[Hypervitaminosis B12 - a new marker and predictor of prognostically unfavorable diseases].

A high serum vitamin B12 level (hypercobalaminemia) is a underestimated anomaly. Clinically, it can be paradoxically accompanied by signs of deficiency, which are related to defects in tissue uptake of vitamin B12. The increase in the level of serum cobalamin occurs mainly in serious diseases that require early diagnosis: hemoblastosis, liver and kidney diseases, etc. This review presents data on the metabolism of vitamin B12 and the potential significance of increasing its level as a marker for the early diagnosis of these diseases.

High frequency of co-segregating CLCN1 mutations among myotonic dystrophy type 2 patients from Finland and Germany.

Based on previous reports the frequency of co-segregating recessive chloride channel (CLCN1) mutations in families with myotonic dystrophy type 2 (DM2) was suspected to be increased. We have studied the frequency of CLCN1 mutations in two separate patient and control cohorts from Germany and Finland, and for comparison in a German myotonic dystrophy type 1 (DM1) patient cohort. The frequency of heterozygous recessive chloride channel (CLCN1) mutations is disproportionally higher (5 %) in currently diagnosed DM2 patients compared to 1.6 % in the control population (p = 0.037), while the frequency in DM1 patients was the same as in the controls. Because the two genes segregate independently, the prevalence of CLCN1 mutations in the total DM2 patient population is, by definition, the same as in the control population. Our findings are, however, not based on the total DM2 population but on the currently diagnosed DM2 patients and indicate a selection bias in molecular diagnostic referrals. DM2 patients with co-segregating CLCN1 mutation have an increased likelihood to be referred for molecular diagnostic testing compared to DM2 patients without co-segregating CLCN1 mutation.

Complications of nephropathia epidemica: three cases.

Haemorrhagic fever with renal syndrome (HFRS) in Scandinavia is called nephropathia epidemica (NE), and is caused by the Puumala-virus, which belongs to the Hanta-virus genus. The clinical course of NE is mostly benign, complications are uncommon, and deaths are rarely observed. We report the cases of three patients who developed serious complications in the course of NE caused by the Puumala-virus. One patient died within 24 h after admission, another developed progressive neuromuscular dysfunction (Guillain-Barré syndrome) which required auxiliary ventilation for several weeks before a slow recovery, and a third patient developed empty sella syndrome with pituitary gland insufficiency. In the first two cases the diagnosis of NE was confirmed by a rapid avidity assay for IgG antibody against Puumala-virus. In the third case the clinical course, and demonstration of NE immunity 16 years later, suggested that NE might have caused the hypopituitarism. Some patients with NE caused by the Puumala-virus may require intensive-care treatment, and the development of late complications such as empty sella syndrome and hypopituitarism should be taken into consideration.

Histamine-immunoreactive nerve fibers in the mammalian spinal cord.

New sensitive antisera against histamine were used to study the distribution of histamine-immunoreactive nerve fibers in the spinal cord of several mammalian species. Tissues were fixed with carbodiimide by transcardiac perfusion or immersion. A few immunoreactive nerve fibers were found in the cervical spinal cord of the rat in the superficial laminae of the dorsal horn, around the central canal and scattered in the anterior horn. The density of immunoreactive fibers in the cervical spinal cord of the guinea pig and tree shrew was higher, but still low. The densest networks of histamine-immunoreactive fibers were seen in the cervical spinal cord of the pig. The laminar distribution of histamine-immunoreactive fibers was similar in all species. Histamine-immunoreactive fibers were densest in lamina X, followed by laminae I-II. Scattered fibers were also seen in the white matter in the lateral and posterior funiculus in the pig. In the rat and the guinea pig, no histamine-immunoreactive cell bodies were seen in the spinal sensory ganglia. The results suggest that the histamine-immunoreactive nerve fibers in the spinal cord may originate from the brain, probably from the posterior hypothalamus, and the fiber projection is more extensive in higher mammalian species. The role of histamine in the spinal cord is not known, but it may be involved in, e.g., pain sensation.

Histamine-immunoreactive nerve fibers in the rat brain.

A new immunohistochemical method that utilizes carbodiimide as a tissue fixative was applied to study the distribution of histamine-immunoreactive neuronal fibers and terminals in the rat brain. Immunoreactive fibers were observed in almost all major regions of the brain. They were most numerous in the different hypothalamic nuclei. Dense networks of immunoreactive fibers were also seen in the medial septum, nucleus of the diagonal band and ventral tegmental area. A moderate density of fibers was seen throughout the cerebral cortex, in some parts of the olfactory bulb and tubercle, bed nucleus of the stria terminalis, amygdala, basal parts of the hippocampus, inferior and superior colliculi, substantia nigra, lateral and medial parabrachial nucleus, and the nucleus of the solitary tract. Few histamine-immunoreactive fibers were seen in most parts of the caudate putamen, most thalamic nuclei, most pontine and ventral medullary nuclei. Histamine-immunoreactive neuronal cell bodies were found exclusively in the tuberomammillary nucleus, in agreement with previous reports. The results provide evidence for a widespread distribution of histamine-containing nerve fibers and terminals in the rat brain. Although immunohistochemical localization of histamine does not give direct evidence of a functional role of histamine in any brain area, this distribution suggests involvement in functions of the limbic system including the septal nuclei, hypothalamus and amygdala. The relatively dense histamine-immunoreactive fiber networks in the colliculi and dorsal cochlear nucleus indicate that this amine may play a role in visual functions and hearing. The paucity of immunoreactive fibers in the pontine and medullary areas suggests that the caudal projections originating from the tuberomammillary complex are minor ones compared to the major rostral projections. Several fiber projections originating from the tuberomammillary complex could be deduced from serial frontal, sagittal and horizontal sections. They contained fibers that crossed the midline at several levels of the brain. The results provide information on the target areas of the histaminergic neurons and form a basis for the examination of cellular contracts between the histaminergic neurons and other cells.

Development of histamine-immunoreactive neurons in the rat brain.

This study was undertaken to reveal the cellular stores of histamine in developing rat brain and to determine the stage of development during which the histamine-immunoreactive neurons can first be detected. Rats from embryonal day 12 to postnatal day 14 were studied. The brains were fixed in 4% 1-ethyl-3(3-dimethylaminopropyl)carbodiimide and standard immunofluorescence technique was used. The first histamine-immunoreactive neurons were seen on embryonic day 13 in the border of mesencephalon and metencephalon. On embryonic day 15 immunoreactive neurons were detected in ventral mesencephalon and rhombencephalon. In caudal, tuberal, and postmammillary caudal magnocellular nuclei histamine-immunoreactive neurons were first detected on embryonic day 20 while those in the hindbrain had disappeared. Histamine-immunoreactive nerve fibers were first detected on embryonic day 15 in rhombencephalon and mesencephalon and in some areas of diencephalon including the mammillary bodies and frontal cortex. On embryonic day 18 the number of immunoreactive nerve fibers in the hindbrain had decreased considerably, but the olfactory bulb, septal and hypothalamic area, and the cerebral cortex showed immunoreaction in fibers. The density of histamine-immunoreactive fiber networks increased until postnatal day 14 when an adultlike pattern of neurons and fibers had developed. Histamine-immunoreactive neurons are present in embryonal CNS and they develop extensive projections to various brain areas.

Carbodiimide as a tissue fixative in histamine immunohistochemistry and its application in developmental neurobiology.

The object of this study was to develop an immunohistochemical method that could be used to study neuronal histamine, especially in nerve fibers and terminals where most previous methods have not been applicable. Three new antisera were produced in rabbits against conjugated histamine, and the fixative used in conjugation, 1-ethyl-3(3-diamethylaminopropyl)-carbodiimide (EDCDI), was used in tissue fixation and compared to paraformaldehyde. Specificity of the antisera was established with dot-blot tests on nitrocellulose, with blocking controls and affinity-purified antibodies. EDCDI appeared to be superior to paraformaldehyde as a fixative, and histamine-immunoreactive nerve cells were visualized in developing rat brain during late fetal development from embryonal day 12. By the second postnatal week, the distribution of histamine-immunoreactive neurons in rat brain had reached the adult pattern and immunoreactive nerve fibers were seen in many areas. Posterior hypothalamic neurons from newborn rat in vitro showed strong immunoreactivity for histamine and developed long varicose fibers, which covered the culture dish by the end of the fourth week in vitro. Fixation with EDCDI also allowed detection of histamine in gastric enterochromaffin-like cells and mast cells in rat. The results suggest that the histamine-containing neuron system in rat brain develops during the late fetal and early postnatal periods, and that immunoreactive neurons develop long fibers both in vivo and in vitro.