Sexual differences in the expression of copper deficiency in rats

The present investigation was undertaken to establish whether the severity of copper deficiency in rats fed diets containing fructose is affected by the presence and type of endogenous sex hormones. Intact and castrated male rats and intact and ovariectomized females were fed from weaning a copper-deficient diet (0.6 ppm) containing 62% fructose for 8 weeks. Regardless of castration, male rats were anemic, exhibited heart hypertrophy, and died of the deficiency. However, castration ameliorated the anemia and delayed the mortality. In contrast, none of the females died of the deficiency. It is suggested that in addition to the sex of the animal, levels of testosterone in the male may also play a role in the severity of copper deficiency.     

A regional localisation for an X-linked suppressor gene (XS) for the Lutheran blood group

Summary Suppression of Lutheran blood group expression is usually associated with an autosomal dominant suppressor gene In(Lu) which results in the rare Lu(a-b-) phenotype. X-linked recessive suppression can also occur under the control of the XS locus with normal (XS1) and suppressor (XS2) alleles. The only known kindred with XS2 segregating was examined for polymorphic DNA markers with known regional localisations on the X chromosome. Two point linkage analysis suggested linkage of XS to DXS14 (p58.1) with =0.00, =1.96. DXS14 is situated near the centromere at Xp11. Recombinants with DXS84 (distal to DXS14 on Xp) and recombinants with DXYS1 (pDP34) (on the proximal part of Xq) suggests a localisation for XS near the centromere, between DXS84 and DXYS1 (Xp21.2-Xq21.1). Linkage to a marker on the X chromosome confirms the original assignment of XS to the X chromosome, which was based on pedigree inspection from this family.     

Galanin-Like Immunoreactivity Is Unchanged in Alzheimer''s Disease and Parkinson''s Disease Dementia Cerebral Cortex

Galanin is a recently isolated neuropeptide that is of particular interest in dementing disorders because of its known colocalization with choline acetyltransferase in magnocellular neurons of the basal nucleus of Meynert. These neurons degenerate in Alzheimer's disease, and there is a corresponding deficiency of cortical choline acetyltransferase activity. In the present study, galanin-like immunoreactivity was measured in the postmortem cerebral cortex and hippocampus of 10 controls and 14 patients who had had Alzheimer's disease. Significant reductions of choline acetyltransferase activity (50-60%) were found in all regions examined; however, there was no significant effect on concentrations of galanin-like immunoreactivity. Similar measurements were made in postmortem tissues of 12 control and 13 demented Parkinsonian patients who had had Alzheimer-type cortical pathology. Choline acetyltransferase activity was again significantly decreased in all regions examined but there were no significant reductions in galanin-like immunoreactivity. Experimental lesions of the fornix in rats produced parallel significantly correlated reductions of both choline acetyltransferase activity and galanin-like immunoreactivity in the hippocampus. Galanin-like immunoreactivity in the human hypothalamus consisted of two molecular-weight species on gel-permeation chromatography, and two forms were resolved by reverse-phase HPLC. The paradoxical preservation of galanin-like immunoreactivity, despite depletion of the activity of choline acetyltransferase, with which it is colocalized, is as yet unexplained. Recent studies have shown that galanin inhibits both acetylcholine release in the hippocampus and memory acquisition; therefore, preserved galanin may exacerbate the cholinergic and cognitive deficits that accompany dementia.     

DETERMINATION OF GUSTATORY SUCROSE THRESHOLD IN WATER BY USE OF A LINEAR SUCROSE GRADIENT

A novel experimental method was developed which allows the determination of the threshold concentration of sucrose by use of a linear sucrose gradient in water. With this method a continuous tasting of the test-liquid is possible. A panel of 15 persons experienced in taste-testing was used. Three gradients of different steepness were applied: 0 to 1.5% (w/w) sucrose in 2 min (I), 3 min (II) and 4 min (III). The results of the new method were compared with those of the standard method (DIN). With gradients I and II we found values which were significantly higher than those of the standard method (I: 0.49% (w/w); II: 0.46% (w/w); DIN: 0.31% (w/w)), whereas with gradient III the same threshold value was found as with the DIN-Method (III: 0.32% (w/w)).     

Cortical Cytochrome Oxidase Activity Is Reduced in Alzheimer's Disease

Abstract: A defect in energy metabolism may play a role in the pathogenesis of neurodegenerative diseases, such as Alzheimer's disease. In the present study, we examined the activities of the enzymes that catalyze oxidative phosphorylation in frontal, temporal, parietal, and occipital cortex from Alzheimer's disease patients and age-matched controls. Complex I and complex II–III activities showed a small decrease in occipital cortex, but were unaffected in the other cortical areas. The most consistent change was a significant decrease of cytochrome oxidase (complex IV) activity of 25–30% in the four cortical regions examined. These results provide further evidence of a cytochrome oxidase defect in Alzheimer's disease postmortem brain tissue. A deficiency in this key energy-metabolizing enzyme could lead to a reduction in energy stores and thereby contribute to the neurodegenerative process.     

Age-Dependent Impairment of Mitochondrial Function in Primate Brain

Abstract: It has been hypothesized that some of the functional impairments associated with aging are the result of increasing oxidative damage to mitochondrial DNA that produces defects in oxidative phosphorylation. To test this hypothesis, we examined the enzymes that catalyze oxidative phosphorylation in crude mitochondrial preparations from frontoparietal cortex of 20 rhesus monkeys (5-34 years old). Samples were assayed for complex I, complex II-III, complex IV, complex V, and citrate synthase activities. When enzyme activities were corrected for citrate synthase activities (to account for variable degrees of mitochondrial enrichment), linear regression analysis demonstrated a significant negative correlation of the activities of complex I (p < 0.002) and complex IV (p < 0.03) with age but no significant change in complex II-III or complex V activities. Relative to animals 6.9 ± 0.9 years old (n = 7), the citrate synthase-corrected activity of complex I was reduced by 17% in animals 22.5 ± 0.9 years old (n = 6) (p < 0.05) and by 22% in animals 30.7 ± 0.9 years old (n = 7) (p < 0.01). Similar age-related reductions in the activities of complexes I and IV were obtained when enzyme activities were corrected for complex II-III activity. These findings show an age-associated progressive impairment of mitochondrial complex I and complex IV activities in cerebral cortices of primates.     

Jugular plasma concentrations of 13,14-dihydro-15-keto-prostaglandin F2 alpha in prepubertal beef heifers treated with progestogen then challenged with oxytocin.

Prepubertal Angus crossbred heifers (n = 24) between 8 and 10 mo of age were used to determine if progestogen treatment would enhance jugular concentrations of 13,14-dihydro-15-keto-prostaglandin F2 alpha (PGFM) after oxytocin (OT) injections. Heifers were stratified by age and weight and allotted to randomized treatments in a 2 x 2 factorial arrangement. Heifers were treated with either a norgestomet (NOR) implant (6 mg) for 9 d or no implant (0 mg; BLK). On d 8 of NOR treatment, jugular veins were catheterized and, on d 9, blood samples were collected every 15 min for 165 min. The first four samples were used to determine basal PGFM concentrations (an indirect measure of uterine PGF2 alpha release). After collection of the fourth sample, either OT (100 IU) or saline (0 IU; SAL) was injected via the jugular catheter. After the 165-min sample was collected, NOR implants were removed. Beginning 48 h after implant removal, a second 165- min blood sampling period was initiated. Average progesterone concentrations were less than 1 ng/ml during both bleeding periods. Within treatment, PGFM concentrations were similar between the first and second sampling periods; therefore, data within treatment were combined. Basal PGFM concentrations were higher (P < .01) in NOR-treated than in BLK heifers. Oxytocin did not increase PGFM concentrations in BLK-OT heifers; however, a marked increase in PGFM was detected in the NOR-OT heifers in response to oxytocin. Average PGFM concentration was greatest (P < .0001) in NOR-OT heifers, and PGFM profiles differed (P < .0001) between NOR-OT and each of the other treatment groups. Results from this study indicate that NOR increases basal PGFM and may "condition" the uterus to respond to OT in prepubertal heifers.     

Measurement of kynurenic acid in mammalian brain extracts and cerebrospinal fluid by high-performance liquid chromatography with fluorometric and coulometric electrode array detection

Kynurenic acid is a broad-spectrum excitatory amino acid (EAA) receptor antagonist which is present in the mammalian central nervous system. We describe a method for the measurement of kynurenic acid using isocratic reverse-phase high-performance liquid chromatography (HPLC) with fluorometric detection enhanced by Zn2+ as a postcolumn reagent. The method requires no prior sample preparation procedures other than extraction with 0.1 M HClO4. The reliability of the primary fluorometric method was verified by comparing measurements of tissue concentrations of kynurenic acid in human cerebral cortex and putamen using three different methods of separation with fluorometric detection, as well as four methods utilizing HPLC with coulometric electrode array system (CEAS) detection. All seven methods produced comparable results. The concentration of kynurenic acid in human cerebral cortex was 2.07 +/- 0.61 pmol/mg protein, and in human putamen, 3.38 +/- 0.81 pmol/mg protein. Kynurenic acid was also found to be present in human cerebrospinal fluid (CSF) at a concentration of 5.09 +/- 1.04 nM. The regional distribution of kynurenic acid in the rat brain was examined. Kynurenic acid concentrations were highest in brainstem (149.6 fmol/mg protein) and olfactory bulb (103.9 fmol/mg protein) and lowest in thalamus (26.0 fmol/mg protein). There were no significant postmortem changes in kynurenic acid concentrations in cerebral cortex, hippocampus, and striatum at intervals ranging from 0 to 24 h. Perfusion of the cerebral vasculature with normal saline prior to sacrifice did not significantly alter kynurenic acid content in rat hippocampus, cerebral cortex, or striatum. The analytical methods described are the most sensitive (10-30 fmol injection-1) and specific (utilizing both excitation and emissions properties and electrochemical reaction potentials, respectively) methods for determining kynurenic acid in brain tissue extracts and CSF. These methods should prove useful in examining whether kynurenic acid modulates EAA-mediated neurotransmission under physiologic conditions, as well as in determining the role of kynurenic acid in excitotoxic neuronal death.