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J Jelinek

Publications and source records attributed to J Jelinek.

50 records · Page 3Linked to original sources
PubMed1990

Role of the renin-angiotensin system in the adaptation to high salt intake in immature rats.

The response of the renin-angiotensin system, extracellular fluid volume, plasma volume, plasma sodium and mean arterial blood pressure to an increase in salt intake (8% NaCl in the diet for 10 days) was compared in immature (20 days) and adult (80 days) rats which were either sham-operated or uninephrectomised. Salt feeding induced a significant increase in plasma sodium in immature animals, and a greater suppression of the renin-angiotensin system in immature than in adult rats, although extracellular fluid volume, plasma volume and blood pressure remained unchanged. Following uninephrectomy, however, the renin-angiotensin system was maximally suppressed in both age groups and in younger animals extracellular fluid volume, plasma volume and blood pressure were significantly increased. It is concluded that (i) the renin-angiotensin system in immature rats is more responsive to a chronically increased salt intake, (ii) this greater responsiveness partly compensates for the lower natriuretic efficiency of the kidneys of immature rats, which becomes evident after reduction of renal mass, and (iii) these events bear a relation to the higher susceptibility of prepubertal rats to the hypertensive effect of a chronically increased salt intake.

Adaptation, Physiological↗
PubMed1990

Lateral ventricular neoplasms of the brain: differential diagnosis based on clinical, CT, and MR findings.

The differential diagnosis of lateral ventricular tumors was explored by retrospective analysis of 47 pathologically proved cases identified by CT and/or MR imaging. Third ventricular tumors adjacent to the foramen of Monro (e.g., colloid cysts) were excluded. Forty-six patients underwent CT, and eight had MR imaging. The most common neoplasms were choroid plexus papilloma (10 cases) and meningioma (nine cases). Other common neoplasms included subependymoma (six cases), subependymal giant cell astrocytoma (five cases), and metastasis/lymphoma (four cases). Important features for differential diagnosis included age of the patient, the tumor's location within the lateral ventricle, and density on CT before IV administration of contrast material. Fifty percent of the tumors were in the ventricular atrium. All intraventricular tumor types (except subependymoma) showed contrast enhancement. MR was most useful in evaluating tumor location, size, and extent, but it did not help in eliminating alternative diagnoses. On the basis of patients' ages, specific tumor location, and the appearance on CT scans or MR images, an algorithm for differential diagnosis of lateral ventricular tumors was developed.

Adolescent↗
PubMed1989

Methylene blue-fast green staining of hemopoietic colonies in agar cultures.

A simple technique is described for the routine in situ identification of the cellular composition of colonies and clusters in agar cultures of hemopoietic cells. The entire culture, dried and formalin vapor fixed within a Petri dish, is stained with a mixture of methylene blue and fast green. By this method cellular ribonucleoproteins (RNP), deoxyribonucleoproteins (DNP) and some cationic (arginine and lysine containing) proteins are detected. Different maturation stages of neutrophils, eosinophils, basophils, monocytes, and macrophages can be easily identified with colonies and clusters on the basis of the cytoplasmic and nuclear staining.

Basophils↗
PubMed1988

Transfection of murine multi-potent haemopoietic stem cells with an E. coli DNA alkyltransferase gene confers resistance to the toxic effects of alkylating agents.

O6-alkylguanine-DNA-alkyltransferase (ATase)-deficient murine haemopoietic stem cells were transfected, following electroporation, with a G418-selectable expression vector containing the protein coding region of the Escherichia coli ATase gene ada. Clones of cells that were resistant to G418 or the chloroethylating agent mitozolomide (Mz) were selected and most were shown to express very high levels of bacterial gene-encoded ATase. In comparison with control cells that were transfected with the parent vector, the ATase-expressing clones were considerably more resistant to the toxic effects of the methylating agents N-methyl-N-nitrosourea and methylmethanesulphonate or the chloroethylating agents Mz or taurine chloroethylnitrosourea, but unchanged in their susceptibility to the bis-chloroethylating agent nitrogen mustard. Thus alkylation damage in DNA that can be repaired by the E. coli ATase constitutes the principal lethal lesion produced by alkylating agents in murine haemopoietic stem cells and the ATase deficiency in these cells can be complemented by electroporation-mediated gene transfection.

Alkyl and Aryl Transferases↗
PubMed1988

Changes in type V collagen in the kidneys of DOCA-NaCl treated rats.

Type V collagen was extracted and quantitated in the kidneys of unilaterally nephrectomized rats exposed to desoxycorticosteron acetate (DOCA-NaCl) treatment. A highly elevated content of collagen type V was found in these kidneys compared with controls. A higher content of collagen type V was present both in the pepsin digest of the total kidney and in the isolated glomerular basement membranes. It was previously reported that one of the factors involved in the growth of the remaining kidney in unilaterally nephrectomized DOCA-NaCl treated rats is the increase of collagen type IV, the effect being more prominent in rats nephrectomized at a younger age. The present study documents that the increase of type V collagen follows the same pattern.

Animals↗
PubMed1984

A primate model of human postmenopausal hot flushes.

The hot flush is the only symptom specifically attributable to the menopause. Hot flushes appear to represent an episodic derangement of thermoregulation as a result of estrogen deficiency but the underlying physiological mechanisms are unknown. We have developed an animal model for the study of hot flushes. Two female monkeys (Macaca arctoides) were trained to accept monitoring of scalp cutaneous temperatures. After baseline temperature recordings were obtained both monkeys were ovariectomized. A few days after operation the previously stable scalp temperature changed to an undulating pattern with cycles lasting approximately 40-50 min. Ethinyl estradiol (20 micrograms orally or im) and (7 alpha,17 alpha)-17-hydroxy-7-methyl-19-nor-pregn-5(10)-en-20-yn-3-one (2.5 mg orally), a steroid with weak estrogenic, progestogenic, and androgenic properties, suppressed the characteristic undulating temperature pattern; this returned after withdrawal of replacement therapy. Clonidine (0.15 mg twice a day) suppressed the cyclic changes for 2 to 3 h. Domperidone and naloxone had no significant effect. This animal model may be useful for the investigation of alternative therapy for the management of menopausal flushes.

Anabolic Agents↗
PubMed1978

Effect of endogenous and exogenous progesterone on human endometrial enzymes.

Activities of 9 enzymes were determined biochemically in the endometrium. In Trial I (five women) 25 mg progesterone were injected i.m. on day 9 of the cycle; and endometrial biopsy taken 24 hours later was compared with endometrium from day 10 and day 21, taken in two untreated cycles from the same volunteers. Similarly, in Trial II (five women) 50 mg progesterone were injected on day 9, biopsy taken on day 11 and compared with days 11 and 21 from untreated cycles. The specific activites of lactate dehydrogenase, isocitrate dehydrogenase (ICDH), malate dehydrogenase, glutamate dehydrogenase, beta-glucuronidase, acid phosphatase (ACP) and alkaline phosphatase (AP) were significantly higher in the secretory phase. Twenty-five milligrams progesterone (after 24 hours) caused increases of some enzymes, significant only for AP. Fifty milligrams (after 48 hours) increased significantly the activity of ICDH and ACP. Biochemical changes, especially increase of ICDH, can be used for detection of the effect of progesterone on the endometrium.

Adult↗
PubMed1976

High salt intake and blood pressure in lower primates (Papio hamadryas).

One year of increased salt intake in monkeys elevates mean blood pressure significantly. This effect is more marked in animals exposed just after birth. In animals exposed as adults, the response in males is more pronounced than in females, mainly due to a marked increase of pulse pressure. Th hypertensive response was potentiated by reduction of renal mass, which caused GFR values (in terms of body weight) to decrease compared with intact salt-fed animals, in which GFR values were elevated above the control level. It is concluded that the mechanisms involved in the hypertensive response are similar to those in the rat and dog.

Age Factors↗
PubMed1970

Receptors for human gamma G globulin on human neutrophils.

Cell surface receptors for human gammaG antibodies directed against bacterial antigens were demonstrated on human neutrophils using an in vitro bacteriocidal-phagocytic assay. These results were confirmed by adherence of sensitized erythrocytes to monolayers of neutrophils or monocytes. Erythrocytes sensitized indirectly with antibacterial gammaG antibodies after passive sensitization with bacterial antigens adhered to both neutrophils and monocytes. Erythrocytes sensitized directly with conventional anti-D gammaG antibodies adhered only to monocytes, while those sensitized with the hyperimmune anti-CD gammaG antibody Ripley adhered to both monocytes and neutrophils. Adherence of anti-Rh or antibacterial gammaG antibodies to monocytes and neutrophils could be inhibited by whole gammaG, myeloma globulins of the gamma(1) or gamma(3) subclasses, or Fc fragments, but not by Fab fragment. These results indicate that receptors for the Fc portion of human gammaG antibodies exist on both neutrophils and monocytes, and that gammaG antibodies differ in their ability to attach to these two cell types. Differences in the behavior of the gammaG antibodies studied may be related to differences in the density of antibodies on the erythrocyte surface and receptors on the phagocytic cells.

Antigen-Antibody Reactions↗
PubMedDate not supplied

Simulation of CT reconstruction artifacts associated with multiple-rotation fan-beam data collection.

Artifacts in reconstructed image caused by the errors in projection data depend on the source of the error itself, on the data collection mode and on the reconstruction algorithm. The effect of the multiple-rotation fan-beam data collection modes and corresponding reordered parallel convolution-backprojection algorithms on reconstruction artifacts of this type is analysed.

Humans↗