Biomedical subjects

H Agricola

Publications and source records attributed to H Agricola.

13 recordsLinked to original sources

PubMed2002

Crickets in space: morphological, physiological and behavioral alterations induced by space flight and hypergravity.

"Crickets in Space" was a Neurolab experiment by which the balance between genetic programs and the gravitational environment for the development of a gravity sensitive neuronal system was studied. The model character of crickets was justified by their external gravity receptors, identified position-sensitive interneurons (PSI) and gravity-related compensatory head response, and by the specific relation of this behavior to neuronal arousal systems activated by locomotion. These advantages allowed to study the impact of modified gravity on cellular processes in a complex organism. Eggs, 1st, 4th and 6th stage larvae of Acheta domesticus were used. Post-flight experiments revealed a low susceptibility of the behavior to micro- and hypergravity while the physiology of the PSI was significantly affected. Immunocytological investigations revealed a stage-dependent sensitivity of thoracic GABAergic motoneurons to 3 g-conditions concerning their soma sizes but not their topographical arrangement. The morphology of neuromuscular junctions was not affected by 3 g-hypergravity. Peptidergic neurons from cerebral sensorimotor centers revealed no significant modifications by microgravity (micro g). The contrary physiological and behavioral results indicate a facilitation of 1 g-readaptation originating from accessory gravity, proprioceptive and visual sense organs. Absence of anatomical modifications point to an effective time window of micro g or 3 g-expo-sure related to the period of neuronal proliferation. The analysis of basic mechanisms of how animals and man adapt to altered gravitational conditions will profit from a continuation of the project "Crickets in Space".

Adaptation, Physiological↗

PubMed2001

Crustacean cardioactive peptide is a modulator of oviduct contractions in Locusta migratoria.

Crustacean cardioactive peptide (CCAP) stimulates the contractions of locust oviducts. CCAP increased the basal tonus and increased the frequency and amplitude of phasic contractions, as well as the amplitude of neurally-evoked oviduct contractions in a dose-dependent manner. Oviducts from Vth instar larvae and adult locusts aged 10 days or less, were more sensitive to CCAP than oviducts from adult locusts aged 12 days or more. This may be indicative of a differential expression of number or subtypes of CCAP receptors on the oviducts at different ages, and may be related to reproductive functions or to functions of CCAP on the oviducts during ecdysis. The oviducts appear more sensitive to CCAP when compared with previously published reports of CCAP actions on the hindgut. CCAP actions on the amplitude of neurally-evoked contractions of the oviducts are similar to those of proctolin, however, the oviducts are more sensitive to CCAP. No CCAP-like immunoreactive structures were discovered in the nerves innervating the oviducts, or on the oviducts themselves, confirming the previously published suggestion (Dircksen et al., 1991) that CCAP acts as a neurohormone at the oviducts. Cells showing CCAP-like immunoreactivity were discovered in the fat body associated with the oviducts and represent a potential source of CCAP, along with CCAP released from the transverse nerve and perivisceral organs.

Journal Article↗

PubMed2000

Central complex in the brain of crayfish and its possible homology with that of insects.

A small, medial heterolateral neuropil in the brain of crustaceans has long been regarded as the central body of the crustacean brain. Its simplicity and the absence of clear layers within its neuropil have led to the question of its homology with the more complex central body that occupies an approximately equivalent position in the brain of insects. We have labelled neurons in the central body of the Australian freshwater crayfish Cherax destructor by the extracellular application of dextrans and by treating the brain with antibodies to anti-CCAP, anti-locustatachykinin, anti-perisulfakinin, anti-proctolin, anti-dip-allatostatin AI, anti-PEA-head-peptide, anti-serotonin, and anti-rabbit anti-substance P, all of which label neurons in the insect brain. The dextran and immunocytochemical labelling have revealed a neural complex associated with the crayfish central body that is very similar in overall anatomical architecture to the subset of neuropils that are incorporated in the central complex of the insects, and in particular to that of the locust. Similarities between the crayfish and locust central complexes extend to the number and position of the neuropils, the location of the cell body clusters of the neurons that belong to the central complex, the numbers of tracts that link some of the constituent neuropils together, and the form and immunoreactivity of many of the individual neuron classes. These similarities are taken as evidence to support a possible homology between the crustacean central complex and that of the insects.

Animals↗

PubMed1999

Structure, distribution, and biological activity of novel members of the allatostatin family in the crayfish Orconectes limosus.

In the central and peripheral nervous system of the crayfish, Orconectes limosus, neuropeptides immunoreactive to an antiserum against allatostatin I (= Dipstatin 7) of the cockroach Diploptera punctata have been detected by immunocytochemistry and a sensitive enzyme immunoassay. Abundant immunoreactivity occurs throughout the central nervous system in distinct interneurons and neurosecretory cells. The latter have terminals in well-known neurohemal organs, such as the sinus gland, the pericardial organs, and the perineural sheath of the ventral nerve cord. Nervous tissue extracts were separated by reverse-phase high-performance liquid chromatography and fractions were monitored in the enzyme immunoassay. Three of several immunopositive fractions have been purified and identified by mass spectroscopy and microsequencing as AGPYAFGL-NH2, SAGPYAFGL-NH2, and PRVYGFGL-NH2. The first peptide is identical to carcinustatin 8 previously identified in the crab Carcinus maenas. The others are novel and are designated orcostatin I and orcostatin II, respectively. All three peptides exert dramatic inhibitory effects on contractions of the crayfish hindgut. Carcinustatin 8 also inhibits induced contractions of the cockroach hindgut. Furthermore, this peptide reduces the cycle frequency of the pyloric rhythms generated by the stomatogastric nervous system of two decapod species in vitro. These crayfish allatostatin-like peptides are the first native crustacean peptides with demonstrated inhibitory actions on hindgut muscles and the pyloric rhythm of the stomatogastric ganglion.

Amino Acid Sequence↗

PubMed1996

Distribution of Dip-allatostatin I-like immunoreactivity in the brain of the locust Schistocerca gregaria with detailed analysis of immunostaining in the central complex.

The distribution and morphology of neurons containing allatostatin-related substances in the brain of the locust Schistocerca gregaria was investigated using an antiserum against Diploptera punctata allatostatin I (Dip-allatostatin I, APSGAQRLYGFGL-amide). In each brain hemisphere, about 550 neurons in the midbrain and 500 neurons in the optic lobe exhibit Dip-allatostatin I-like immunoreactivity, including about eight lateral neurosecretory cells with processes to the retrocerebral complex. All major brain areas except the antennal lobe, the mushroom body, and large parts of the lamina, are innervated by Dip-allatostatin I-immunoreactive processes. Immunostaining in the central complex was studied in detail. The central complex is innervated by more than 260 Dip-allatostatin I-immunoreactive neurons belonging to six different cell types, four sets of tangential neurons and two sets of columnar neurons. These neurons give rise to intense immunostaining in the protocerebral bridge, in several layers of the upper division of the central body, and in the dorsalmost layer of the lower division of the central body. Double-label experiments show colocalization of Dip-allatostatin I- and serotonin-like immunoreactivities in one type of columnar and one type of tangential neurons of the central complex. The similar patterns of Dip-allatostatin I- and galanin message-associated peptide-like immunoreactivities result from cross-reactivity of the anti-galanin message-associated peptide antiserum with Dip-allatostatin I. The results provide further insight into the anatomical and neurochemical organization of the locust central complex and suggest a prominent neuroactive role for Dip-allatostatin I-related peptides in this brain area.

Animals↗

PubMed1995

FMRFamide-like and allatostatin-like immunoreactivity in the lateral heart nerve of Periplaneta americana: colocalization at the electron-microscopic level.

Both allatostatin immunoreactivity (AS-IR) and FMRFamide immunoreactivity (FMRFa-IR) have been demonstrated light-microscopically in the lateral heart nerve of Periplaneta americana. The identical labeling of some fibers suggests the coexistence of the two antigens. Electron-microscopically, six granule types in the peripheral part of the lateral heart nerve can be distinguished according to their size and density (types 1-6). These granule types can be subdivided immunocytochemically by means of a new mirror-section technique. Granules of types 4 and 5 always exclusively show FMRFa-IR. In the populations of fibers containing granules of types 1 and 6, axon profiles can be found that contain granules colocalizing FMRFa-IR and AS-IR. Other axon profiles of these populations only contain immunonegative granules of the same ultrastructure. Granules of type 2 can be differentiated immunocytochemically in three forms in the same section: In some fibers, they are nonreactive; in other fibers of the same section, they show FMRFa - IR, whereas in a third fiber type, granules show AS - IR. Finally, granules of type 3 can be observed with FMRFa-IR. In other fibers, they occur with the same ultrastructure but exhibit no immunoreactivity. Two soma types occur in the lateral heart nerve. Soma type I is characterized by the production of electron-dense granules that show FMRFa-IR. Type II is in close contact with various fibers, forming different types of axosomatic synapses, hitherto unknown in Insecta.

Amino Acid Sequence↗

PubMed1994

Expression of the allatostatin gene in endocrine cells of the cockroach midgut.

Cockroach allatostatins are neuropeptides that have been isolated from the brain of Diploptera punctata and shown to inhibit juvenile hormone production by the corpora allata. Enzyme-linked immunoassay and immunocytochemistry with antisera to two allatostatins, ASB2 (AYSYVSEYKRLPVYNFGL-NH2) and ASAL (APSGAQRLYGFGL-NH2), revealed that allatostatins were located not only in the insect brain but also in several peripheral tissues including the cockroach midgut and hindgut. Allatostatin-like immunoreactivity was found in nerve fibers of the stomatogastric nervous system as well as in intrinsic endocrine cells of the midgut. Midgut extracts were shown to be biologically active in an allatostatin bioassay and to contain several allatostatin-like peptides, including the octadecapeptide ASB2, which was identified by mass spectrometry following HPLC purification. Reverse transcription of brain mRNA followed by PCR with degenerate oligonucleotides for ASB2 and ASAL yielded a 338-bp fragment of the allatostatin gene that encoded six allatostatins. In situ hybridization with this probe confirmed that an allatostatin gene is expressed in intrinsic endocrine cells of the midgut. Reverse transcription of midgut mRNA followed by PCR and sequencing of the product revealed that the same gene is expressed in the midgut and in the brain. Allatostatins are thus an example of insect "brain-gut peptides" and we suggest that their function may not be restricted to the regulation of juvenile hormone production.

Amino Acid Sequence↗

PubMed1988

Morphology of neurones associated with the antennal heart of Periplaneta americana (Blattodea, Insecta).

Innervation of the antennal heart, an independent accessory circulatory motor in the head of insects, was investigated in the cockroach Periplaneta americana by use of axonal cobalt filling and transmission electron microscopy. The muscles associated with this organ are innervated by neurones located in a part of the suboesophageal ganglion, generally considered to be formed by the mandibular neuromere. Dorsal unpaired median (DUM) and paired contralateral neurones were stained. The axons of all these neurones run along the circumoesophageal connectives and through the paired nervus corporis cardiaci III into the corpora cardiaca. They pass through these organs forming fine arborizations there and exit anteriorly as a small pair of nerves which terminate at the antennal heart-dilator muscles. Numerous branches of these nerves extend beyond the lateral borders of the large transverse dilator muscle and terminate in the ampullar walls of the antennal heart. These neurosecretory fibres form neurohaemal areas which obviously release their products into the haemolymph, which is pumped into the antennae. The possible functions of the neurones associated with the antennal heart are discussed with respect to both, their role as a modulatory input for the circulatory motor and as a neurohormonal release site.

Animals↗

PubMed1981

Immunocytochemical identification of proctolinlike immunoreactivity in the terminal ganglion and hindgut of the cockroach Periplaneta americana (L.).

In the American cockroach, the distribution and connections of neuronal elements of the terminal ganglion-proctodeal nerve-hindgut system were investigated by means of immunohistochemical methods and axonal CoCl2 iontophoresis. Proctolinlike immunoreactivity was localized within neurons of the terminal ganglion projecting into the proctodeal nerve on the one hand, and in nerve cells without a direct connection to this system on the other. Immunohistochemically, in whole mount preparations fibres of the proctodeal nerve and terminal structures in the hindgut musculature exhibit strong proctolinlike immunoreactivity. At the light- and electron-microscopic levels the pathways of about 30 somata of the proctodeal neural system were characterized by cobalt chloride iontophoresis. The relationships of cobalt filled and immunoreactive neuronal structures are discussed.

Animals↗

PubMed1979

Synaptic connections of the nervus connectivus in the frontal ganglion of Periplaneta americana L. (Insecta). An electron microscopic and iontophoretic study.

The course of the Nervus connectivus (N.c.), its branches, and synaptic connections within the frontal ganglion (FG) were investigated electron microscopically after cobalt iontophoresis of the N.c. The subsequent treatment of ultrathin sections with Timm's method was found to be very suitable for identifying the smallest branches. In the neuropil, fibers of the N.c. form Gray-I-type synapses, but also dyads are abundant, whereby the N.c. fibers occur exclusively in postsynaptic position with neurosecretory fibers. The possible role of these relationships is discussed.

Animals↗

PubMed1976

[Clinical problems of premature labor. 1. Diagnosis of threatening premature labor and the screening procedure].

At first the allround etiology of premature birth is explained in the paper. There are to distinguish three groups: 1. Causes with known etiologic mechanism. 2. Causes with partly known etiologic mechanism. 3. Dispositions for premature birth. These are concluded from statistically investigations. In the last group are collected the patients from which are established some known scores for diagnosis of the risk of premature birth. All the scores but have a detriment. If they want to detect about 90% from premature births one must carry out examination and observation about 40% from all pregnant women. For this the scores are not suitable for selection of patients to observe in a special consultation. The organised care for pregnant women must be in such a way that all the criterias of imminent prematurity will be detected. This way has been successfull in our hospital.

Adolescent↗

PubMed1975

Translocation +(7p+; Bq-) associated with recurrent abortion.

A balanced translocation was found in a normal female with a history of four abortions. On the basis of the Giemsa-banding pattern the abnormality was interpreted as to be a translocation of a part of the long arm of chromosome 13 to the short arm of chromosome some 7:t(7;13)(7qter leads to 7p22::13q14 leads to 13qter;13q14 leads to 13pter::7p22 leads to 7 pter). Problems in genetic counseling are discussed with respect to this case.

Abortion, Habitual↗

PubMedDate not supplied

Crickets in space.

"Crickets in Space" (CRISP) was a Neurolab experiment by which the balance between genetic programs and the gravitational environment for the development of a gravity sensitive neuronal system was studied. The model character of crickets was justified by their external gravity receptors, identified position-sensitive interneurons (PSI) and gravity-related compensatory head response, and by the specific relation of this behavior to neuronal activation systems. These advantages allowed us to study the impact of modified gravity on cellular processes in a complex organism. Eggs, 1st, 4th and 6th stage larvae of Acheta domesticus were used. Post-flight experiments revealed a low susceptibility of the behavior to microgravity and hypergravity (hg) while the physiology of the PSI was significantly affected. Immunocytological investigations revealed a stage-dependent sensitivity of thoracic GABAergic motoneurons to 3g-conditions concerning their soma sizes but not their topographical arrangement. Peptidergic neurons from cerebral sensorimotor centers revealed no significant modifications by microgravity. The contrary physiological and behavioral results indicate a facilitation of 1g-readaptation by accessory gravity. proprioceptive and visual sense organs. Absence of anatomical modifications point to an effective time window of microgravity or hg-exposure related to the period of neuronal proliferation. Grant numbers: 50WB9553-7.

Adaptation, Physiological↗