influence "presentation" of the cleavage site to signal peptidase. The +1 residue substitutions had minor effects on the extent of co-translational translocation and processing. However, these +1, as well as h/c boundary mutations, had dramatic effects on the site of cleavage chosen by signal peptidase, indicating that residues flanking the c-region of this prototypic eukaryotic signal peptide can affect the fidelity of its proteolytic processing. The site(s) selected by canine microsomal and purified hen oviduct signal peptidase were very similar, suggesting that "intrinsic" structural features of this prepeptide can influence the selectivity of eukaryotic signal peptidase cleavage, independent of the microsomal membrane and associated translocation apparatus.

Restoration of energy metabolism and resolution of oedema following profound ischaemia

Cerebral ischaemia was produced in 2 groups of gerbils by occlusion of the common carotid arteries for 30 minutes, resulting in cerebral oedema. In group 1 cerebral oedema was measured by specific gravity microgravimetry, and in group 2 brain metabolism and blood flow were measured by 31P and 1H NMR spectroscopy and hydrogen clearance respectively. In group 1 the brain water content did not return to control levels by 180 minutes of reperfusion. Energy metabolism, determined by 31P NMR spectroscopy returned to control by 12 minutes, intracellular pH (pHi) by 20 minutes, and lactate, determined by 1H NMR spectroscopy, by 50 minutes. There was a lag of about 10 minutes before lactate began to be cleared from the brain. We suggest that while pHi is low, Na+/H+ exchange will negate the Na+ extrusion driven by the Na+/K+ ATPase. When pHi approaches normal there will be a net extrusion of Na+, taking osmotic water with it, and presumably with passive washout of lactate. This may be the cause of the initial delay in lactate clearance.

Parallel effects of signal peptide hydrophobic core modifications on co-translational translocation and post-translational cleavage by purified signal peptidase

The length of the hydrophobic core of the bovine parathyroid hormone signal peptide was modified by in vitro mutagenesis. Extension of the hydrophobic core by three amino acids at the NH2-terminal end had little effect on the proteolytic processing of the signal peptide by microsomal membranes. Deletion of 6 of the 12 amino acids in the core eliminated translocation and processing of the modified protein. Deletion of pairs of amino acids across the core resulted in position-dependent inhibition of signal activity unrelated to hydrophobicity but inversely related to the hydrophobic moments of the modified cores. Deletions in the NH2-terminal region of the core were strongly inhibitory for proteolytic processing whereas deletions in the COOH-terminal region had no effect or increased processing when assessed either co-translationally with microsomal membranes or post-translationally with purified hen oviduct signal peptidase. Deletion of cysteine 18 and alanine 19 increased processing, but deletion of cysteine alone or substitution of leucine for cysteine did not increase processing more than deletion of both residues at 18 and 19. Translations of the translocation-defective mutants with pairs of amino acids deleted in a wheat germ system were inhibited by addition of exogenous signal recognition particle suggesting that interactions of the modified signal peptides with signal recognition particle were normal. The position-dependent effects of the hydrophobic core modifications indicate that structural properties of the core in addition to hydrophobicity are important for signal activity. The parallel effects of the modifications on co-translational translocation and post-translational processing by purified signal peptidase suggest that proteins in the signal peptidase complex might be part of, or intimately associated with, membrane proteins involved in the translocation. A model is proposed in which the NH2-terminal region of the hydrophobic core binds to one subunit of the signal peptidase while the other subunit catalyzes the cleavage.

Stable dicentric chromosomes induced by chemical mutagens in L5178Y mouse lymphoma cells

Stable, tandem dicentric chromosomes were discovered in two mutant cell colonies resulting from exposure of L5178Y mouse lymphoma cells to chemical mutagens. These unusual dicentrics were present in all metaphase cells examined from these colonies, even after approximately 65 cell generations in culture. Observation of cells in metaphase and anaphase suggests that the interstitial centromere in these dicentrics is non-functional, and that the terminal centromere is solely responsible for their orderly anaphase segregation.

Chromosome analysis of trifluorothymidine-resistant L5178Y mouse lymphoma cell colonies

Cells from small (sigma) and large (lambda) trifluorothymidine-resistant (TFTr) colonies induced by chemical mutagen treatment of TK+/-L5178Y mouse lymphoma cells were examined for chromosomal abnormalities. Analysis of G-banded metaphase chromosomes from 34 sigma-TFTr colonies revealed that cells from 20 (59%) possessed one or more chromosomal abnormalities. The most frequent (16/20 colonies) abnormality observed in cells from sigma-TFTr colonies involved the addition of extra chromatin to the distal region of one chromosome number 11. In 13 of these 16 colonies, the origin of the chromatin translocated to chromosome number 11 could not be identified; the chromatin was not missing elsewhere in the genome. The remaining three sigma-TFTr colonies with an abnormal chromosome number 11 had apparently whole chromosomes translocated, in tandem, to the distal region of chromosome number 11. Chromosomal abnormalities observed in cells from sigma-TFTr colonies with normal number 11 chromosomes included 2N/4N and 2N/4N/8N mosaicism (two colonies), a Robertsonian translocation involving chromosome 10 and a marker chromosome (one colony), and trisomy 7 (one colony). In most (14/16) sigma-TFTr colonies with structural damage to chromosome number 11, the cells within a colony were heterogeneous in that some possessed chromosomal damage whereas others were apparently normal. Analysis of chromosomes in cells from eight lambda-TFTr colonies revealed one colony in which all cells had a Robertsonian translocation involving chromosomes 1 and 16 plus other structural abnormalities. The chromosomes of cells from the remaining lambda-TFTr colonies were apparently normal.

Effective bone palliation as related to various treatment regimens

Various dose-time treatment plans have been used to obtain long duration pain relief in patients with metastatic bone disease. Very little has appeared in the literature evaluating the relationship of dose and fractionation to initial, delayed and permanent bone pain relief. At the Swedish Hospital Tumor Institute, 152 treatment fields in 110 patients were evaluated, with a clinical follow-up in many of over five years. Those treated at lower total doses with less fractionation achieved the same quality and duration of pain relief as higher doses. Treatment plans also were compared using the Ellis method of nominal standard dose.

Brain-stem abscess in childhood. Case report

✓ A rare case is reported of a solitary abscess of the brain-stem which was suspected clinically, confirmed surgically, and successfully removed. The few reports of similar cases in the literature are reviewed.