Age-related changes in regional brain mitochondria from Fischer 344 rats.

Brain mitochondrial function has been posited to decline with aging. In order to test this hypothesis, cortical and striatal mitochondria were isolated from Fischer 344 rats at 2, 5, 11, 24 and 33 months of age. Mitochondrial membrane potential remained stable through 24 months, declining slightly in mitochondria from both brain regions at 33 months. The ability of calcium to induce mitochondrial swelling and depolarization, characteristics of the permeability transition, was remarkably stable through 24 months of age and increased at advanced ages only for cortical, but not striatal, mitochondria. Striatal mitochondria were more sensitive to calcium than were cortical mitochondria throughout the first 2 years of life. A two-fold increased resistance to calcium was observed in striatal mitochondria between 5 and 11 months. Although these measurements do demonstrate changes in mitochondrial function with aging, the changes in polarization are relatively small and the increased cortical susceptibility to the permeability transition only occurred at very advanced ages. Thus mitochondrial decline with advanced age depends upon brain region.

Differential cytotoxicity and DNA-damaging effects produced in human cells of the Mer+ and Mer- phenotypes by a series of 1-aryl-3-alkyltriazenes.

A series of arylalkyltriazenes has been investigated for its differential cytotoxicity towards the HT-29 (Mer+) and BE (Mer-) cell lines and for its ability to cause DNA strand breaks and cross-links. A monomethyltriazene (MMPT) and some hydroxymethyltriazene derivatives capable of generating the monomethyltriazene in situ were preferentially cytotoxic to the BE cell line when compared with the HT-29 cell line. The differential toxicity of MMPT is very similar to the analogous monochloroethyltriazene. In contrast, the dimethyl- and monoethyltriazenes in the series display reduced toxicity towards the BE cell line with little or no differential toxicity between the BE and HT-29 cell lines. MMPT and monochloroethyltriazene caused single strand DNA breaks in the two cell lines, whereas little or no DNA strand breaks were observed in either cell line after exposure to the monoethyl- or dimethyltriazene. However, these lesions could not account for the differential cytotoxicity observed. In measurements of DNA interstrand cross-linking none of the agents tested, including monochloroethyltriazene and MMPT, was found to cause such linkages. In contrast to previous results obtained with bifunctional monochloroethylating agents, which produced a similar differential cytotoxicity between these two cell lines, our results tend to suggest that lesions other than DNA interstrand cross-links may be responsible for the mechanisms of cell killing by chloroethylating agents.

Prenatal malnutrition and development of the brain.

In this review, we have summarized various aspects as to how prenatal protein malnutrition affects development of the brain and have attempted to integrate several broad principles, concepts, and trends in this field in relation to our findings and other studies of malnutrition insults. Nutrition is probably the single greatest environmental influence both on the fetus and neonate, and plays a necessary role in the maturation and functional development of the central nervous system. Prenatal protein malnutrition adversely affects the developing brain in numerous ways, depending largely on its timing in relation to various developmental events in the brain and, to a lesser extent, on the type and severity of the deprivation. Many of the effects of prenatal malnutrition are permanent, though some degree of amelioration may be produced by exposure to stimulating and enriched environments. Malnutrition exerts its effects during development, not only during the so-called brain growth spurt period, but also during early organizational processes such as neurogenesis, cell migration, and differentiation. Malnutrition results in a variety of minimal brain dysfunction-type syndromes and ultimately affects attentional processes and interactions of the organism with the environment, in particular producing functional isolation from the environment, often leading to various types of learning disabilities. In malnutrition insult, we are dealing with a distributed, not focal, brain pathology and various developmental failures. Quantitative assessments show distorted relations between neurons and glia, poor formation of neuronal circuits and alterations of normal regressive events, including cell death and axonal and dendritic pruning, resulting in modified patterns of brain organization. Malnutrition insult results in deviations in normal age-related sequences of brain maturation, particularly affecting coordinated development of various cell types and, ultimately, affecting the formation of neuronal circuits and the commencing of activity of neurotransmitter cell types and, ultimately, affecting the formation of neuronal circuits and the commencing of activity of neurotransmitter systems. It is obvious that such diffuse type "lesions" can be adequately assessed only by interdisciplinary studies across a broad range of approaches, including morphological, biochemical, neurophysiological, and behavioral analyses.

Hereditary paroxysmal ataxia: response to acetazolamide.

From early childhood, eight patients in a kindred had paroxysmal bouts of ataxia, dysarthria, and nystagmus. The disorder was inherited as an autosomal dominant. Attacks occurred weekly and lasted 1 to 6 hours; there were slight cerebellar signs between attacks. Although the etiology was not determined, a serendipitous trial of acetazolamide completely abolished attacks, and all patients have remained free of attacks for as long as 5 years.

Protein synthesis in liver following infusion of the catabolic hormones corticosterone, epinephrine, and glucagon in rats.

The mediator(s) and mechanism(s) of acute-phase protein synthesis in the liver following injury and sepsis are not fully known. Elevated plasma levels of the catabolic hormones cortisol, glucagon, and epinephrine have been reported in trauma and sepsis. In previous reports, when these hormones were infused simultaneously (triple hormone infusion), several, but not all, of the metabolic alterations characteristic of sepsis occurred. In the current investigation, the effect of triple hormone infusion on hepatic protein synthesis was studied. Rats were infused intravenously during 16 hours with a solution containing corticosterone (4.2 mg/kg/h), glucagon (2.5 micrograms/kg/h), and epinephrine (6 micrograms/kg/h). Control animals were infused with a corresponding volume of vehicle. Total hepatic protein synthesis in vivo was measured with a flooding dose technique using [14C]-leucine. The synthesis of total secretory proteins and of the individual proteins albumin, complement component C3, and alpha 1-acid glycoprotein was measured in isolated, perfused liver using [3H]-leucine and a recirculating technique. Urinary excretion of nitrogen and plasma concentration of glucose were higher and plasma total amino acid concentration was lower in hormone-infused than in control rats. Total hepatic protein synthesis in vivo, expressed as the proportion of the protein pool that was replaced each day, was increased from 39% +/- 2% per day to 48% +/- 3% per day (P less than .05) by hormone infusion, but synthesis of secretory proteins in perfused liver was not significantly altered. The results suggest that although total hepatic protein synthesis may be increased by catabolic hormones, other mediator(s) are probably responsible for the stimulation of acute-phase protein synthesis in sepsis.

Regional brain amino acid and neurotransmitter derangements during abdominal sepsis and septic encephalopathy in the rat. The effect of amino acid infusions.

Regional amino acids and brain neurotransmitters were studied in 33 normal and 32 rats with sepsis (induced by cecal ligation and puncture) infused with different amino acid formulations. The brain amino acid pattern during sepsis showed increased concentrations of most essential and six of the nonessential amino acids. The most consistent finding was the accumulation of indoleamines in all six brain regions studied during sepsis; increased brain tryptophan levels presumably resulted in enhanced metabolism of serotonin (5HT), increased production of 5-hydroxyindoleacetic acid (5HIAA), and a high 5HT/5HIAA ratio. Infusion of branched-chain amino acid-enriched formulas restored brain amino acid and neurotransmitter profiles, decreasing levels of tryptophan, tyrosine, 5HIAA, and 5HT/5HIAA ratios while increasing norepinephrine levels in some regions. These alterations in brain neurotransmitter metabolism may be at least partially responsible for the development of septic encephalopathy.

Muscle prostaglandin production in the rat. Effect of abdominal sepsis and different amino acid formulations.

Recent in vitro studies attribute regulatory functions to prostaglandins (PGs) in muscle protein metabolism, particularly enhancing proteolysis. In the present study, the amount of muscle PG production from endogenous precursors was determined in control and septic animals (cecal ligation and puncture) that were infused with 5% dextrose or dextrose with three amino acid formulations differing in their branched-chain amino acid (BCAA) content. We could not detect any differences in prostaglandin E, 6-keto-prostaglandin F1 alpha, and thromboxane B2 production between control and septic animals. Furthermore, the infusion of BCAAs, which have previously been shown to be nitrogen sparing following injury, did not influence the production of any of the PGs studied in either control or septic muscle. It is likely that the effects of the BCAAs on muscle synthesis and degradation are independent of the PGs.

The effect of indomethacin on muscle and liver protein synthesis and on whole-body protein degradation during abdominal sepsis in the rat.

It has been recently suggested that increased muscle protein degradation during injury or infection is at least partially mediated by the increased production of prostaglandin E2 in muscle, and some have suggested that cyclooxygenase inhibitors might decrease protein loss in injured or septic patients. In these experiments, fractional synthesis rates of mixed muscle and liver protein and whole-body tyrosine flux were measured by constant intravenous infusion of tyrosine labeled with carbon 14 in 17 rats with sham operations and 15 severely septic rats with or without indomethacin treatment (20 mg/kg/d). Fractional synthesis rates in muscle and liver were decreased in late sepsis and were lowest in the septic group receiving indomethacin. Unlike the fractional synthesis rate, which was affected by indomethacin in septic rats only, tyrosine flux was significantly lower in indomethacin-treated rats with sham operations and those with sepsis. Although indomethacin reduced total-body protein breakdown during sepsis, it was also associated with lower plasma albumin levels and with decreased protein synthesis in muscle and liver at a time when the survival of the septic host may be dependent on its ability to produce new protein for a variety of vital functions. These results do not support the use of indomethacin in sepsis.

Power spectral analysis of hippocampal and cortical EEG activity following severe prenatal protein malnutrition in the rat.

We have studied the effects of prenatal protein malnutrition on development of the hippocampal and frontal cortical electroencephalographic (EEG) activity. Using power spectral analyses in rats of several age groups we found that protein malnutrition, instituted prenatally and continued postnatally, produces marked alterations in power spectral measures, i.e., alterations in peak theta frequency in the hippocampus during rapid eye movement (REM) sleep. Peak theta frequency was found to be significantly retarded in malnourished animals, especially during the preweaning period of development. Protein malnutrition, therefore, appears to affect mechanisms responsible for generating the tonic component of theta activity.

Effects of prenatal protein malnutrition on perforant path kindling in the rat.

Rats born to dams fed either a 6% (malnourished) or 25% (control) casein diet during gestation were all fostered to lactating dams on the 25% casein diet 24 h after birth and were maintained on this diet throughout life following weaning. At 90-120 days of age electrographic and behavioral responses to electrical kindling of the medial perforant pathway were investigated in animals from both the straight 25% diet (designated 25%/25% for the pre- and postnatal periods) and the dietary rehabilitated (designated 6%/25% casein diet for the pre- and postnatal periods) groups. Animals of the dietary rehabilitated group (6%/25%) were found to: (1) require a significantly lower stimulus intensity to evoke afterdischarge activity in the ipsilateral dentate gyrus; (2) progress through the various behavioral stages of kindling in a markedly different manner from the 25%/25% group, and; (3) require significantly more daily kindling stimulations to attain the full motor convulsive stage indicative of the kindled state. These results indicate that dietary protein rehabilitation at birth is incapable of reversing or significantly ameliorating the effects of gestational protein deficiency on susceptibility to seizure activity and acquisition of the kindled state. These findings indicate that gestational protein deficiency results in long-lasting, if not permanent, changes in neuronal systems in the hippocampal formation which are involved in both the electrographic and behavioral correlates of the kindling process.

Effect of protein malnutrition on hippocampal kindling: electrographic and behavioral measures.

Rats born to dams fed either a 6% (malnourished) or a 25% (control) casein diet during gestation and lactation and maintained on the diet of the dam after weaning were tested for electrographic and behavioral responses to electrically induced kindling of the CA1 field of the hippocampus beginning at 44 days of age. Animals in the 6% diet group had a significantly lower threshold to afterdischarge (AD), a significantly faster spread of AD activity to distal recording sites, significantly longer average duration of AD activity at all recording sites and a markedly altered behavioral progression toward seizure activity compared to control animals. These findings indicate that prenatal protein malnutrition results in hippocampal dysfunction as evidenced by both the electrographic and behavioral correlates of the kindling process. The data presented suggest that prenatal proteins malnutrition alters the response of hippocampal CA1 pyramids to electrical stimulation and that this alteration results in marked changes to both the electrographic and behavioral correlates of kindling.

Spectral analysis of the electroencephalogram in the developing rat.

Power spectral measures of the EEG obtained from the frontal cortex and hippocampal formation during different vigilance states in the developing rat have been computed and compared. The most significant ontogenetic changes were observed in the hippocampal power spectra obtained during the vigilance state of REM sleep. These spectral analyses have revealed in the hippocampus: (1) a significant increase in the frequency at which the peak power occurs in the theta-frequency (4-11 Hz) band from 14 to 45 days of age; (2) a decrease in the quality factor of the peak from 14 to 45 days of age; (3) a decrease in the relative power co-ordinate for the center of spectral mass associated with the 0-4-Hz frequency band coupled with an increase in the frequency coordinate of the 4-11-Hz frequency band from 14 to 45 days of age, and; (4) a significant decrease in the average percent relative power associated with the 0-4-Hz frequency band from 14 to 22 days of age. For the EEG obtained from the frontal cortex, the major findings of note were: (1) a dominant contribution of relative power in the 0-4-Hz frequency band which was observed at every age and during every vigilance state tested, and; (2) a significant increase in the average percent relative power associated with this band at 18, 22, and 45 days of age. The results of this study provide a quantitative description of the electroencephalographic (EEG) ontogeny of the hippocampal formation and the frontal cortex in the rat. These ontogenetic changes in EEG activity relate closely to development of the internal circuitry and synaptic maturation in the hippocampal formation and frontal cortex.

Studies of dentate granule cell modulation: paired-pulse responses in freely moving rats at three ages.

Dentate granule cell population responses to paired-pulse stimulations applied to the perforant pathway across a range of interpulse intervals (IPI) were examined in freely moving rats at 15, 30, and 90 days of age. The profile of the paired-pulse index (PPI), a measure of the type and degree of modulation of dentate granule cell excitability, was shown to change significantly as a function of age.

Prenatal protein malnutrition and hippocampal function: rapid kindling.

A stimulation paradigm evoking rapidly recurring seizure activity from the hippocampal dentate gyrus was used to examine perforant path kindling in prenatally protein malnourished adult rats. Biphasic electrical stimulations (50 Hz) of five s duration were applied to the perforant path every five min for one hour over five consecutive days. Behavioral manifestations of seizure activity were assessed using the standard 0-5 scale. Prenatally malnourished rats exhibited significantly fewer convulsive seizures (stage 5) and required significantly more stimulations to attain the first stage 5 seizure than controls. Animals of the malnourished group also exhibited significantly more stage 1 seizures than control animals, indicating a significant retardation in the kindling rate of these animals. Additionally, 3 of the 11 malnourished animals failed to exhibit a single stage 5 seizure during the 60 stimulation test period. These findings parallel previous results reported for prenatally protein malnourished rats using the traditional one stimulation-per-day kindling paradigm and indicate that this rapid kindling paradigm can be effectively used to study the impact of various insults on seizure susceptibility and development in a shortened time frame.

Quantitative analysis of long-term potentiation in the hippocampal dentate gyrus of the freely-moving 15-day-old rat.

The magnitude and duration of long-term potentiation (LTP) of perforant path/dentate granule cell synapses was examined in freely moving rats beginning at 15 days of age. Measures of dentate granule cell population EPSP slope and population spike amplitude (PSA) obtained before and after tetanization were used to evaluate the level of LTP. Tetanization resulted in significant enhancement of both the population EPSP slope (approximately +75%) and PSA (approximately +40%) measures. This enhancement was maintained without significant change for 18 h, after which both measures began a steady and continuous rise. Daily input/output response measures from age-matched nontetanized animals were used to factor out enhancement related to normal development. Under this schema, tetanization-induced enhancement of both EPSP slope and PSA measures decayed slowly, beginning 18-24 h after tetanization, returning to baseline 5 days after tetanization. Enhancement obtained from 90-day-old animals decayed to baseline 24 h after tetanization. The longer duration of LTP obtained from preweanlings is discussed with regard to the development of inhibitory systems modulating granule cell excitability.

Neonatal isolation alters LTP in freely moving juvenile rats: sex differences.

We have previously reported that neonatal isolation significantly enhanced the magnitude of hippocampal long-term potentiation (LTP) recorded from freely moving male rats tested at 30 days of age. The present study extends this work to examine the effects of neonatal isolation on hippocampal LTP in male and female juvenile rats. Changes in dentate granule cell population measures, i.e., EPSP slope and population spike amplitude (PSA), evoked by tetanization of the medial perforant pathway were used to assess the effects of neonatal isolation on LTP over a period of 96 hrs. Prior to tetanization, significant sex differences were obtained for input/output (I/O) response measures of EPSP slope and PSA, with males showing consistently higher values than females. No significant effect of treatment was obtained within either sex for baseline measures. Following tetanization significant sex differences were also obtained for both measures, with males showing significantly greater enhancement than females. Comparisons made at 1 hr post-tetanization (establishment of LTP) indicated that isolated males showed significantly greater enhancement than any other group. On the other hand, treatment differences were not obtained from females. At 96 hrs (maintenance of LTP), however, both neonatally isolated males and females showed significantly greater enhancement than either non-isolated siblings or unhandled controls. These results indicate that males and females exhibit different enhancement profiles with respect to both the magnitude and duration of LTP, and that neonatal isolation alters these profiles in a sex-specific manner.

Prenatal protein malnutrition alters behavioral state modulation of inhibition and facilitation in the dentate gyrus.

We have examined the effects of prenatal protein malnutrition on interneuronally mediated inhibition and facilitation in the dentate gyrus of the rat using the paired-pulse technique. Field potentials were recorded in the dentate gyrus in response to paired stimuli delivered to the perforant path. The paired-pulse index (PPI) was used as a measure of the net short-term facilitation or interneuronally mediated inhibition effective at the time of the paired-pulse test and was computed by dividing the amplitude of the second population spike (p2) by the amplitude of the first population spike (p1). PPIs were classified according to p1 in order to compare PPIs between behavioral states and dietary treatments since population spike amplitudes in the dentate gyrus vary in relation to behavioral state. Testing was performed during 4 behavioral states: slow-wave sleep (SWS), paradoxical sleep (REM), immobile waking (IW) and exploratory locomotion (AW) using interpulse intervals (IPI) from 20 to 400 ms. The magnitude and duration of interneuronally mediated inhibition was significantly increased in prenatal protein malnourished animals when compared with controls. Paired-pulse tests performed using an IPI of 20 ms under the high p1 (p1 greater than median) condition showed significantly smaller PPIs in prenatal protein malnourished rats regardless of behavioral state. For IPIs greater than 20 ms PPIs were consistently smaller in prenatal protein malnourished rats during SWS and IW. These data indicate that both the magnitude and duration of interneuronally mediated inhibition are increased in prenatally malnourished rats. No consistent diet-related differences were found during AW and REM using IPIs greater than 20 ms because interneuronally mediated inhibition was relatively suppressed during these behavioral states for both dietary groups. There was no consistent behavioral state modulation of paired-pulse facilitation (IPI = 40 to 80 ms) or late inhibition (IPI = 400 ms) in either diet group. In addition, a new relation between PPI and IPI was found under the low p1 (p1 greater than median) condition. During AW the PPIs observed using IPIs of 40 and 50 ms were smaller than those observed using IPIs of 30 and 60 ms. This depression interrupts what is generally considered the "facilitatory" phase of paired-pulse response and may indicate an interaction between perforant path stimulation and hippocampal theta rhythm which is masked when p1 amplitude is high.(ABSTRACT TRUNCATED AT 400 WORDS)

Treatment of an infected silicone right atrial catheter with combined fibrinolytic and antibiotic therapy: case report and review of the literature.

Tunnelled silicone rubber right atrial catheters are commonly used to administer long-term total parenteral nutrition (TPN), cancer chemotherapeutic agents, and antimicrobial agents. The indwelling devices potentiate platelet-fibrin thrombi formation, providing a nidus for infection. Although many episodes of sepsis associated with thrombotic tunnelled catheters respond to antimicrobial therapy alone, a significant number require catheter removal. Evidence from case studies and small clinical trials suggests that fibrinolytic agents may increase the response rate and prevent removal of the device when combined with antimicrobial therapy. We present the first case reported of bacterial sepsis secondary to a thrombotic indwelling Hickman catheter for long-term TPN successfully treated with a combination of streptokinase and antibiotic therapies.

Fat emulsion effects on prothrombin time in warfarin anticoagulated patients: an in vitro study.

The effect of lipid emulsions on prothrombin time in blood from anticoagulated patients was determined. Blood samples were obtained from 23 patients therapeutically anticoagulated with warfarin (prothrombin time 1.3-2.0 x control). Varying amounts of an intravenous lipid emulsion (Intra-lipid) were added to the blood to simulate concentrations seen in vivo with a constant lipid infusion. The prothrombin time was measured on the plasma from these samples and compared to the prothrombin time of the plasma samples without lipid. The mean decrease in prothrombin times were: 0.29 sec at 50 micrograms/ml, 0.23 sec at 100 micrograms/ml, and 0.29 sec at 200 micrograms/ml. All concentrations showed a statistically significant decrease (p less than 0.05) when compared to the control by the Scheffe test. Lipid emulsions appear to decrease the prothrombin times in anti-coagulated patients. The differences however, were small and not of clinical significance at the concentrations tested.

The effect of different intravenous nutritional regimens on renal function during acute renal failure in the rat.

Acute renal failure in the surgical patient is accompanied by a state of hypermetabolism and increased catabolism. Nutritional therapy is therefore directed at the preservation of body cell mass and protein synthesis for repair of wounds and damaged renal tubuli and for maintenance of host defense mechanisms. We examined the effect of two levels of protein intake (18.4 +/- 1.4 and 30.8 +/- 2.4 mg N/100 g BW/day) and three different amino acid formulations (Freamine III, Nephramine, and a made-up mixture of Nephramine + Freamine HBC) on renal function following mercury chloride-induced acute renal failure in the rat. All animals suffered severe renal failure manifested by increased plasma urea and creatinine levels, decreased creatinine clearance, and increased fractional excretion of sodium. On day 4 of acute renal failure, rats receiving low dose amino acids had better-preserved renal function than those receiving high dose amino acids. However, the type of solution infused did not affect recovery of renal function.