PubMed Health⌕ Search

Biomedical subjects

E Stark

Publications and source records attributed to E Stark.

At least 19 recordsLinked to original sources
PubMed1992

Presynaptic inhibitory effect of TNF-alpha on the release of noradrenaline in isolated median eminence.

The effect of tumor necrosis factor-alpha (TNF-alpha) on the stimulation-evoked release of noradrenaline (NA) from isolated rat median eminence (ME) was investigated, using a low-volume perfusion system. Median eminence, loaded with [3H]noradrenaline, was superfused with Krebs solution and stimulated electrically (2 Hz, 120 shocks). The effect of TNF-alpha was studied on the S2/S1 ratio. It was found that stimulation-evoked release of NA from noradrenergic axon terminals in the isolated rat ME was inhibited by TNF-alpha and this effect was concentration-dependent. In contrast, TNF-alpha had no effect on the release of [3H]NA from the spleen. Since NA released in the ME might be involved in the modulation of corticotropin-releasing factor (CRF) production, it is suggested that TNF-alpha, through presynaptic modulation of NA release from noradrenergic nerve terminals in the ME, might regulate CRF and other neurohormone release in this hypothalamic structure.

Analysis of Variance↗
PubMed1992

Effect of chronic ACTH treatment on the physical state of lipid droplets in rat adrenocortical cells.

A histophysical method has been adapted to determine the thermotropic phase transitions of adrenocortical lipid droplets using a polarizing microscope equipped with a cold/hot stage. Cryosections of freshly-removed, unfixed adrenals, derived from control (untreated), and 14 days ACTH-treated rats were examined. The lipid droplets in the zona fasciculata and zona reticularis of the untreated rats were birefringent at room temperature (22 degrees C). The birefringence of zona glomerulosa lipids selectively increased in the temperature range from -10 to -15 degrees C. In cryosections prepared from ACTH-treated rats, thermotropic phase transitions of the lipid droplets appeared at a temperature range between -30 and -40 degrees C in each cortical zone. The chemical analysis of the isolated lipids revealed that the relative amount of triglycerides in the zona fasciculata lipids increased, while that of free and esterified cholesterol decreased after chronic ACTH treatment. Present data suggest that the increased fluidity of lipid droplets promotes lipid mobilization in response to the enhanced demand of the chronically stimulated adrenocortical cells. Viscosity-dependent mobilization of free cholesterol from lipid droplets is not a rate-limiting process in adrenal steroidogenesis, but rather may represent an important control of the availability of precursor from lipid stores.

Adrenal Cortex↗
PubMed1992

Early onset MS under the age of 16: clinical and paraclinical features.

MS in juvenile patients under the age of 16 occurred in 31 (5%) of our whole MS population of 620 patients in the time from 1975-1991. It does not differ clinically from the disease as observed in 72 patients with later onset MS in respect to symptoms at onset, course, progression rate, rate of relapses and abnormalities in CSF and MRI. However, fever, headache, nausea and vomiting with pleocytosis in CSF during the first episode and development of oligoclonal bands with passage of time may be characteristic in some juvenile patients. The presence of oligoclonal bands and MRI results are of high diagnostic value in this special group of patients.

Adolescent↗
PubMed1992

CRF-dependent and CRF-independent mechanisms involved in hypophysial-adrenal system activation by bacterial endotoxin.

The immune system and the hypothalamic-pituitary-adrenal (HPA) axis play important role in the overall inflammatory response. The mechanism through which lipopolysaccharide (LPS, endotoxin) stimulates the HPA axis is not well understood. In order to clarify the role of hypophysiotropic peptides of paraventricular origin in the effect of LPS on ACTH and corticosterone secretion, the effect of LPS was studied on rats with lesions of hypothalamic paraventricular nucleus (PVN). It was shown that 90 min after 2 mg/kg LPS i.p. the ACTH, but not the corticosterone response was effectively blunted in PVN-lesioned rats, as compared to sham operated animals. However, in PVN-lesioned rats 240 min after treatment with LPS a significantly higher plasma ACTH and corticosterone level was monitored. It is, therefore, suggested that in response to LPS activation of HPA both CRF(s)-dependent and CRF(s)-independent mechanisms are involved, even a direct effect of the adrenal cortex should be taken into account.

Adrenocorticotropic Hormone↗
PubMed1991

The use of recombinant antigens in ELISA procedures for the quantification of intrathecally produced HIV-1-specific antibodies.

An ELISA procedure is described for the quantification of intrathecally synthesized immunoglobulin G antibodies to human immunodeficiency virus (HIV) antigens. Recombinant p17, p24, endonuclease (END), reverse transcriptase (RT), a peptide from the transmembrane region of gp41 (ENV80) and a fusion protein containing HIV-1 and HIV-2 epitopes were compared with a commercially available ELISA. Using a reference serum, antibodies in serum and cerebrospinal fluid (CSF) to all of the antigens could be measured quantitatively in a reliable and reproducible fashion. Despite the fact that the titer varied up to 10(5)-fold between CSF and serum, interassay variability ranged from 3.87% for p17 to 8.41% for RT and intra-assay variability varied from 3.9% +/- 1.2% for p17 to 14.3% +/- 3.9% for the commercial ELISA. Antibody specificity indices (ASI) obtained by relating CSF/serum titers with reference to the corresponding IgG concentrations can be used to detect intrathecal synthesis of virus specific antibodies.

Enzyme-Linked Immunosorbent Assay↗
PubMed1991

Extended multiplicative signal correction and spectral interference subtraction: new preprocessing methods for near infrared spectroscopy.

Near infrared (NIR) spectroscopy spectra can be converted mathematically to precise quantitative information of chemical and physical nature by multivariate calibration. This makes NIR analysis useful for a variety of "difficult" sample types (powders, slurries), more or less without any sample preparation. The paper emphasizes the importance of using prior knowledge for spectral preprocessing of spectral data prior to the linear multivariate calibration modelling. Two new preprocessing methods are presented: extended multiplicative signal correction (EMSC) for elimination of uncontrollable path length or scattering effects, and spectral interference subtraction (SIS) for elimination of known spectral interferences. Determination of toluene in mixtures with benzene and xylene from NIR spectra with gross simulated light scattering effects is used for illustration.

Calibration↗
PubMed1991

Serum antibodies to GM1 and GM3-gangliosides in systemic lupus erythematosus with chronic inflammatory demyelinating polyradiculoneuropathy.

Acute symmetric demyelinating polyneuropathy of the Guillain-Barré type is known in systemic lupus erythematosus (SLE). Chronic idiopathic demyelinating polyneuropathy (CIDP) has been reported rarely with SLE. A case is reported of CIDP accompanying SLE with autoantibodies against GM1- and GM3-gangliosides. There was no historical evidence to suggest SLE, and CIDP was the first manifestation of SLE. The 38-year-old patient had elevated CSF-protein, slow nerve conduction velocities, sural nerve biopsy revealed mixed axon loss with demyelination and CIDP white matter lesions were observed in magnetic resonance imaging, the GM1- and GM3-autoantibodies may play a role in the pathogenesis of CIDP in SLE.

Adult↗
PubMed1991

Action of ACTH in the luteal ovary.

Oestrous rats and golden hamsters were anesthetized with pentobarbital, one of the femoral arteries and veins and one of the ovarian veins were cannulated. Blood fractions were collected from the ovary. After the first two fractions synthetic adrenocorticotropic hormone (ACTH) or human chorionic gonadotropin (hCG) was injected i.v. Blood pressures and ovarian blood flow were continuously recorded. Progesterone (P) and oestradiol-17 beta (E2) were determined from the ovarian venous blood by radioimmunoassay (RIA). ACTH induced a temporary elevation in the ovarian blood flow, P and E2 secretion both in rats and hamsters. In rats and hamsters hCG induced a continuous elevation in P secretion but the ovarian blood flow and E2 secretion remained unchanged. Luteal cells from pseudopregnant rats or oestrous hamsters were dispersed with collagenase and incubated with ACTH or hCG. A sample of the cells was preincubated with polymixin-B, indomethacin or ibuprofen. P and 6-keto-prostaglandin F1 alpha (6-keto-PGF1 alpha) contents of the medium and cyclic 3,5 adenosine monophosphate (cAMP) content of the cells were determined by RIA. ACTH stimulated the release of 6-keto-PGF1 alpha and the secretion of P from the luteal cells of both species, which was inhibited by indomethacin or ibuprofen, but ACTH did not alter the cAMP content of luteal cells. The polymixin-B prevented ACTH to stimulate P secretion, but it did not elevate the 6-keto-PGF1 alpha release, while the cAMP content of the cells remained unchanged. It is supposed that the polyphosphoinositol-Ca(2+)-protein kinase-C second messenger system is involved in the ACTH induced stimulation of P secretion.

6-Ketoprostaglandin F1 alpha↗
PubMed1991

Effects of beta 2-adrenergic stimulants on the progesterone and oestradiol-17 beta serum levels in pseudopregnant rats.

In CFY rats pseudopregnancy (PSP) was induced by mechanical stimulation of cervix uteri. On the days 1 or 7 of PSP indvelling catheter was built in one of the jugular veins and blood was collected daily until 7th or 14th days of PSP respectively, meanwhile the animals were daily injected with clenbuterol (0.1 mg/kg bw), fenoterol (0.5 mg/kg bw), ritodrin (1.0 mg/kg bw), propranolol (2.0 mg/kg bw) or 1.0 ml/kg bw 0.9% NaCl subcutaneously. From the blood samples progesterone (P) and oestradiol-17 beta (E2) were determined by RIA. beta 2-adrenergic agonists did not influence the serum levels of P either in the first or in the second half of PSP and the propranolol failed to alter also the serum levels of P during the PSP. Clenbuterol and ritodrin, however, decreased the serum levels of E2 in the first half of PSP, while in the second half of PSP fenoterol and ritodrin elevated, the propranolol diminished it. It was supposed that in PSP rats beta 2-adrenergic mechanism has a more pronounced effects on the theca-interstitial cells than that of the luteal cells.

Adrenergic beta-Agonists↗
PubMed1990

Loss of the effects of clonidine on the growth hormone release and hypotensive action in long-term castrated rats: the possible role of testosterone on alpha-2-adrenergic mechanisms of clonidine.

The effect of testosterone on the growth hormone (GH)-releasing and hypotensive actions of clonidine was evaluated in vivo using male Wistar rats. Clonidine at various doses and by various routes (5 micrograms/kg, i.c.v.; 15 micrograms/kg, i.v., and 7, 15, 31, 125 and 250 micrograms/kg, i.p.) induced a significant increase in plasma GH levels in rats. Intracerebroventricular (5 micrograms/kg) injection of clonidine significantly decreased blood pressure. The effects of clonidine on the GH release and blood pressure were lost in long-term castrated rats, but were restored by testosterone replacement in the castrates. In addition, the hypotensive response to clonidine in testosterone-replaced castrated rats lasted longer than in the sham-operated rats. The injection of yohimbine (3 mg/kg, i.p.) strongly inhibited the secretion of GH induced by clonidine treatment in sham-operated animals, and its inhibitory action was significantly attenuated in castrates. In long-term castrated rats, basal blood pressure decreased significantly compared with that of sham-operated rats. This was also restored after testosterone administration to castrates. The results of the present study indicate that the alpha 2-adrenergic receptor-mediated effects of clonidine on the GH release and blood pressure might be dependent on the endogenous testosterone secretion.

Animals↗
PubMed1990

Rethinking homicide: violence, race, and the politics of gender.

Although homicide is the fourth leading cause of premature mortality in the United States and the leading cause of death for young blacks, the health professions have been largely oblivious to violence. Prevailing explanations contribute to this neglect by emphasizing biological or psychiatric factors that make homicide unpredictable and cultural and environmental factors such as the emergence of a new "underclass" that link violence to race. Focusing on instances where no other crime is involved, this article proposes that "primary" homicide be reconceptualized as a by-product of interpersonal violence, a broad category of social entrapment rooted in the politics of gender inequality and including wife abuse, child abuse, and assaults by friends and acquaintances. The data show that blacks are no more violent than whites, though they are arrested and die more often as the consequence of violence. In addition, a majority of homicides are between social partners or involve gender stereotypes, are preceded by a series of assaults that are known to service providers, and grow out of "intense social engagement" about issues of male control and independence. Professional failure to respond appropriately is a major reason why assaults become fatal, particularly among blacks. An international strategy that combines sanctions against interpersonal assault, gun control, and the empowerment of survivors might prevent half of all homicides.

Adolescent↗
PubMed1989

Effects of ACTH-(11-24) on the corticosteroid production of isolated adrenocortical cells.

The steroidogenic action of ACTH-(11-24) was studied on isolated zona glomerulosa and zona fasciculata cells dispersed by collagenase. ACTH-(11-24) stimulated the corticosterone production of zona fasciculata cells and the aldosterone production of zona glomerulosa cells; in addition, it potentiated the effects of ACTH-(1-39) on both cell systems. It is suggested that the ACTH molecule contains more active sites for steroidogenesis than usually acknowledged, as has been found for lipolysis and behavior.

Adrenal Cortex↗
PubMed1989

Acute stimulatory effects of an LH-RH agonist on the ovary in pseudopregnant rats.

Pseudopregnant rats were anaesthetized on day 5 of pseudopregnancy with pentobarbital and hypophysectomy or sham operation was performed. Polyethylene cannulas were inserted into one of the femoral arteries and utero-ovarian veins. Five-minute blood samples were collected from the ovary for 40 minutes. Following the first five minute blood fraction LH-RH, an agonistic analogue (D-Phe6, des Gly-NH10(2)-LH-RH-ethylamide) or an antagonistic analogue (Formyl-D-Tryp1,3, D-pCl-Ph2, D-Phe6LH-RH) were superfused into the ovarian bursa for 5 minutes in a volume of 50 microliters. Blood pressure, ovarian venous outflow and haematocrit were continuously measured. From the blood samples progesterone and oestradiol-17 beta were determined by RIA and the secretion rate was calculated. It was found, that LH-RH and its antagonistic analogue has no effect on the blood flow, progesterone (P) and oestradiol-17 beta (E2) secretion of ovary. However, an agonistic analogue of LH-RH induced a rapid elevation of blood flow, diminished vascular resistance in the ovary, and in a dose of 50 ng increased the secretion rate of E2. In sham operated animals the effects of agonistic analogue was similar to the effects of 1.0 IU of hCG.

Animals↗
PubMed1989

[The effect of composite filling materials on the diameter of the blood vessels of the dental pulp in rat teeth].

The authors tested the effect of some of the characteristic types of composite filling materials in a vital-microscope test. The results show that all the four tested filling materials (Biogloss, Evicrol, Isomolar, Isopast) significantly widened the pulpal arteriola; the Biogloss was ineffective for the diameter of the venula, but employing Evicrol, Isomolar and Isopast it was significantly increased. Between the tested materials compared to each difference was observed only during the development of their effect. The hyperaemia observed by us is important in case of short-time inspections as the indicator of acute reactions. Further test is required whether is there any connection between the tested hyperaemia and the toxic effect.

Animals↗
PubMed1988

An automated device for immunocytochemistry.

A microprocessor controlled device for automation of immunoenzyme histological and cytological staining procedures is described. As the sequence of processing is controlled by a computer program, the apparatus is flexible and the possibility of technical errors is reduced.

Automation↗
PubMed1988

Immunocytochemical demonstration of human immunodeficiency virus infected cells in the cerebrospinal fluid.

Although involvement of the central nervous system represents one of the most common manifestations of the acquired immunodeficiency syndrome (AIDS), a standard diagnostic test for this condition has not yet been established. At necropsy human immunodeficiency virus (HIV) has been demonstrated in brain macrophages in such patients. HIV antigen was detected in CSF macrophages by immunocytochemistry in six out of 11 HIV infected patients. In addition to the detection of intrathecal synthesis of anti-HIV antibodies this method may be suitable for early diagnosis of CNS involvement in AIDS patients.

Acquired Immunodeficiency Syndrome↗