Search PubMed⌕ Search

Biomedical subjects

G Horn

Publications and source records attributed to G Horn.

At least 19 recordsLinked to original sources
PubMed1992

Multiple observations on a single unrestrained cat of long-lasting facilitation of transmission through the lateral geniculate nucleus.

The field potential responses of the lateral geniculate nucleus (LGN) to test electrical stimuli delivered to the optic tract (OT) were recorded in an unanaesthetised, freely moving cat. The response consisted of two waves, one attributable to depolarisation of the OT terminals (t), and one attributable to the postsynaptic response (r) of LGN neurones. A train of 300 electrical stimuli at 0.2 Hz to the OT alone did not influence the amplitude of these waveforms. In contrast after a train of 150 pulses had been delivered to both the OT (at 0.2 Hz) and LGN (pseudo-random with mean intervals of 0.2 Hz), the amplitude of both the t and r waves to test OT electrical stimuli was markedly enhanced for the following 6 days. Enhancement of the t wave followed that of the r wave.

Animals↗
PubMed1992

The effect of the neurotoxin DSP4 on the development of a predisposition in the domestic chick.

Under certain conditions, dark-reared chicks preferentially approach objects resembling conspecifics. In the current study we investigated the effect of the catecholaminergic neurotoxin DSP4 on this predisposition. After hatching, chicks received an intraperitoneal injection of either DSP4 or vehicle (controls). The chicks were individually placed in running wheels for 2 x 1 hr, 24 hr before testing. The chicks were maintained in darkness until given a preference test, which involved the simultaneous presentation of an illuminated red box and a stuffed fowl at 36, 48, 60, 66, or 72 hr after hatching. The approach of each chick toward the two objects was recorded over 5 min and a preference score calculated. Control chicks placed in the running wheels at 24 and 36 hr posthatch and tested 24 hr later showed a significant preference for the fowl compared to the red box. In contrast, DSP4-treated chicks did not show such a preference at corresponding ages, but did express a greater preference for the fowl when placed in the running wheels at 42 and 48 hr posthatch and tested 24 hr later. These results suggest that experience of the running wheel or of associated factors, e.g., handling, must occur during a restricted period of time to influence the emergence of the predisposition to approach the stuffed fowl. DSP4 treatment delays the onset of this period.

Animals↗
PubMed1992

Intra- and extragenic marker haplotypes of CFTR mutations in cystic fibrosis families.

In order to facilitate the screening for the less common mutations in the cystic fibrosis (CF) gene viz., the CF transmembrane conductance regulator gene (CFTR), marker haplotypes were determined for German non-CF (N) and CF chromosomes by polymerase chain reaction analysis of four polymorphisms upstream of the CF gene (XV-2c, KM.19, MP6-D9, J44) and six intragenic polymorphisms (GATT, TUB9, M470V, T854T, TUB18, TUB20) that span the CFTR gene from exon 6 through exon 21. Novel informative sequence variants of CFTR were detected in front of exons 10 (1525-61 A or G), 19 (3601-65 C or A), and 21 (4006-200 A or G). The CF locus exhibits strong long-range marker-marker linkage disequilibrium with breakpoints of recombination between XV-2c and KM.19, and between exons 10 and 19 of CFTR. Marker alleles of GATT-TUB9 and TUB18-TUB20 were found to be in absolute linkage disequilibrium. Four major haplotypes encompass more than 90% of German N and CF chromosomes. Fifteen CFTR mutations detected on 421 out of 500 CF chromosomes were each identified on one of these four predominant 7-marker haplotypes. Whereas all analysed delta F508 chromosomes carried the same KM.19-D9-J44-GATT-TUB9-M470V-T854T haplotype, another frequent mutation in Germany, R553X, was identified on two different major haplotypes. Hence, a priori haplotyping cannot exclude a particular CF mutation, but in combination with population genetic data, enables mutations to be ranked by decreasing probability.

Alleles↗
PubMed1992

Impairment of learning by localized injection of an N-methyl-D-aspartate receptor antagonist into the hyperstriatum ventrale of the domestic chick.

A restricted part of the domestic chick forebrain is critically involved in the learning process of imprinting. This region is the intermediate and medial part of the hyperstriatum ventrale (IMHV). The effect on imprinting of local injection of the N-methyl-D-aspartate (NMDA) receptor blocker D-amino-5-phosphonopentanoic acid (D-AP5) into the left IMHV was studied in chicks in which the right IMHV had been lesioned. The left IMHV is essential for imprinting when chicks have been lesioned in this way. Injection of approximately 0.7 nmol D-AP5 into the left IMHV significantly impaired imprinting. Injection of approximately 0.2 nmol D-AP5 into the left IMHV, or of approximately 0.7 nmol D-AP5 into the left hyperstriatum accessorium, was without significant effect on imprinting. These results suggest that NMDA receptors in the left IMHV may play an important part in this learning process.

2-Amino-5-phosphonovalerate↗
PubMed1992

[Forum: dermopigmentation or medical tattooing. History of tattooing].

Tattooing has been performed all over the world since prehistoric times, as indicated by numerous ancient relics. The significance of tattoos has differed at times and in different civilisations (means of communication, social identification mark, religious origin). Today, it is performed by real artists who have inspired its medical applications. Medical dermopigmentation was initially used in the context of breast reconstruction (nipple areola complex) and, with subsequent refinements, its indications have been extended to the treatment of residual scars and to the permanent make-up.

Esthetics↗
PubMed1992

[Rhabdomyoma of the mouth floor--a case report].

We report a rare case of an adult rhabdomyoma of the floor of the mouth in a 52-year-old woman. To date only 25 cases of such tumors have been described in the oral cavity. In spite of its large size (approximately 10 x 8 x 6 cm), the tumor could be completely removed. Up to now, 20 months after the removal of tumor, no recurrences, have occurred.

Biomarkers, Tumor↗
PubMed1992

Tardyferon therapy in hyposiderosis of infancy and childhood.

In the majority of cases iron deficiency of infancy and early childhood is caused by nutritional factors. Among diseases, absorption disorders are the most frequent causes of iron deficiency. Tardyferon has been used for controlling iron deficiency in 21 children younger than two years of age not suffering from malabsorption and in 38 children suffering from coeliac disease. At the onset of the disease 71% of coeliac disease patients suffered from iron deficiency. The normalization of iron metabolism of these patients could be achieved with oral treatment of 5-6 mg Fe++/kg/day of 3-6 months. Iron deficiency of patients with initially normal ferritin level developed as a result of the intensive weight gain occurring in response to the gliadin-free diet. After the patients had been put on a gliadin containing diet again, hyposiderosis also occurred more frequently. Tardyferon therapy was well tolerated by the patients, in the infants taking bébé-Tardyferon difficulties of dosage or notable side-effects were not observed.

Age Factors↗
PubMed1991

The development of hemispheric asymmetries in neuronal activity in the domestic chick after visual experience.

Previous experiments have shown that a restricted part of the forebrain, the intermediate and medial part of the hyperstriatum ventrale (IMHV), is involved in the learning process of imprinting. Through this process chicks selectively approach, and so recognise, a visually conspicuous object to which they have been exposed. Previous work has also demonstrated that the left and right IMHV regions play different roles in the recognition memory of imprinting, and that exposure to an object results in changes in synaptic organisation in the left, but not in the right IMHV. We have enquired whether training has a differential effect on spontaneous multiple-unit impulse activity in the two regions. Thirty-two chicks were reared in darkness. Sixteen were trained by exposing them to a flashing, rotating box; the remaining chicks serving as dark-reared controls. The trained chicks were anaesthetised either immediately after training (0-h trained chicks) or returned to the dark incubator and anaesthetised 6 h after the end of training (6-h trained chicks). A single microelectrode penetration was made through the left IMHV simultaneously with a single penetration through the right IMHV; a single penetration was also made through a visual projection area, the left hyperstriatum accessorium. Recordings were made from between 3 and 7 sites in each penetration, and the mean multiple-unit firing rate for these sites was calculated. Spontaneous activity in the right IMHV changed in respect of activity in the left IMHV with time after training; no such effects were found in the left hyperstriatum accessorium.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Quantitative analysis of the ultrastructural distribution of GABA-like immunoreactivity in the intermediate and medial part of hyperstriatum ventrale of chick.

The intermediate and medial part of the hyperstriatum ventrale of the chick telencephalon plays a crucial role in the learning processes of imprinting. The distribution within the intermediate and medial part of the hyperstriatum ventrale of the neurotransmitter gamma-amino butyric acid was studied with light and electron microscopy using an antibody against this amino acid. The antibody labelled 18.4% of neuronal somata. GABA-labelled terminals made symmetrical synapses onto somata and dendrites of labelled and unlabelled neurons. Labelled somata received about three times as many synaptic boutons as unlabelled somata. Approximately 21% of synaptic terminals on labelled somata were themselves labelled; unlabelled somata received a higher proportion (37.6%) of such terminals. Most labelled terminals synapsing with dendrites were confined to the shafts; very few labelled terminals contributed to axospinous synapses. Synaptic contacts made on dendritic shafts by labelled boutons were intermingled with symmetrical and asymmetrical contacts from non-immunoreactive terminals. The proportion of labelled terminals received by labelled dendrites (33.1%) was approximately twice that received by unlabelled dendrites (15.9%). Labelled neurons therefore received a higher proportion of labelled terminals on their dendrites and a lower proportion on their somata compared with unlabelled neurons. No immunoreactivity was seen in glial cells or ependyma.

Animals↗
PubMed1991

Synaptic transmission and recognition memory: time course of changes in N-methyl-D-aspartate receptors after imprinting.

Previous studies have shown that a restricted region of the chick forebrain (the intermediate and medial parts of the hyperstriatum ventrale, IMHV) is crucial for the learning process of imprinting. A learning-related increase in N-methyl-D-aspartate (NMDA) receptor binding has previously been shown in the left IMHV 8.5 hr after training with an imprinting stimulus. The present experiments showed that this increase in binding in the left IMHV does not occur until 6-8.5 hr after training: There was no significant change in binding in either the left or right IMHV less than 0.5, 3, or 6 hr after training. No significant change in binding occurred in the right IMHV 8.5 hr after training. It is probable that the increase in binding in the left IMHV is associated with the recognition memory of imprinting.

Animals↗
PubMed1991

Use of Cosilat food preparation in paediatric practice.

Cosilat is the sole Hungarian therapeutic food preparation which may be successfully used in several clinical conditions due to it's hydrolyzed protein and MCT fat content and the absence of lactose. In infancy it may be given orally, in older children in form of tube feeding. The authors have reported on their observations in healthy and diseased children. The required weight gain could be obtained with Cosilat in all examined groups. Side-effects were not observed. They recommend the use of the formula for the treatment of premature infants and in postoperative and malabsorption cases as well. All clinical conditions in which the use of Cosilat may be justified because of it's composition are described in the report.

Humans↗
PubMed1991

Learning, memory and the brain.

Human and non-human animals acquire information about the world through the process of learning, and store that information as memory. Yet central as the storage process is to adaptive behaviour, progress in understanding its neural bases has been slow and only recently efforts have shown clear signs of being successful. The knowledge that comes from this progress strongly suggests that different kinds of learning involve different neural circuits and accordingly involve different memory systems. Indeed, it is becoming increasingly clear that multiple memory systems may be a fundamental part of the design of the vertebrate brain. It has long been supposed that learning leads to the formation, or to the strengthening of particular pathways in the brain. Once formed, or strengthened in this way a pathway was viewed as a 'trace' or 'engram' 'representing' the particular experience or relationship which had been learned. There is substantial evidence that neural pathways, especially synaptic connectivity, can be modified by experience-as by rearing rats in an 'enriched' environment with other rats rather than rearing them in isolation--as well as by modifying the diet or by depriving young rats of their thyroid gland. This evidence demonstrates that the central nervous system is plastic, but provides no hint that such plasticity is involved in learning. The evidence that synaptic plasticity is indeed involved in learning and memory is relatively recent.

Animals↗
PubMed1990

[Chronic recurrent abdominal pain and lactose malabsorption in childhood].

The Authors examined 515 children with abdominal pain in the outpatient clinics for a period of two years. The pain was frequently periumbilical or mid epigastric with a history of more than two months. Persistent lactose malabsorption was found in 252 children (48,9%), which justifies the use of Breath Hydrogen Test as a first diagnostic procedure for assessing recurrent abdominal pain. Putative pathogens were identified in the stool specimens of 21 patients. Oesophagitis was diagnosed in 18 children and duodenal ulcer in one. 91 patients (less than 6 years old) improved after successful treatment of the chronic upper respiratory inflammations. The authors did not find any causes in 18.1 per cent of the children examined and they think that the abdominal pain in these children may be psychogenic. The use of high-fiber diet is proposed for the later group.

Abdominal Pain↗
PubMed1990

[Leukocyte migration inhibition test in celiac disease].

The leukocyte migration inhibition test is a method used to assess the cell-mediated immune function. The authors examined 251 samples for a period of 3 years; 169 samples from celiac patients and 82 were control. The sensitivity of this test was 34/35 (97%) in proved gluten sensitive patients, but this was found after repeating the test at different periods of time. According to these results the authors conclude that the efficacy of this test is less sensitive in the newly diagnosed celiac patients, which means that it is not suitable for screening purpose, but useful for detecting gliadin sensitivity during the diagnostic period of celiac disease (e. i. the 3 biopsies). LMT may be used to indicate the proper time for the 2nd and/or 3rd biopsy, and can also be used to reveal the gluten-free diet defaults. The authors agree with those who believe that this test cannot substitute the performance of the small intestinal biopsy.

Adolescent↗
PubMed1990

Neural bases of recognition memory investigated through an analysis of imprinting.

Through a learning process known as imprinting, the young of some animals, including the domestic chick, come to recognize an object by being exposed to it. Visually naive chicks vigorously approach a wide range of objects. After an adequate period of exposure to one object chicks selectively approach it in a recognition test. The nervous system of dark-reared chicks is not a tabula rasa, as chicks have predispositions to approach some stimuli rather than others. Nevertheless, visual imprinting leads to changes in a nervous system that may not have been 'marked' by previous visual experience, and so encourages the hope of discovering the neural bases of the learning process. The intermediate and medial part of the hyperstriatum ventrale, a sheet of cells within the cerebral hemispheres, plays a crucial role in visual imprinting, particularly in the memory process of recognition. The cellular and sub-cellular changes that take place in this part of the hyperstriatum ventrale after imprinting are described. The right and left hyperstriatum ventrale regions play different roles in the imprinting process, and evidence is given for the existence of multiple memory systems in the chick brain.

Animals↗
PubMed1990

[The value of the d-xylose loading test in the diagnosis of malabsorption syndromes].

The test of d-xylose concentration in blood has been used for approximately two decades for the examination of the absorption. The authors compared in 261 cases the total d-xylose blood level with the histological picture of the small intestine. Good correlation was observed between the 2 examinations. The d-xylose loading was found to select with favorable efficacy the new cases of celiac disease, of 63 fresh diagnosed subtotal and total villus atrophy cases the blood level of 61 was under the 1,64 mmol/l limit. At the 3rd stage of partial villus atrophy the blood level was pathological in 17 new patients. The sensitivity of the examination was 92.2% in selection of the new cases. Significant differences were found between the new cases and patients with excess gliadin (0.929 +/- 0.44 mmol/l and 1383 +/- 0.052 mmol/l) with identical rate of duodenal tissue impairments. On this basis the significant decrease of d-xylose level (0.5-1 mmol/l) must be regarded as the sign of relapse in patients with excess gliadin. Giardia lamblia and slight villus impairment was found in the biopsy material of further 28 children. The d-xylose level was pathological in 14 of them. D-xylose absorption was pathological before treatment in each of the 13 patients with contaminated (Gram-negative aerobic bacteria) small intestinal syndrome. D-xylose test is a useful method in the diagnostics of conditions associated with malabsorption and completed with other techniques it provides means for the separation of conditions associated with the diffuse impairment of the small intestine.

Celiac Disease↗
PubMed1990

[Contaminated small bowel syndrome in infants caused by gram-negative bacteria and yeasts].

The upper small intestine is usually "sterile" in a healthy individuals, but due to some reasons the number of microorganisms may reach or increase above 10(4)/ml, leading to the contamination of the small intestine, which may cause severe malabsorption. The authors have diagnosed this syndrome in 50 children, aged between 1 month and 3 years, using breath hydrogen test and duodenal juice culture. Most of these children had growth retardation. According to their experience the authors found that the oral antibiotic is the effective treatment of this syndrome.

Anti-Bacterial Agents↗