Low-radio-frequency eclipses of the redback pulsar J2215+5135 observed in the image plane with LOFAR.

The eclipses of certain types of binary millisecond pulsars (i.e. 'black widows' and 'redbacks') are often studied using high-time-resolution, 'beamformed' radio observations. However, they may also be detected in images generated from interferometric data. As part of a larger imaging project to characterize the variable and transient sky at radio frequencies <200 MHz, we have blindly detected the redback system PSR J2215+5135 as a variable source of interest with the Low-Frequency Array (LOFAR). Using observations with cadences of two weeks - six months, we find preliminary evidence that the eclipse duration is frequency dependent (∝ν-0.4), such that the pulsar is eclipsed for longer at lower frequencies, in broad agreement with beamformed studies of other similar sources. Furthermore, the detection of the eclipses in imaging data suggests an eclipsing medium that absorbs the pulsed emission, rather than scattering it. Our study is also a demonstration of the prospects of finding pulsars in wide-field imaging surveys with the current generation of low-frequency radio telescopes.

Has active immunization against gonadotrophin-releasing hormone any effect on testis innervation in the pig? An immunohistochemical study.

The innervation of porcine testes was studied in intact animals and in boars undergoing active immunization against gonadotrophin-releasing hormone (GnRH) by means of immunohistochemistry using antibodies to tyrosine hydroxylase (TH), dopamine beta-hydroxylase (D beta H), vasoactive intestinal polypolypeptide (VIP), neuropeptide Y (NPY), synaptosome-associated protein of 25 kDa (SNAP-25) and protein gene product 9.5 (PGP 9.5). Moreover, the distribution of luteinizing hormone (LH) receptors in clusters of Leydig cells was also investigated. To identify these cells easily, either the NADPH-diaphorase histochemical technique or the Mayer counter-staining procedure was applied. Differences in the distribution pattern and relative density of particular subsets of intratesticular nerve fibres were observed in immunized boars as compared to those found in the intact animals. In the testes of non-treated animals, only single TH-immunoreactive (TH-IR) nerve fibres were observed. However, many D beta H-IR nerve terminals surrounded blood vessels in the tunica albuginea and parenchyma. Very scarce VIP-IR nerves occurred only in the tunica albuginea, mainly in close vicinity to blood vessels. Immunoreactivity to NPY occurred in single nerve fibres. Immunoreactivity to SNAP-25 and PGP 9.5 was found in single nerve fibres distributed mainly in the tunica albuginea. The interstitial cells were heavily stained for LH-receptors and NADPH-diaphorase. In the testes of immunized animals, only single TH-IR nerve fibres, scattered mainly in the tunica albuginea, were observed. Some TH-IR nerve terminals were also encountered in the parenchyma of the organ, where they were always associated with blood vessels. D beta H-IR nerve fibres formed a dense network distributed throughout the testis in association with the capsule, vasculature and interstitium. Some fibres were observed to run between seminiferous tubules. VIP-IR nerve fibres were located in the neighbourhood of blood vessels in the tunica albuginea and parenchyma. Only single VIP-IR nerves were found between seminiferous tubules. Numerous NPY-IR nerve fibres occurred in the tunica albuginea and parenchyma of the organ. SNAP-25-IR and PGP 9.5-IR nerve terminals formed a dense network distributed throughout the testis and many fibres were observed between seminiferous tubules. Interstitial cells were very weakly stained for LH receptors or NADPH-diaphorase.

Fetal porcine ventral mesencephalon graft. Determination of the optimal gestational age for implantation in parkinsonian patients.

Human fetal ventral mesencephalon tissue has been used as dopaminergic striatal implants in Parkinsonian patients, so far with variable effects. Fetuses from animals that breed in large litters, e.g., pigs, have been considered as alternative donors of dopaminergic tissue. The optimal gestational age of the porcine fetal donors has not been studied systematically. We collected ventral mesencephalic (VM) tissue from fetal pigs, embryonal ages E21, E28, E42, and E70, and examined the viability of the fetal VM cells after dissociation, the expression of tyrosine hydroxylase (TH) in culture, the presence of catecholamines, and the cellular survival and outgrowth up to 10 months after intrastriatal implantation in rats. The highest viability was found in suspensions prepared from E28 fetuses. The highest number of TH-positive cells was found in cell cultures prepared from E28 VM tissue. Explants with a gestational age of 28 and 42 days contained the largest amount of dopamine. Only E28-derived grafts showed TH-cell survival after implantation in rat striatum. Our results show that a gestational age of 28 days must be considered to be the optimal age for dopaminergic tissue derived from pig fetuses for therapeutic use as intrastriatal grafts in Parkinsonian patients.

Ontogenesis of embryonic porcine ventral mesencephalon in the perspective of its potential use as a xenograft in Parkinson's disease.

Human fetal neural dopaminergic tissue can be transplanted and can ameliorate neurological deficiencies in patients with Parkinson's disease (PD). Donor tissue from other species has been used experimentally for several years in animal experiments and is now being considered an attractive alternative, particularly from a donor species that breeds in large litters, e.g., the pig. We have studied the early ontogenetic development of the mesencephalic dopaminergic system in the pig, utilising an anti-tyrosine hydroxylase (TH) immunocytochemical technique, and demonstrated the earliest appearance of its cell bodies at embryonic day 20 (E20). We compared the porcine data with those of human fetal development, as revealed by the same technique. Embryonic dopaminergic cell groups resembling the A8, A9, and A10 of the rat are present in the pig and differentiate into the homologous cell groups of human, although interesting quantitative differences are apparent. In the pig, prolonged presence of immature characteristics of TH-immunoreactive (TH-i.r.) cell bodies was observed, notwithstanding the early outgrowth of TH-i.r. axons into the ganglionic eminence. In the human, on the other hand, cell divisions and maturation of dendrites have progressed to a further degree than in the pig, before such distinct outgrowth of axons takes place. In pig embryos of 28 days, cells in the ventral mesencephalon had differentiated into TH containing neurons, which indicates their potential to synthesize dopamine. In spite of their differentiation, these cells still showed immature morphological features (rounded cell bodies with undifferentiated, short processes). Dopamine synthesis by these cells was demonstrated in previous studies by the high performance liquid chromatographic technique (HogenEsch et al. [1993] Can. J. Neurol. Sci. 20(suppl. 4):P.S. 235). In a separate paper, we have described that these porcine 28-day dopaminergic cells retain their potential for development and outgrowth in culture (van Roon et al. [1995] Res. Neurol. Neurosci. 7:199-205). We conclude that the ventral mesencephalon in pig embryos of 28 days is a potential source of dopaminergic neurons to be used as a xenograft in PD.

Bilateral cryptorchidism in a dog with persistent cranial testis suspensory ligaments and inverted gubernacula: report of a case with implications for understanding normal and aberrant testis descent.

The genital system of a dog with bilateral intra-abdominal testes is described. External virilisation was normal except for an empty scrotum. Internally there was a prostate of normal macroscopic and histological appearances and, bilaterally, a fully developed male genital tract. Testicular vasculature was normal. Cranial to each testis, there was a strong ligament lying at the free edge of the gonadal/genital mesentery and running between the cranial tip of the testis/epididymis and the area craniolateral of the ipsilateral kidney. It was impossible to push the testes into the inguinal canal because of this strong ligament. Caudal to each testis, there was an elongated whitish structure between the caudal pole of the epididymis and the area of the internal inguinal ring. On closer inspection this structure appeared to be the inverted and elongated processus vaginalis sac. There was a minor ligament at the free border of the inguinal fold of the genital mesentery between the tip of this inverted processus vaginalis and the adjacent junction of the cauda epididymidis and vas deferens. The findings suggest that persistence of the fetal cranial gonadal suspensory ligaments could have been the major aetiological factor in this case of cryptorchidism. Their persistence could have prevented caudal outgrowth of the processus vaginalis with its consequent development into an intra-abdominal papilla-like structure. Inappropriate persistence of the cranial suspensory ligaments in male rodents, pig, and cattle has been associated with insufficient exposure of their primordia to androgen during fetal life. It is uncertain whether a similar deficiency could underlie persistence of these structures in the present specimen. The findings add further weight to the hypothesis that regression of the cranial gonadal suspensory ligament in males is a key event in the process of testis descent. The human homologue of this ligament deserves more attention in the analysis and treatment of human cryptorchidism.

Fetal porcine ventral mesencephalon grafts: dissection procedure and cellular characterization in culture.

The objective of this study was to develop an optimal dissection procedure for fetal porcine ventral mesencephalon (VM) grafts and to characterize the cellular composition of such an explant, in particular with respect to the dopaminergic and GABAergic components. We have used a monolayer cell culture system to study and identify the various VM cell types. The in vitro development of the fetal VM cells and the effect of the addition of brain-derived neurotrophic factor (BDNF) was investigated during a culture period of 5 days. Extracellular dopamine levels were measured by means of high performance liquid chromatography (HPLC) with electrochemical detection (LCEC). Our results indicate that the ratio of dopaminergic to GABAergic neurons changed in favour of the dopaminergic component when a more selective dissection technique was used. Although addition of BDNF to the cultures appeared to exert trophic influences on all the cellular components of pig fetal VM, this effect was most pronounced on the TH-positive cells. Highest extracellular DA levels were found in the VM culture with the addition of BDNF and when a more selective dissection method was used. Our in vitro findings suggest that porcine fetal dopaminergic cells retain their potential for development and outgrowth after proper explantation and dissociation. Anticipating on the results of ongoing transplantation studies in rat, they suggest that pig fetal VM can be a suitable alternative for the use of fetal human VM as a graft for Parkinson's disease.

Lesions in the hypothalamus after active immunisation against GnRH in the pig.

The terminals of the hypothalamic gonadotrophin hormone-releasing hormone (GnRH) neurons are located within the median eminence and thereby extend beyond the protection of the blood-brain barrier. Thus, these terminals may be subjected to direct autoimmune action in animals that are actively immunised against GnRH. Boars (male pigs) (n = 108) were actively immunised against GnRH by two successive injections with synthetic GnRH, covalently coupled to KLH and dissolved in CFA or IFA. They were killed at 26 weeks of age. Immunised boars were selected on the basis of the resultant testes size, which indicates the effectiveness of the immunisation. The hypothalami of 25 selected animals were studied by histological and immunocytochemical techniques and compared with the hypothalami of three sham- and nine control animals. In the immunised animals, changes in the GnRH system had taken place. These comprised dystrophy of the perikarya and a sharp decrease of the GnRH immunocytochemical reactivity in the terminals within the median eminence. In addition, various degrees of inflammatory reactions were present, particularly within the median eminence. These consisted of tissue disruption by edema, collapse of the capillaries, fibrosis and infiltration with fibroblasts. In addition, accumulations of neurosecretum within the median eminence in combination with hypertrophy of magnocellular neurons within the hypothalamus were present. The reactions were restricted to the median eminence and did not involve other neurohemal organs or other parts of the hypothalamus. A correlation could be established between the incidence of the lesions and the effectiveness of the GnRH autoimmunity (as indicated by the size and endocrine function of the gonads and the anti-GnRH titres). Changes in extra- and intracellular IgG immunocytochemical reactivity within the median eminence indicated the involvement of IgG. The effects were absent from control and sham vaccinated animals and after vaccinations with other compositions of the vaccine. Thus, hypothalamic lesions have been observed in this selected group of animals, vaccinated against GnRH with this particular vaccine.

Distribution of interleukin 1 beta immunoreactivity within the porcine hypothalamus.

The presence and localization of interleukin 1 beta immunoreactivity (IL 1 beta i.r.) was studied in the hypothalamus of four healthy, male pigs at 7 months of age, using immunocytochemical techniques on 100 mu vibratome and 10 mu paraffin sections. IL 1 beta i.r. was found in neuronal cell bodies and their processes within nuclei and fiber tracts of the hypothalamus as well as in varicose fibers, terminals and deposits within the median eminence. In addition, IL 1 beta i.r. was found in the walls of several, but not all, blood vessels and in very few glial cells.

Repair of UV-induced (6-4)photoproducts measured in individual genes in the Drosophila embryonic Kc cell line.

The nucleotide excision repair (NER; dark-repair) of (6-4)photoproducts ((6-4)PPs) was assayed in cells from a permanent Drosophila melanogaster embryonic cell line, Kc, after exposure to 20 or 40 J/m2 ultraviolet (UV) light. Induction rates in the transcriptionally active genes Gart and Notch as well as in the inactive white locus is similar. They are formed with a frequency of about one-third of that of cyclobutane pyrimidine dimers (CPDs). In all three genes, (6-4)PPs are repaired with the same rate and to the same extent: 31% of the (6-4)PPs are removed in 4 hours post-irradiation and after 16 hours repair is nearly complete. In none of the three genes strand-specific repair was found. Exposure of cells that were irradiated with 40 J/m2 UV to photoreactivating light for 1 hour prior to dark-repair incubation, resulted in enhanced repair of (6-4)PPs.

A vasopressin and oxytocin containing nucleus in the pig hypothalamus that shows neuronal changes during puberty.

A vasopressin and oxytocin containing nucleus is described for the first time in the pig hypothalamus. It is located near the third ventricle, just dorsal to the suprachiasmatic nucleus, and consists of magnocellular neurons, similar to those of the supraoptic nucleus and paraventricular nucleus. Morphometric analysis of neuronal number, size, density, and volume was performed at four different ages: 1 day, 7 weeks, 16 weeks, and 30 weeks postnatally. No sex difference in these parameters was observed. In this period the volume of the nucleus increased gradually from 6.6 x 10(-3) to 54.2 x 10(-3) mm3. One day after birth 1,215 +/- 191 (mean +/- SEM) neurons were present in the vasopressin and oxytocin containing nucleus, followed by a decrease to 771 +/- 80 neurons at 7 weeks and 697 +/- 116 at 16 weeks. Between 16 and 30 weeks (puberty) there was a dramatic increase in neuron number up to 1,765 +/- 214 neurons. This increase in the number of vasopressin and oxytocin containing neurons in the pig hypothalamus is much later in development than has ever been reported so far.

Prototyping with AIDA for a hospital pharmacy system.

The CENTRASYS system for the Hospital Pharmacy, developed as part of a research project of the Department of Medical Informatics is described. The role of AIDA, a fourth-generation software package, as a prototyping tool is discussed. It is concluded that AIDA facilitates prototyping and is also very suitable as a vehicle for systems in operation. It is further concluded that prototyping is of great help in the developmental phase of a project, but that great care has to be taken during evaluation of the prototypes: minimize the number of test sites and try to avoid that users become dependent on the system, because every prototype needs further tuning before it really becomes an operational system.

Performance of AIDA during development and operation.

A system for hospital pharmacies (CENTRASYS) and a system for primary health care (ELIAS), both developed using prototyping and a fourth-generation tool (AIDA), are introduced. Differences in development strategies are analyzed and conclusions are drawn with respect to the use of AIDA for management, development and operation of the systems. The use of AIDA increases development speed enormously, enabling a productivity of over 40 lines per day, which is more than twice the amount that is accepted as reasonable.

PAP complex: a pitfall in immunocytochemistry of the pig hypothalamus.

Use of rabbit peroxidase-antiperoxidase (PAP) complex in immunostaining of the pig hypothalamus resulted in false positive staining of elements of the supraoptic and paraventricular nuclei due to binding of rabbit PAP complex and rabbit immunoglobulins to these structures. This phenomenon seriously hampers immunohistochemical investigation of the pig hypothalamus. Specific binding of swine immune serum against luteinizing hormone-releasing hormone has been detected with the protein A-biotin-streptavidin method employed on paraffin and vibratome sections of fetal and postnatal pig hypothalamus.

Ascending projections from the lateral descending and common sensory trigeminal nuclei in python.

The primary sensory trigeminal system of Python is characterized by the presence of an additional nucleus which is involved in processing data obtained by infrared sensors. This so-called lateral descending nucleus (LTTD) is strictly separated from the nuclei of the common sensory trigeminal system. The present study was undertaken in order to establish the relation between the two sensory trigeminal systems and higher brainstem structures. Further we studied whether the projections of these two systems remain separated at higher brainstem levels. It is shown that the organization of particularly the thalamus is characterized by the presence of specific projection areas of each of the two trigeminal systems: a) the ability of infrared preception is reflected particularly in the presence of an unique thalamic nucleus: the nucleus pararotundus and probably also in the enlargement of nucleus rotundus; and b) distinct subnuclei in the thalamic ventral nuclear complex are related to the various nuclei of the common sensory trigeminal system. The main ascending projection of LTTD runs via a distinct tract to the central gray layer (SGC) of the contralateral tectum mesencephali and the nucleus pararotundus (PR). Rostrally, numerous fibres decussate again via the tectal commissure and terminate ipsilaterally in the rostral part of SGC and in PR. The ascending projections of the common sensory trigeminal nuclei resemble those of mammals by gaining thalamic nuclei (ventral nuclear complex). No projections of the tectum nor to the striatum (like in birds) were observed. The two sensory trigeminal systems remain separately organised, in their projections as well as in their structure. No major connection between the two trigeminal system is present.