Effects of brainstem lesions on amino acid levels in the rat cochlear nucleus

There is evidence for glutamate, γ-amino butyric acid (GABA), and glycine as neurotransmitters of centrifugal pathways to the cochlear nucleus, but the quantitative extent of their contributions to amino acid neurotransmission in cochlear nucleus regions has not been known. We used microdissection of freeze-dried tissue sections of rat cochlear nucleus, with mapping of sample locations, combined with a high performance liquid chromatography (HPLC) assay, to measure amino acid levels in cochlear nucleus subregions of rats with unilateral lesions of centrifugal pathways to the cochlear nucleus. In rats with lesions transecting all or almost all pathways to the cochlear nucleus from brain stem regions, GABA, aspartate, and glutamate levels were reduced, compared to contralateral values, in almost all ipsilateral cochlear nucleus regions. The largest reductions, in dorsal (DCN), anteroventral (AVCN), and posteroventral (PVCN) cochlear nucleus regions, approached 50% for GABA, 40% for aspartate, and 30% for glutamate. In contrast, glutamine and taurine levels were typically higher in lesioned-side cochlear nucleus regions than contralaterally. Effects on glycine levels were mixed but usually included increased lesioned-side values compared to contralateral, probably reflecting a balance between increases during protein breakdown and decreases of free glycine in transected pathways. More limited lesions transecting just dorsal pathways showed much less effect on amino acid levels. Lesion of the ipsilateral trapezoid body connection plus ipsilateral superior olivary nuclei resulted in decreases of GABA, aspartate, and glutamate levels especially in ventral cochlear nucleus regions. No clear contralateral effects of this lesion could be shown. The results most strongly support centrifugal GABAergic pathways to the cochlear nucleus, providing almost half of GABAergic neurotransmission in most regions. Our results support and extend previously published measurements of lesion effects on GABA uptake and release in cochlear nucleus subdivisions.

Chemical Effects of Kainic Acid Injection into the Rat Superior Olivary Region

Kainic acid injections have been used to destroy neuron somata in particular regions without damaging fiber tracts. We injected a solution of kainic acid into the region of the rat superior olivary complex in an effort to destroy its cholinergic projections to the cochlea and cochlear nucleus, which derive especially from the lateral superior olivary nucleus and ventral nucleus of the trapezoid body. In the lateral superior olivary nucleus, there were relatively small but fairly consistent decreases of choline acetyltransferase (ChAT) activity, larger decreases of acetylcholinesterase (AChE) activity, and consistent decreases of malate dehydrogenase activity, as a marker for oxidative metabolism. Other superior olivary regions were less affected by the kainic acid injections, but most showed overall significant decreases of AChE activity. Our results suggest that the cholinergic neurons giving rise to the centrifugal pathways to the cochlea and cochlear nucleus are more resistant to the effects of kainic acid than are those that receive major ascending input from the cochlear nucleus and project to higher levels of the auditory system. Comparison with published anatomical studies suggests that this resistance to the effects of kainic acid is related to relatively little glutamatergic input to the somata and proximal dendrites of these neurons. We also found a consistent approximately 16 % decrease of ChAT activity in the injected-side facial nerve root, which is most easily explained as a small effect of kainic acid on the facial nerve fibers passing through the injection site.

Effects of surgical lesions on choline acetyltransferase activity in the cat cochlea

Although it is well established that the choline acetyltransferase (ChAT, the enzyme for acetylcholine synthesis) in the mammalian cochlea is associated with its olivocochlear innervation, the distribution of this innervation in the cochlea varies somewhat among mammalian species. The quantitative distribution of ChAT activity in the cochlea has been reported for guinea pigs and rats. The present study reports the distribution of ChAT activity within the organ of Corti among the three turns of the cat cochlea and the effects of removing olivocochlear innervation either by a lateral cut aimed to totally transect the left olivocochlear bundle or a more medial cut additionally damaging the superior olivary complex on the same side. Similarly to results for guinea pig and rat, the distribution of ChAT activity in the cat outer hair cell region showed a decrease from base to apex, but, unlike in the guinea pig and rat, the cat inner hair cell region did not. As in the rat, little ChAT activity was measured in the outer supporting cell region. As previously reported for whole cat cochlea and for rat cochlear regions, transection of the olivocochlear bundle resulted in almost total loss of ChAT activity in the hair cell regions of the cat cochlea. Lesions of the superior olivary complex resulted in loss of ChAT activity in the inner hair cell region of all cochlear turns only on the lesion side but bilateral losses in the outer hair cell region of all turns. The results are consistent with previous evidence that virtually all cholinergic synapses in the mammalian cochlea are associated with its olivocochlear innervation, that the olivocochlear innervation to the inner hair cell region is predominantly ipsilateral, and that the olivocochlear innervation to the outer hair cells is bilateral.

Analysis of the effects of chitosan on inflammation, angiogenesis, fibroplasia, and collagen deposition in polyvinyl alcohol sponge implants in rat wounds

Chitosan is a large molecular weight, positively charged polysaccharide extracted and purified from the chitin of crab shells. This compound has been shown to have hemostatic activity and has been suggested for use as a topical agent in tissue repair. The objective of this study was to analyze the effect of chitosan on the wound healing response to a standardized injury in the rat. The polyvinyl alcohol sponge implant model was used as a means to deliver either chitosan or its vehicle to a standardized subcutaneous wound on the backs of Sprague-Dawley rats. On days 8 and 14, the chitosan-treated implants contained primarily polymorphonuclear leukocytes compared with the vehicle controls which contained mainly macrophages, fibroblasts, collagen, and new blood vessels. High-performance liquid chromatography analysis for hydroxy-L-proline deposited in the sponge implants showed significantly lower amounts on both days 8 and 14 in the chitosan treatment group. These histologic and biochemical studies suggest that chitosan modulates wound healing by first reducing the influx of activated tissue macrophages, which in turn reduces the subsequent events of angiogenesis, fibroplasia, and connective tissue deposition.

Effect of flax supplementation and growth promotants on lipoprotein lipase and glycogenin messenger RNA concentrations in finishing cattle1

Lipoprotein lipase (LPL) hydrolyzes triacylglycerols into monoacylglycerol and fatty acids, which are taken up by tissues and used for energy. Glycogenin is the core protein on which glycogen molecules are synthesized. There is one molecule of glycogenin per molecule of glycogen in skeletal muscle; therefore, glycogen storage is limited by the amount of glycogenin present in muscle. The objective of this study was to investigate the effect of feeding flaxseed, a source of PUFA, and administering a growth promoter on steady-state LPL and glycogenin mRNA content of muscle in finishing cattle. Sixteen crossbred steers (initial BW = 397 kg), given ad libitum access to a 92% concentrate diet for 28 d, were used in a four-treatment, 2 x 2 factorial experiment, with flaxseed supplementation (0 or 5% of dietary DM) and implanting (not implanted or implanted with Revalor-S) as the main effects. Muscle biopsies were obtained from the LM at 0, 14, and 28 d, and used to quantify LPL and glycogenin mRNA concentrations using real-time quantitative PCR. Implanting with Revalor-S did not affect LPL (P = 0.13) or glycogenin (P = 0.98) mRNA concentrations. A day x flaxseed interaction (P < 0.001) was observed for both LPL and glycogenin mRNA concentrations. No differences (P > 0.10) were observed between 0 and 5% flaxseed supplemented steers; however, at 28 d, nonflaxseed-fed steers had 4.1- and 5.7-fold increases (P < 0.001) over flaxseed steers for LPL and glycogenin mRNA concentrations, respectively. To further evaluate the effects of alpha-linolenic acid (alpha-LA) on LPL and glycogenin mRNA concentrations, muscle satellite cells were isolated from five finishing steers, and different alpha-LA concentrations were applied in culture. The RNA was isolated from the bovine satellite cells. Addition of alpha-LA numerically increased (P = 0.16) the LPL mRNA concentration 48% at 1 microM alpha-LA compared with the control. The expression of glycogenin was increased (P < 0.05) 50% at 1 microM alpha-LA compared with the control. These results suggest that flaxseed supplementation to finishing steers for 28 d decreased gene expression of both LPL and glycogenin compared with not feeding flaxseed. Alterations in local concentrations of these two proteins could affect the ability of muscle to use fatty acids and glucose for energy, and, ultimately, affect carcass quality.

Effects of flax supplementation and a combined trenbolone acetate and estradiol implant on circulating insulin-like growth factor-I and muscle insulin-like growth factor-I messenger RNA levels in beef cattle1,2

We evaluated effects of a 5% (dry matter basis) ground flaxseed supplement (flax) and a trenbolone acetate and estradiol-17beta implant, Revalor-S, on circulating IGF-I and muscle IGF-I messenger RNA (mRNA). Sixteen crossbred yearling steers (initial BW = 397 kg) were assigned randomly to one of four treatments: 1) flax/implant; 2) nonflax/implant; 3) flax/nonimplant; and 4) nonflax/nonimplant. Serum was harvested from blood collected on d 0 (before implant or flax addition), 14, and 28, and used in subsequent analyses of circulating IGF-I. Biopsy samples (0.5 g) were obtained from the longissimus muscle on d 0, 14, and 28. Total RNA was isolated from the muscle samples, and real-time quantitative-PCR was used to assess relative differences in IGF-I mRNA. Flax supplementation had no effect (P > 0.10) on circulating IGF-I concentrations. Following implantation, sera from implanted steers had 52 and 84% greater (P < 0.05) IGF-I concentrations than sera from nonimplanted steers on d 14 and 28, respectively. On d 28, local muscle IGF-I mRNA levels increased 2.4-fold (P < 0.01) in biopsy samples obtained from implanted compared with nonimplanted steers. Muscle biopsy samples from nonflax cattle had 4.4-fold higher (P < 0.01) levels of IGF-I mRNA than those from flax cattle on d 28. To determine whether a component of flax, alpha-linolenic acid (alphaLA), was directly responsible for IGF-I mRNA down-regulation, we incubated primary cultures of bovine satellite cells, from implanted and nonimplanted steers, in two concentrations of alphaLA (10 nM and 1 microM). An implant x dose interaction (P < 0.05) was observed for IGF-I mRNA concentrations in bovine satellite cells cultured for 72 h with alphaLA. Satellite cells from nonimplanted steers had similar (P > 0.10) IGF-I mRNA concentration regardless of the level of alphaLA exposure; however, satellite cells from implanted steers exposed to 10 nM and 1 microM alphaLA had 2.5- and 2.0-fold greater IGF-I mRNA levels, respectively, than cells from implanted steers that were not exposed to alphaLA (P < 0.05). Administration of a Revalor-S implant increased circulating IGF-I and local muscle IGF-I mRNA concentrations in finishing cattle. However, muscle IGF-I mRNA levels were decreased by flax supplementation. Muscle cell culture experiments suggested that alphaLA was not responsible for the IGF-I mRNA down-regulation.

Time course of changes in growth factor mRNA levels in muscle of steroid-implanted and nonimplanted steers1,2,3

We used a muscle biopsy technique in conjunction with real-time PCR analysis to examine the time course of changes in muscle IGF-I, IGFBP-3, myostatin, and hepatocyte growth factor (HGF) mRNA in the longissimus muscles of Revalor-S-implanted and nonimplanted steers on d 0, 7, 12, and 26 after implantation (nine steers/treatment group). Administration of a Revalor-S implant increased (P < 0.01) ADG and improved (P < 0.05) feed efficiency, 36 and 34%, respectively, compared with steers that received no implant during the 26-d trial. Daily dry matter intake did not differ (P > 0.15) between nonimplanted and implanted steers. Steers receiving the Revalor-S implant had increased (P < 0.001) circulating IGF-I concentrations compared with nonimplanted steers. The longissimus muscles of steers receiving the Revalor-S implant contained increased (P < 0.001) IGF-I mRNA levels compared with longissimus muscles of nonimplanted steers over the 26-d duration of the study. Longissimus muscle IGF-I mRNA levels in implanted steers were increased (P < 0.003) relative to d-0 concentrations on d 7 and 12 (101% and 128%, respectively), and byd 26, longissimus muscle mRNA levels were more than three times (P < 0.0001) those in the longissimus muscles of the same steers on d 0. There was no treatment effect on the level of IGFBP-3, myostatin, or HGF mRNA in the longissimus muscle at any time point; however, levels of IGFBP-3, myostatin, and HGF mRNA increased with time on feed. Based on current and previous studies, we hypothesize that the increased IGF-I level in muscle of implanted steers by d 7 of implantation stimulates satellite cell proliferation and maintains a high number of proliferating satellite cells at a point in the growth curve where satellite cell numbers and activity are normally dropping off. This would prolong the period of rapid muscle growth, resulting in the observed increased rate and efficiency of muscle deposition in implanted steers.

Patient safety in America: comparison and analysis of national and Texas patient safety research

The Institute of Medicine (IOM) report on patient safety in late 1999, To Err is Human, attracted great national attention when it announced that 44,000 to 98,000 patients die each year in American hospitals because of patient safety problems and that a patient safety crisis exists in American health care and American hospitals. The report relied heavily on a Harvard group's study of hospital care in New York in 1984 and another Harvard group's study of hospital care in Utah and Colorado in 1992. This article reviews and compares American hospital inpatient safety research and corresponding Texas hospital patient safety research. It focuses on the major patient safety research of the last two decades that led to the IOM report, and compares information from the major studies with the work of the Texas Medical Foundation (TMF). The Harvard patient safety studies that have received great national attention are compared here with a stronger, broader, and more robust database from TMF, the peer review organization for Texas. The TMF studies of 300,000 patient admissions during 3 years in more than 400 hospitals are compared with the Harvard studies of 30,000 charts in 51 hospitals in New York in 1984 and 15,000 charts in 28 hospitals in Utah and Colorado in 1992. The TMF data and a close look at the Harvard data show a positive patient safety picture that has been ignored too often in the current debate, with low rates of significant injury and death caused by any medical care or hospital care safety or negligence problems.

Powerlessness regarding health-service barriers: construction of an instrument

PURPOSE

The purpose of the study was to develop a scale to calculate college students' powerlessness regarding health service barriers (PHSB).

METHODS

Scale items were generated to represent two domains of interest: powerlessness and college students' powerlessness regarding health service barriers. The final 20-item instrument was subjected to multiple measures of validity with college students and panels of nurse experts in the area of nursing diagnosis. Reliability was assessed by two samples (n = 92 and n = 33) of college-age students. A final administration was conducted with 197 college students.

FINDINGS

The PHSB scale was determined to be an accurate and consistent measure.

CONCLUSIONS

This instrument will provide a reliable and valid measure to conduct research.

Effect of sinoaortic denervation on arterial pressure changes evoked by bed nucleus stimulation

To assess whether evoked changes in arterial pressure after stimulation of the bed nucleus of the stria terminalis (BST) are opposed by baroreceptor input to the central nervous system, the rostral BST of sinoaortic-denervated (SAD), urethane- (1.3 g/kg) anesthetized, male Sprague-Dawley rats was probed for cardiovascular reactive sites. Electrical stimuli (50 microA, 50 Hz), delivered through stereotaxically placed glass semimicroelectrodes, were directed to the rostral medial BST. Sham-operated animals served as controls. Stimulation sites were correlated with cytoarchitecturally distinct areas within the rostral BST, and changes in mean arterial pressure (MAP) were subjected to statistical analysis. Consistent with our previous observations, stimulation of the rostral BST produced changes (p < 0.05) in MAP in both sham-operated and SAD rats. Medial stimulation produced pressor responses; lateral stimulation produced depressor responses. In contrast, neither the magnitude nor the duration of the stimulation-evoked changes in MAP were affected by SAD. Thus, in the urethane-anesthetized rat, the rostral medial BST influence on cardiovascular function is not affected by changes in baroreceptor activity.

Cardiovascular responses to electrical stimulation of the bed nucleus of the stria terminalis

To determine whether the influence of the bed nucleus of the stria terminalis (BST) on cardiovascular function can be localized to specific cytoarchitectural areas within the BST, urethane (1.3 g/kg)-anesthetized male Sprague-Dawley rats were probed for cardiovascular reactive sites. Electrical stimuli (50 microA, 50 Hz, and a 0.5 ms pulse duration), delivered through stereotaxically placed glass semimicroelectrodes, were localized to the BST. Sham-stimulated animals served as controls. Stimulation sites were correlated with cytoarchitecturally distinct areas within the BST, and changes in mean arterial pressure (MAP) were subjected to statistical analysis. Systematically probing the BST for cardiovascular reactive sites showed a correlation between evoked responses and distinct cytoarchitectural areas. Stimulation of the medial BST produced increases in MAP; stimulation of the lateral aspect of the BST produced decreases in MAP. Both pressor and depressor responses were evoked from the area ventral to the anterior commissure. Pressor responses were elicited from the area immediately ventral to the anterior commissure, and depressor responses followed stimulation of an area more ventral. All subnuclei showed corroborating cardiovascular responses to 20-30 nl microinjection of sodium glutamate. Taken together, these data provide substantial evidence to indicate that the BST, particularly at more rostral areas, consists of a medial pressor area, a lateral depressor area, and a ventral area with both pressor and depressor zones.

Manipulation of central nervous system histamine or histaminergic receptors (H1) affects food intake in rats

The reported studies were designed to examine relationships between central nervous system histamine, histaminergic receptors (H1) and food intake in rats. The hypothesis being tested was as follows: "One component of the neuroregulation of food intake involves histaminergic activity in the hypothalamus as influenced by variation of histamine levels and/or H1 receptor concentrations." We performed combinations of dietary, surgical and pharmacological treatments on male or female rats. We fed groups of male or female rats diets containing either 4 g casein/100 g diet (low protein diet) or 25 q casein/100 g diet (normal protein). Rats with surgical ablation of the paraventricular nucleus did not decrease food intake when fed the low protein diet, whereas adrenalectomized rats did. Increasing central histamine levels decreased food intake, whereas decreasing central histamine increased food intake. Rats injected with histaminergic (H1) antagonists lost the ability to detect low protein diet in short-term experiments and had improved efficiency of weight gain. Rats that were fed the low protein diet or pair-fed the normal protein diet had greater H1 receptor concentrations in whole brain preparations when compared with rats fed the normal protein diet. No differences were noted due to gender. Thus, manipulation of histamine levels affected food intake as hypothesized, i.e., increasing central histamine decreased food in rats fed the normal protein diet, whereas decreasing central histamine or blockade of H1 receptors increased food intake in rats fed the low protein diet.

Future legal issues in emergency medicine

This article analyzes past legal trends in emergency medicine with an effort to project those trends and current developments into future legal issues that will confront emergency physicians and emergency departments. Special emphasis is placed on insurance trends and professional liability insurance developments along with medical malpractice claims past, present, and future. Also discussed in this article is the health care industry environment and ways that it might affect future legal challenges for emergency medicine.

Acute gastric volvulus in children: a rare disorder

A case of acute gastric volvulus has been presented. Although this disorder can occur in a chronic intermittent fashion, the potentially catastrophic acute form should be diagnosed early and surgically corrected. Careful attention to presenting signs and a high index of suspicion lead to prompt recognition and treatment.

Contribution of centrifugal innervation to choline acetyltransferase activity in the cat cochlear nucleus

Using a quantitative microchemical mapping approach combined with surgical cuts of fiber tracts, the contributions of centrifugal pathways to choline acetyltransferase activity were mapped three-dimensionally in the cat cochlear nucleus. Large reductions of choline acetyltransferase activity, averaging 70%, were measured in almost all parts of the lesion-side nucleus following transection of virtually all its centrifugal connections. More superficial cuts, penetrating just through the olivocochlear bundle, also led to significant reductions of enzyme activity, especially most rostrally in the anteroventral cochlear nucleus and superficial granular region, where the reductions were similar to those following the complete cuts. Lesions encroaching upon the superior olivary complex gave bilateral effects. Transverse cuts between rostral and caudal parts of the cochlear nucleus gave some small effects. The results suggest that, as in rats, most choline acetyltransferase activity in the cat cochlear nucleus is associated with its centrifugal innervation. However, unlike the situation in rats, the enzyme activity in cats is related more to olivocochlear branches than to ventral fibers in the trapezoid body region. Also, the choline acetyltransferase activity related to olivocochlear collateral innervation is much less uniformly distributed within the cochlear nucleus in cats than in rats.

Histidine, histamine, and the neuroregulation of food intake: a review and hypothesis

Feeding, a behavior regulated by the central nervous system (CNS), includes the acquisition of specific essential nutrients and the maintenance of energy balance. Modulation of feeding behavior is a normal part of survival, but certain pathological conditions interrupt or modify regulatory aspects of feeding, thereby leading to inappropriate intake. This review examines aspects of metabolism associated with the anorexia seen in animals suffering from protein-energy malnutrition (PEM). The main focus is the indispensable amino acid histidine (His), the biosynthetic precursor of the neurotransmitter histamine (HA). In kwashiorkor-like PEM, His is elevated in plasma and brain, whereas all other indispensable amino acids are decreased. The elevation of His in the brain is to concentrations five times normal. Because the rate of HA synthesis in the brain is a function of the His concentration, His elevation raises the possibility of a profound direct effect of CNS function. In children, PEM consistently produces the symptoms of depressed food intake, edema, growth failure, and psychomotor changes. One known central effect of HA is the stimulation of ACTH and corticosteroid release. Based on these observations, the hypothesis being examined is as follows: one component of the pathophysiological neuroregulation of food intake involved the His-induced variation of HA concentration in the hypothalamus and the subsequently altered neurochemical activity at the corticotropin-releasing factor (CRF) neurons o the paraventricular nucleus (PVN).

Effect of septal ablation on choline acetyltransferase in the paraventricular nucleus

To determine whether there is a cholinergic projection from the lateral septum to the paraventricular nucleus of the hypothalamus (PVH), a quantitative histochemical analysis of the effects of unilateral ablation (0.5 microliter of a 10 micrograms/ml solution of ibotenic acid) of the lateral septum (LSV) on the choline acetyltransferase (ChAT) activity of the PVH and surrounding perinuclear area was undertaken. Comparisons of the ChAT activity of the PVH region ipsilateral to the LSV lesion (lesioned side) with that of the PVH contralateral (nonlesioned side) to the ablated LSV showed a 20% reduction (p less than 0.05) of ChAT activity in 2 areas of the PVH on the lesioned side. When ChAT activity of LSV-ablated and intact control rats was compared, a 20% difference in activity (p less than 0.05) was noted in four areas on the nonlesioned side and a 35% difference (p less than 0.05) of ChAT activity was noted in five regions of the PVH on the lesioned side of LSV-ablated animals. Taken together these data suggest that the pathway from the LSV to the PVH contains a small, bilateral cholinergic component. However, the data also indicate that this is not the only cholinergic projection to the PVH.

Brain histidine and food intake in rats fed diets deficient in single amino acids

Histidine (His) is elevated in plasma and brain during protein deficiency as well as in several pathological conditions, leading to the possibility of a direct effect on central nervous system (CNS) function. In this study, groups of weanling rats were fed diets containing graded levels of casein or a single indispensable amino acid (IAA: Leu, Val, Ile, Phe, Trp, Thr, Met or Lys) in order to produce nutritionally-deficient states. Body weight gains and food intakes were recorded daily for 2 wk. Whole brain and serum samples were obtained and analyzed for amino acid (AA) content. All weight gain and food intake responses could be predicted by the Saturation Kinetics Model. The only consistent pattern observed in AA profiles which could be correlated with food intake was an increase in brain His concentrations. Limiting dietary casein or IAA elevated brain His above controls 2.5- and 1.5-fold, respectively. Food intake was generally depressed by 50% at brain His concentrations above 105 nmol/g. Since His is the precursor of the depressant neurotransmitter histamine (HA), systemic increases may be significant in that HA could be a possible cause of the anorexia observed in protein and IAA deficiency.

Effect of melittin on pituitary-adrenal responsiveness to stress

We previously have shown that melittin evokes a sustained increase in plasma corticosterone levels of the female rat. Significant increases occurred only during the morning and the duration of the response was increased from 48 h to 8 days by a second milittin injection 3 days after initial exposure to melittin. To further evaluate the effect of melittin on adrenocortical function, rats were given melittin at 09.00 h on days 1 and 4 and on day 8 rats were subjected to a variety of different stresses. Saline-injected rats served as controls. Blood for determining non-stress and stress levels of corticosterone concentration (RIA) was collected by decapitation. In all cases morning but not afternoon non-stress plasma corticosterone levels of melittin-injected rats were higher than those of saline-injected controls; afternoon non-stress corticosterone levels did not differ between groups. Melittin- and saline-treated rats showed comparable corticosterone responses to a morning 2-min restraint stress. In contrast, melittin treatment facilitated the pituitary-adrenal response to rotational and surgical stress as well as the stress of removing one rat from a cage of two. Fifteen min after removal of the first rat of a cage of two, plasma corticosterone levels of the melittin-injected rat were significantly higher than those of saline-injected rats. Likewise, plasma corticosterone levels of melittin-treated rats were higher (P less than 0.05) than those of saline-injected rats 15 min after rotational (10 rpm) and surgical (jugular cutdown and blood withdrawal) stress.(ABSTRACT TRUNCATED AT 250 WORDS)

Melittin-evoked increase in plasma corticosterone levels

The present study was undertaken to systematically evaluate the effect of melittin on nonstress pituitary-adrenal function of the adult female rat. In the first study rats were given melittin (0.5 mg.kg-1) or saline (0.5 ml) intraperitoneally at 0800 hr. Blood for determining plasma corticosterone levels was collected by decapitation at 4, 8, 24 or 48 hrs post-injection. Corticosterone levels of rapidly decapitated rats provided basal corticosterone levels. In general, plasma corticosterone levels of melittin-treated animals were higher than those of saline-injected rats at 4, 24, and 48 hrs but significant differences (p less than 0.05) occurred only at 4 and 48 hrs. A second study showed the melittin-evoked corticosterone response to be present at 3 days but by 6 days the response was absent. However, the duration of the increase in plasma corticosterone levels was extended to 8 days by using a double injection protocol (0.5mg.kg-1 melittin on day 1 and day 4). In all studies melittin-evoked increases in corticosterone levels were observed only in the AM and the melittin-induced increases in plasma corticosterone levels were suppressed with dexamethasone (DECADRON, 100 micrograms.kg-1, s.c.). These data indicate that a 0.5mg.kg-1 dose of melittin evokes a significant increase in adrenocortical activity and the evoked response is feedback sensitive.

Differential plasma corticosterone responses to electrical stimulation of the medial and lateral septal nuclei

To pursue the possibility that subdivisions within the medial and lateral septal nuclei are differentially involved in adrenocortical function, plasma samples obtained prior to and following electrical stimulation of the septal nuclei of urethane (1.30 g/kg)-anesthetized female rats were assessed for corticosterone concentration. Hippocampal EEG, ECG, heart rate (HR), mean arterial pressure (MAP) and respiration were routinely monitored, and timed blood samples (0.15 ml) were obtained from a catheterized tail artery. Blood samples were taken 0.5 min prior to and at 5, 10, 15 and 30 min after initiation of stimulation. Whereas no change in Cpd B levels were observed following sham stimulation or stimulation of the corpus callosum, fornix or anterior commissure, stimulation of the medial septal nuclei produced differential responses. Decreased plasma Cpd B responses followed stimulation of the medial septal nucleus (MS); increases in plasma Cpd B followed stimulation of the dorsal (LSD) and ventral (LSV) division of the lateral septal nucleus. The overall increase in plasma Cpd B levels following LSD and LSV stimulation was 16 and 32%, respectively. The overall decrease in corticosterone concentration subsequent to MS stimulation was 18%. The largest increases in Cpd B levels occurred at 5 min (36%) and 10 min (24%) for LSV and LSD groups, respectively; the largest decrease was noted at 15 min (25%). Plasma Cpd B responses to stimulation of the intermediate area of the lateral septal nucleus produced varying and inconsistent responses. Collectively, these data support the hypothesis that subdivisions within the septal nuclei are differentially involved in adrenocortical function.

Characteristics of the frequent visitor to the industrial medical department and implications for health promotion

The number of visits to an in-house industrial medical clinic, of absences in three categories, and of late arrivals found in 1,505 employees of an automobile assembly plant were compared with respect to the age, sex, race, department, and shift characteristics of the employees. Less than 16% of the work force was found to account for over 50% of the medical visits. Those 235 frequent visitors were found to have significantly more absences and more tardiness compared with the rest of the plant population. The frequent visitors who completed a health risk appraisal had significantly greater health risks compared with a responding sample of nonfrequent visitors.

Plasma corticosterone responses to electrical stimulation of the bed nucleus of the stria terminalis

The effect of ventral septal stimulation on pituitary-adrenal function was assessed by evaluating plasma corticosterone obtained prior to and following sham or electrical stimulation of the bed nucleus of the stria terminalis (BNST) of female rats anesthetized with urethane (1.3 g X kg-1). Hippocampal EEG, ECG, heart rate, blood pressure and respiration were routinely monitored; timed blood samples (0.2 ml) for determining plasma corticosterone (RIA) were obtained from a catheterized tail artery. Samples were taken at 0.5 min prior to and at 5, 10, 15 and 30 min after initiation of stimulation. Whereas increased plasma corticosterone levels followed stimulation of the medial aspect of the BNST, lateral stimulation resulted in decreased plasma corticosterone levels. The overall increase in plasma corticosterone following medial stimulation was 24%; the overall decrease was 13%. The largest increase in plasma corticosterone (36%) occurred at 30 min poststimulation; the largest decrease (22%) occurred at 15 min. Stimulation of the most rostral aspect of the BNST produced plasma corticosterone responses similar to that observed following medial stimulation. In contrast, no changes in corticosterone levels were observed following either sham stimulation or stimulation of the corpus callosum, fornix or anterior commissure.

Risk management in emergency medicine

This article discusses risk management and control of malpractice risk in the Emergency Department. Particular emphasis is placed on actuarial information related to Emergency Department losses.

Effect of olivocochlear bundle transection on choline acetyltransferase activity in the rat cochlear nucleus

Using a microdissection and quantitative microassay approach, choline acetyltransferase activities were mapped in the cochlear nuclei of rats having complete transections of the olivocochlear bundle on one side in the brain stem. In rats in which the trapezoid body was not significantly damaged by the lesion, consistent reductions of choline acetyltransferase activity in subregions of the lesion-side cochlear nucleus, as compared to the control side, averaged about 20%. Nevertheless, a profound lesion-side reduction of choline acetyltransferase activity was found in a branch connection from the olivocochlear bundle to the cochlear nucleus. The results suggest that branches from the olivocochlear bundle are cholinergic, but contribute a relatively minor proportion of the cholinergic synapses in all regions of the rat cochlear nucleus. In the light of previous results with more extensive lesions, it can be proposed that synapses in all regions of the rat cochlear nucleus. In the light of previous results with more extensive lesions, it can be proposed that most cholinergic input into the rat cochlear nucleus enters by a ventral route along the trapezoid body. It is noted that this represents a quantitatively somewhat different situation from that in the cat.

Effects of trapezoid body and superior olive lesions on choline acetyltransferase activity in the rat cochlear nucleus

Using a microdissection and quantitative microassay approach, choline acetyltransferase activities were mapped in the cochlear nuclei of rats having either transection of the trapezoid body or destruction of the superior olivary complex on one side in the brain stem. Lateral trapezoid body transection resulted in dramatic loss of choline acetyltransferase activity in all parts of the ipsilateral cochlear nucleus, while more medial transection had little effect. Destruction of the superior olivary complex resulted in dramatic loss of choline acetyltransferase activity in the ipsilateral cochlear nucleus, and detectable loss also contralaterally. The results suggest that most of the centrifugal cholinergic projections to the rat cochlear nucleus derive from or traverse the vicinity of the superior olivary complex bilaterally and enter the cochlear nucleus ventrally from the region of the trapezoid body.

Differential cytolysis of murine spleen, bone-marrow and leukemia cells by melittin reveals differences in membrane topography

L1210 leukemia cells are 2-4 fold more sensitive to the cytolytic effects of melittin, the membrane-active toxin of bee venom, than normal DBA/2 mouse spleen and bone-marrow cells. Lysis of the normal cells was abolished when either 75 mM galactosamine, glucosamine or 100 microM beta-lactoglobulin was added to the melittin-cell reaction, but lysis of the leukemia cells was unaffected. The amino-groups appeared necessary for blocking melittin-mediated lysis since glucose, galactose and the N-acetyl derivatives were not inhibitory. Bone-marrow cells were more readily protected from lysis than spleen cells. Since melittin-inhibitor complexes were not detected by gel chromatography and the inhibitor could be added to the cell suspension after melittin, the evidence suggests that bone-marrow cells are rich in membrane binding sites for carbohydrates that decrease in mature spleen cells and are virtually absent after neoplastic transformation.

Quantitative distributions of aspartate aminotransferase and glutaminase activities in the rat cochlea

The intra-cochlear distributions of aspartate aminotransferase and glutaminase, prominent enzymes of aspartate and glutamate metabolism, have been studied by quantitative microchemical techniques. Also measured was choline acetyltransferase, the enzyme synthesizing acetylcholine, and a marker for the olivocochlear bundle. Aspartate aminotransferase activity was highest in the stria vascularis, about half this high in the organ of Corti synaptic (hair cell) zones, somewhat lower in the organ of Corti non-synaptic (Hensen's cell) zones, lower yet in Reissner's and lowest in the tectorial membrane. Glutaminase, on the other hand, had its highest activity in synaptic zones, about a third of that activity in the organ of Corti non-synaptic zones, and a barely detectable activity in Reissner's and tectorial membranes, and stria vascularis. Seven days after transection of the olivocochlear bundle, no significant difference was found between lesion- and control-side aspartate aminotransferase or glutaminase activities, even though no choline acetyltransferase activity remained in the lesion-side of the organ of Corti. Both the distribution of aspartate aminotransferase activity and the lesion results would seem to implicate it in energy more so than neurotransmitter metabolism. The distribution of glutaminase activity could be consistent with a role in neurotransmission; however, the lesion data were unable to demonstrate a specific association with the olivocochlear bundle.