Biomedical subjects

B Fischer

Publications and source records attributed to B Fischer.

At least 109 records · Page 6Linked to original sources

PubMed1999

Expression of the arylhydrocarbon receptor and the arylhydrocarbon receptor nuclear translocator during early gestation in the rabbit uterus.

The arylhydrocarbon receptor (AhR) and the arylhydrocarbon receptor nuclear translocator (ARNT) are members of the PAS gene family mediating toxic effects of xenobiotics such as dioxin and polychlorinated biphenyls. We have analyzed the expression and cellular distribution of rabbit AhR and ARNT mRNA and protein level in the nonpregnant uterus and the pregnant and pseudopregnant uterus at Days 6 to 12 of gestation. In the preimplantation uterus at Day 6 of gestation and in the interimplantation and pseudopregnant uterus at Days 7, 8, 9, and 12 of gestation, low levels of AhR transcripts were detected in the glandular uterine epithelium. Upon attachment of the blastocyst at Day 7 of gestation, a strong expression of AhR and ARNT mRNA was observed in the luminal and glandular epithelium of the antimesometrial uterine compartment. In contrast, AhR and ARNT expression was low in the luminal epithelium of the paraplacental and the mesometrial placental fold. AhR mRNA was also detected in the trophoblast cells. During early placentation at Day 9 of gestation, expression of AhR and ARNT was first observed in the perivascular decidualized stromal cells and, at Day 12, extended to the decidualized stromal cells of the placental bed. Within the placenta, the syncytiotrophoblast expressed only low levels of AhR and ARNT mRNA and no protein. The specific expression patterns of AhR and ARNT during early gestation suggest functional roles for both transcription factors during feto-maternal interactions in the rabbit.

Animals↗

PubMed1999

2-thioether 5'-O-(1-thiotriphosphate)adenosine derivatives as new insulin secretagogues acting through P2Y-Receptors.

P2-Receptors (P2-Rs) represent significant targets for novel drug development. P2-Rs were identified also on pancreatic B cells and are involved in insulin secretion. Therefore, novel P2Y-R ligands, 2-thioether 5'-O-phosphorothioate adenosine derivatives (2-RS-ATP-alpha-S), were synthesized as potential insulin secretagogues. An efficient synthesis of these nucleotides and a facile method for separation of the chiral products are described. The enzymatic stability of the compounds toward pig pancreas type I ATPDase was evaluated. The rate of hydrolysis of 2-hexylthio-5'-O-(1-thiotriphosphate)adenosine (2-hexylthio-ATP-alpha-S) isomers by ATPDase was 28% of that of ATP. Some 2-thioether 5'-(monophosphorothioate)adenosine derivatives (2-RS-AMP-S) exerted an inhibitory effect on ATPDase. The apparent affinity of the compounds to P2Y(1)-R was determined by measurement of P2Y-R-promoted phospholipase C activity in turkey erythrocyte membranes. 2-RS-ATP-alpha-S derivatives were agonists, stimulating the production of inositol phosphates with K(0.5) values in the nanomolar range. 2-RS-AMP-S derivatives were full agonists, although 2 orders of magnitude less potent. All the compounds were more potent than ATP. The effect on insulin secretion and pancreatic flow rate was evaluated on isolated and perfused rat pancreas. A high increase, up to 500%, in glucose-induced insulin secretion was due to addition of 2-hexylthio-ATP-alpha-S in the nanomolar concentration range, which represents 100-fold enhancement of activity relative to ATP. 2-Hexylthio-AMP-S was 2.5 orders of magnitude less effective.

Adenosine↗

PubMed1999

Characterization of "mini-nucleotides" as P2X receptor agonists in rat cardiomyocyte cultures. An integrated synthetic, biochemical, and theoretical study.

The design and synthesis of "mini-nucleotides", based on a xanthine-alkyl phosphate scaffold, are described. The physiological effects of the new compounds were evaluated in rat cardiac cell culture regarding Ca(2+) elevation and contractility. The results indicate biochemical and physiological profiles similar to those of ATP, although at higher concentrations. The biological target molecules of these "mini-nucleotides" were identified by using selective P2-R and A(1)-R antagonists and P2-R subtype selective agonists. On the basis of these results and of experiments in Ca(2+) free medium, in which [Ca(2+)](i) elevation was not observed, we concluded that interaction of the analogues is likely with P2X receptor subtypes, which causes Ca(2+) influx. Theoretical calculations analyzing electronic effects within the series of xanthine-alkyl phosphates were performed on reduced models at quantum mechanical levels. Calculated dipole moment vectors, electrostatic potential maps, and volume parameters suggest an explanation for the activity or inactivity of the synthesized derivatives and predict a putative binding site environment for the active agonists. Xanthine-alkyl phosphate analogues proved to be selective agents for activation of P2X-R subtypes, whereas ATP activated all P2-R subtypes in cardiac cells. Therefore, these analogues may serve as prototypes of selective drugs aiming at cardiac disorders mediated through P2X receptors.

Animals↗

PubMed1999

Induction of arylhydrocarbon receptor expression in embryoblast cells of rabbit preimplantation blastocysts upon degeneration of Rauber's polar trophoblast.

The arylhydrocarbon receptor (AhR) is a ligand-activated transcription factor and mediates carcinogenic, teratogenic, and toxic effects of xenobiotics such as dioxin and coplanar polychlorinated biphenyls. The AhR nuclear translocator (ARNT) is involved in AhR signal transduction. We have analyzed the expression of AhR and ARNT mRNA and AhR protein in Day 3 pc (postcoitum) rabbit morulae and Days 4 and 6 pc blastocysts using RT-PCR, nested PCR, whole mount in situ hybridization, and whole mount immunohistochemistry with subsequent confocal laser scanning analysis. AhR and ARNT transcripts were detected in all stages investigated, indicating coexpression of both transcription factors. AhR protein was localized in the cytoplasm. It was detected in Day 3 pc morulae and in blastocysts. In Day 4 pc blastocysts, only trophoblast cells but not embryoblast cells were immunopositive. However, at Day 6 pc, the embryoblast cells also expressed AhR protein and this expression was correlated with the degeneration of Rauber's trophoblast layer.

Animals↗

PubMed1999

Molecular cloning and localization of caprine relaxin-like factor (RLF) mRNA within the goat testis.

The relaxin-like factor (RLF) is one of the insulin-like molecules, which also includes insulin, insulin-like growth factor I and II, placentin, and relaxin. Employing RT- and RACE-PCR on RNA isolated from goat testicular tissue, we report the cloning and nucleic acid sequence of goat RLF. The caprine RLF cDNA coding sequence consisted of 396 base pairs encoding a peptide of 131 amino acids. Caprine RLF showed the highest homology in nucleic acid and amino acid sequence with bovine and sheep RLF, suggesting conservation of the RLF gene among ruminants. Northern blot analysis revealed a single 0.9 kb RLF transcript expressed in the goat testis but not in the epididymis, liver, or muscle tissue. Only a single goat RLF gene is present in the goat genome as determined by Southern blot analysis. Employing nonradioactive in situ hybridization for goat RLF mRNA and immunohistochemistry for 3beta-hydroxysteroid dehydrogenase (3beta-HSD) and 17alpha-hydroxylase, we identified the Leydig cells as the sole source of RLF mRNA in the goat testis.

Amino Acid Sequence↗

PubMed1999

Stage-specific effects of defined mixtures of polychlorinated biphenyls on in vitro development of rabbit preimplantation embryos.

PCBs adversely affect various reproductive functions. Little is known about the embryo- toxic effects during the preimplantation period in mammals. In the present study the effects of various mixtures of highly purified PCB-congeners on embryo morphology, blastocyst formation, embryo size and cell proliferation were investigated. For 24 hr, day 3 morulae and day 4 blastocysts were cultured in the presence/absence of coplanar congeners (PCB77, PCB126, and PCB169), non-coplanar congeners (PCB28, PCB52, PCB101, PCB118, PCB138, PCB153, PCB180) or both mixtures in concentrations ranging from 0.3 ng/mL to 60 microg/mL total PCB. The main effects were (1) degeneration of all embryos at 60 microg/mL, (2) reduction of cell proliferation in day 4 embryos only by coplanar PCB; in day 3 embryos, however, by all PCB-mixtures, and (3) reduction of cell proliferation in a non-linear dose response with the strongest impairment caused by the lowest concentration. Cell proliferation was decreased by 0.3 ng/mL coplanar PCB to 50% of the level in control blastocysts. Our results show that purified PCB congeners in the range of 0.3 ng/mL to 30 microg/mL affect the development of preimplantation embryos in a stage-specific and congener-specific manner. This study provides first evidence for an embryotoxic potential of coplanar PCB congeners.

Animals↗

PubMed1999

The recognition and correction of involuntary prosaccades in an antisaccade task.

This paper reports a striking misperception associated with involuntary saccadic eye movements: when subjects are instructed to look to the opposite side of a suddenly presented stimulus (antisaccade), they produce a certain number of involuntary prosaccades to the stimulus before they move their eyes to the other side by a corrective saccade of approximately twice the size. When asked to indicate at the end of each trial whether they believed that they made such a detour sequence of two saccades, one finds that, on average, 50+/-25% of these involuntary movements are not recognized. The average size and correction time for recognized prosaccades is larger than unrecognized prosaccades, while their mean reaction times are the same. The corrective saccades compensate for the size of both the recognized and unrecognized errors. When similar sequences of saccades are made voluntarily, the time spent at the stimulus side was 222 ms compared with 95 ms for unrecognized and 145 ms for recognized errors. The distributions of the corresponding correction times differ in their multimodal composition. Whether voluntary and involuntary saccades and their corrections are associated with different effects on the updating of the perceptual spatial frame and attention allocation is discussed.

Attention↗

PubMed1999

Arylhydrocarbon receptor expression in the human endometrium.

OBJECTIVE: To determine the expression and localization of the arylhydrocarbon (dioxin) receptor in human endometrium throughout the normal menstrual cycle. DESIGN: Retrospective immunohistochemical and in situ hybridization study. SETTING: Academic research unit. PATIENT(S): Premenopausal women (n = 86), aged 25 to 45 years, with histologically normal endometrium undergoing curettage or hysterectomy. INTERVENTION(S): Endometrial samples were collected from days 3 to 26 of the cycle by superficial scrapings of the uterine cavity or by hysterectomy. MAIN OUTCOME MEASURE(S): Expression of arylhydrocarbon receptor mRNA and protein. RESULT(S): Arylhydrocarbon receptor was expressed in 43% of the endometria studied and was correlated with the day of the cycle. The maximum of immunopositive endometria was found around the time of ovulation. Immunostaining decreased with increasing age of the patients. The receptor protein was localized exclusively in the apical part of the cytoplasm in the epithelial cells of the endometrial glands. In women positive for arylhydrocarbon receptor, arylhydrocarbon receptor mRNA was expressed in the cytoplasm of endometrial epithelial cells. CONCLUSION(S): Our results describe the expression of the arylhydrocarbon receptor in human endometrium and indicate a possible involvement of this transcription factor in endometrial function in women during the reproductive phase.

Adult↗

PubMed1999

Relaxin-like factor expression in a human ovarian Sertoli-Leydig cell tumor.

Relaxin-like factor (RLF), a new member of the insulin-like growth factor family, is a reliable marker for normal Leydig cells in the human postpubertal testis (1). Expression of the RLF gene appears to be developmentally regulated, given that only during puberty is RLF expression up-regulated. We recently demonstrated down-regulation of the human RLF gene in testicular Leydig cell tumors indicating dedifferentiation of the Leydig cells within the tumor (2). Ovarian Sertoli-Leydig cell tumors (SLCTs), histologically typed as androblastomas, are rare, potentially malignant sex-cord stromal tumors exhibiting testicular-like structure and differentiation of various degrees. In the present study, we investigated the expression of RLF, 17alpha-hydroxylase, 3beta-hydroxysteroid dehydrogenase (3beta-HSD), Ki-67, and cytokeratin 18 in a human ovarian SLCT of low differentiation.

3-Hydroxysteroid Dehydrogenases↗

PubMed1999

Coprinus comatus (shaggy cap) is a potential source of aeroallergen that may provoke atopic dermatitis.

BACKGROUND: Basidiospores are universal components in the air and established as important causes of respiratory allergies. Recent reports indicate that aeroallergens may aggravate eczematous skin lesions in subjects with atopic dermatitis (AD). OBJECTIVE: The aim of the study was to investigate whether spores of Coprinus comatus, a species of basidiomycetes, may elicit delayed-type skin reactions in subjects with an atopic predilection, especially dermatitis. METHODS: Sixty-six study subjects were categorized in groups having AD or respiratory allergy with regard to the skin prick test (SPT) reactivity to C comatus extract. Twenty nonatopic individuals served as control subjects. Atopy patch tests (APTs) were performed with extract of C comatus spore containing tissue at a concentration of 1. 35 mg of protein per gram of petrolatum (Vaseline) and C comatus cap at a concentration of approximately 5 mg of protein per gram of petroleum jelly. APT reactions were evaluated after 48 and 72 hours. RESULTS: Of the subjects with AD completing the study, 12 (32%) of 38 showed a positive APT reaction, with 8 (57%) also having a positive SPT response to C comatus. Only 1 (9%) of 11 subjects with asthma had a positive SPT and APT response to C comatus. No positive test reaction was observed in the nonatopic control subjects or in subjects with respiratory allergy and negative SPT responses to C comatus. CONCLUSION: Our results demonstrate that C comatus can induce delayed-type reactions in atopic individuals, particularly in those with AD. Because spores of Coprinus species are ubiquitous, basidiomycetes have to be considered as possible aeroallergens when investigating causes of eczematous skin lesions in AD.

Adolescent↗

PubMed1999

Anomalous expression of microtubule-associated protein 1B in the hippocampus and cortex of aged rats treated with pentylenetetrazole.

The aim of the present study was to assess the age-dependent response of microtubule-associated protein 1B, a plasticity-associated protein deriving from a late gene, following administration of an epileptogenic stimulus. The effect of a single administration of the convulsant pentylenetetrazole on microtubule-associated protein 1B expression in the hippocampal formation and cortex of three-, 18- and 28-month-old rats was assessed using northern blot analysis, in situ hybridization and immunohistochemistry. In three-month-old rats, we detected initial increases in microtubule-associated protein 1B messenger RNA at 15 h following pentylenetetrazole administration in the granule cells of the dentate gyrus, in the CA3 region of the hippocampus and in layers II/III of the entorhinal cortex, and these reached a maximum at 44 h. However, in the hippocampus and cortex of 18-month-old rats, the peak occurred at 15 h, and in the brains of 28-month-old rats a blunted peak was reached at 3 h. Pentylenetetrazole treatment in young rats resulted in a robust induction of microtubule-associated protein 1B immunoreactivity in the granule cells of the dentate gyrus and in layers II/III of the entorhinal cortex, but also produced a large decrease in the retrosplenial cortex. However, following pentylenetetrazole treatment in older rats, the granule cells of the dentate gyrus were nearly devoid of microtubule-associated protein 1B immunoreactivity, whereas the retrosplenial cortex showed no changes at all, and the entorhinal cortex had an expression pattern similar to that of young rats. Aberrant immunolabeling of microtubule-associated protein 1B occurred in cortical layer VI of the aged rats where, unlike in young rats, there was heavy staining of neuronal somata. These results suggest that the regulation of the plasticity-associated protein microtubule-associated protein 1B is altered in the ageing rat brain, with the peak of expression shifted to earlier times in 18-month-old rats and blunted, variable increases at even earlier times in 28-month-old rats.

Aging↗

PubMed1999

HLA-DR/DQ interaction in patients with erosive rheumatoid arthritis presenting articular and extraarticular disease manifestations.

In the present study we have analysed the effect of HLA-DRB1 and -DQB1 alleles on disease progression and genetic predisposition among 201 RA patients. We clearly confirm the association of RA with HLA class II alleles sharing the (Q)R/KRAA amino acid (AA) cassette in the third hypervariable region (HVR3) of the DR beta-chain. The HVR3 (Q)R/KRAA motif was significantly overrepresented among RA patients (79% vs. 40%, P < 0.001), with one third of the patients homozygous (28% vs. 6.7%, P < 10(-9)) and the number of rheumatoid factor positive (RF+) patients was significantly increased among HVR3 (Q)R/KRAA homozygous in comparison to HVR3 (Q)R/KRAA negative individuals. Erosive disease defined by the Larsen Score and personal disability determined using the Health Assessment Questionnaire (HAQ) was significantly increased among patients positive for the HVR3 motif with the worst outcome among HVR3 (Q)R/KRAA homozygous patients. In contrast, there was no association of the shared HVR3 AA cassette and disease severity in the majority of patients presenting systemic (extraarticular) disease. Homozygosity for the shared HVR3 motif was only marginally increased among patients presenting 'severe' extraarticular disease in comparison to patients with articular disease (33% vs. 43%, P = ns). Similarly, patients with nodular disease were not more often homozygous for the HVR3 (Q)R/KRAA motif. Furthermore, we observed no HLA-DR independent association of DQB1 alleles among HVR3 (Q)R/KRAA positive patients and controls. Our analysis supports the predominant role of HLA-DR for genetic susceptibility to RA. In the clinical setting, however, HLA-DR typing may be limited to assess the individual risk of patients for disease progression.

Adult↗

PubMed1999

Expression of relaxin-like factor is down-regulated in human testicular Leydig cell neoplasia.

In addition to their role in steroidogenesis in the male, testicular Leydig cells constitutively express large amounts of the peptide relaxin-like factor (RLF), also known as Ley-IL. The Leydig cell-derived RLF belongs to the insulin-like superfamily, which also includes relaxin, insulin and the insulin-like growth factors, and within the testis is a specific marker of Leydig cells. Little information is available either on the regulation of gene expression or on the function of this Leydig cell-derived peptide. In the present study we have investigated the expression pattern of human RLF in patients with rare Leydig cell hyperplasia and adenoma. The expression of both mRNA and protein appear to be decreased in hyperplastic Leydig cells, whereas in the Leydig cell adenomas studied, large central areas of the adenoma were devoid of RLF mRNA and protein. Only Leydig cells located at the periphery of the adenoma displayed expression of RLF, with full agreement between in-situ hybridization and immunohistochemistry. It thus appears that the expression of the RLF gene and its products are down-regulated in Leydig cell hyperplasia and adenoma, consistent with a concomitant dedifferentiation of these cells.

Adenoma↗

PubMed1999

Nucleic acid sequence of feline preprorelaxin and its localization within the feline placenta.

The cat placenta is known to secrete large amounts of relaxin. We employed uteroplacental tissue at approximately Day 35 of gestation to determine the nucleic acid sequence of feline preprorelaxin using reverse transcription- and rapid amplification of cDNA ends-polymerase chain reaction. Feline preprorelaxin cDNA was found to consist of 540 base pairs encoding a protein of 180 amino acids (aa). We identified a signal peptide of 25 aa, a B domain of 33 aa, a C domain of 98 aa, and an A domain of 24 aa. The putative receptor binding region in the N'-terminal part of the B domain contained one substitution from the classical GRELVR motif (L-->F). Feline preprorelaxin shared highest homology with porcine and equine preprorelaxin. Northern analysis revealed a specific 1-kilobase transcript present in total RNA of feline uteroplacental tissue but not of liver tissue. Nonradioactive in situ hybridization was used to localize relaxin mRNA, and immunohistochemistry was used to localize the relaxin hormone and cytokeratin, in tissues of the feto-maternal interface recovered from two queens at Day 35 of gestation. Specific hybridization signals for relaxin mRNA were exclusively detected in cells located in the lamellar placental labyrinth but were absent from other placental and nonplacental uterine parts. The cells expressing relaxin mRNA also displayed immunoreactivity for cytokeratin and were, therefore, identified as trophoblast cells. Immunoreactive relaxin colocalized in those placental areas expressing relaxin mRNA. Trophoblast cells located at the villous chorioallantoic tips invading the endometrium and extravillous trophoblast cells in the junctional placental zone were devoid of relaxin.

Amino Acid Sequence↗

PubMed1999

Canine preprorelaxin: nucleic acid sequence and localization within the canine placenta.

Employing uteroplacental tissue at Day 35 of gestation, we determined the nucleic acid sequence of canine preprorelaxin using reverse transcription- and rapid amplification of cDNA ends-polymerase chain reaction. Canine preprorelaxin cDNA consisted of 534 base pairs encoding a protein of 177 amino acids with a signal peptide of 25 amino acids (aa), a B domain of 35 aa, a C domain of 93 aa, and an A domain of 24 aa. The putative receptor binding region in the N'-terminal part of the canine relaxin B domain GRDYVR contained two substitutions from the classical motif (E-->D and L-->Y). Canine preprorelaxin shared highest homology with porcine and equine preprorelaxin. Northern analysis revealed a 1-kilobase transcript present in total RNA of canine uteroplacental tissue but not of kidney tissue. Uteroplacental tissue from two bitches each at Days 30 and 35 of gestation were studied by in situ hybridization to localize relaxin mRNA. Immunohistochemistry for relaxin, cytokeratin, vimentin, and von Willebrand factor was performed on uteroplacental tissue at Day 30 of gestation. The basal cell layer at the core of the chorionic villi was devoid of relaxin mRNA and immunoreactive relaxin or vimentin but was immunopositive for cytokeratin and identified as cytotrophoblast cells. The cell layer surrounding the chorionic villi displayed specific hybridization signals for relaxin mRNA and immunoreactivity for relaxin and cytokeratin but not for vimentin, and was identified as syncytiotrophoblast. Those areas of the chorioallantoic tissue with most intense relaxin immunoreactivity were highly vascularized as demonstrated by immunoreactive von Willebrand factor expressed on vascular endothelium. The uterine glands and nonplacental uterine areas of the canine zonary girdle placenta were devoid of relaxin mRNA and relaxin. We conclude that the syncytiotrophoblast is the source of relaxin in the canine placenta.

Allantois↗

PubMed1999

Pneumonia in febrile neutropenic patients and in bone marrow and blood stem-cell transplant recipients: use of high-resolution computed tomography.

PURPOSE: To obtain statistical data on the use of high-resolution computed tomography (HRCT) for early detection of pneumonia in febrile neutropenic patients with unknown focus of infection. MATERIALS AND METHODS: One hundred eighty-eight HRCT studies were performed prospectively in 112 neutropenic patients with fever of unknown origin persisting for more than 48 hours despite empiric antibiotic treatment. Fifty-four of these studies were performed in transplant recipients. All patients had normal chest roentgenograms. If pneumonia was detected by HRCT, guided bronchoalveolar lavage was recommended. Evidence of pneumonia on chest roentgenograms during follow-up and micro-organisms detected during follow-up were regarded as documentation of pneumonia. RESULTS: Of the 188 HRCT studies, 112 (60%) showed pneumonia and 76 were normal. Documentation of pneumonia was possible in 61 cases by chest roentgenography or micro-organism detection (54%) (P < 10(-6)). Sensitivity of HRCT was 87% (88% in transplant recipients), specificity was 57% (67%), and the negative predictive value was 88% (97%). A time gain of 5 days was achieved by the additional use of HRCT compared to an exclusive use of chest roentgenography. CONCLUSION: The high frequency of inflammatory pulmonary disease after a suspicious HRCT scan (> 50%) proves that pneumonia is not excluded by a normal chest roentgenogram. Given the significantly longer duration of febrile episodes in transplant recipients, HRCT findings are particularly relevant in this subgroup. Patients with normal HRCT scans, particularly transplant recipients, have a low risk of pneumonia during follow-up. All neutropenic patients with fever of unknown origin and normal chest roentgenograms should undergo HRCT.

Adult↗

PubMed1999

Fetal type lymphocytes in insulin dependent diabetes mellitus.

CD5+ B and gamma/delta T lymphocytes constituting a major population in the fetus and newborn infant, represent two small subsets of the B and T lymphocyte compartment in healthy adults. There is evidence for their potential involvement and relative expansion in autoimmune disorders. In insulin-dependent diabetes mellitus (IDDM) CD5+ B lymphocyte counts have been found to be increased or normal. The aim of our study was to determine the percentage of both "fetal type" lymphocyte subsets in peripheral blood of 22 recently diagnosed children with IDDM, in that of 13 high risk subjects (islet cell antibody (ICA) positive non-diabetic Ist degree relatives of diabetic children) and in 43 healthy controls. The percentage of gamma/delta TCR+ cells and of CD5+ B lymphocytes was found to be significantly (p < 0.0001 and p = 0.03, respectively) higher in the diabetic and prediabetic groups as compared to controls. Young children with IDDM associated antibodies carry a higher risk of developing clinical IDDM than older individuals. In our hands, the percentage of both CD5+ B and gamma/delta T lymphocytes was higher in the younger population. However, age-dependent decrease for both lymphocyte subpopulations in IDDM-prediabetic patients was less than in healthy controls. Since the above subpopulations are supposed to play a role in immune response to conserved structures, these observations would suggest a higher capacity of older individuals to 'natural autoimmunity" and would explain at least in part the increased risk of antibody positive young children to develop IDDM.

Adolescent↗

PubMed1999

[Reaction of the pituitary gland to a single GnRH administration in the dependence of energy balance in cattle in the puerperium].

After reviewing the relevant literature about the relationship of negative energy balance post partum and the onset of cyclicity the aim of this study will be described. The objective of this trial was to evaluate the influence of negative energy balance on the sensitivity of the pituitary for GnRH. Two groups of Holstein Friesian cows were randomly treated either with GnRH (Fertagyl) or a placebo. Considering the weekly calculated negative energy balance, the reaction of the pituitary was determined by analyzing LH in 16 blood samples, collected every 20 minutes starting one hour before and ending four hours after treatment. All cows treated with GnRH showed an intensive LH-surge, significantly different from the controls. These data suggest, that the sensitivity of the pituitary gland is not directly influenced by negative energy balance. The hypothalamus has the inhibiting priority over the pituitary delaying post partum cyclicity.

Animals↗