Distribution of prostaglandin EP(3) and EP(4) receptor mRNA in the rat parabrachial nucleus

By using in situ hybridization, the distribution of mRNA for the PGE(2) receptors EP(3) and EP(4) was examined in the rat parabrachial nucleus (PB), a major brain stem relay for autonomic and nociceptive processing. EP(3) receptor mRNA was present in most subnuclei, with the densest labeling in the external lateral, dorsal lateral, superior lateral, central lateral and Kölliker-Fuse nuclei. EP(4) receptor mRNA expressing cells had a more restricted distribution, largely being confined to the superior lateral and adjacent parts of the dorsal and central lateral nuclei in a pattern complementary to that for EP(3) receptor mRNA. These findings suggest that EP(3) and EP(4) receptors in PB have distinct functional roles that include nociceptive processing, blood pressure regulation and feeding behavior.

Cytoarchitectonic and immunohistochemical characterization of a specific pain and temperature relay, the posterior portion of the ventral medial nucleus, in the human thalamus

Previous studies in the macaque monkey have identified a thalamic nucleus, the posterior portion of the ventral medial nucleus (VMpo), as a dedicated lamina I spinothalamocortical relay for pain and temperature sensation. The dense plexus of calbindin-immunoreactive fibres that characterizes VMpo in primates enables its homologue to be identified in the human thalamus by immunohistochemical labelling for calbindin. We have now analysed in detail the cytoarchitectonic characteristics of VMpo and its relationship with immunoreactivity for calbindin, substance P and calcitonin gene-related peptide (CGRP) in the human thalamus. The area in the posterolateral thalamus in which dense calbindin-immunoreactive fibre terminations are present coincides nearly completely with a distinct region that contains small to medium-sized cells with round or oval shapes that are aggregated in clusters separated by cell sparse areas. This region, which we identify as VMpo, is located posteromedial to the ventral posterior lateral (VPL) and ventral posterior medial (VPM) nuclei, ventral to the anterior pulvinar and centre médian nuclei, lateral to the limitans and parafascicular nuclei and dorsal to the medial geniculate nucleus. Calbindin-immunoreactive fibres enter VMpo from the spinal lemniscus and form large patches of dense terminal-like staining over clusters of VMpo neurons. A few of these clusters also display terminal-like substance P labelling. Small bursts of CGRP staining are intercalated between the calbindin-labelled clusters, but there is little or no overlap between these two markers. CGRP immunoreactivity is also present over small, non-clustered neurons in the calbindin-negative area that separates VMpo from the VPL and VPM nuclei, which we denote as the posterior nucleus (Po). These observations provide a concise description of VMpo in the human thalamus. Further, they suggest that the lamina I spinothalamic tract fibres (represented by calbindin and probably also substance P immunoreactivity) and vagal-solitary-parabrachial afferents (represented by CGRP immunoreactivity) form closely related, but separate, termination fields that can be considered to represent different aspects of enteroceptive information regarding the physiological status of the tissues and organs of the body. The location of VMpo and the adjacent Po fits with clinical descriptions of the thalamic area from which pain, temperature and visceral sensations can be evoked by microstimulation, and where nociceptive and thermoreceptive neurons have been recorded in humans. It also corresponds to the area in which infarcts cause analgesia and thermoanaesthesia and can lead to the paradoxical development of central pain.

Determination of the enantiomers of omeprazole in blood plasma by normal-phase liquid chromatography and detection by atmospheric pressure ionization tandem mass spectrometry

An enantioselective assay of omeprazole in blood plasma using normal-phase liquid chromatography on a Chiralpak AD column and detection by mass spectrometry is described. Omeprazole is extracted by a mixture of dichloromethane and hexane and, after evaporation, redissolution and injection, separated into its enantiomers on the chiral stationary phase. Detection is made by a triple quadrupole mass spectrometer, using deuterated analogues as internal standards. The method enables determination in plasma down to 10 nmol/l (LOQ) and shows excellent consistency suited for pharmacokinetic studies in man.

Progesterone receptor expression in the brainstem of the female rat

By using in situ hybridization and immunohistochemistry, the presence of neurons expressing progesterone receptor mRNA (PR mRNA) and progesterone receptor-like immunoreactivity (PR-LI) was examined in the brainstem and spinal cord of female rats. Neurons expressing PR mRNA and PR-LI were seen in the ventrolateral medulla, the parvocellular reticular formation and the nucleus of the solitary tract. PR mRNA, but not PR-LI, was seen in the hypoglossal nucleus, the inferior olive, the locus coeruleus and the parabrachial nucleus. No consistent labeling was present in the spinal cord. These findings show that progesterone receptors are expressed in brainstem areas involved in various functions, including autonomic regulation and pain modulation.

Estrogen-induced alterations of spinal cord enkephalin gene expression

Enkephalin-synthesizing neurons in the superficial laminae of the spinal and trigeminal dorsal horn are critical components of the endogenous pain-modulatory system. We have previously demonstrated that these neurons display intracellular estrogen receptors, suggesting that estrogen can potentially influence their enkephalin expression. By using Northern blot, we now show that a bolus injection of estrogen results in a rapid increase in spinal cord enkephalin mRNA levels in ovariectomized female rats. Thus, 4 h after estrogen administration the enkephalin mRNA-expression in the lumbar spinal cord was on average 68% higher (P<0.05) than in control animals injected with vehicle only. A small increase in the amount of enkephalin mRNA was also seen after 8 h (P<0.05), whereas no difference between estrogen-injected and control animals was found after 24 h or at time periods shorter than 4 h. Taken together with the previous anatomical data, the present findings imply that estrogen has an acute effect on spinal opioid levels in areas involved in the transmission of nociceptive information.

Spinal cord-projecting vasopressinergic neurons in the rat paraventricular hypothalamus

The paraventricular hypothalamic nucleus (PVH) is a key structure for the maintenance of homeostasis. Homeostatic regulation includes modulation of signaling in the spinal cord. This may be exerted by neurons in the PVH with spinal projections. However, the PVH is not a homogeneous structure, but consists of anatomically and functionally distinct subdivisions. In this study, we have analyzed the distribution of spinal cord-projecting PVH neurons that express vasopressin, an important neuropeptide in autonomic regulation. Vasopressinergic neurons were identified with a radiolabeled riboprobe complementary to vasopressin mRNA combined with immunohistochemical labeling of retrogradely transported cholera toxin subunit b in spinally projecting neurons. More than 40% of the spinally projecting neurons in the PVH of naive Sprague-Dawley rats were found to express vasopressin mRNA. The lateral parvocellular subdivision and the ventral part of the medial parvocellular subdivision contained the densest distribution of spinal cord-projecting vasopressin mRNA-expressing neurons. The magnocellular subdivisions displayed large numbers of vasopressin mRNA-expressing neurons, but very few of those projected to the spinal cord. The dorsal parvocellular subdivision contained a large number of spinally projecting neurons, but very few of those expressed vasopressin mRNA. These findings show that the PVH gives rise to a major vasopressinergic projection to the spinal cord and that the spinal cord-projecting vasopressinergic neurons are parceled into anatomically distinct cell groups. This provides an anatomical basis for a selective activation of functionally different groups in the PVH as part of a behaviorally adaptive response, including modulation of autonomic activity and pain processing at the spinal level.

Distribution of preprovasopressin mRNA in the rat central nervous system

Vasopressin released in the central nervous system has been shown to be involved both in homeostatic mechanisms (e.g., water balance, thermoregulation, cardiovascular regulation, metabolism, and antinociception) and in higher brain functions (e.g., social recognition and communication, and learning and memory). Many nuclear groups have been proposed to synthesize vasopressin, but available data are conflicting. We have used a sensitive in situ hybridization technique to identify the distribution of the neurons that may be the origin of the vasopressin in the central nervous system of the male Sprague-Dawley rat. Vasopressin mRNA-expressing neurons were most abundant in the hypothalamus (e.g., the paraventricular, supraoptic, and suprachiasmatic nuclei) but were also seen in the medial amygdaloid nucleus, the bed nucleus of stria terminalis, and the nucleus of the horizontal diagonal band. Previously unreported vasopressinergic neurons were seen in the entorhinal and piriform cortices, the ventral lateral portion of the parabrachial nucleus, the pedunculopontine nucleus, and the rostral part of the ventral periaqueductal gray matter and the adjacent portion of the mesencephalic reticular nucleus. Vasopressin mRNA expression suggestive of neuronal labeling was seen in the pyramidal layer of the CA1-3 fields and the dentate gyrus of the hippocampus. In addition, vasopressin mRNA expression, probably representing axonal mRNA, was detected over the hypothalamopituitary tract. No or insignificant preprovasopressin mRNA expression was present in the cerebellum, locus coeruleus, subcoeruleus, or the spinal cord. These findings provide novel information on the distribution of vasopressin neurons that are important for our understanding of how vasopressin acts in the brain.

A distinct thermoreceptive subregion of lamina I in nucleus caudalis of the owl monkey

An immunohistochemically distinct zone was identified in the superficial aspect of trigeminal nucleus caudalis of the New World owl monkey that is not immunoreactive for substance P or serotonin, in stark contrast to the dense staining present in the surrounding laminae I and II. Thionin-stained sections in different planes showed that this is a subregion of lamina I containing clusters of neurons that appear to have pyramidal or polygonal somata. Extracellular microelectrode recordings in this region revealed clusters of thermoreceptive-specific (COLD) cells with nasal or labial receptive fields, whereas nociceptive neurons were found in the adjacent portions of lamina I. Anterograde tracer injections in this region produced trigeminothalamic terminal labeling in the site homologous to the lamina I spino-thalamo-cortical relay nucleus identified previously in the Old World macaque monkey and in humans. Retrograde tracer injections involving this thalamic site, where recordings of trigeminal COLD-like neurons were obtained, produced clusters of retrogradely labeled trigeminothalamic neurons in this immunohistochemically distinct subregion of lamina I, nearly all of which are pyramidal neurons. We conclude that the nocturnal owl monkey has a specialized perinasal thermoreceptive trigeminothalamic sensory pathway that is probably of behavioral significance during olfactory sniffing. In addition, these observations corroborate other findings that have indicated that lamina I COLD cells are pyramidal neurons and are not physiologically modulated by substance P or serotonin, in contrast to nociceptive neurons.

Preprocholecystokinin mRNA-expressing neurons in the rat parabrachial nucleus: subnuclear localization, efferent projection, and expression of nociceptive-related intracellular signaling substances

The pontine parabrachial nucleus (PB) is a major target for ascending fibers from nociresponsive dorsal horn neurons. Several different neuropeptides have been identified in the PB. By using double-labeling methods that combine in situ hybridization histochemistry with retrograde tract tracing and immunohistochemistry, we have examined the subnuclear localization of preprocholecystokinin mRNA (ppCCK)-containing neurons, investigated their efferent projection, and analyzed their expression of intracellular signaling substances that may be of importance for nociceptive processing. The results show that neurons containing ppCCK are preferentially localized to the superior lateral subnucleus (PBsl), whereas other subnuclei, such as the dorsal lateral, external lateral, central lateral, and ventral lateral subnuclei, and the Kölliker-Fuse nucleus, contain only moderate to small numbers of such neurons. Injections of the retrograde tracer cholera toxin subunit b into the ventromedial hypothalamus demonstrated that ppCCK-containing neurons in PBsl were projection neurons. Following nociceptive stimulation, the ppCCK-containing neurons expressed FOS protein as well as phosphorylated cyclic AMP-responsive element-binding protein (CREB). In addition, Ca2+/calmodulin-dependent kinase II (CaMKII) was heavily and rather selectively expressed in PBsl and was co-localized to ppCCK-containing neurons. These observations show that nociceptive stimuli activate a cholecystokinin pathway from the parabrachial nucleus to the ventromedial hypothalamus that may be important for homeostatic responses to tissue damage, and point to a putative intracellular route for Ca2+-mediated FOS transcription via CaMKII and CREB for the regulation of ppCCK transcription.

Short and long term course of elderly patients with peptic ulcer bleeding--analysis of factors influencing fatal outcome

OBJECTIVE

To study long and short term survival in patients aged 60 years or over admitted with a peptic ulcer bleeding and find out which factors influence outcome.

DESIGN

Cohort study with matched controls.

SETTING

Two emergency hospitals, Sweden

PATIENTS

676 of the 687 patients aged 60 years or over admitted to the two emergency hospitals serving Gothenburg, Sweden during 1989-1993 who fulfilled the diagnostic criteria and whose case notes were available for study.

MAIN OUTCOME MEASURES

Seven year survival rates and odds ratios for risk factors based on multiple logistic regression analyses.

RESULTS

37 patients died and the timing was evenly distributed within the first 30 days of admission with a cumulated case-fatality rate of 5.5% at day 30. Mortality was increased among the patients compared with the control group during the subsequent years. Factors that influenced day 30 mortality were age and Forrest class.

CONCLUSION

Mortality is increased among patients with peptic ulcer bleeding even long after the event. Old age and signs of recent haemorrhage increase the risk.

Preprodynorphin mRNA-expressing neurones in the rat parabrachial nucleus: subnuclear localization, hypothalamic projections and colocalization with noxious-evoked fos-like immunoreactivity

The dorsal lateral subnucleus of the rat pontine parabrachial nucleus is a major target for ascending nociceptive information from the spinal cord. With in situ hybridization histochemistry, using a radiolabelled cRNA probe, we demonstrate that neurones in and near the dorsal lateral subnucleus express preprodynorphin mRNA. The cRNA probe was constructed from a PCR product amplified from rat genomic DNA. Sequencing of the PCR product revealed that it corresponded to the sequence 466-1101 of the rat preprodynorphin gene exon 4. Tract tracing experiments, using injection of cholera toxin subunit B into the hypothalamic median preoptic nucleus, showed a retrograde labelling pattern of neurones in the parabrachial nucleus that was almost identical to that of the preprodynorphin mRNA expressing neurones. Double-labelling, combining immunohistochemical detection of tracer and in situ hybridization, revealed that the retrogradely labelled neurones expressed preprodynorphin mRNA. A similar double-labelling, combining in situ hybridization with immunohistochemical detection of noxious-evoked fos following formalin injection into one hindpaw of awake animals, showed that almost all fos-immunoreactive neurones in the dorsal lateral parabrachial subnucleus also expressed preprodynorphin mRNA. Quantitative analysis suggested that the evoked fos immunoreactivity was accompanied by an increased preprodynorphin mRNA expression. The findings provide evidence that neurones in the dorsal lateral subnucleus produce dynorphin and project to the median preoptic nucleus, and that noxious stimulation in awake animals synaptically activates the dynorphinergic neurones in this subnucleus. These observations are consistent with the idea of a functional and chemical heterogeneity among different parabrachial subnuclei that serves to produce specific homeostatic responses to stimuli that changes the physiological status of the organism, including tissue damage.

Preproenkephalin messenger RNA-expressing neurons in the rat parabrachial nucleus: subnuclear organization and projections to the intralaminar thalamus

The pontine parabrachial nucleus, which is a key structure in the central processing of autonomic, nociceptive and gustatory information, is rich in a variety of neuropeptides. In this study we have analysed the distribution of parabrachial neurons that express preproenkephalin messenger RNA, which encodes for the precursor protein for enkephalin opioids. Using an in situ hybridization method, we found that preproenkephalin messenger RNA-expressing neurons were present in large numbers in four major areas of the parabrachial nucleus: the Kölliker-Fuse nucleus, the external lateral subnucleus, the ventral lateral subnucleus, and in and near the internal lateral subnucleus. Many preproenkephalin messenger RNA-expressing neurons were also seen in the central lateral subnucleus, and in the medial and external medial subnuclei. Few labeled neurons were found in the dorsal and superior lateral subnuclei. Injection of the retrograde tracer substance cholera toxin subunit B into the midline and intralaminar thalamus demonstrated that the enkephalinergic neurons in and near the internal lateral subnucleus were thalamic-projecting neurons. Taken together with the results of previous tract-tracing studies, the present findings show that many of the enkephalinergic cell groups in the parabrachial nucleus are located within the terminal zones of the ascending projections that originate from nociresponsive neurons in the medullary dorsal horn and spinal cord, as well as from viscerosensory neurons within the nucleus of the solitary tract. The enkephalinergic neurons in the parabrachial nucleus may thus transmit noci- and visceroceptive-related information to their efferent targets. On the basis of the present and previous observations, we conclude that these targets include the intralaminar and midline thalamus, the ventrolateral medulla and the spinal cord. Through these connections, nociceptive and visceroceptive stimuli may influence several functions, such as arousal, respiration and antinociception.

Differential expression of the AP-1/CRE-binding proteins FOS and CREB in preproenkephalin mRNA-expressing neurons of the rat parabrachial nucleus after nociceptive stimulation

Several subgroups in the brainstem parabrachial nucleus (PB), which is a major target for nociresponsive neurons in the medullary and spinal dorsal horn, contain large numbers of preproenkephalin (ppENK) mRNA-expressing neurons. To elucidate how noxious stimuli may regulate ppENK transcription in these neurons, we have in the present study investigated whether immunoreactivity for the transcription factors FOS and phosphorylated CREB (pCREB), respectively, is displayed in the ppENK mRNA-expressing neurons after peripheral nociceptive stimulation. Rats received injection of formalin into one hindpaw, and were killed 30-80 min later. With a combination of immunohistochemistry and in situ hybridization, we found that only a small number of ppENK mRNA-expressing neurons in PB displayed FOS-immunoreactivity after nociceptive stimulation. In contrast, large numbers of ppENK mRNA-expressing neurons displayed pCREB-like immunoreactivity after nociceptive stimulation. Most of the ppENK mRNA/pCREB-expressing neurons were found in the Kölliker-Fuse and internal lateral subnuclei, but many double-labeled cells were also seen in the ventral lateral and central lateral subnuclei. In addition, a cluster of ppENK mRNA/pCREB-expressing neurons was found in the medial part of the medial parabrachial nucleus. Our findings suggest that CREB rather than FOS regulates nociceptive-related second messenger activation of ppENK transcription in parabrachial neurons.

Subnuclear localization of FOS-like immunoreactivity in the parabrachial nucleus after orofacial nociceptive stimulation of the awake rat

We used FOS-like immunohistochemistry to detect neuronal activity in the pontine parabrachial nucleus after injection of formalin into the lower lip of the awake rat and compared the labeling pattern with that seen after formalin injection into the hindpaw. One hour after a formalin injection into the lip, many FOS-immunoreactive cells were seen in the parabrachial nucleus, preferentially on the side ipsilateral to the injection site. Detailed anatomical analysis revealed that FOS-immunoreactive neurons were localized predominantly to three regions of the parabrachial nucleus: the external lateral, the external medial, and the Kölliker-Fuse subnuclei, with sparser labeling present in the dorsal and superior lateral subnuclei and in the medial parabrachial nucleus. In contrast, a formalin injection into the hindpaw resulted in dense FOS-labeling in the superior, dorsal, and central lateral subnuclei, with sparse to moderate labeling in the Kölliker-Fuse nucleus, and sparse labeling in the external lateral and external medial subnuclei, as described previously (Hermanson and Blomqvist, J. Comp. Neurol., [1996] 368:45-56). The distribution of FOS-labeled neurons after noxious orofacial stimulation corresponds to the termination pattern in the parabrachial nucleus of fibers that originate from neurons in the marginal zone of the trigeminal dorsal horn and is different from that seen after nociceptive stimulation of other body parts. Considering the differences in efferent connections of parabrachial subnuclei, the present findings imply that noxious information from the orofacial region to the parabrachial nucleus has other functional roles than noxious information from the trunk and limbs. Such roles may include the integration of somatosensory and gustatory information, which has been suggested to be of importance for feeding behavior.

Thalamic-projecting preprocholecystokinin messenger RNA-expressing neurons in the dorsal column nuclei of the rat

This study aimed at investigating the expression of preprocholecystokinin messenger RNA among thalamic-projecting neurons in the dorsal column nuclei of the rat. Thalamic-projecting neurons were identified by injection of cholera toxin subunit b into the ventroposterolateral nucleus. Following immunohistochemical detection of retrogradely transported tracer substance, the expression of preprocholecystokinin messenger RNA in the projection neurons of the dorsal column nuclei was detected by in situ hybridization, using autoradiographic visualization of a 35S-labeled RNA probe complementary to preprocholecystokinin messenger RNA. Many preprocholecystokinin-expressing neurons were seen in the dorsal column nuclei. A large proportion of these neurons were also labeled with cholera toxin. The double-labeled neurons, as well as neurons single-labeled with preprocholecystokinin messenger RNA or cholera toxin, were preferentially found within the middle region of the dorsal column nuclei, located just caudal to the obex. These findings demonstrate that neurons in the dorsal column nuclei express preprocholecystokinin messenger RNA, and show that these neurons provide a peptidergic projection from the dorsal column nuclei to the ventroposterolateral nucleus of the thalamus. These observations suggest that cholecystokinin may be involved in the transmission of somatosensory (tactile) information from the dorsal column nuclei to the thalamus.

Optimal non-linear health insurance

Most theoretical and empirical work on efficient health insurance has been based on models with linear insurance schedules (a constant co-insurance parameter). In this paper, dynamic optimization techniques are used to analyse the properties of optimal non-linear insurance schedules in a model similar to one originally considered by Spence and Zeckhauser (American Economic Review, 1971, 61, 380-387) and reminiscent of those that have been used in the literature on optimal income taxation. The results of a preliminary numerical example suggest that the welfare losses from the implicit subsidy to employer-financed health insurance under US tax law may be a good deal smaller than previously estimated using linear models.

GABA-like immunoreactivity in the thalamic nucleus submedius of the cat

The distribution of GABAergic elements and their synaptic contacts in the nucleus submedius, a specific nociceptive relay in the medial thalamus of the cat, was studied using light and electron-microscopic postembedding immunohistochemical methods. About one-fourth of the neurons in nucleus submedius were GABA immunoreactive. These neurons were generally smaller than the unlabeled neurons and are probably local circuit neurons. Electron microscopy showed GABA immunoreactivity in two types of vesicle-containing profiles, F-terminals and presynaptic dendrites. F-terminals formed simple synapses with the dendrites of presumed thalamocortical relay cells. Presynaptic dendrites were involved in more complex synaptic arrangements that included ascending trigeminothalamic and spinothalamic tract terminals and thalamocortical relay cell dendrites. Analysis of single sections showed that about 40% of the trigeminothalamic and spinothalamic tract terminals, identified by anterograde transport of horseradish peroxidase, were presynaptic to GABAergic presynaptic dendrites. These results show that GABAergic neurons are frequent in nucleus submedius and that the GABAergic elements make synaptic connections similar to those described for other sensory relay nuclei, including the somatosensory ventroposterior nucleus. This suggests that GABAergic mechanisms play an important role in the processing of nociceptive and thermoreceptive information.

Colocalization of oestrogen receptor immunoreactivity and preproenkephalin mRNA expression to neurons in the superficial laminae of the spinal and medullary dorsal horn of rats

A double-labelling procedure combining immunohistochemical staining with in situ hybridization using a radiolabelled cRNA probe was employed to demonstrate oestrogen receptor-like immunoreactivity and preproenkephalin-A mRNA in the medullary and spinal dorsal horn of female rats. Both markers labelled large numbers of neurons in the substantia gelatinosa and its trigeminal homologue. Many of these neurons were double-labelled, displaying both oestrogen receptor-like-immunoreactivity and preproenkephalin-A mRNA; cell counts showed that 40-60% of the of the oestrogen receptor-like-immunoreactive cells in the superficial laminae also were labelled for preproenkephalin-A mRNA, and that 60-70% of the preproenkephalin-A mRNA-labelled neurons in the same laminae displayed oestrogen receptor-like immunoreactivity. Previous studies have shown that oestrogen receptors can bind to the promoter region of the preproenkephalin-A gene, and studies on the hypothalamus have demonstrated that oestrogen regulates enkephalin expression in select neuronal populations. The present results demonstrate that enkephalinergic neurons in the superficial dorsal horn contain oestrogen receptors and suggest that oestrogen may play an important role in the modulation of sensory and nociceptive processing in the lower medulla and spinal cord.

Quality of life assessment after laparoscopic and open fundoplications. Results of a prospective, clinical study

BACKGROUND

In the evaluation of different treatment alternatives, assessment of the patients' own perceived situation can give important clinical information in addition to the conventional efficacy variables used.

METHODS

Fifty patients with chronic gastroesophageal reflux disease (GERD) were operated on with either an open fundoplication (n = 25; 17 men; mean age, 51.5 years) or with a fundoplication through the laparoscope (n = 25; 16 men; mean age, 49.8 years). In each case adequate control of the GERD was achieved with the operation, also when objectively assessed. Twelve months after surgery the quality of life was studied by using a battery of self-administered questionnaires (the Psychological General Well-being (PGWB) index and the Gastrointestinal Symptom Rating Scale (GSRS), and a visual analogue scale, depicting specific reflux-related symptoms (RVAS).

RESULTS

After antireflux surgery the overall PGWB scores were normalized with no obvious difference between the two procedures. In the GSRS scale, however, differences were shown between the two procedures, with more dyspeptic and indigestion symptoms in patients having a laparoscopic total fundic wrap.

CONCLUSION

These data emphasize the clinical efficacy of antireflux surgery, with normalization of the quality of life in terms of well-being after these procedures. It should be noted that these instruments are sensitive enough to pick up significant differences between different antireflux procedures and should therefore be frequently used in the attempt to refine and optimize long-term therapeutic alternatives in reflux disease.

AMPA-selective glutamate receptor subunits and their relation to glutamate- and GABA-like immunoreactive terminals in the nucleus submedius of the rat

Glutamate plays an important role in supraspinal nociceptive systems. Thus, glutamate is present in the nucleus submedius of the medial thalamus, a major relay for nociceptive information. In this study, immunoreactivity for the four subunits (GluR1-4) of alpha-amino-3-hydroxy-5-methyl-4-isoxasoleproprionate (AMPA) receptors was examined by a preembedding immunohistochemical method in order to evaluate the presence of this glutamate receptor subtype in the nucleus submedius. Combining the preembedding method with a postembedding immunogold technique, we found that AMPA receptor-like immunoreactivity was present postsynaptically to glutamatergic terminals but not to terminals containing gamma-aminobutyric acid (GABA). These findings suggest a role for AMPA receptors in excitatory synaptic transmission in the nucleus submedius of the rat thalamus.

Ca2+/calmodulin-dependent kinase II immunoreactivity in the rat hypothalamus

The distribution of Ca2+/calmodulin-dependent kinase II (CaMKII) in the rat hypothalamus was studied using immunohistochemistry. Differences in labelling density were seen both between different nuclei and within nuclei. Dense labelling of cell bodies and dendrites was present in several nuclei, including the medial preoptic, suprachiasmatic, ventromedial and arcuate nuclei. In the paraventricular nucleus many labelled neurones were seen in some parvocellular regions, whereas its posterior magnocellular part was unlabelled. Dense terminal-like labelling was present in, for example, the ventromedial nucleus and the supramammillary nucleus. We suggest that differences in CaMKII distribution reflect differences in the mechanisms of calcium signalling in these neurones, which may be related to their different neurochemical phenotypes and/or connective relationships.

Fine structural organization of spinothalamic and trigeminothalamic lamina I terminations in the nucleus submedius of the cat

We examined lamina I trigemino- and spinothalamic tract (TSTT) terminals labeled with Phaseolus vulgaris leucoagglutinin in the nucleus submedius (Sm), a nociceptive relay in the cat's thalamus. Volume-rendered (three-dimensional) reconstructions of ten lamina I TSTT terminals identified with light and electron microscopy were built from serial ultrathin sections by computer, which enabled the overall structures of the terminal complexes to be characterized in detail. Two fundamentally different terminations were observed: compact clusters of numerous boutons, which predominate in the dense focus of a lamina I terminal field in the Sm, and boutons-of-passage, which are present throughout the terminal field and predominate in its periphery. Reconstructions of cluster terminations reveal that all boutons of each cluster make synaptic contact with protrusions and branch points on a single dendrite and involve presynaptic dendrites (PSDs) in triadic arrangements, providing a basis for the secure relay of sensory information. In contrast, reconstructions show that boutons-of-passage are generally characterized by simple contacts with PSDs, indicating an ascending inhibitory lamina I influence. These different synaptic arrangements are consistent with physiological evidence indicating that the morphologically distinct nociceptive-specific and thermoreceptive-(cold)-specific lamina I TSTT neurons terminate differently within the Sm. Thus, a suitable structural substrate exists in the cat's Sm for the inhibitory effect of cold on nociception, a behavioral and physiological phenomenon of fundamental significance. We conclude that the Sm is more than a simple relay for nociception, and that it may be an integrative comparator of ascending modality-selective information that arrives from neurons in lamina I.

Cytoplasmic CREB alpha-like antigens in specific regions of the rat brain

We have investigated the expression of the alpha-region of CREB (amino acids 88-101) in the rat brain. This region is encoded by a separate exon and has been reported to enhance the transcriptional efficiency of CREB. Light microscopic immunohistochemistry showed labeled neurons in several brain regions, such as the spinal cord, pontine reticular formation, cerebellum, hypothalamus, hippocampus and olfactory cortex. The labeling was exclusively cytoplasmic, and electron microscopy revealed that the CREB alpha-immunoreactivity was localized to the Golgi apparatus and axon terminals. Immunoblotting after SDS-PAGE showed specifically detected proteins of 21 and 160 kD. We suggest that neuronal CREB alpha-proteins represent alternatively spliced isoforms of CREB that lack the nuclear translocation signal. These isoforms may be involved in the regulation of CREB-mediated transcription.

Differential distribution of calcium-binding proteins in the dorsal column nuclei of rats: a combined immunohistochemical and retrograde tract tracing study

This study aimed to investigate whether different calcium-binding proteins are present in morphologically and functionally separate cell groups in the dorsal column nuclei of rats. Thalamic-projecting neurons were identified by iontophoretic injection of an intraaxonal tracer substance, choleragenoid, into the ventroposterolateral thalamic nucleus, which was localized by extracellular recordings of the responses to natural peripheral stimulation. The presence of the calcium-binding proteins calbindin and paravalbumin in the projection neurons was detected by a double-labelling immunofluorescent method. The vast majority of the thalamic-projecting neurons contained paravalbumin, but not all parvalbumin-immunoreactive cells were retrogradely labelled. Calbindin-immunoreactive neurons were also found in the dorsal column nuclei, but only a small minority of these neurons projected to the thalamus. These findings are generally consistent with the notion that the different calcium-binding proteins represent functionally separate neuronal populations. Taken together with previous observations that parvalbumin is present in large dorsal root ganglion cells, which project to the dorsal column nuclei, and in the thalamocortical relay cells that receive dorsal column nuclear input, the present findings suggest that parvalbumin is associated with neurons that transmit modality-specific low-threshold mechanoreceptive information from the periphery to the somatosensory cortex. However, the presence of parvalbumin-immunoreactive cells that appeared not to project to the thalamus, as well as the occurrence of thalamic-projecting calbindin-immunoreactive neurons, indicate that parvalbumin and calbindin are present within several, functionally different, groups of neurons in the dorsal column nuclei.

Preprovasopressin mRNA is not present in dorsal root ganglia of the rat

Immunohistochemical studies on colchicine-treated rats have suggested that more than half of the neurons in dorsal root ganglia (DRG) contain vasopressin. Thus, vasopressin would be the most commonly found peptide in DRG neurons. In the present study we have reexamined the presence of vasopressin in DRG neurons, using a sensitive in situ hybridization method employing long riboprobes that will detect very small amounts of mRNA. The C3, C6, T2, T12, L2 and L5 DRG were studied. None of these ganglia contained any preprovasopressin mRNA. Yet, dense labeling for preprovasopressin mRNA was seen on simultaneously processed hypothalamic sections and a heavy preprotachykinin mRNA expression was seen in adjacent DRG sections. These findings demonstrate that vasopressin is not produced in DRG in normal rats.

Subnuclear localization of FOS-like immunoreactivity in the rat parabrachial nucleus after nociceptive stimulation

The effect of noxious stimulation on the expression of FOS-like immunoreactivity (FOS-LI) in neurons of the parabrachial nucleus (PB) was studied in awake, freely moving rats. In one series of experiments, the rats were subjected to noxious mechanical stimulation (pinch) of either the nape of the neck or the base of the tail for 20 seconds every 5 minutes for 90 minutes, and then they were killed by transcardial perfusion after 45-210 minutes. Control animals received innocuous mechanical stimulation (brush) of the tail. Noxious stimuli resulted in FOS-LI in neurons in the dorsal part of the lateral PB, with heavy labeling in the superior lateral (PBsl) and the dorsal lateral (PBdl) subnuclei. FOS-LI was also elicited in the central lateral subnucleus (PBcl) and, although much more sparsely, in the external lateral subnucleus and the Kölliker-Fuse nucleus. Tail and neck stimulation resulted in similar labeling patterns, but more neurons, particularly in PBsl, expressed FOS-LI after pinch of the tail than of the neck. In another series of experiments, rats received injection of 5% formalin into one hindpaw. After 75-90 minutes, FOS-LI was seen in the same parts of PB as after noxious mechanical stimulation. The heaviest labeling was seen on the side contralateral to the injection side, with statistically significant (P < 0.05) side differences present in PBsl and PBdl. In a third series of experiments, rats were hemisected at low cervical-upper thoracic segments, allowed 2 weeks to recover, and then given formalin injections in both hindpaws. Significantly more neurons were FOS-labeled in PBdl, PBsl, and PBcl on the side contralateral to the hemisection than on the ipsilateral side. These observations are discussed in relation to the organization of the spinal afferent input and the efferent connections of PB. It is concluded that the FOS-LI expression in PBdl and PBsl and probably also in PBcl, to a large extent, is evoked by the ascending spinal nociceptive input to PB. Because these subnuclei project to several hypothalamic regions, it is suggested that neurons in PB that express FOS after noxious mechanical and chemical stimulation primarily are involved in autonomic and homeostatic responses to behavioral situations that involve tissue-damaging stimuli.

Evidence for glutamate as a neurotransmitter in spinothalamic tract terminals in the posterior region of owl monkeys

Previous studies have suggested that glutamate is a neurotransmitter in ascending somatosensory pathways to the thalamus. The present study examined with quantitative immunohistochemical methods the presence of glutamate in spinothalamic tract terminals of owl monkeys (Aotus trivirgatus). Such terminals in the posterior region, in which a nucleus was recently identified as a specific pain and temperature relay in macaques and humans, were labeled by anterograde transport of wheat germ agglutinin conjugated to horseradish peroxidase, injected into the spinal dorsal horn. Glutamate-like immunoreactivity was demonstrated with a postembedding immunogold procedure using a well-characterized glutamate antiserum. Quantitative analysis of the immunogold labeling demonstrated that the spinothalamic tract terminals contained more than twice the tissue average of glutamate-like immunoreactivity. Enrichment of glutamate-like immunoreactivity was also found in terminals of presumed cortical origin. Presynaptic dendrites, cell bodies and non-vesicle-containing dendrites displayed low levels of glutamate-like immunoreactivity. A strong positive correlation (r = 0.69; P < 0.0001) was found between the density of synaptic vesicles and the density of gold particles in spinothalamic tract terminals, in contrast to a weak negative relationship (r = -0.28; P = 0.089) present in GABAergic presynaptic dendrites. These data provide strong evidence that the gold labeling in the spinothalamic tract terminals represents transmitter labeling, implying that glutamate is a neurotransmitter for ascending nociceptive and thermoreceptive information in primates.

Estrogen receptor-like immunoreactivity in the medullary and spinal dorsal horn of the female rat

Using an immunohistochemical technique, we demonstrate that large numbers of neurons in the laminar spinal trigeminal nucleus and spinal gray matter of the female rat express estrogen receptors (ER). Densely packed ER-immunoreactive neurons were present in lamina II, but labeled neurons were also present in lamina I, the neck of the dorsal horn, and in lamina X. Labeling was present throughout the length of the spinal cord, with the exception of segments caudal to S1, which were unlabeled. The distribution of ER-containing neurons to areas that are involved in processing of primary afferent nociceptive information suggests that the pain modulatory effects of estrogen may be exerted at the spinal level.

Enkephalinergic and catecholaminergic neurons constitute separate populations in the rat Kölliker-Fuse/A7 region

Using a double-labeling immunohistochemical and in situ hybridization technique for the simultaneous detection of tyrosine hydroxylase and preproenkephalin mRNA, we demonstrate that catecholaminergic and enkephalinergic neurons in the Kölliker-Fuse nucleus (K-F)/A7 region in the dorsolateral pons constitute separate populations. The enkephalinergic cell group is much larger than the catecholaminergic cell group. Most of the enkephalinergic neurons are located caudal to the catecholaminergic neurons, but enkephalinergic neurons are also interspersed among the catecholaminergic neurons. Taken together with previous demonstrations that the enkephalinergic neurons in K-F give rise to descending projections to the ventrolateral medulla and spinal cord, the current observations suggest that the antinociceptive effects that result from electrical stimulation of K-F may be a consequence of the activation of enkephalinergic neurons, either alone or in conjunction with catecholaminergic neurons.

Preproenkephalin mRNA-expressing neurones in the rat thalamus

We investigated the expression of preproenkephalin mRNA in the rat thalamus by in situ hybridization histochemistry using a radiolabelled full-length cRNA probe. Enkephalinergic neurones were present in the ventral thalamus, epithalamus, and intralaminar and midline nuclei of the dorsal thalamus. The largest number of labelled cell bodies was found in the zona incerta, the fields of Forel, and the ventral lateral geniculate, thalamic reticular, central medial and central lateral nuclei. Sparse labelling was present in the parafascicular, paracentral, paraventricular, and lateral habenular nuclei. The principal nuclei of the dorsal thalamus were unlabelled. The distribution of the enkephalinergic neurones suggests an involvement in arousal and attentional mechanisms, being in line with the sedative effects of exogenous opioids.

Spinal projections to the parabrachial nucleus are substance P-immunoreactive

Substance P plays an important role in nociceptive processing in the spinal cord. Substance P is also present in several supraspinal regions, such as the pontine parabrachial nucleus, a major relay for autonomic regulation. In this study we examined in the cat with an immunogold method the presence of substance P-like immunoreactivity in spinoparabrachial terminals that were labelled by anterograde transport of unconjugated and lectin-conjugated horseradish peroxidase. We found that dense core vesicles in anterogradely labelled terminals were substance P-immunoreactive. Taken together with previous observations that noxious stimuli increase preprotachykinin expression in ascending nociceptive pathways from the spinal dorsal horn, the present finding provides evidence that substance P is involved in nociceptive processing also in the brain stem.

Evidence for glutamate as neurotransmitter in trigemino-and spinothalamic tract terminals in the nucleus submedius of cats

The nucleus submedius in the medial thalamus of cats is an important termination site for lamina I trigemino-and spinothalamic tract (TSTT) neurons, many of which are nociceptive-specific, and the nucleus submedius has been proposed to be a dedicated nociceptive substrate involved in the affective aspect of pain. In the present study, the distribution of glutamate was examined by immunocytochemical methods in order to evaluate the possible role of this amino acid as a neurotransmitter in TSTT terminals in the nucleus submedius. TSTT terminals were identified by anterograde transport of horseradish peroxidase and wheatgerm agglutinin-horseradish peroxidase conjugate from the spinal cord or the medullary dorsal horn. Quantitative analysis of immunogold labelling revealed that TSTT terminals contain about twice the tissue average of glutamate-like immunoreactivity. A strong positive correlation was found between the density of synaptic vesicles and the density of gold particles in these terminals, whereas no relationship was seen between these variables in GABAergic presynaptic dendrites. Enrichment of glutamate-like immunoreactivity (approximately 250% of the tissue average) was also observed in terminals of presumed cortical origin. Presynaptic dendrites and neuron cell bodies in the nucleus submedius were found to contain relatively low levels of glutamate-like immunoreactivity, at or below the tissue average. These observations provide evidence that glutamate is a neurotransmitter in lamina I TSTT terminals in the nucleus submedius. The findings also suggest glutamatergic neurotransmission between cortical afferents and nucleus submedius neurons. Glutamate is therefore likely to be an important mediator of nociceptive processing in the medial thalamus.

A thalamic nucleus specific for pain and temperature sensation

The existence of a posterolateral thalamic relay nucleus for pain and temperature sensation was postulated in 1911, on the basis of the stroke-induced analgesia and thermanaesthesia found paradoxically in patients with thalamic pain syndrome. Pain or temperature sensations can be evoked in humans by electrical stimulation in a vaguely defined region of the posterolateral thalamus. Here we use anterograde tracing and single unit recordings to demonstrate that there is a distinct nucleus in the posterior thalamus of the macaque monkey that receives a dense, topographic input from spinothalamic lamina I neurons and in which almost all neurons are nociceptive- or thermoreceptive-specific. Immunohistochemical staining showed that this nucleus is defined by a dense calbindin-positive fibre plexus in the macaque, so we applied the same staining method to sections of human thalamus. We found a nearly identical fibre plexus localized within a distinct nucleus that is cytoarchitectonically homologous to the lamina I relay nucleus in the macaque thalamus. The stereotaxic coordinates of this nucleus and its location relative to the main somatosensory representation fit clinical descriptions of the pain-producing region in humans. We conclude that this is a specific thalamic nucleus for pain and temperature sensation in both monkey and human.

Autoradiographic visualization of 35S-labeled cRNA probes combined with immunoperoxidase detection of choleragenoid: a double-labeling light microscopic method for in situ hybridization and retrograde tract tracing

We describe a protocol for simultaneous light microscopic visualization of a neuron's efferent projections and its expression of mRNA. We have combined immunohistochemical visualization of the retrograde marker cholera toxin subunit B (CTb) with autoradiographic visualization of 35S-labeled cRNA probes. Injections of CTb were made into rat brain. Immunoreactivity for CTb was demonstrated by modification of the peroxidase-anti-peroxidase immunohistochemical technique, with DAB and nickel ammonium sulfate or cobalt acetate as chromogen. On the same sections, in situ hybridization was performed with a 35S-labeled RNA probe complementary to preproenkephalin mRNA or tyrosine hydroxylase mRNA. Many double-labeled neurons were detected. These neurons contained peroxidase reaction product and were covered by an accumulation of silver grains in the overlaying emulsion layer. The present method has several advantages over double-labeling methods using the combination of fluorescent tracers and oligonucleotide probes. Both reaction products are permanent and can be visualized simultaneously by light microscopy. Furthermore, both CTb and cRNA probes are very sensitive markers. In addition, the sections can be counterstained.

Activation of a bulbospinal opioidergic projection by pain stimuli in the awake rat

We examined the expression of preproenkephalin mRNA in pain-modulating regions of the rat's brainstem using in situ hybridization histochemistry. We found that neurones in the Kölliker-Fuse nucleus, which receives projections from spinal nociceptive-specific cells, express enkephalin mRNA, that this expression is increased by noxious pinch applied to the skin of awake animals, and that these enkephalinergic neurones are part of a descending system that terminates in the rostroventral medulla and the spinal cord. These findings show that natural noxious stimuli activate opioidergic bulbospinal neurones that could directly modulate spinal nociceptive transmission.

Serotoninergic innervation of the dorsal column nuclei and its relation to cytoarchitectonic subdivisions: an immunohistochemical study in cats and monkeys (Aotus trivirgatus)

The serotoninergic innervation of the dorsal column nuclei (DCN) was investigated in cats and owl monkeys (Aotus trivirgatus) with immunohistochemical methods. A dense network of serotonin-immunoreactive fibers was present in the reticular regions of DCN in cats, and in the pars triangularis of the cuneate nucleus and the peripheral and caudal regions of the gracile nucleus in owl monkeys. The cat's cluster regions and the monkey's rotund regions were more sparsely innervated. Electron microscopic examination showed that the labeled fibers were thin and unmyelinated. Vesicle-containing, terminal-like structures were small. They were in contact with dendrites, other terminals and cell bodies, but synapses were rare. The results demonstrate that the serotoninergic projection to the DCN in both cats and owl monkeys is heterogeneously distributed in a pattern that is faithfully related to the cytoarchitectonic subdivisions of the DCN. The densely innervated reticular regions in the DCN of cats and the corresponding regions in monkeys are predominantly involved in the processing of sensory information to the cerebellum, either directly, or indirectly through projections to the inferior olive, pontine gray, tectum, pretectum, red nucleus, or zona incerta. Thus, the present findings suggest that the serotoninergic innervation of the DCN is primarily related to the DCN's involvement in motor functions.

Determination of (22R,S)budesonide in human plasma by automated liquid chromatography/thermospray mass spectrometry

(22R,S)Budesonide was isolated from human plasma by solid-phase extraction. Switching from reversed-phase conditions during sample application and washing to normal-phase conditions during elution afforded a very clean extract. Budesonide was derivatized with acetic anhydride to form the 21-acetyl derivative before analysis by reversed-phase liquid chromatography combined with thermospray mass spectrometry. Deuterium-labelled budesonide was used as internal standard. Standard samples prepared in human albumin solution were used for the calibration curve. An automated liquid chromatography/mass spectrometry system, allowing unattended overnight operation, was used for routine analysis. The recovery of budesonide from plasma was 88.9 +/- 5.9% (mean +/- SD) and the method was linear over the range 0.30-30 pmol (amount analysed), corresponding to plasma concentrations of 0.10-10 nmol l-1. Budesonide could be measured down to 0.10 nmol l-1 with a within-day variation of 10-18% (CV). The error was less than +/- 15% at 0.10 nmol l-1 and less than +/- 7% at concentrations of 0.20 nmol l-1 or higher. The total imprecision between days was 9% (CV) at a concentration of 0.30 nmol l-1.

Lamina I spinocervical tract terminations in the medial part of the lateral cervical nucleus in the cat

The terminations of spinocervical tract fibers in the lateral cervical nucleus (LCN) of the cat were examined with anterogradely transported Phaseolus vulgaris leucoagglutinin (PHA-L) in order to analyze their organization relative to the most medial part and the main body (the lateral two-thirds) of the LCN, which have differential projections and physiological characteristics. Iontophoretic injections of PHA-L in laminae I-V of the spinal dorsal horn yielded dense labeling in somatotopically appropriate regions of the main body of the LCN, and, as seen previously with horseradish peroxidase, additional terminations were present in the medial LCN after injections at either cervical or lumbar spinal levels. The morphological characteristics of the PHA-L labeling in these two parts of the LCN were different. Terminations in the lateral LCN consisted of dense clusters of thick fibers bearing large numbers of boutons. The terminal axons in the medial part of the LCN displayed a reticulated network of longitudinally oriented, fine fibers with well-spaced varicosities. Some of the fine fibers in the medial LCN appeared to be collaterals of thicker fibers that terminated in the lateral LCN. Injections of PHA-L that were restricted to lamina I resulted in terminal labeling only in the medial LCN. The labeling was more sparse than that observed in the medial LCN after larger dorsal horn injections but displayed the same morphological characteristics. Lamina I terminations were seen in the medial LCN after cervical or lumbar injections on both the ipsilateral and contralateral sides. The PHA-L observations were corroborated by the presence of many retrogradely labeled lamina I cells at both cervical and lumbar spinal levels, following injections of cholera toxin subunit b or rhodamine-labeled microspheres in the medial LCN. In addition, double-immunofluorescent labeling for PHA-L and substance P was performed in a few cases, since substance P immunoreactivity is present in fibers in the medial LCN and also in cell bodies in lamina I; however, very few spinocervical fibers displayed immunoreactivity for both antigens. These observations indicate that the medial part of the LCN receives input from lamina I neurons, and probably from lamina III-V neurons as well, at cervical and lumbar spinal levels. The lamina I input to the medial LCN provides a basis for the small population of nociceptive neurons that differentiate the medial LCN. The lamina I input could also be responsible for the general inhibition of lateral LCN neurons by wide-field noxious stimulation, via activation of GABAergic interneurons in the medial LCN.(ABSTRACT TRUNCATED AT 400 WORDS)

Electron microscopic identification of lamina I axon terminations in the nucleus submedius of the cat thalamus

Ascending lamina I axons were labeled with Phaseolus vulgaris leucoagglutinin and the synaptic connections of their terminals in nucleus submedius (Sm) were studied in the electron microscope. The terminals were large, contained rounded synaptic vesicles, and were involved in complex synaptic aggregations with pre- and postsynaptic dendrites. It was observed that clustered large boutons from a single axon could contact a single dendritic shaft. These observations support a sensory role for lamina I input to Sm.

A re-examination of the spino-reticulo-diencephalic pathway in the cat

One commonly accepted idea is that affective aspects of pain sensation are derived from a flow of information from the spinal cord through the reticular formation to the intralaminar thalamus and subthalamus. Little is known, however, about the extent to which spinoreticular terminations and reticulodiencephalic neuronal cell bodies overlap. This study used a combination of anterograde and retrograde tracing techniques to compare these distributions in the cat. Whereas spinoreticular terminations were concentrated caudally and laterally, neurons projecting to intralaminar thalamus and subthalamus were concentrated rostrally and medially. Thus, information conveyed from the spinal cord to the reticular formation appears to have direct access to intralaminar thalamus and subthalamus only by way of a few widely scattered neurons. When considered with the results of others, these results encourage less emphasis on a putative spino-reticulo-diencephalic pathway for pain. Rather, the reticular formation's role in pain is more likely to involve its full complement of interconnected descending and ascending connections.

The Swedish patient insurance scheme and guarantee insurance for prosthodontic treatment

During 1975-76 a no-fault compensation system for treatment injuries in dentistry and failures within prosthodontics was introduced in Sweden. The guarantee insurance scheme for prosthetic treatment has changed somewhat during the years and, in 1987, became mandatory for all dentists in Sweden. All necessary retreatment not included in the National Dental Insurance Scheme (eg allergy to dental materials, all treatment following radiotherapy-related xerostomia) is included. For fixed prosthodontics, all replacements are covered by the scheme for the first 2 years. For removable prosthodontics, this is limited to the first year. A patient may choose any dentist in Sweden to carry out the retreatment. The claim system is simple and the number of cases has steadily increased, probably because dentists are becoming more familiar with the system and are willing to use it. The costs are paid for by private practitioners, the Public Dental Service and private dental laboratories. The insurance files are available for research purposes.

Origin of neuronal inputs to the region of the tuberomammillary nucleus of the rat brain

The origin of afferent connections of the hypothalamic tuberomammillary nucleus has been examined by using retrograde and anterograde tracing techniques. Retrogradely labeled neurons were found in about 70 cell groups of the forebrain and brainstem after injection of tracer into the ventral subgroup of the tuberomammillary nucleus. The majority of the labeled neurons were seen in the forebrain, with particularly large numbers in the infralimbic cortex, lateral septal nucleus, and preoptic region. The anterograde tracing experiments supported the general results of the retrograde tracing experiments. However, we did not observe any single cell group that selectively projected to the cell-rich core of the nucleus. In general, only a few fibers entered the core, whereas many labeled fibers seemed to terminate immediately adjacent to the cell group. Thus the target for the afferents is not primarily the perikarya of the neurons of the tuberomammillary nucleus, but either dendrites radiating out from the nucleus or neurons not belonging to the tuberomammillary nucleus. The results of the present study demonstrate that the histaminergic tuberomammillary nucleus derives its main input from the limbic forebrain. Through their widespread projections, the histaminergic neurons may transmit information originating from the limbic system to most if not all parts of the brain.

Evaluation of an automated thermospray liquid chromatography-mass spectrometry system for quantitative use in bioanalytical chemistry

An automated thermospray liquid chromatography-mass spectrometry system is described, including an autosampler and a gradient liquid chromatography system controlled from the mass spectrometer data system. The performance and reliability of the equipment during unattended operation were evaluated by repeated injections of standard solutions of some antiasthmatic drugs, using deuterium-labelled analogues as internal standards. High sensitivity and reproducibility were achieved during a 19-hour run, incorporating gradient elution and a total of 54 injections. The relative standard deviation of the peak area measurement of the internal standards was in the range of 6.5-8.2%. The corticosteroid budesonide can be routinely measured in plasma down to 0.1 nmol/l. Direct injection of a small plasma volume into the thermospray liquid chromatography-mass spectrometry system could be used to monitor drug plasma levels during a toxicity study in dogs.

Neonatal exposure to substance P alters behavioral and substance P levels in the central nervous system of the adult rat

Substance P (SP) administered subcutaneously to male and female rats during a neonatal period (days 1-7 after birth), produced long-term effects. Thermal/pain perception and elements of both male and female copulatory behavior were altered. A significant increase in the SP level in the dorsal part of the spinal cord was demonstrated by radioimmunoassay and by micro-fluorescence. The present study indicates that exposure to SP during the neonatal period, when the role of SP in transmission is likely to be established, has biochemical and functional consequences for SP systems in the adult.

Immunocytochemical identification of GABA in astrocytes located in white matter after inhibition of GABA-transaminase with gamma-acetylenic GABA

Several lines of evidence suggest that astrocytes contribute to the uptake and degradation of the inhibitory neurotransmitter gamma-aminobutyric acid (GABA). Recent immunohistochemical studies have shown that GABA-like immunoreactivity can be demonstrated in astrocytes in the grey matter of the rat's brainstem. The present study investigates whether GABA is also present in astrocytes located in the white matter. Adult rats were given gamma-acetylenic GABA (GAG), which inhibits the GABA-degratory enzyme GABA-alpha-ketoglutaric acid aminotransferase, and tissue sections from the cerebral cortex and brainstem were processed for GABA immunohistochemistry using an antiserum to GABA. Light microscopic examination of the sections showed numerous small GABA-immunoreactive cells in fibre tracts as well as in nuclear regions. Electron microscopic examination of the immunoreactive cells showed that they were fibrous astrocytes. The results provide evidence that the large increase in GABA in fibre tracts found in biochemical studies of rats injected with GAG is due to an increase in astrocytic GABA and suggest that fibrous astrocytes regulate GABA levels in the extracellular space of white matter.

GABA-like immunoreactivity in the tuberomammillary nucleus: an electron microscopic study in the rat

The organization of GABAergic elements in the histaminergic tuberomammillary nucleus has been examined by using antibodies against gamma-aminobutyric acid (GABA) and light and electron microscopy. Most neuronal perikarya of the ventral subgroup of the tuberomammillary nucleus were GABA immunoreactive (GABA-i). The morphology of the GABA-i perikarya was similar to the morphology of histaminergic perikarya described by Hayashi et al. ('84: J. Comp. Neurol. 229: 223-241) and Wouterlood et al. ('86: J. Comp. Neurol. 252:227-243). The GABA-i perikarya were contacted by relatively few terminals. The mean bouton covering ratio of GABA-i perikarya was 6.1%, whereas the mean bouton covering ratio for GABA-i dendrites in the tuberomammillary nucleus was 31%. Some of the presynaptic terminals were GABA-i. In addition, GABA-i perikarya and dendrites formed close contacts that never presented synaptic specializations. These results suggest that neurons of the histaminergic tuberomammillary nucleus contain the neurotransmitter GABA. Furthermore, GABA may act as a modulator of cellular processes within the tuberomammillary nucleus.

The doctor as double agent: information asymmetry, health insurance, and medical care

In a model incorporating uncertainty and state-dependent utility of health services, as well as information asymmetry between patients/buyers and physicians/sellers, two types of equilibria are compared: (1) when consumers have conventional third-party insurance and doctors are paid on the basis of fee-for-service; and (2) when insurance is through an HMO which provides health services through its own doctors. Conditions are found under which contractual or legal incentives can overcome the information asymmetry problem and bring about an efficient allocation of resources to health services provision.