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Biomedical subjects

M Heinrichs

Publications and source records attributed to M Heinrichs.

At least 19 recordsLinked to original sources
PubMed2002

Hypothalamic-pituitary-adrenal axis reactivity to psychological stress and memory in middle-aged women: high responders exhibit enhanced declarative memory performance.

According to recent studies, elevated cortisol levels are associated with impaired declarative memory performance. This specific effect of cortisol has been shown in several studies using pharmacological doses of cortisol. The present study was designed to determine the effects of endogenously stimulated cortisol secretion on memory performance in healthy middle-aged women. For psychological stress challenging, we employed the Trier Social Stress Test (TSST). Subjects were assigned to either the TSST or a non-stressful control condition. Declarative and non-declarative memory performance was measured by a combined priming-free-recall-task. No significant group differences were found for memory performance. Post hoc analyses of variance indicated that regardless of experimental condition the subjects with remarkably high cortisol increase in response to the experimental procedure (high responders) showed increased memory performance in the declarative task compared to subjects with low cortisol response (low responders). The results suggest that stress-induced cortisol failed to impair memory performance. The results are discussed with respect to gender-specific effects and modulatory effects of the sympathetic nervous system and psychological variables.

Adult↗
PubMed2001

Effects of suckling on hypothalamic-pituitary-adrenal axis responses to psychosocial stress in postpartum lactating women.

In several studies lactation has been shown to be associated with a hypothalamic-pituitary-adrenal axis hyporesponsiveness to physical and psychological stressors. As it is not known whether the marked blunting of endocrine stress reactivity in women can be ascribed to suckling as a short-term effect or to lactation in general, the acute effects of suckling on the hypothalamic-pituitary-adrenal axis and the sympathetic-adrenal-medullary system responses to mental stress were investigated in lactating women. Forty-three lactating women were randomly assigned either to breast-feed or to hold their infants for a 15-min period with the onset 30 min before they were exposed to a brief psychosocial stressor (Trier Social Stress Test). Both breast-feeding and holding the infant yielded significant decreases in ACTH, total plasma cortisol, and salivary free cortisol (all P < 0.01). There were no significant differences in baseline hormone levels between the groups 1 min before the stress test. In response to stress exposure, ACTH, total plasma cortisol, salivary free cortisol, norepinephrine, and epinephrine were significantly increased in all lactating women (all P < 0.001). However, total cortisol and free cortisol responses to stress were attenuated in breast-feeding women (P = 0.001 and P = 0.067, respectively), who also showed significantly decreasing PRL levels during the stress test (P = 0.005). In addition, there was no change in plasma oxytocin or vasopressin in response to the stressor. Breast-feeding as well as holding led to decreased anxiety (P < 0.05), whereas, in contrast, stress exposure worsened mood, calmness, and anxiety in the total group (all P < 0.001). From these data we conclude that lactation in women, in contrast to that in rats, does not result in a general restraint of the hypothalamic-pituitary-adrenal axis response to a psychosocial stressor. Rather, suckling is suggested to exert a short-term suppression of the cortisol response to mental stress.

Adrenocorticotropic Hormone↗
PubMed2000

Social desirability scores are associated with higher morning cortisol levels in firefighters.

OBJECTIVE: To examine the association of social desirability (SD) responding ("defensiveness") and cortisol levels. METHODS: Marlowe-Crowne SD scores and morning salivary cortisol were measured in firefighters. RESULTS: SD scores were associated with higher cortisol levels (r=.28) in 60 firefighters under age 45, but not in 25 older firefighters (or the combined sample). CONCLUSION: The results are consistent not only with SD scores being an indicator of coarctation of experience as a coping mechanism, but also (at least for younger persons) perhaps a risk factor for the psychobiological dysfunctions associated with chronic elevations of cortisol.

Adaptation, Psychological↗
PubMed2000

Simulation to estimate the capacity of a stroke unit.

Preceding the implementation of a Stroke Unit (SU), data have been collected and used for building a simulation model of patient flow. This model was subsequently used to estimate the optimal capacity of the SU to be implemented. Because stroke patients require acute hospital care, this implies a highly variable number of immediate admissions. This variability complicates optimizing the capacity. In order to support decisions with regard to staffing (i.e. capacity) of the SU, different scenarios are simulated and compared to provide insight in the trade-off between regular understaffing and a low bed occupancy rate. In 1996 the Department of Neurology of the Academic Medical Center in the Netherlands implemented its SU to improve the quality of care for stroke patients. Data collected in the years 1997 and 1998 that the SU has been operational were evaluated and confirm the predictions made from simulating different scenarios. We conclude that simulation models provide a powerful tool for supporting decision making with regard to resource planning at the departmental level in our hospital.

Computer Simulation↗
PubMed1999

[Psychobiological aspects of posttraumatic stress disorder].

The exposure to a traumatic event may result in posttraumatic stress disorder (PTSD), which is characterized by a complex symptomatology, clustered into three groups of symptoms, i.e. intrusive memories, avoidance behavior, and hyperarousal. Since PTSD is a stress reaction, alterations of stress-responses of neurobiological systems have been examined in patients suffering from PTSD. The investigation of biological parameters refers to the hypothalamic-pituitary-adrenal axis (HPA), studies of the noradrenergic and the endogenous opiate system as well as psychophysiological and neuroimaging studies. Besides others, the observed biological dysregulations refer to hypocortisolism with an enhanced negative feedback of the HPA axis, enhanced noradrenergic activity, and neuroanatomical changes. To elucidate the specificity of this findings for PTSD, the dysregulations will be discussed with reference to findings in major depression and somatoform disorders.

Brain↗
PubMed1999

RITA/Registry of Industrial Toxicology Animal data: a comparative immunohistochemical study of 77 islet cell carcinomas in Sprague-Dawley and Wistar rats using antibodies against insulin, glucagon, somatostatin and gastrin.

UNLABELLED: The objective of this study was to investigate spontaneous islet cell carcinomas with particular reference to possible existing strain differences between Sprague Dawley (SD) and Wistar (W) rats in incidence and immunohistochemical staining pattern. Secondly the occurrence of somatostatin and/or gastrin-positive islet cell tumors should be tested. Islet cell adenocarcinomas (34 from SD, 43 from W-rats) were selected from the RITA-data base and company in-house data base out of an animal pool of 3915 (1681 SD, 2234 W-rats). They were untreated or sham-treated (vehicle) control animals from carcinogenicity studies and whole life-span experiments. Islet cell carcinomas occurred in a higher incidence in male rats (2.98% for SD, 3.23% for W) than in female rats (1.07% for SD, 0.63% for W). All specimens were immunohistologically stained with antibodies against insulin, glucagon, somatostatin and gastrin and, selected specimens with additional antibodies (pancreatic polypeptide, lipase, chymotrypsin, S100-protein, actin and cytokeratin). 94% (SD) and 93% (W), respectively, were insulin-positive and the mean staining intensity (on a scale ranging from 0-4) for insulin was 3.58 (SD) versus 3.37 (W). This high insulin staining incidence and intensity characterized most islet cell carcinomas as malignant insulinomas. 24% (SD) and 37% (W), respectively, were glucagon-positive. Except two tumors in W-rats with a focal strong glucagon expression, the mean staining intensity for glucagon was low (0.38 SD, 0.72 W). 38% (SD) and 44% (W), respectively, were somatostatin-positive, but except for five cases having a focal to multifocal, moderate to marked staining, only a few tumor cells were positive for somatostatin in the other cases and the mean staining intensity for somatostatin was low (0.50 SD, 0.84 W). 6% (SD) and 23% (W), respectively, were gastrin-positive, but only one case of a male Wistar rat exhibited a focal strong staining in parts of the tumor. The other cases showed only a few tumor cells which were positive for gastrin. The mean staining intensity for gastrin was low (0.06 SD, 0.35 W). In all tumors with marked glucagon, somatostatin or gastrin expression, the immunostaining for insulin was still predominating. Thus, insulin was the major hormone produced by most of the tumor cells. Five out of 77 tumors evaluated were immunohistologically negative with all applied antibodies. CONCLUSION: This study presents the first immunohistochemical survey on spontaneous islet cell carcinomas in SD and Wistar rats stained with antibodies against the endocrine pancreas hormones insulin, glucagon, somatostatin and gastrin. No major differences in incidence or immunohistochemical staining pattern between SD and W-rats could be detected. In contrast to SD rats, Wistar rats had multihormonal coexpression in 16.3%. The multihormonal appearance of the neoplasms is well comparable with the findings in other animal species and human insulinomas. Moreover, this is the first study in rats which reports five cases with a marked co-expression of somatostatin and one case with marked focal co-expression of gastrin in malignant islet cell adenocarcinomas.

Animals↗
PubMed1998

Prevalence of symptoms of posttraumatic stress disorder in German professional firefighters.

OBJECTIVE: This study investigated the prevalence of posttraumatic stress disorder (PTSD) and comorbid symptoms among professional firefighters in Germany and examined not only primary but also secondary traumatic stress disorder experienced by these firefighters who were exposed to the sufferings of others. METHOD: To estimate the prevalence of trauma-related disorders, a representative group of 402 professional firefighters from the State of Rheinland-Pfalz in Germany was surveyed through use of the General Health Questionnaire, a PTSD Symptom Scale, a stress coping questionnaire, and a self-rating scale to assess bodily complaints. RESULTS: The current prevalence rate of PTSD symptoms among professional firefighters was 18.2%. About 27% of the recruited subjects had a mental disorder according to the General Health Questionnaire. Predictors for the extent of traumatic stress were longer job experience and the number of distressing missions during the last month. Traumatic stress also predicted psychiatric impairment beyond PTSD, such as depressive mood, psychosomatic complaints, social dysfunction, and substance abuse. CONCLUSIONS: The high prevalence of PTSD and other psychiatric impairments in firefighters indicates that they often fail to cope with primary and particularly secondary stress in their daily work. This problem, together with the individual psychological consequences and expenses related to work absenteeism and early retirement, seems to be very specific for the profession of firefighters. The present findings provide a better understanding of the relationship between secondary traumatic stress and PTSD in professional helpers and high-risk populations such as firefighters, emergency workers, and the police.

Adaptation, Psychological↗
PubMed1995

Aberrant craniopharyngeal structures within the neurohypophysis of rats.

Aberrant craniopharyngeal structures within the neurohypophysis were analyzed in 17 rats, originating from four different colonies of Sprague-Dawley- and Wistar-derived strains, which were used for toxicity studies in five different laboratories. Males were more frequently affected than females. The incidence of these findings, which occurred spontaneously and mainly in aged rats, was very low. Predominant features included tubular or acinar glandular structures, rarely embedded in a fibrous stroma, and, as a rule, not compressing adjacent tissue. In some cases, large cysts filled with colloid-like, amorphous material and cellular debris were present. The tubular structures consisted of a rather flat epithelium, while the cystic elements were lined by a cuboidal or columnar, rarely ciliated epithelium, containing goblet cells, or by a stratified squamous epithelium. These structures reacted positively for cytokeratin. Acinar structures mimicked salivary glands of the serous or mucinous type. In a few cases, small, round or fusiform cells were present. Distribution and predominance of the various epithelial structures depended on the strain and colony of rats. Considering the ontogenic development of the pituitary gland, the morphological aspect of these lesions, their immunoreactivity and former reports on similar findings, we concluded that these rats have aberrant craniopharyngeal structures within the pars nervosa of the hypophysis, originating from remnants of the oro-pharyngeal epithelium of the craniopharyngeal duct (RATHKE's pouch). These lesions, which occurred in different strains and colonies of laboratory rats, represent heterotopias or choristomas, consisting of non-neoplastic growth disturbances. Being of a distinctly non-proliferative nature, they should not be confused with craniopharyngiomas.

Animals↗
PubMed1994

Quantitative analysis of the neu oncogene in normal and transformed epithelial breast cells by fluorescence in situ hybridization and laser scanning microscopy.

In this study we evaluated indirect fluorescence in situ hybridization of the neu oncogene in combination with laser scanning microscopy for the detection and quantification of fluorescence signals in single cells. Cell lines from human tumor tissue with neu oncogene amplification and one nonneoplastic human epithelial cell line from a lactating breast with a neu single copy as the reference were used. After quantitative fluorescence analysis of three mixed cell populations (neoplastic cells and reference cells), we evaluated the cell morphology and location of the fluorescence signal by laser scanning microscopy. Finally, the number of oncogene copies in the tumor cell population could be estimated from the ratio of its mean background-corrected integrated fluorescence intensities to those of the reference cells. In all mixed cultures the ratio of fluorescence intensities was within the limits of oncogene copy numbers known from the literature and evaluated by southern blot analysis. The lowest oncogene copy number possible to quantify was four to eight genomic copies.

Breast Neoplasms↗
PubMed1991

Response of life threatening dimenhydrinate intoxication to sodium bicarbonate administration.

This is a report of an intentionally administered overdose of dimenhydrinate to a 4 month-old infant who subsequently presented with status epilepticus, coma, and life threatening ventricular dysrhythmias. Initial toxicologic analysis of the serum by fluorescence polarization immunoassay was positive for tricyclic antidepressants. Repeat analysis of the serum at 6 hours post ingestion by gas chromatography mass spectrometry analysis defined diphenhydramine 4.8 micrograms/mL. The infant was managed with IV sodium bicarbonate as utilized in tricyclic antidepressant intoxication. The dysrhythmias resolved and the infant recovered without sequelae.

Arrhythmias, Cardiac↗
PubMed1990

Immunocytochemical study of the subcommissural organ of rats with induced postnatal hydrocephalus.

The subcommissural organ (SCO)-Reissner's fiber (RF) complex of rats suffering from postnatal hydrocephalus was investigated immunocytochemically (peroxidase-antiperoxidase technique) by use of an anti-serum against bovine RF. Hydrocephalus was induced by injecting kaolin into the cisterna magna or by intracerebral infection with Borna disease virus. The kaolin-injected, hydrocephalic male rats were divided into two groups: (1) possessing an open communication between the fourth ventricle and the central canal of the spinal cord; (2) enduring an obliteration of this communication. In the latter group of rats the dilation of the ventricular cavities was far greater than in the former group. The Borna disease virus-infected female rats developed a severe hydrocephalus although in these animals all ventricular cavities and the central canal were in fully open communication. All rats belonging to the above-mentioned three groups displayed essentially the same alterations of their SCO-RF complex: (i) A reduction in the size of SCO and in the height of the ependymal secretory cells. (ii) A progressive disappearance of the immunoreactive hypendymal cells. (iii) The amount of AFRU-immunoreactive secretory material located in the rough endoplasmic reticulum was reduced. (iv) In contrast, the amount, location and immunoreactivity of the apical secretory granules did not undergo variations in comparison to sham-operated rats. (v) In the area of the SCO the layer of pre-RF material was thin or missing and a RF was not formed, and thus the central canal was also free of such secretory products. (vi) Clusters of AFRU-immunoreactive material were found attached to the wall of the Sylvian aqueduct.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Immunocytochemical demonstration of proopiomelanocortin-derived peptides in pituitary adenomas of the pars intermedia in horses.

Adenomas of the pars intermedia from 19 horses and normal pituitary glands from seven horses were evaluated histologically and immunocytochemically for adrenocorticotropic hormone (ACTH), alpha-melanocyte-stimulating hormone (alpha-MSH), beta-endorphin (beta-END), proopiomelanocortin (POMC), prolactin, neuron specific enolase, and glial fibrillary acidic protein (GFAP). The 26 horses ranged in age from 7 to 31 years. Histologically, all adenomas had a uniform pattern characterized by cords of large columnar cells forming palisades and pseudoacini separated by a delicate fibrovascular stroma. Immunostaining of adenomas derived from the pars intermedia was similar to that of non-neoplastic equine pars intermedia. An immunocytochemical evaluation revealed a diffuse, strong cytoplasmic reaction for POMC, a moderate to strong reaction for alpha-MSH and beta-END, a weak reaction for ACTH, and negative immunostaining for prolactin, GFAP, and neuron specific enolase in the adenomas. The unique clinicopathologic syndrome that develops in horses with pituitary adenomas appears to be the result of an over-production of POMC-derived peptides in addition to space-occupying effects resulting in dysfunction of the hypothalamus and neurohypophysis.

Adenoma↗
PubMed1990

[Post-hypoglycemic encephalopathy in type I diabetes mellitus in childhood and its treatment].

In type-I-diabetes insuline-induced hypoglycaemia is the most frequent and permanent therapeutic complication. In severe courses proceeding to unconciousness, it is essential to decide on the irritation of exclusively cortical or subcortical structures. The latter one is classified as posthypoglycaemic encephalopathy correlated with a relatively high lethality. Consequently, differential diagnosis and carefully calculated treatment are of vital importance.

Brain Damage, Chronic↗
PubMed1989

[Immunohistochemical demonstration of L- and M2-pyruvate kinase in primary renal cell carcinomas and their metastases].

Seventeen renal cell carcinomas (RCC) were classified histologically and investigated for their expression of L- and M2-pyruvate kinase (PK) immunohistochemically. Using monoclonal antibodies we were able to demonstrate L-PK within 15 RCC and two metastases (in thyroid gland and bone) after fixation with aceton and paraffin embedding. In normal renal tissue the enzyme was localized within proximal tubules selectively. No enzyme reaction of L-PK could be demonstrated in renal oncocytoma, thyroid carcinoma, and in carcinomas of renal pelvis and lung. In contrast to this the M2-PK was detectable in all tumors and metastases investigated in this study. The results presented in this paper are able to show that (1) RCC derive from the proximal renal tubules, but not the renal oncocytoma, (2) the detection of L-PK may be helpful for identification of metastases of RCC even if they are undifferentiated and (3) there is an enzyme shift from L-PK to M2-PK within tumor cells of RCC resulting in alteration of glucose utilization from energy supply to syntheses of substrates essential for tumor cells.

Carcinoma, Renal Cell↗
PubMed1988

Electrophoretically monodisperse cytochrome c oxidases.

A discontinuous gradient polyacrylamide gel electrophoresis under nondenaturing conditions has been used to demonstrate monodispersity of procaryotic and eucaryotic cytochrome c oxidase preparations. Alkaline treated bovine enzyme which contains nine subunits as analysed by subsequent discontinuous SDS-polyacrylamide gel electrophoresis is a monodisperse dimer in 0.1% Triton X-100 and a monomer in 0.1% dodecyl maltoside. The Mr-values corrected for bound detergent are 286,000 in Triton X-100 and 152,000 in dodecyl maltoside respectively. The two-subunit bacterial cytochrome c oxidase of Paracoccus denitrificans is proved to be a monomer with a corrected Mr of 76,000 in both nonionic detergents Triton X-100 and dodecyl maltoside.

Animals↗
PubMed1987

Identification of different quaternary structures of beef heart cytochrome-c oxidase by two-dimensional polyacrylamide gel electrophoresis.

A two-dimensional gel electrophoresis is described to identify different quaternary structures of the heart cytochrome-c oxidase. Bovine enzyme was purified and separated by discontinuous gradient polyacrylamide gel electrophoresis under nondenaturing conditions in the 1st dimension into several discrete complexes and thereupon shown to be heterodisperse in Triton X-100 and dodecyl maltoside. A discontinuous SDS-polyacrylamide gel electrophoresis in the 2nd dimension was used to determine the subunit composition of the isolated complexes. One of these represents the intact enzyme with 12 different polypeptides while the others have an incomplete subunit composition.

Animals↗
PubMed1987

Human erythrocyte pyruvate kinase (L'/R-PK): production and characterization of a monoclonal antibody.

Two preparations of L'/R-type pyruvate kinase from human erythrocytes characterized by SDS-PAGE were used for immunization of BALB/c mice. Their spleen cells were fused with mouse myeloma cells by polyethylene glycol according to standard techniques. Supernatants of hybridomas resulting from two separate experiments were assayed by ELISA and further characterized by immunoblotting. Using those monoclonal antibodies reacting with L'/R-PK in immunoblotting, a major band of 62 KDa MW was recognized in both preparations employed for immunization. Additionally, four smaller bands were detected. Furthermore, the monoclonal antibodies also detected a single band of 62 KDa MW in a highly purified L-PK prepared from human liver. In contrast, they showed no reaction with muscle and brain tissues containing M1-type PK. However, they reacted strongly with a single band of approximately 62 KDa in liver and kidney homogenates which is in line with immunocytochemical studies showing immunoreactive material in hepatocytes and proximal tubules of the kidney.

Antibodies, Monoclonal↗