Music therapy increases serum melatonin levels in patients with Alzheimer's disease

CONTEXT

Music therapy is known to have healing and relaxing effects. Although these effects appear to be mediated by release of neurotransmitters and neurohormones, the specific neurohormonal systems involved have not been fully investigated.

OBJECTIVE

To assess the effects of a music therapy intervention on concentrations of melatonin, norepinephrine, epinephrine, serotonin, and prolactin in the blood of a group of patients with Alzheimer's disease.

DESIGN

Blood samples were obtained before initiating the therapy, immediately at the end of 4 weeks of music therapy sessions, and at 6 weeks follow-up after cessation of the sessions.

SETTING

Miami Veterans Administration Medical Center, Miami, Fla.

PATIENTS

20 male inpatients with Alzheimer's disease.

INTERVENTION

30- to 40-minute morning sessions of music therapy 5 times per week for 4 weeks.

MAIN OUTCOME MEASURES

Changes in melatonin, norepinephrine, epinephrine, serotonin, and prolactin following music therapy.

RESULTS

Melatonin concentration in serum increased significantly after music therapy and was found to increase further at 6 weeks follow-up. A significant increase was found between baseline values and data recorded after the music therapy sessions as well as at 6 weeks follow-up. Norepinephrine and epinephrine levels increased significantly after 4 weeks of music therapy, but returned to pretherapy levels at 6 weeks follow-up. Serum concentration of prolactin and platelet serotonin levels remained unchanged after 4 weeks of music therapy and at 6 weeks follow-up.

CONCLUSION

Increased levels of melatonin following music therapy may have contributed to patients' relaxed and calm mood.

Differential expression and selective localization of vascular permeability factor/vascular endothelial growth factor in the rat uterus during the estrous cycle

This study examines the expression of the multi-functional cytokine, vascular permeability factor/vascular endothelial growth factor (VPF/VEGF) in the rat uterus during early proestrus, proestrus, estrus and diestrus. Groups of ovariectomized or hypophysectomized rats served as endocrine controls. Expression of VPF/VEGF mRNA was 2-fold greater in uteri during proestrus and estrus than in other phases of the estrous cycle. In situ hybridization techniques indicated that VPF/VEGF mRNA expression was confined to the luminal epithelium during proestrus, but shifted to the stromal compartment during estrus. Ovariectomized, hypophysectomized or diestrus rats exhibited scattered localization of VPF/VEGF mRNA among glandular epithelium and endometrial stromal compartments. Although VPF/VEGF mRNA was expressed throughout the estrous cycle, but in different compartments of the endometrium depending on the stage of the estrous cycle, VPF/VEGF protein expression appears to be restricted to the epithelial compartment during proestrus and estrus. Results indicate that circulating levels of gonadal steroids and LH may be associated with the differential expression of VPF/VEGF mRNA and its translation activity in the endometrium during different stages of the estrous cycle.

Cocaine abuse and HIV-1 infection: epidemiology and neuropathogenesis

The epidemiology of cocaine abuse and potential relationships of cocaine withdrawal to human immunodeficiency virus type 1 (HIV-1)-associated dementia (HAD) are discussed. Neuroendocrinological changes in HIV-1 infection of the central nervous system (CNS) are discussed with the relevant impact of cocaine abuse. HIV-1 load in the brain tissue of infected substance users is described along with possible associations with neuropathology and HAD. Finally, the molecular epidemiology and sequence heterogeneity of HIV-1 and their implications for neuropathogenesis are summarized. The complex context of addressing cocaine abuse in the setting of HIV-1 infection appears more tractable when decomposed into its components.

Long-term function and survival of elderly donor kidneys transplanted into young adults

BACKGROUND

Traditionally, elderly donor kidneys have not been widely accepted for transplantation on the assumption of inferior performance. However, the United Network for Organ Sharing reports an increase in the number of elderly donors from less than 2% in 1982 to 24% in 1995. This trend is commensurate with the increase of older dialysis patients and an overall increase in the elderly population in the United States (1). Optimal utilization of these kidneys is essential to overcome the acute organ shortage.

METHODS

In this study, we transplanted 25 kidneys from elderly donors (ages 56-72 years) into young adult recipients (ages 20-50 years) (group 1) over a 4-year period. We compared the results with matched recipients of young adult donor kidneys (group 2) with regard to long-term kidney function and graft survival. A pretransplant biopsy of elderly donor kidneys was carried out and a frozen section report was obtained. Only those kidneys showing glomerulosclerosis of less than 20% were accepted for transplantation. All cadaveric kidneys were preserved in University of Wisconsin solution.

RESULTS

Pretransplant biopsies of elderly donor kidneys showed structural deficits, which included glomerulosclerosis in 85%, arteriolar and/or mesangial thickening in 75%, and interstitial lymphocyte infiltration in 30%. The mean serum creatinine was 2.4+/-0.74, 2.2+/-0.56, and 2.9+/-0.76 mg/100 ml in group 1 and 1.5+/-0.55, 2.3+/-2.24, and 1.7+/-0.62 in group 2 at 1, 3, and 5 years, respectively. The patient survival was 92%, 92%, and 88% in group 1, and 100%, 100%, and 100% in group 2 at 1, 3, and 5 years, respectively. The graft survival was 80%, 64%, and 56% in group 1 and 100%, 96%, and 88% in group 2 at similar time intervals. The differences in the serum creatinine and graft survival between the two groups were statistically significant (P < 0.05).

CONCLUSIONS

Most of the elderly donor kidneys with structural deficits transplanted into young adults provided suboptimal function and inferior long-term graft survival. To maximize the utilization and optimize the survival of elderly donor kidneys, we propose transplantation of these kidneys into age-matched recipients with similar physiological requirements as those of donors, with regard to kidney function.

The effect of selected classical music and spontaneous imagery on plasma beta-endorphin

This study explored the effect of music and imagery on plasma beta-endorphin in 78 undergraduates. Subjects screened for relevant psychological and health criteria were assigned to music imaging, silent imaging, music listening, and control conditions. Subjects donated 15 ml of blood prior to and following the 2-hr intervention period. There were no group differences in potential confounding variables. Split-plot factorial analysis controlling for individual differences in pretest level of beta-endorphin revealed that those in the music imaging group experienced a significant pre-post decline in beta-endorphin, while no other group demonstrated any significant pre-post difference. These data suggest that music imaging may lower peripheral beta-endorphin levels in healthy subjects. Further exploration of the effects of music and imagery interventions on physiology and health may be warranted.

Lack of change in fluoxetine and norfluoxetine kinetics when switching from fluoxetine to paroxetine

Pharmacokinetic interactions are possible with the prescription of two or more psychotropics. This caution could also apply to the proximal use of selective serotonin (5-hydroxytryptamine) reuptake inhibitors (SSRIs), especially those that may be potent inhibitors of specific hepatic metabolizing enzyme systems. Both fluoxetine (FLX) and paroxetine (PAR) are inhibitors of the cytochrome P4502D6 enzyme system. In order to assess the potential pharmacokinetic interactions between these two SSRIs, nine patients were first treated with fixed therapeutic doses of FLX for a minimum of 6 weeks. Subsequently, in a double-blind design, some of these patients were abruptly switched to PAR, 20 mg/day, and others were switched to placebo. Serum levels of FLX, norfluoxetine (NFLX), and PAR were collected before and at specific points after the switch. The results suggest that the clearance kinetics of FLX and NFLX are not affected by the abrupt switch to PAR. It was not possible to determine whether the kinetics of PAR were influenced by the residual FLX and NFLX concentrations.

A second and differentially expressed glutamyl-tRNA reductase gene from Arabidopsis thaliana

5-Aminolevulinic acid (ALA) is the universal precursor of tetrapyrroles (e.g., chlorophylls and hemes). In the chloroplasts of plants and in several eubacterial species ALA is formed in a two-step process known as the C5 pathway. In the first step, glutamyl-tRNA reductase (GluTR), converts glutamate of glutamyl-tRNA to glutamate 1-semialdehyde (GSA) which is rearranged to ALA by glutamate 1-semialdehyde-2,1-aminomutase (GSA-A) in the second step. Since ALA formation is a limiting step in chlorophyll biosynthesis, GluTR, which is encoded by the HEMA gene in Arabidopsis thaliana plays a vital role in that biosynthesis. Here we report the occurrence of a second functional HEMA gene (HEMA2) in A. thaliana. This gene was isolated by screening a genomic library with a probe from HEMA1. The nucleotide sequence of the cDNA and the corresponding genomic DNA indicates that the Arabidopsis HEMA2 gene contains two short introns (285 bp and 159 bp). The deduced amino acid sequence predicts a HEMA2 protein of 530 amino acids with 79% identity to the HEMA1-encoded GluTR. The 5'-flanking sequence of the HEMA2 gene includes several motifs (e.g., GT-1 boxes, GATA motifs) similar to light-responsive regulatory elements found in light-inducible genes. Unlike the HEMA1 transcript, which is present in all parts of the plant, HEMA2 is expressed in low levels in roots and flowers. The presence of a second functional HEMA gene in Arabidopsis raises the possibility that two C5 pathways exist in chloroplasts.

Serotonin uptake and its kinetics in platelets of women with Alzheimer's disease

The uptake of serotonin (14C-5-hydroxytryptamine, 5HT) in platelets and its kinetic characteristics were investigated in a group of women (n = 20) with probable Alzheimer's Disease (mean age = 76.0, years, SD = 8.27, range = 63-88) and in healthy normal women (n = 18, mean age = 72.6 years, SD = 7.24, range = 61-84). Both the apparent affinity of binding of 5HT to the platelet membrane (Km) and the maximum velocity (Vmax) of the rate of transport of 14C-5HT into platelets were significantly higher in the Alzheimer's Disease group than in the normal comparison group. Initial velocity of 14C-5HT uptake not passive diffusion (nonspecific uptake of 14C-5HT at 4 degrees C) differed significantly in the two groups. Our findings suggest abnormalities in the kinetic mechanisms involved in the uptake of 14C-5HT by platelets in women with Alzheimer's Disease.

Peripheral serotonin in Alzheimer's disease

The platelet has been suggested to be a peripheral model of the central serotonergic neuron. This investigation was carried out in order to test the hypothesis that levels of serotonin (5-HT) in the platelet will be decreased in Alzheimer's disease (AD) since neurochemical studies suggest that levels of 5-HT are decreased in the brain of AD patients. We investigated platelet and plasma 5-HT in a group of AD patients (n = 22) as well as in age-matched normal control subjects (n = 20). The results show that the platelet level of 5-HT was significantly reduced in AD (65.7 +/- 28.41 ng/10(8) platelets in AD vs. 112.9 +/- 35.11 ng/10(8) platelets in controls; p = 0.0001). There was no effect on the levels of its metabolite 5-hydroxyindoleacetic acid. These findings suggest that the peripheral serotonergic system in AD is adversely affected.

Rapid purification of tRNA(Lys) from rat liver

Fast protein liquid chromatography (FPLC) system using Mono Q (HR 5/5) anion-exchange column chromatography followed by highly cross-linked urea-polyacrylamide gel electrophoresis (urea-PAGE) was used for the purification of lysine-specific tRNA (tRNA(Lys)) from rat liver. Crude tRNA from rat liver was fractionated with a linear gradient of NaCl (0.3-0.8 M) in triethanolamine-HCl buffer, pH 4.5, and the activity of tRNA(Lys) was found to elute between 0.51 and 0.57 M NaCl. Using this concentration range of NaCl, tRNA(Lys) was refractionated on the same column with a shallow gradient, where a single peak of tRNA(Lys) activity was obtained. tRNA(Lys)-rich fractions recovered from the second run were electrophoretically separated on 16% polyacrylamide-7 M urea gel into one major band and three minor bands. The major band showed a specific activity of 997 pmols/A260 U for tRNALys with a 43-fold purification and approximately 17% recovery. The minor bands displayed negligible or no activity for lysine. tRNA(Lys) obtained by this method was found to be homogeneous by competitive aminoacylation. The advantages of FPLC followed by urea-PAGE in the purification of an amino acid-specific tRNA over conventional column chromatography are discussed.

Light regulation of chlorophyll biosynthesis at the level of 5-aminolevulinate formation in Arabidopsis

5-Aminolevulinic acid (ALA) is the universal precursor of tetrapyrroles, such as chlorophyll and heme. The major control of chlorophyll biosynthesis is at the step of ALA formation. In the chloroplasts of plants, as in Escherichia coli, ALA is derived from the glutamate of Glu-tRNA via the two-step C5 pathway. The first enzyme, Glu-tRNA reductase, catalyzes the reduction of Glu-tRNA to glutamate 1-semialdehyde with the release of intact tRNA. The second enzyme, glutamate 1-semialdehyde 2,1-aminomutase, converts glutamate 1-semialdehyde to ALA. To further examine ALA formation in plants, we isolated Arabidopsis genes that encode the enzymes of the C5 pathway via functional complementation of mutations in the corresponding genes of E. coli. The Glu-tRNA reductase gene was designated HEMA and the glutamate 1-semialdehyde 2,1-aminomutase gene, GSA1. Each gene contains two short introns (149 and 241 nucleotides for HEMA, 153 and 86 nucleotides for GSA1). The deduced amino acid sequence of the HEMA protein predicts a protein of 60 kD with substantial similarity (30 to 47% identity) to sequences derived from the known hemA genes from microorganisms that make ALA by the C5 pathway. Purified Arabidopsis HEMA protein has Glu-tRNA reductase activity. The GSA1 gene encodes a 50-kD protein whose deduced amino acid sequence shows extensive homology (55 to 78% identity) with glutamate 1-semialdehyde 2,1-aminomutase proteins from other species. RNA gel blot analyses indicated that transcripts for both genes are found in root, leaf, stem, and flower tissues and that their levels are dramatically elevated by light. Thus, light may regulate ALA, and hence chlorophyll formation, by exerting coordinated transcriptional control over both enzymes of the C5 pathway.

Effect of chronic DDC treatment on LHRH and substance P amidation processes in the rat

We examined the effects of chronic diethyldithiocarbamate (DDC) treatment on the concentrations of methionine-enkephalin, mature and unamidated forms (-Gly) of luteinizing hormone releasing hormone (LHRH) and substance P (SP) in various regions of the central nervous system (CNS). Chronic DDC treatment resulted in elevations of LHRH-Gly like immunoreactivity in the preoptic area (POA) and the medial basal hypothalamus (MBH), as well as elevations in SP-Gly like immunoreactivity in all areas of the CNS examined. Castration altered the ratios of SP-G-like/SP-like immunoreactivity in the pons, and LHRH-Gly like immunoreactivity in the MBH. Met-enkephalin concentrations were significantly elevated in the pons and medulla of intact DDC-treated animals, and in the POA of both intact- and castrated DDC-treated animals. Results demonstrate that it is possible to detect basal levels of unamidated LHRH and SP in many areas of the CNS, with ratios of unamidated/amidated peptides representing a unique and sensitive method for determining altered posttranslational processing of these transmitters, especially under altered endocrine states such as castration. Pharmacological blockade of terminal enzymatic processing of these peptides may be useful in studying upstream regulatory events in peptidergic neurons.

Influence of halothane and methoxyflurane on regional brain and spinal cord concentrations of methionine-enkephalin in the rat

Rats were exposed to either oxygen (controls), 1.5% halothane in oxygen, or methoxyflurane (0.5%) in oxygen over a period of 2 h, then sacrificed at the end of exposure (2-h group), 4 h after removal from environmental chamber (4-h group), or at 24 h following anesthetic exposure (24-h group). Pituitary (excluding the neural lobe, Pit), brain, and spinal cord areas were isolated and processed with Met-enkephalin tissue concentrations determined. In halothane-exposed animals, Met-enkephalin concentrations in pit and across CNS areas studied were significantly lower at 2 h following anesthetic exposure than in control animals. Concentrations of Met-enkephalin in many areas of CNS and Pit of 4-h group approached control levels. Concentrations of Met-enkephalin in all areas studied except spinal cord returned to basal levels by 24 h following halothane exposure. Exposure to methoxyflurane resulted in less dramatic changes in Met-enkephalin concentrations across CNS regions examined. Exposure to methoxyflurane resulted in significant decreases in Met-enkephalin levels in olfactory bulb, thalamus, and hippocampus only. Met-Enkephalin levels did not change significantly in other areas of the central nervous system following methoxyflurane exposure. These results indicate that halothane and methoxyflurane may have differential effects on the endogenous opioid system.

Abnormal pituitary-adrenocortical response in early HIV-1 infection

The corticotropin-adrenocortical response to cold pressor challenge was investigated in a study of human immunodeficiency virus (HIV) infection. Data obtained from 16 HIV-1-positive and 28 HIV-1-negative subjects are presented in this report. After the insertion of a venicatheter and following 30 min of rest, the subjects immersed one of their hands in an ice-water mixture for 2 min, and serial blood samples were obtained for the determination of ACTH and cortisol levels. The results show a significant blunting in the ACTH response and marginally lower levels of cortisol, over all time points, in HIV-1-positive subjects compared to that in HIV-1-negative subjects.

Arabidopsis alternative oxidase sustains Escherichia coli respiration

Glutamyl-tRNA reductase, encoded by the hemA gene, is the first enzyme in porphyrin biosynthesis in many organisms. Hemes, important porphyrin derivatives, are essential components of redox enzymes, such as cytochromes. Thus a hemA Escherichia coli strain (SASX41B) is deficient in cytochrome-mediated aerobic respiration. Upon complementation of this strain with an Arabidopsis thaliana cDNA library, we isolated a clone which permitted the SASX41B strain to grow aerobically. The clone encodes the gene for Arabidopsis alternative oxidase, whose deduced amino acid sequence was found to have 71% identity with that of the enzyme from the voodoo lily, Sauromatum guttatum. The Arabidopsis protein is expressed as a 31-kDa protein in E. coli and confers on this organism cyanide-resistant growth, which in turn is sensitive to salicylhydroxamate. This implies that a single polypeptide is sufficient for alternative oxidase activity. Based on these observations we propose that a cyanide-insensitive respiratory pathway operates in the transformed E. coli hemA strain. Introduction of this pathway now opens the way to genetic/molecular biological investigations of alternative oxidase and its cofactor.

Glutamyl-tRNA reductase from Escherichia coli and Synechocystis 6803. Gene structure and expression

In the cyanobacterium Synechocystis sp. PCC 6803 and in the enterobacterium Escherichia coli delta-amino-levulinic acid (ALA) is formed from glutamyl-tRNA by the sequential action of two enzymes, glutamyl-tRNA reductase (GluTR) and glutamate-1-semialdehyde aminotransferase. E. coli has two GluTR proteins with sizes of 45 kDa (GluTR45) and 85 kDa (GluTR85) (Jahn, D., Michelsen, U., and Söll, D. (1991) J. Biol. Chem. 266, 2542-2548). The hemA gene, isolated from E. coli and several other eubacteria, has been proposed to encode a structural component of GluTR. Because of the inability to overexpress this gene in E. coli, we demonstrate directly GluTR function for the E. coli hemA gene product by its expression and functional analysis in yeast, which does not form ALA from Glu-tRNA. Gel filtration experiments demonstrated definitively that the yeast-expressed HemA protein corresponded to GluTR45. Furthermore, analysis of GluTR activity in an E. coli strain with a disrupted hemA gene displayed GluTR85, but not GluTR45 activity. The hemA gene from Synechocystis 6803 was cloned by functional complementation in E. coli. DNA sequence analysis revealed an open reading frame capable of encoding a 427-amino acid polypeptide (molecular mass of 47,525 Da). The Synechocystis 6803 amino acid sequence shows significant similarity upon alignment with HemA sequences from E. coli, Bacillus subtilis, Salmonella typhimurium, and Chlorobium vibrioforme but does not contain the amino acid sequence derived from the N terminus of the previously purified GluTR protein (Rieble, S., and Beale, S. I. (1991) J. Biol. Chem. 266, 9740-9745). These experiments are the first direct demonstration of GluTR activity of the HemA protein and provide further evidence for two pathways of ALA formation in prokaryotes.

Synthesis and secretion of immunoreactive methionine-enkephalin from rabbit reproductive tissues in vivo and in vitro

The expression of the proenkephalin gene has been demonstrated in the reproductive tissues of several animal species. The objectives of the experiments reported here were to (a) examine the presence of immunoreactive methionine-enkephalin (ir-MENK) in rabbit ovary, oviduct, and uterus and in a rabbit endometrial cell line (HRE-H9), (b) characterize ir-MENK biochemically, (c) investigate the effect of eCG + hCG treatment on the synthesis and secretion of ir-MENK in vivo, and (d) study the effect of K+ depolarization on the secretion of ir-MENK from HRE-H9 cells. Uterine fluid was collected by flushing the uterine lumen with saline. Reproductive tissues and HRE-H9 cells were extracted with 0.1 N acetic acid. Both the uterine fluid and extracts of uterus, ovary, oviduct, and HRE-H9 cells exhibited inhibition curves parallel to that of authentic MENK in the MENK RIA system. Sephadex G-15 gel filtration profiles indicated that in the extracts of rabbit uterus and HRE-H9 cells, most ir-MENK co-eluted with standard MENK, with a minor portion eluting near the void volume (Vo). Reverse-phase-HPLC (RP-HPLC) profiles showed a major peak coinciding with standard MENK, plus a minor peak of highly hydrophilic ir-MENK. The effect of eCG + hCG treatment was studied by i.m. injection of eCG (150 IU), followed by i.v. injection of hCG (75 IU) 4 days later. Ir-MENK concentration in the uteri and ovaries was significantly (p less than 0.05) increased (9.06 +/- 1.89 and 2.05 +/- 0.32 ng/mg protein, respectively), compared to control levels (2.31 +/- 0.86 and 0.24 +/- 0.77).(ABSTRACT TRUNCATED AT 250 WORDS)

Utilisation of pearl millet (Pennisetum typhoides) for egg production

1. The performance of White Leghorn laying hens on diets providing pearl millet (Pennisetum typhoides) at 300 and 600 g/kg to replace maize, part per part, or "maize mix" isoenergetically and isonitrogenously in the first experiment and at 600 g/kg diet to replace maize in toto, part per part, in the second experiment were examined. In the first experiment, 3 groups of 12 laying hens were placed on each of the 5 dietary treatments for 3 x 28 d, whereas in the second experiment, each of the two diets was offered to 10 groups of 15 laying hens for 6 x 28 d. 2. Inclusion of pearl millet in the diet at the expense of maize, part per part, did not significantly influence hen-day egg production, feed intake, feed efficiency and body weight in either experiment. Incorporation of pearl millet isoenergetically at the expense of "maize mix" at any level, i.e. 300 g or 600 g/kg (Experiment 1), also did not influence hen-day egg production but at the end of periods 2 and 3 did result in decreased feed intakes with consequent improvements in feed efficiency. 3. Egg weight in general showed a tendency to improve with diets providing pearl millet at 600 g/kg. 4. Profits from egg sales over feed cost were directly proportional to the inclusion of pearl millet in the diet either at the expense of maize, part per part, or "maize mix" isoenergetically.

Mono Q chromatography permits recycling of DNA template and purification of RNA transcripts after T7 RNA polymerase reaction

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Prolongation of allograft survival in diabetic rats treated with cyclosporine by deoxyguanosine pretreatment of pancreatic islets of Langerhans

In vitro pretreatment of islets of Langerhans with deoxyguanosine (dGuo) has been shown to be effective for the prolongation of islet allograft survival in rats. [This study evaluates the effect of pretreatment of islets with dGuo transplanted into CsA-treated recipients.] Transplantation of dGuo-treated islets from Wistar rats into diabetic hooded (PVG) rats resulted in 36% graft survival without immunosuppression (dGuo-group) and 89% islet survival after a short course of cyclosporine was used in recipients (dGuo + CsA group). In contrast, transplantation of untreated islets into rats without immunosuppression (controls) and with CsA (CsA group) immunosuppression resulted in 0 and 56% survival, respectively. The differences in graft survival between dGuo versus control group (P less than 0.001), (dGuo + CsA) versus control group (P less than 0.0001), and CsA versus control group (P less than 0.002) are statistically significant. Donor-strain skin-graft challenge failed to induce rejection of transplanted normoglycemic rats in (dGuo) and (dGuo + CsA) groups. The results indicate that a state of immunologic unresponsiveness may have been induced in the recipients of dGuo-treated islets, and further treatment with CsA synergistically prolongs islet survival in fully mismatched rats.

Effect of nitrous oxide on the concentrations of opioid peptides, substance P, and LHRH in the brain and beta-endorphin in the pituitary

Many studies have indicated that nitrous oxide (N2O) exposure results in specific effects on the reproductive system, some of which are antigonadotropic. The neurochemical events regulating the pituitary-gonadal axis are probably influenced by N2O, but precise documentation is lacking. The effects of exposure to 30% N2O in air on the brain tissue concentrations of luteinizing hormone releasing hormone (LHRH), substance P (SP), met-enkephalin, and beta-endorphin and on beta-endorphin concentrations of the pituitary gland are described in this study. Female rats were exposed to either N2O or air for 8 hr a day over one estrous cycle, and the brain and pituitary tissues were collected and processed. Neuropeptide concentrations were measured by specific radioimmunoassays. Exposure to N2O resulted in significant elevation of LHRH in the preoptic area, with a concomitant decrease in SP. The SP concentration of the medial basal hypothalamus was significantly elevated in N2O-exposed animals. Exposure to N2O resulted in significant increases in met-enkephalin in the brainstem area and beta-endorphin in the pituitary. These results suggest that exposure to N2O alters the interactive neural system activity regulating gonadotropin secretion from the pituitary. The significance of increased met-enkephalin in the brainstem of N2O-exposed animals is not known.

Glycosidic bond cleavage of 5-fluoro-2'-deoxyuridine and 5-fluorouridine by amino acyl-tRNA synthetases

Lysyl-tRNA synthetase isolated from rat liver cleaves glycosidic bond of 5-Fluorouridine and 5-Fluoro-2'-deoxyuridine to generate 5-Fluorouracil. The generation of 5-Fluorouracil was monitored by cellulose thin layer chromatography and by spectrophotometry. The enzyme was found to be 1.4 fold more efficient in cleaving the glycosidic bond of 5-Fluoro-2'-deoxyuridine than 5-Fluorouridine.

Effect of early exposure to delta-9-tetrahydrocannabinol on the levels of opioid peptides, gonadotropin-releasing hormone and substance P in the adult male rat brain

The effects of neonatal exposure to delta-9-tetrahydrocannabinol (THC) on the adult animal brain neurochemistry and pain perception were evaluated. Newborn rat pups were culled to a litter size of 8 (males and females) and treated either with THC (2 mg/kg) or oil (control) daily, during days 1-4 after birth. After weaning, the THC-treated males were housed 4 per cage. During the juvenile period (day 50), the THC-treated animals exhibited significantly lower baseline tail-flick values (a measure of pain perception) than the control. However, as adults, the THC-treated animals exhibited significantly higher sensitivity to pain following 5 mg/kg morphine challenge. Furthermore, the THC-treated animals had significantly elevated beta-endorphin and methionine-enkephalin levels in almost all the brain areas sampled for the study. In addition, the neonatally THC-treated rats exhibited significantly higher levels of substance P (SP) and significantly lower levels of gonadotropin releasing hormone (GnRH) in the anterior hypothalamus-preoptic area. The SP and GnRH levels did not differ among the THC-treated and control animals in the medial basal hypothalamus. The results of this study indicate that even a very low dose of THC administered during the neonatal period has a long-lasting effect on the brain neurochemistry. In particular, neonatal administration of THC appears to alter functioning of the endogenous opioid system.

A spectrophotometric method for detection of 5'-fluorouracil in plasma

A quantitative method using spectrophotometry was devised for the detection of 5'-Fluorouracil (FUra) in plasma. Plasma samples obtained at different time intervals from drug treated rabbits were deproteinised using phenol. The aqueous phase was lyophilised and dissolved in 0.01 N NaOH and absorption was monitored at 305 nm. Levels of FUra in the plasma were calculated by comparing with a standard graph generated from known concentrations of FUra. As low as 1 microgram of the drug per ml of plasma could be detected by this method.

Electron and light microscopy of pancreatic islets of Langerhans isolated by Trowell's T8 medium

The isolation and purification of high yields of islets of Langerhans are important areas of investigation. Although it is well established that warm and cold ischemia affect islet yield and function, little information is available about the damage that occurs during the digestion period. We used Trowell's T8 medium and conventional Hank's balanced salt solution to obtain high yields of islets with morphologically-intact cells. Light and electron microscopy were used to characterize the islets isolated by the two media. Results reveal that the islets isolated by Trowells T8 medium were less fragmented and had better fine-structural integrity than those isolated by the conventional medium.

A modified HPLC technique for simultaneous measurement of 5-hydroxytryptamine and 5-hydroxyindoleacetic acid in cerebrospinal fluid, platelet and plasma

A sensitive, reliable and simplified HPLC assay for simultaneous measurement of 5-hydroxytryptamine (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) in human cerebrospinal fluid (CSF), platelets and plasma is described. Perchloric acid is used for one step precipitation of proteins and extraction of 5-HT and 5-HIAA. Precision of the assay has been increased by calibration of the instrument using serotonin-free plasma spiked with known amount of standards and N-w-methyl-5-hydroxytryptamine as internal standard. Integration of the peaks and calculations are achieved by a preprogrammed data module using ratio method. As little as 20 pg/ml of serotonin in the deproteinated sample can be detected using this procedure. In a group of surgical patients, plasma 5-HT concentration is (Mean +/- S D) 3.4 +/- 2.7 ng/ml and that of platelet 748.3 +/- 448.3 ng/10(9) platelets. In CSF, 5-HT is found to be 3.3 +/- 3.4 ng/ml and 5-HIAA is 15.1 +/- 7.3 ng/ml. A good correlation (r = 0.648, p less than .0001) is observed between 5-HT and 5-HIAA in CSF.

Rapid isolation of lysyl-tRNA synthetase from rat liver

The high molecular weight aminoacyl-tRNA synthetase complex (the 24S complex) was isolated from rat liver by ultracentrifugation. The lysyl-tRNA synthetase (E.C. 6.1.1.6) was selectively dissociated by hydrophobic interaction chromatography on 1,6 diaminohexyl agarose followed by hydroxylapatite chromatography and DEAE chromatography. The lysyl-tRNA synthetase dissociated from the 24S synthetase complex was purified approximately to 2700 fold with 14% yield.

Intracellular sodium in proximal tubules of diabetic rats. Role of glucose

Renal hypertrophy is a common consequence of diabetes mellitus that precedes and possibly accounts for the increased glomerular filtration rate. We have postulated that the glucose-mediated increase in the intracellular concentration of sodium [Na]i initiates the chain of events leading to the increase in cell size and eventually cell number. Experiments were conducted on Sprague-Dawley rats made diabetic by the intravenous injection of 45 mg/kg body wt of streptozotocin dissolved in a 5 mM citrate buffer solution. Control animals were injected with the vehicle alone. Ninety-six hours and 11 weeks later, measurements of [Na]i were done by NMR spectroscopy on suspensions of proximal tubules, using dysprosium tripolyphosphate as an extracellular shift reagent. At 96 hours after the induction of the diabetes, there was a 60% increase in [Na]i compared to control (P less than 0.01). No further increase in [Na]i was observed during the subsequent 11 weeks of observation. Addition of ouabain (1.0 mM) resulted in a fourfold increase in [Na]i in tubules from control animals, and a 2.5-fold increase in tubules from 96-hour diabetic rats. Ouabain-inhibitable Na+-K+-ATPase activity was substantially higher in the renal tubules of diabetic rats, the increase being proportional to that of [Na]i. In order to ascertain the effect of hyperglycemia on [Na]i, proximal tubules prepared from kidneys of normal and diabetic rats were exposed to low (5 mM) and high (25 mM) concentration of glucose in the media.(ABSTRACT TRUNCATED AT 250 WORDS)

Renal reabsorption of phosphate during development: tubular events

Studies performed in our laboratory on the isolated perfused kidney of the guinea pig have demonstrated that the rate of Pi reabsorption is substantially greater in the newborn than in the adult, when appropriate corrections are being made either for differences in glomerular filtration rate (GFR) or in renal tubular mass. In order to determine the location of this enhanced reabsorption along the nephron, micropuncture experiments were performed on euvolemic, non-fasted guinea pigs 5-14 and 42-49 days of age, maintained on standard guinea-pig chow diet (0.76% Pi). Concomitant measurements of overall kidney function were also obtained. The results confirmed that fractional reabsorption of Pi (TRPi%) across the entire kidney was significantly higher (P less than 0.01) in the newborn (89.93 +/- 2.55%) than in the adult (78.25 +/- 2.89%) animals. The difference was also significant (P less than 0.05) when TRPi was expressed in mol/ml GFR (1.87 +/- 0.14 vs 1.53 +/- 0.12, respectively). At comparable locations along the proximal tubule (TF/Pin of 1.90 +/- 0.16 in the newborn, and 1.79 +/- 0.15 in the adult, P greater than 0.70), the fraction of the filtered load of Pi reabsorbed was significantly higher (P less than 0.001) in the immature (76.66 +/- 2.74%) than in the mature (67.21 +/- 2.74%) guinea pigs. Estimates based on the differences between proximal Pi reabsorption and the urinary excretion of Pi indicate that the reabsorption of Pi in tubular segments located beyond the proximal tubule is also enhanced in the newborn when compared with the adult (15.62 +/- 2.11% vs 10.51 +/- 1.83%, respectively, P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Factors affecting proximal tubular reabsorption during development

Studies performed in several animal species have demonstrated that glomerulotubular balance is maintained throughout development despite the many changes that occur in the factors known to control it. In an attempt to understand the nature of this phenomenon we quantified the magnitude and described the profile of these changes in guinea pigs. The changes in physical forces were assessed from measurements of hydrostatic and oncotic pressures, whereas those in the permeability characteristics of the proximal tubule epithelium were estimated from permeance to macromolecules of graded radii, histologic measurements of the intercellular channels, and measurements of end-proximal ratio of tubular fluid-to-plasma osmolality (TF/Posm). Between 1 and 50 days of age the net pressure for reabsorption increased from 15.0 to 30.9 mmHg (P less than 0.01, n = 15) with the major change occurring during the first 2-3 wk of postnatal life. The urinary recovery of inulin, sucrose, and creatinine, injected in the early segment of proximal tubules did not vary with age. The urinary recovery of mannitol (MW 180 daltons, Stokes-Einstein radius 4.0 X 10(-10) m) increased from 92% at birth to 100% at 49 days of age (P less than 0.001, n = 24), consistent with a decrease of approximately 0.5 X 10(-10) m in the luminal openings of the paracellular channels. The length of the zonulae occludens and the width of the intercellular channels did not change during this period; however, the length of the channels increased from 5.0 +/- 0.17 to 8.9 +/- 0.48 micron (P less than 0.01, n = 16). These changes should result in an increase in resistance across the intercellular channels. Consistent with this assertion is the observation that the mean TF/Posm of the fluid collected toward the end of the proximal convoluted tubule decreased as a function of age from 1.05 at day 2 to 0.98 at day 80 (P less than 0.001, n = 24). The findings support the hypothesis that during early postnatal life glomerulotubular balance is made possible by a high permeability of the proximal tubule, which compensates for the low net reabsorptive pressure. As the animal matures and the proximal tubule epithelium becomes tighter, for glomerulotubular balance to be maintained, an increase in the number of intercellular channels and in the active transport of sodium need to be postulated.

NMR measurement of intracellular water volume in rat kidney proximal tubules

Knowledge of cell water volume is essential for the measurement of concentrations of intracellular ions and metabolites in kidney proximal tubules. We have developed a method which utilizes 35Cl-NMR as a measure of extracellular volume and 2H-NMR, in combination with a membrane-impermeable shift-reagent [Dy-DTPA]2-, as a measure of the ratio of intra- and extracellular water volumes. Measurement of extracellular volume by 35Cl-NMR is possible, since the resonance of intracellular 35Cl is too broad to be detectable in kidney cells. The 2H-NMR measurement exploits the fact that only extracellular water is in direct contact with [Dy-DTPA]2-. However, rapid exchange of water across the cell membrane results in only a single 2H2O resonance at a chemical shift which is a weighted average of the shifted extra- and unshifted intracellular water resonances. Expression of the extracellular volume as a fraction of the total volume by fCl and as a fraction of the total water-volume by fD, permits the calculation of the fractional cell-water content fw = [(1/fD)-1]/[(1/fCl)-1]. This approach was applied to proximal tubular suspensions prepared from the rat kidney. The water content was found to be 76.9 +/- 1.8% (n = 6) at 37 degrees C. Increasing extracellular osmolality from 295 to 390 mOsm/kg H2O, by addition of mannitol, decreased the water content by 21%. Our results are in good agreement with those obtained by the gravimetric method.

23Na NMR spectroscopy of proximal tubule suspensions

Intracellular sodium concentrations in proximal tubule suspensions of rat kidney were measured by NMR spectroscopy. A simple method for the preparation of proximal tubule suspension is described. Examination by light microscopy revealed these preparations to contain 93.6 +/- 0.6% (N = 5) proximal tubules, and electron microscopy demonstrated that the tubules were open. When incubated with trypan blue for five min, only 2% of tubules picked-up the dye. The basal oxygen consumption rate was 0.42 +/- 0.01 microliter min-1 mg protein-1 (N = 6). Addition of succinate (5 mM) resulted in a fivefold increase in the rate of oxygen consumption. The 23Na spectra were obtained in proximal tubules incubated for 30 min in the aqueous shift reagent dysprosium tripolyphosphate Dy(PPPi)2(7-). The NMR observable sodium concentration was 34.1 +/- 1.8 mM at room temperature and 16.3 +/- 0.6 mM (P less than 0.001) at 37 degrees C. Addition of ouabain (10(-4) M) at 37 degrees C resulted in an increase in intracellular sodium to 30.9 +/- 2.9 mM (P less than 0.001), while nystatin increased the concentration of sodium to 72.0 +/- 9.1 mM (P less than 0.001), compared to basal concentration. Thus NMR permits the measurement of intracellular concentration of sodium in proximal tubules under basal conditions and to monitor, in the same preparation, the changes that occur under various experimental conditions without interfering with the morphologic integrity of the cells.

Early exposure to delta 9-tetrahydrocannabinol influences neuroendocrine and reproductive functions in female rats

Sexual differentiation of the rat brain is affected by certain compounds administered during the neonatal period. We evaluated the effects of exposure to THC during the critical period of sexual differentiation of the female rat brain on postpubertal estrous cycles and brain neurotransmitter levels. Newborn female rats were injected either with vehicle (oil) or with different doses of THC (0.38; 1.9 or 3.8 mg/100 g) subcutaneously during the first 5 days after birth. The rats were examined daily by vaginal lavage smears from 3 to 10 months of life for phases of estrous cyclicity. The animals were then sacrificed and the anterior hypothalamus preoptic area (AHPOA) and medial basal hypothalami (MBH) were collected, processed and the methionine-enkephalin (met-enkephalin), beta-endorphin-like immunoreactivity (beta-end LI), LHRH and substance-P were measured by radioimmunoassays. In addition, serum LH and prolactin levels were measured by radioimmunoassay. Compared with the control rats, the rats perinatally exposed to THC exhibited either constant metestrus diestrus type vaginal smears or irregular estrous cycles. In the THC-treated animals, the met-enkephalin and beta-end LI levels were lower in the AHPOA and higher in the MBH. The LHRH levels of THC-treated rats were significantly lower in the MBH. The substance-P levels were significantly lower in the AHPOA of THC treated animals. In the THC-treated rats, serum LH was low but, the prolactin levels were not significantly different from the control animals.(ABSTRACT TRUNCATED AT 250 WORDS)

Evidence for PAH extraction from superficial cortical efferent vessel plasma

Consistent with its anatomical association with the proximal tubule we have previously shown that superficial cortical efferent vessel blood contains an admixture of early and late proximal tubular reabsorbate. Since tubular secretion of p-aminohippurate (PAH) occurs predominantly in the late proximal tubule, extraction of this compound should occur preferentially from efferent vessel blood. As a result, the midportion of the proximal convoluted tubule supplied by the more downstream peritubular capillaries would receive blood containing a disproportionately reduced concentration of PAH. To study this, proximal and distal tubular fluid and efferent vessel blood samples were collected from rats. The data confirm that preferential secretion of PAH occurs in the pars recta and demonstrate that PAH is extracted from efferent vessel plasma by the pars recta. This in turn preferentially reduces PAH concentration in early postglomerular blood before it reaches the peritubular capillary network. We speculate that PAH and similar substances secreted by the pars recta are short-circuited by rapid extraction from early postglomerular blood, reducing their delivery to the mid-proximal convoluted tubule. Such circumstances must be considered in any analysis of organic compound secretion by the in vivo proximal tubule.

Protein quality of the bacterium Hydrogenomonas eutropha

Hydrogenomonas eutropha cells harvested from semicontinuous autotrophic culture and washed free of substrate contain about 13% of nitrogen on a dry-solids basis. Biological value and digestibility of the bacterial nitrogen were determined in the rat by use of an abbreviated Mitchell-Thomas nitrogen balance technique and casein as the standard protein. Casein nitrogen was 99% digestible, and that of both whole boiled and sonically ruptured bacterial cells was 93%. Biological value of casein and the bacterial preparations was uniformly 77%. Amino acid composition of the bacteria, as in the case of casein, indicates a first limitation of sulfur-containing amino acids. These compositional features suggest that H. eutropha may be potentially valuable as a protein supplement in animal feeds.