Bioavailability of co-supplemented organic and inorganic zinc and selenium sources in a white fishmeal-based rainbow trout (Oncorhynchus mykiss) diet.

The bioavailability of trace elements in fishmeal diets is influenced by their chemical forms and dietary anti-nutritional factors. In formulated fish feed, supplemented organically bound minerals may be more bioavailable than inorganic minerals. A 10-week feeding trial was undertaken with rainbow trout (Oncorhynchus mykiss) to determine whether the inclusion of organically bound selenium (Se) and zinc (Zn) improved uptake and assimilation of these elements compared to commonly used inorganic forms. The three diets tested included a control diet, no added Zn or Se; an organic Se-yeast and Zn-proteinate supplemented diet; and an inorganic sodium selenite and Zn-sulphate supplemented diet. The endpoints tested were apparent digestibility, whole body levels, tissue distribution and Se- and Zn-dependent enzyme activities. Digestibility of residual Se in the basal diet was 54.2 +/- 1.0% and supplemented Se-yeast was significantly more digestible than selenite (p < 0.05). Digestibility of residual Zn was 21.9 +/- 2.0% and no significant difference was found between the treatments (p = 0.89). Whole body Se was raised by both Se sources and to a greatest extent by Se-yeast (p < 0.001). Zn-sulphate, and to a lesser extent Zn-proteinate, both raised whole body Zn (p < 0.05). Dietary Zn in the basal diet was found to be above requirements, yet Zn-sulphate had a significantly greater retention than Zn-proteinate in those tissues that responded to Zn supplementation. Se-yeast significantly raised Se in all tissues to a greater extent than selenite, except in the pyloric caeca and liver where the greatest increases were by selenite. Only Se-yeast elevated Se-dependent thioredoxin reductase activity (p < 0.05) and neither forms of Se affected glutathione peroxidise activity (p = 0.059). Alkaline phosphatase and carboxypeptidase B were not affected by Zn supplementation (p = 0.51 and p = 0.88 respectively). In all aspects, Se-yeast was found to be a highly bioavailable form of Se in comparison to selenite. Because of its superior bioavailability, organically bound Se would be a preferred Se source for supplementation of fishmeal trout diets than selenite.

Cortical edema in moderate fluid percussion brain injury is attenuated by vagus nerve stimulation.

Development of cerebral edema (intracellular and/or extracellular water accumulation) following traumatic brain injury contributes to mortality and morbidity that accompanies brain injury. Chronic intermittent vagus nerve stimulation (VNS) initiated at either 2 h or 24 h (VNS: 30 s train of 0.5 mA, 20 Hz, biphasic pulses every 30 min) following traumatic brain injury enhances recovery of motor and cognitive function in rats in the weeks following brain injury; however, the mechanisms of facilitated recovery are unknown. The present study examines the effects of VNS on development of acute cerebral edema following unilateral fluid percussion brain injury (FPI) in rats, concomitant with assessment of their behavioral recovery. Two hours following FPI, VNS was initiated. Behavioral testing, using both beam walk and locomotor placing tasks, was conducted at 1 and 2 days following FPI. Edema was measured 48 h post-FPI by the customary method of region-specific brain weights before and after complete dehydration. Results of this study replicated that VNS initiated at 2 h after FPI: 1) effectively facilitated the recovery of vestibulomotor function at 2 days after FPI assessed by beam walk performance (P<0.01); and 2) tended to improve locomotor placing performance at the same time point (P=0.18). Most interestingly, results of this study showed that development of edema within the cerebral cortex ipsilateral to FPI was significantly attenuated at 48 h in FPI rats receiving VNS compared with non-VNS FPI rats (P<0.04). Finally, a correlation analysis between beam walk performance and cerebral edema following FPI revealed a significant inverse correlation between behavior performance and cerebral edema. Together, these results suggest that VNS facilitation of motor recovery following experimental brain injury in rats is associated with VNS-mediated attenuation of cerebral edema.

Fos expression and 2-deoxyglucose uptake following seizures in developing genetically epilepsy-prone rats.

Juvenile genetically epilepsy-prone rats (GEPR)-3s display one of three types of seizures in response to sound: a typical class 3 seizure consisting of an explosive running/bouncing episode followed by a clonic seizure (audiogenic response score, ARS-3); an ARS-3 seizure followed by a forebrain seizure that includes facial and forelimb (F&F) clonus with rearing (ARS-3f); or, a running/bouncing episode followed by a severe tonic seizure with complete hindlimb extension (ARS-9) not accompanied with subsequent F&F clonus. The adult seizure phenotype, manifest in all GEPR-3s by age 45 days of age, consists of an ARS-3 not followed by F&F clonus or tonic extension. The present studies sought to determine the neuronal networks activated during these various developmental convulsive patterns by examining anatomical patterns of [(14)C]2-deoxyglucose (2-DG) uptake or immediate-early-gene (Fos) expression subsequent to seizures. Many, but not all, brain areas of control rats showed age-related increases in Fos expression in response to the acoustic stimulation. An age effect was not observed in 2-DG uptake. In GEPRs, the profiles of Fos expression and 2-DG uptake following seizures were often parallel; however, there were notable exceptions. For example, increased 2-DG uptake in the cochlear nuclei, central region of the inferior colliculi, and the substantia nigra were not accompanied by increased Fos expression in these areas regardless of the seizure phenotypes. Reciprocally, other regions, particularly in the amygdala, ventromedial hypothalamus and parabrachial areas, displayed intense seizure related Fos labeling without detectable increases in 2-DG uptake. Fos and 2-DG uptake patterns in response to acoustic stimulation varied according to brain region, seizure phenotype and severity. In general, the degree of 2-DG uptake correlated with seizure severity. For example, the ARS-9 seizures, being the most intense, resulted in significant increases in 2-DG uptake in almost all brain regions examined. 2-DG uptake following the ARS-3f and ARS-3 seizures, although increased, did not reach statistical significance in most brain areas. In contrast to the 2-DG findings, a seizure-severity dependent effect was not seen with Fos. Rather, the induction of Fos associated with acoustic stimulation and seizure was more associated with age and seizure-phenotype. Thus, the developmental profiles of Fos expression and 2-DG uptake in response to seizures are distinctly different and concurrent examination of both markers is useful in the identification of brain circuitry involved in seizure development.

The treatment of high-grade soft tissue sarcomas with preoperative thermoradiotherapy.

PURPOSE: To explore the use of a novel program of preoperative radiation and hyperthermia in the management of high-grade soft tissue sarcomas (STS). METHODS AND MATERIALS: Eligible patients were adults over 18 with Grade 2 or 3 STS, surgically resectable without a local excision prior to referral to Duke University Medical Center and without distant metastases. Patients were staged generally with CT and/or MR imaging. The diagnosis was established with fine needle aspiration or incisional biopsy. Patients were then treated with 5000 to 5040 cGy, 180-200 cGy per fraction. Chemotherapy was usually not employed. Generally two hyperthermia treatments per week were given with a planned thermal dose of 10-100 CEM 43 degrees T90. Invasive thermometry and thermal mapping were done in all patients. Surgical resection was planned 4-6 weeks after the completion of radiation and hyperthermia. RESULTS: Ninety-seven patients were treated on study between 1984 and 1996. Follow-up ranged from 12 to 155 months (median 32). All tumors were high-grade in nature, 44 greater than 10 cm in size (maximum tumor diameter), 43 5-10 cm in size, 10 less than 5 cm. Seventy-eight of the 97 tumors were located in an extremity. Of the 97 patients, 48 remain alive and continually free of disease following initial therapy. Of the remaining 49 patients, 44 have relapsed (34 dead, 10 living with disease), 3 have died secondary to complications of therapy, and 2 have died of unrelated causes. Ten-year actuarial overall survival, cause-specific survival, and relapse-free survival are 50, 47, and 47% respectively. The predominant pattern of failure has been distant metastases with only 2 patients developing local failure alone. Ten-year actuarial local control for extremity tumors is 94%, 63% for the 19 patients with tumors at sites other than the extremity. Of the 78 patients with extremity lesions, 63 have had limb preservation and remain locally controlled. Overall 38 patients experienced 57 major complications. There were 3 deaths, one due to adriamycin cardiomyopathy and two secondary to wound infections. Four patients required amputation secondary to postoperative wound healing problems. Complications directly attributable to hyperthermia occurred in 15 patients with 11 instances of second- or third-degree burns and two instances of subcutaneous fat necrosis. The hyperthermia complications were generally not severe and either healed readily or were excised at the time of surgical resection of the primary tumor. CONCLUSIONS: For these aggressive high-grade soft tissue sarcomas, this treatment program of preoperative thermoradiotherapy provided excellent local regional control for extremity lesions (95%) and satisfactory local regional control (63%) of nonextremity sarcomas, but did not appear to influence the rate of distant metastases or survival. Complications were frequent but apart from the direct thermal burns, not too different from those reported for preoperative radiotherapy alone. More effective adjuvant systemic therapy is necessary to impact favorably on survival.

Reproductive endocrinopathy in acute streptozotocin-induced diabetic male rats. Studies on LHRH.

Streptozotocin-(STZ) treated diabetic male rats have significant reproductive endocrinopathy. To determine the functional responsiveness of luteinizing hormone-releasing hormone (LHRH) neurons in STZ-treated diabetic male rats, stimulated LHRH release was assessed using hypothalami from short-term STZ-treated, STZ-treated insulin-replaced, and control male rats. LHRH release from control, STZ-treated, and STZ-treated, insulin-replaced explants in response to an initial and second 30-min pulse of phenylephrine were not different. A terminal pulse, containing 45 mM KCl, a general secretogogue, also revealed no differences between groups in stimulated LHRH release. Glucose and testosterone levels in the controls and the diabetic rats were significantly different. Cell counts on serial brain sections processed for LHRH immunohistochemistry suggested that the number of LHRH neurons in the preoptic area (POA) and septal areas were not different between control and STZ-treated rats. Thus, the short-term STZ-treated rats of this study were diabetic, and they displayed associated endocrinopathy; however, explants obtained from control and STZ-treated rats exhibited a typical LHRH responsiveness to both phenylephrine and KCl, and appeared similar in LHRH neuron number. Therefore, these findings suggest that reproductive endocrinopathy accompanying short-term STZ-induced diabetes in male rats does not result from deficiency in LHRH neurons per se.

Effects of intraventricular locus coeruleus transplants on seizure severity in genetically epilepsy-prone rats following depletion of brain norepinephrine.

Audiogenic seizures (AGS) in genetically epilepsy-prone rats (GEPR) of the moderate-seizure substrain (GEPR-3s) were investigated to determine whether norepinephrine (NE) depletion induced by 6-hydroxydopamine (6-OHDA) microinfusion into the locus coeruleus (LC) could alter the efficacy of intraventricular NE tissue grafts in promoting reductions in seizure severity in AGS. GEPR-3s were stereotaxically infused with 6-OHDA (4 micrograms/side/rat), or vehicle into the region of the LC. Following 6-OHDA treatment all animals were subjected to 3 AGS tests. GEPR-3s seizure severities were increased in 39.5% of the animals after microinfusion of 6-OHDA into the region of the LC. Following the third AGS test, each rat was stereotaxically implanted with 17 gestational day rat fetal tissue obtained from the dorsal pons and containing the primordia of the LC or with tissue obtained from the neocortex or were sham-grafted. Subsequent to grafting, rats were subjected to 3 additional AGS tests. 53% (10/19) of 6-OHDA treated GEPRs showed a significant reduction in seizure severity following transplantation of fetal LC tissue. In contrast, only 20% (1/5) of GEPRs infused with saline rather than 6-OHDA showed a reduction of seizure severity following fetal LC transplantation. NE content in the cortex and pons/medulla was decreased by 78% and 46% respectively following 6-OHDA microinfusion into the LC. Prominent grafts with numerous TH positive neurons and neurites were present within the third ventricle of grafted animals, while cortex grafts contained no TH immunostained structures. These findings suggest that the efficacy of fetal LC tissue to promote reductions in seizure severity in GEPRs is increased following depletion of central NE by microinfusion of 6-OHDA.

Synergistic interaction between opioid receptor blockade and alpha-adrenergic stimulation on luteinizing hormone-releasing hormone (LHRH) secretion in vitro.

The effects of opioid receptor blockade, alpha-adrenergic receptor stimulation and concomitant opioid blockade and adrenergic stimulation on LHRH neurosecretion was examined in tissue culture using perifused preoptic area-mediobasal hypothalamic (POA-MBH) explants. Blockade of opioid receptors using naloxone (NAL) resulted in increased (p less than 0.05) LHRH secretion from POA-MBH explants obtained from intact postpubertal female rats. After washout of the NAL-medium, basal release rate was reset to a lower baseline. Subsequent exposure of POA-MBH explants to phenylephrine (PHEN), an alpha-adrenergic agonist, resulted in a slight but statistically insignificant increase in LHRH release from adult explants. The attenuated response to PHEN may have been due to a sustained inhibition of LHRH release following the NAL exposure since PHEN not preceded by NAL resulted in a marked stimulation of LHRH release. In three separate experiments, the LHRH response in postpubertal rat explants to simultaneous PHEN and NAL was greater and more prolonged than the responses to either of the substances alone. This study demonstrates that the stimulatory effects of PHEN are much more profound in the presence of opioid receptor blockage. The observations of the stimulatory effects of PHEN and NAL potentiating each other also suggest that separate mechanisms of LHRH control by each class of neurotransmitter are present. Similar to the postpubertal rat explants, explants obtained from prepubertal rats increased LHRH release in response to NAL and showed a sustained inhibition of LHRH release following washout of NAL. Explants obtained from prepubertal rats also significantly increased LHRH release in response to PHEN.(ABSTRACT TRUNCATED AT 250 WORDS)

Sexual dimorphism in the synaptogenic effect of estradiol in prepuberal female rats.

A study has been made of the effects of estradiol benzoate (EB) on synaptogenic induction in the hypothalamic arcuate nucleus (ARC), medial preoptic area (MPOA), and medial septal area (MSA) of prepuberal male and female rats. Subcutaneous administration of EB to 25-day-old female rats induces accelerated synaptogenesis in the ARC concomitant with a precocious surge of plasma luteinizing hormone (LH) at 1600 h on day 27 of age. The synaptic area densities (No. synapses/unit area of tissue section) of the MPOA and MSA are not increased at 27 days of age in rats treated with EB on day 25 of age. The synaptic area densities of the ARC, MPOA, and MSA are significantly higher on day 31 compared to day 27. However, only the ARC exhibits a further increase of synaptic numbers in EB-treated female rats. Similar estrogen treatment to prepuberal male rats induces neither an LH surge in plasma nor increased synaptogenesis in the ARC, MPOA, or MSA. Male 27-day-old rats of both estrogen-treated and control groups exhibit a synaptic area density in the ARC similar to 27-day-old control female rats. These data indicate that the sexually dimorphic positive response to estrogen with LH secretion has an equally sexually dimorphic neuromorphological response in rats. In addition, the synaptogenic effect of EB in the prepuberal female rat ARC remains manifest for at least 6 days after estrogen treatment.

Increase in hypothalamic nicotinic acetylcholine receptors in prepuberal female rats administered estrogen.

In previous studies, it has been reported that the administration of estrogen to prepuberal female rats produces precocious surges in the serum concentrations of luteinizing hormone (LH) and prolactin and the number of synaptic contacts in the arcuate nucleus. In the study reported here, we tested the hypothesis that the concentration of hypothalamic nicotinic acetylcholine receptors is the synaptic event initiating the precocious hormonal surges. A single injection of estrogen was administered to prepuberal female rats on day 25 and the serum concentrations of LH and prolactin and the concentration of the binding sites for alpha-bungarotoxin (BuTX), a putative nicotinic acetylcholine receptor ligand, were measured on day 27. The concentration of hypothalamic BuTX binding sites was increased by the estrogen treatment, but we found no evidence that this increase in receptors precedes or initiates the serum hormonal surges.

Synaptic changes in the hypothalamus of the prepuberal female rat administered estrogen.

Subcutaneous administration of estradiol benzoate (EB) to prepuberal female rats can advance vaginal opening, phasic pituitary gland luteinizing hormone (LH) secretion, and ovulation, presumably through a neural mechanism. This study investigated whether these effects are associated with changes in synaptic profiles in the arcuate nucleus of the hypothalamus (ARC) and the preoptic area (POA). Twenty-five-day-old female rats were administered EB, EB followed by progesterone on day 27, or oil vehicle alone; or they received no treatment. Blood was collected by jugular venipuncture at 1600 hr, on day 27, and plasma was assayed for LH by radioimmunoassay. Rat brains were immediately perfused for electron microscopy, and the ARC and POA were dissected out. Tissue blocks from these areas were processed with phosphotungstic acid for selective staining of neural synapses. Serum LH was markedly elevated in the EB-treated rats compared with controls. In the treated groups, LH values in serum were above 1,000 ng/ml, whereas the control values were less than 50. This acute rise of serum LH was accompanied by an acute increase of synaptic volume percent, area density, and numerical density in the ARC of EB-treated rats. The numerical density of the control groups was approximately 800 million observed synapses per cubic millimeter, whereas in the EB-treated groups, there were approximately 1.8 billion synapses per cubic millimeter. We found no differences in synaptic profiles of the POA in EB-treated animals as compared to the controls. We conclude from this study that estrogens act through neural mechanisms to accelerate maturation of neuroendocrine processes that govern phasic pituitary gland LH release and that this maturation process entails synaptogenesis in the ARC.

A decrease of cytosol estrogen receptors in the hypothalamus as a result of treatment of neonatal rats with glutamate.

Experiments were performed to determine whether the neuroendocrine dysfunctions of rats treated neonatally with monosodium glutamate (MSG) could be related to a loss of cytoplasmic estrogen receptors. Female rats treated with MSG as neonates were ovariectomized as adults and killed by decapitation 2 or 3 weeks after ovariectomy. Body, gonadal and anterior pituitary gland weights in MSG-treated rats were depressed when compared to that seen in their littermate controls. Serum prolactin concentration was elevated in the MSG-treated rats. Serum luteinizing hormone (LH) concentration was significantly lower in MSG-treated rats than in controls at 2 weeks, but not at 3 weeks after ovariectomy, suggesting a sluggish postovariectomy rise of serum LH concentration. Serum follicle-stimulating hormone (FSH) concentration was not altered by the MSG treatment. The concentration of cytosol estrogen receptors in the anterior pituitary gland was similar to that of controls, but hypothalamic concentration of estrogen receptors decreased as a result of the MSG treatment. After dissection of different hypothalamic regions, it was found that the greatest depletion of the cytosol estrogen receptors occurred in the arcuate-median eminence region. The results raise the possibility that some reproductive impairments of MSG-treated rats could stem from a decrease in cytosol estrogen receptors in the arcuate-median eminence region.