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D Dietrich

Publications and source records attributed to D Dietrich.

35 records · Page 2Linked to original sources
PubMed2000

Schwannosis: role of gliosis and proteoglycan in human spinal cord injury.

Schwannosis (aberrant proliferation of Schwann cells and nerve fibers) has been reported following spinal cord injury (SCI). In this study, we examined the incidence of schwannosis following human SCI, and investigated its relationship to gliosis. We found evidence of schwannosis in 32 out of 65 cases (48%) of human SCI that survived 24 h to 24 years after injury; this incidence rose to 82% in those patients who survived for more than 4 months. Schwannosis was not observed in cases that survived less than 4 months after injury. In affected cases, it was generally noted in areas that had low immunoreactivity for glial fibrillary acidic protein (GFAP), suggesting that reduced gliosis might have contributed to the aberrant proliferation of Schwann cells following SCI. Since chondroitin sulfate proteoglycan (CSPG) has been proposed to play a role in Schwann cell/glial interaction, we performed immunohistochemical staining for CSPG to investigate its potential relationship with schwannosis. CSPG in the injured cord was generally associated with the blood vessel walls, but was also sometimes noted in reactive astrocytes. In SCI with schwannosis, CSPG staining was more prominent and confined largely to the extracellular matrix and basal lamina of proliferating Schwann cells. Our study suggests that Schwann cells, which may have been displaced from spinal roots and introduced into the injured cord through a break in the pial surface, are capable of proliferating and producing CSPG, particularly in the setting of reduced gliosis. Since CSPG has been associated with inhibition of neurite outgrowth, its increased production by aberrant Schwann cells may impair spinal cord regeneration after injury.

Adolescent↗
PubMed1999

Analysing metabotropic glutamate group III receptor mediated modulation of synaptic transmission in the amygdala-kindled dentate gyrus of the rat.

Metabotropic glutamate receptors (mGluRs) provide a powerful control of synaptic transmission in the hippocampus and may serve as a target for drug development in human temporal lobe epilepsies. Agonists and antagonists at these receptors influence the development and propagation of seizures in some animal models of epilepsy. Experimental seizures can change the level of expression of mGluRs in the rat hippocampus. In the human dentate gyrus of patients suffering from temporal lobe epilepsy (TLE), group III mGluR mediated inhibition of synaptic transmission is almost lost in the sub-group with Ammon's horn sclerosis. We tested the modulation of synaptic transmission by the group III mGluR specific agonist L(+)-2-amino-4-phosphonobutyric acid (L-AP4) in the dentate gyrus outer molecular layer in control and amygdala-kindled rats, a common model for TLE. Extracellular field potential recordings upon subthreshold stimulation of lateral perforant path fibers were measured simultaneously in the outer molecular layer and granule cell layer. Analysis of 'paired-pulse' characteristics in the absence and presence of L-AP4 and group III mGluR mediated inhibition of synaptic transmission in the lateral perforant path revealed no significant alterations in fully kindled rats. Since there is no evidence of altered L-AP4 responses, a loss of group III mGluR function, particularly that of subtype mGluR8, seems not necessary for the kindling epilepsy.

Amygdala↗
PubMed1999

Two electrophysiologically distinct types of granule cells in epileptic human hippocampus.

We investigated the electrophysiology of morphologically identified human granule cells with conventional current-clamp recordings. Slices were prepared from 14 human epileptic sclerotic hippocampi. Granule cells appeared to have a diverse electrophysiology. Each cell was distinguished by the shape of the afterhyperpolarization following single action potentials. Two types could be discerned: type I afterhyperpolarizations were monophasic and brief (typically 10-40 ms), whilst type II afterhyperpolarizations were biphasic and long (typically 50-100 ms). The two types also differed in their repetitive firing behaviour and action potential morphology: type I cells had significantly weaker spike frequency adaptation, lower action potential amplitude and smaller action potential upstroke/downstroke ratio. Thus, the firing pattern of type I cells resembled that of rodent dentate interneurons. In contrast, the corresponding parameters of type II cells were comparable to rodent dentate granule cells. Despite the distinct firing patterns, membrane properties were not different. The two types of cells also differed in their synaptic responses to stimulation of the perforant path. At strong suprathreshold stimulation intensity, type I cells always generated multiple action potentials, whereas type II cells usually spiked once only. Slow inhibitory postsynaptic potentials were not detected in type I neurons, but were easily identified in type II neurons. Extracellular recordings of perforant path-evoked field potentials in the cell layer confirmed that the majority of granule cells showed multiple discharges even when we recorded simultaneously from a type II cell that generated one action potential only. The morphology of both types of cells was characteristic of what has been described for primate dentate granule cells. Based on comparisons with previous studies on rodent and human granule cells, we tentatively hypothesize that: (i) the majority of granule cells from sclerotic hippocampus display an hyperexcitable epileptogenic electrophysiology; (ii) there is a subset of granule cells whose electrophysiology is preserved and is more comparable to granule cells from non-epileptic hippocampus.

Adult↗
PubMed1999

Reduced function of L-AP4-sensitive metabotropic glutamate receptors in human epileptic sclerotic hippocampus.

Human temporal lobe epilepsy is characterized by strong synaptic reorganization that leads to abnormal recurrent excitatory synaptic connections among hippocampal neurons. In addition, electrophysiological studies show that synaptic activity of the main afferent input to the hippocampus, the perforant path, is prolonged and amplified by changes in postsynaptic glutamate receptors. The current view is that these morphological and physiological abnormalities contribute significantly to the hyperexcitability seen in the hippocampus of temporal lobe epilepsy. Recently, it was found that presynaptic inhibitory metabotropic glutamate receptors are an important negative feedback mechanism that controls synaptic release of glutamate in the hippocampus. In this study, we assessed the functionality of this feedback system by investigating the metabotropic glutamate receptor mediated depression of excitatory synaptic transmission in surgically removed hippocampi from patients with marked synaptic reorganization (Ammon's horn sclerosis group) and from patients without detectable reorganization (lesion group). We report here that this control of synaptic transmission is lost in hippocampi from the Ammon's horn sclerosis group whereas this control is preserved in hippocampi from the lesion group. The data presented here suggest that the loss of feedback inhibition mediated by metabotropic glutamate receptors could be a further, previously not recognized, mechanism in the pathophysiology of temporal lobe epilepsy.

Action Potentials↗
PubMed1997

Metabotropic glutamate receptors modulate synaptic transmission in the perforant path: pharmacology and localization of two distinct receptors.

Metabotropic glutamate receptors (mGluRs) have emerged as an interesting family of eight different receptor subtypes that can be divided into three groups according to their pharmacology and sequence similarity. In the present study, the specific mGluR agonists (1S,3R)-1-aminocyclopentane-1,3-dicarboxylic acid ((1S,3R)-ACPD) and L(+)-2-amino-4-phosphonobutyric acid (L-AP4) depressed field excitatory postsynaptic potentials (fEPSPs) in the rat dentate gyrus evoked by perforant path stimulation in a concentration-dependent, rapid and reversible manner (EC50: L-AP4 5.9 +/- 1.6 microM, (1S,3R)-ACPD 80 +/- 34 microM). In a 'paired-pulse' stimulation protocol, the first fEPSP showed a stronger reduction, resulting in 'paired-pulse' facilitation. The effects of L-AP4 but not of (1S,3R)-ACPD could be antagonized by the group III mGluR antagonists (S)-2-amino-2-methyl-4-phosphonobutanoic acid (MAP4) and (RS)-alpha-methyl-4-phosphonophenylglycine (MPPG). Moreover, (1S,3R)-ACPD was still potently depressing fEPSPs after preperfusion of near saturating concentrations of L-AP4. Together, the results suggest that both substances act on different mGluRs. The effects of (1S,3R)-ACPD could not be further differentiated by selective group I or group II mGluR agonists. Although (2S,1'S,2'S)-2-carboxycyclopropylglycine (L-CCG-I) blocked fEPSPs at concentrations >> 1 microM, these effects, as well as L-AP4 effects, were potently antagonized by MAP4. This suggests that mGluR8 might be responsible for the actions of L-AP4 and L-CCG-I. The two different mGluRs showed a distinct distribution when fEPSPs were recorded simultaneously in the outer and middle molecular layer (OML/MML): The L-AP4 sensitive receptor, possibly mGluR8, seems to be located in the OML while (1S,3R)-ACPD showed its main effect in the MML.

Aminobutyrates↗
PubMed1997

Biochemical characterization of microcystin toxicity in rainbow trout (Oncorhynchus mykiss).

The kinetics and biochemical effects of microcystins in rainbow trout were studied with freeze-dried toxic cells of Microcystis aeruginosa, strain PCC 7806. Following in vivo exposure the changes in liver histology were observed over a 72 hr period and the absorption of microcystins from the gastrointestinal tract into the blood and liver, as well as the inhibition of hepatic protein phosphatase 1 and 2A activities, were recorded using the protein phosphatase inhibition assay. The interaction between microcystins and trout liver phosphatases was further tested in vitro using the protein phosphatase inhibition assay. The in vivo experiments demonstrated a high organotropy of microcystins for the liver, where rapid and total inhibition of protein phosphatase 1 and 2A activity was observed. Maximal inhibition of phosphatases was observed 3 hr after gavage. At that time-point, approximately 63% of the toxin present in the liver was refractive to detection via the phosphatase inhibition assay and therefore most likely covalently bound to cellular proteins. The inhibition of hepatic protein phosphatases 1 and 2A proved to be transient only, as a progressive increase in phosphatase activity was observed beginning 12 hr after gavage of the fish, reaching approximately 50% of the control activity at 72 hr. In contrast, liver damage continued to progress despite this renewed protein phosphatase activity.

Animals↗
PubMed1995

Degradation of 4,4'-dichlorobiphenyl, 3,3',4,4'-tetrachlorobiphenyl, and 2,2',4,4',5,5'-hexachlorobiphenyl by the white rot fungus Phanerochaete chrysosporium.

The white rot fungus Phanerochaete chrysosporium has demonstrated abilities to degrade many xenobiotic chemicals. In this study, the degradation of three model polychlorinated biphenyl (PCB) congeners (4,4'-dichlorobiphenyl [DCB], 3,3',4,4'-tetrachlorobiphenyl, and 2,2',4,4',5,5'-hexachlorobiphenyl) by P. chrysosporium in liquid culture was examined. After 28 days of incubation, 14C partitioning analysis indicated extensive degradation of DCB, including 11% mineralization. In contrast, there was negligible mineralization of the tetrachloro- or hexachlorobiphenyl and little evidence for any significant metabolism. With all of the model PCBs, a large fraction of the 14C was determined to be biomass bound. Results from a time course study done with 4,4'-[14C]DCB to examine 14C partitioning dynamics indicated that the biomass-bound 14C was likely attributable to nonspecific adsorption of the PCBs to the fungal hyphae. In a subsequent isotope trapping experiment, 4-chlorobenzoic acid and 4-chlorobenzyl alcohol were identified as metabolites produced from 4,4'-[14C]DCB. To the best of our knowledge, this the first report describing intermediates formed by P. chrysosporium during PCB degradation. Results from these experiments suggested similarities between P. chrysosporium and bacterial systems in terms of effects of congener chlorination degree and pattern on PCB metabolism and intermediates characteristic of the PCB degradation process.

Basidiomycota↗
PubMed1994

Spontaneous tibial compartment syndrome: case report.

We report the case of an obese 34-year-old woman who spontaneously developed compartment syndrome in her right calf. The patient was treated with four-compartment fasciotomy and debridement of necrotic tissue. Four months after treatment she was ambulating without the use of aids and had full range of motion and muscle strength.

Adult↗
PubMed1992

Priming outside of awareness and subsequent stimulus identification.

The influence of priming outside of awareness on performance of a color-recognition task was investigated. Using a tachistoscope, a color word that matched ("congruent prime") or did not match ("incongruent prime") the target color or a blank prime was followed by a pattern mask and the target color. Identification performance was superior on the blank prime trials to the congruent prime trials, with performance on the incongruent prime trials being the lowest. A subsequent study included a meaningless (XXX) prime condition, and it was found that meaningless primes interfered with target-color identification more than the congruent and blank prime conditions, but less than the incongruent prime condition, suggesting that primes, in addition to producing semantic activation, impose demands on information-processing capacity of the perceptual system.

Adult↗
PubMed1990

Some factors influencing abusers' justification of their child abuse.

The interviews of abusive caretakers originally carried out by Kadushin and Martin (1981) were coded and subjected to statistical analyses to determine what aspects of the caretakers' situation and of their interaction with the abused child had contributed to their belief that their treatment of the youngster was justified or not. A multiple regression analysis employing scores on the various indices obtained from the sample of 73 interviews indicated that the abusers tended to believe their behavior was justified if they thought the child had been defiant and they themselves had been under considerable environmental stress. On the other hand, they generally regarded their action as less justified if they had lost their temper and had been experiencing emotional distress. The latter finding suggests, in accord with Berkowitz's analysis of emotional aggression, that some instances of child battering were impulsive reactions to a provocative event. Although major emphasis is given to the meaning of these findings for the theoretical analysis of aggression, implications for protective service practice are also indicated.

Adult↗
PubMed1989

Energy turnover in hypoxic heart muscle.

In isolated rabbit papillary muscles at 20 degrees C, we studied the relationship between demand, supply, and utilisation of energy in hypoxia. Since shortage of energy is an important factor in loss of contractile performance following an hypoxic period, we tried to find a relationship between the loss of force production upon reoxygenation and the demand, supply, and utilisation of energy. Energy demand in hypoxia was defined as the -P turnover found in oxygen under further identical conditions. Energy supply in hypoxia was determined from lactate formation, using a P/lactate ratio of 1, while energy utilisation in hypoxia was obtained from the sum of: -P supply, the decrease of PCr and ATP, and the increase of AMP. Energy demand in hypoxia was varied by stimulating the hypoxic muscles at 0.2 Hz or not at all. For contracting hypoxic muscles energy supply by glycolysis was only 23% of energy demand. After 40 min of hypoxia force did only partially recover (78%) upon reoxygenation. For muscles at rest in hypoxia, force recovery was significantly (p less than 0.05) better (94% of control). However, energy supply was no more than 15% of the demand because supply was almost proportionally lower. It is concluded that the loss of force production upon reoxygenation is not related to the supply: demand ratio. By taking the integrated difference after 40 min of hypoxia between energy demand and utilisation, the energy deficit built up in hypoxia was estimated. In contracting muscle this was 2 times higher than in resting ones. It is suggested that a relationship could exist between the energy deficit and the loss of contractile performance upon reoxygenation. Experiments to test this idea are discussed.

Animals↗
PubMed1979

A retrospective analysis of the TATs of children at risk who subsequently broke down.

A retrospective evaluation of stories told to three Thematic Apperception Test (TAT) cards by children at risk isolated six characteristics that were associated with functioning six to 10 years later. The characteristics included lack of individual initiative, denial of mother-child relationships, denial of negative outcomes, and lack of autonomy. The TATs of children at risk (due to one parent's hospitalization for a psychotic illness) who subsequently suffered major decompensation themselves (requiring hospitalization or intensive outpatient therapy) could be discriminated from those of children at risk with apparently normal development. The TAT characteristics were independent of the level of adjustment at the time the TATs were administered, not related to the child's IQ, socioeconomic status, race, or other family characteristics, and moderately negatively correlated with story length.

Child↗
PubMed1979

[An attempt to analyze the state of gastric cancer control in the German Democratic Republic (author's transl)].

Starting from the records of the county cancer control offices, an attempt is made to analyze the quality of detection and treatment of gastric cancer in the G.D.R. Possibilities and results of curative treatment strongly depend upon the extent of the disease and the age of the patient at the time of diagnosis. During the period of observation (Berlin 1955--1974, county Königs Wusterhausen 1960--1974), the proportion of elderly patients (65-yrs.) increased, stage distribution remained about the same, the rate of curative operations increased a little. When comparing the situation in the capital Berlin with the district Erfurt, the city of Dresden and the rural county Königs Wusterhausen, it can be demonstrated that the quality of diagnosis and treatment in Berlin is somewhat better then in the other teritories.

Adult↗
PubMed1976

[Malignant neoplasms of the stomach in Berlin, capital of the G.D.R. - An analysis of the state of diagnosis and treatment].

In Berlin, capital of the German Democratic Republic, 7,386 new cases of gastric cancer (ICD 151) were registered in the period from 1955 to 1969 and in year 1973. 52 percent of patients were male. Percentage of cases 75 years old and more, increased from 21% (1955-1959) to 36% (1965-1969). There were only slight changes in incidence. About 30% of cases were in the operable stages I and II. With rising age, the proportion of the advanced stages III and IV increases. No real progress as made in early diagnosis of stomach cancer as measured by stage distribution during observation period. Patient's delay from first symptom to first visit was shorter than one month in 40%, physician's delay from first visit to correct diagnosis was shorter than one month in 54%. 15% of patients were treated within one month after first symptom and 47% within three months. There was no correlation between duration of history and percentage of early stages. When observation periods 1955 to 1959, 1960-1964, 1965-1969 and 1973 are compared, we find an increase in old patients (75+ years), a decrease of localized stages I + II, and a decrease in resection rate. Therefore, a decrease in survival rates is to be expected. Crude 5-year survival rate was 6.4% (1955-1959) and 6.2% (1960-1964). When we compare data from Berlin with observations in the Region of Erfurt and in Birmingham Region, the situation of detection and treatment of stomach cancer in Berlin seems to be somewhat better. Finally, some suggestions for the improvement of control of stomach cancer are made.

Adult↗