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Biomedical subjects

J Klein

Publications and source records attributed to J Klein.

At least 541 records · Page 30Linked to original sources
PubMed1990

Diversity in peritoneal macrophage response of CAPD patients to 1,25-dihydroxyvitamin D3.

A major complication of continuous ambulatory peritoneal dialysis (CAPD) is peritonitis. Increasing the activity of the peritoneal macrophages, the predominant cell type found in the peritoneal cavity, may be a promising treatment for this infection. The effect of 1,25-dihydroxy-vitamin D3 [1,25(OH)2D3] on the activity of peritoneal macrophages from CAPD patients and nonuremic controls was studied. 1,25(OH)2D3 had a biphasic effect on superoxide generation in the concentration range of 2.5 10(-9) M to 5 x 10(-6) M with a peak at 2 x 10(-8) M. The addition of 2 x 10(-8) M 1,25(OH)2D3 to nonuremic control macrophages for 24 hours caused a significant twofold increase in superoxide generation in response to phorbol myristate acetate (PMA), from 2.21 + 0.2 to 4.1 + 0.2 nmol/10(6) mac (P less than 0.001), and enhanced the bactericidal activity from 60 + 7% to 85 + 9% (P less than 0.005). CAPD patients were divided into two groups: Group A, patients with high peritonitis incidence (HPI); group B, patients with low peritonitis incidence (LPI). Macrophages from HPI patients show a lower bactericidal activity (37 +/- 5%) and were not affected by 1,25(OH)2D3 after 24 hours of treatment. The increase in macrophage activity was seen only after three days of incubation with the hormone. Macrophages from this group generated a high amount of prostaglandin E2 (PGE2) during the first 24 hours in culture (7.8 +/- 0.52 ng/ml as compared with 0.35 +/- 0.03 ng/ml in the controls).(ABSTRACT TRUNCATED AT 250 WORDS)

Calcitriol↗
PubMed1990

Regulation and action of insulin-like growth factors at the cellular level.

Present understanding of IGF-1 as a growth factor mediating integration of nutritional-hormonal interactions indicates that IGF-1 acts in both an endocrine mode on distant targets and an autocrine-paracrine mode on local targets. In the liver, the combined presence of GH, insulin, and critical metabolic fuels such as essential amino acids results in increased levels of IGF-1 messenger RNA, increased production of a high-MW IGF-1 precursor, and increased release of IGF-1 into the circulation, permitting action on distant target tissues bearing specific receptors for IGF-1. The net effect is distant amplification of anabolic hormone action via IGF-1 acting in an endocrine mode. In extrahepatic tissues, both 'general' anabolic hormones (insulin and GH) as well as 'specific' hormones (e.g. gonadotropins) acting on a wide variety of targets (including fibroblasts and chondrocytes as well as granulosa and Leydig cells) promote both local secretion of IGF-1 and an increase in IGF-1 receptors. Local actions of IGF-1 then result in a secondary increase in both hormone receptors and hormone responses. The net effect is local amplification of hormone action via IGF-1 acting as a growth factor in an autocrine-paracrine mode.

Animals↗
PubMed1990

Simple measurement of captopril in plasma by high-performance liquid chromatography with ultraviolet detection.

Captopril is an orally active inhibitor of angiotensin-converting enzyme. A rapid, accurate, and sensitive high-performance chromatography (HPLC) method is described for measuring plasma concentrations of captopril. Captopril was stabilized by forming an adduct with p-bromophenacyl bromide. This adduct was measured by HPLC using a C-18 reverse-phase column and monitoring the column effluent by ultraviolet absorption at 260 nm. The method proved to be linear in the clinical range of 10-1,000 ng/ml. The plasma levels of captopril in a young patient given a small oral dose were determined by this method.

Acetophenones↗
PubMed1990

Small rises in plasma choline reverse the negative arteriovenous difference of brain choline.

The concentrations of free choline in blood plasma from a peripheral artery and from the transverse sinus, in the CSF, and in total brain homogenate, have been measured in untreated rats and in rats after acute intraperitoneal administration of choline chloride. In untreated rats, the arteriovenous difference of brain choline was related to the arterial choline level. At low arterial blood levels (less than 10 microM) as observed under fasting conditions, the arteriovenous difference was negative (about -2 microM), indicating a net release of choline from the brain of about 1.6 nmol/g/min. In rats with spontaneously high arterial blood levels (greater than 15 microM), the arteriovenous difference was positive, implying a marked net uptake of choline by the brain (3.1 nmol/g/min). The CSF choline concentration, which reflects changes in the extracellular choline concentration, also increased with increasing plasma levels and closely paralleled the gradually rising net uptake. Acute administration of 6, 20, or 60 mg of choline chloride/kg caused, in a dose-dependent manner, a sharp rise of the arterial blood levels and the CSF choline, and reversed the arteriovenous difference of choline to markedly positive values. The total free choline in the brain rose only initially and to a quantitatively negligible extent. Thus, the amount of choline taken up by the brain within 30 min was stored almost completely in a metabolized form and was sufficient to sustain the release of choline from the brain as long as the plasma level remained low. We conclude that the extracellular choline concentration of the brain closely parallels fluctuations in the plasma level of choline.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Mass spectrometric peptide mapping analysis and structural characterization of dihydrodiol dehydrogenase isoenzymes.

The direct molecular weight determination and structural analysis of polypeptides and peptide mixtures have become amenable by the recent development of fast atom bombardment (FABMS) and 252Cf-plasma desorption (PDMS) mass spectrometry. FABMS and PDMS peptide mapping, i.e., the direct analysis of peptide mixtures resulting from proteolytic digestion, have been developed as powerful methods for the structural characterization of epoxide-metabolizing isoenzymes. The major advantage of this approach is provided by the selectivity of the endoproteolytic cleavage, combined with the specific and accurate molecular weight determination of complex digest mixtures containing peptides up to several thousands daltons in size. Furthermore, the mass spectrometric peptide mapping analysis can be combined with a range of protein-chemical modification reactions and with sequential degradation such as by carboxypeptidases. Both FABMS and PDMS peptide mapping have already been successfully applied to the structural differentiation of glutathione transferase and epoxide hydrolase isoenzymes in cases where references sequence data for at least one isoenzyme form was available. In the application described here, for a series of dihydrodiol dehydrogenase (DDH) isoenzymes with hitherto undetermined primary structures, a direct correlation between the structural differentiation from peptide mapping data and differences in their substrate specificities could be demonstrated. The mass spectrometric peptide mapping analysis of isoenzymes proved to be an efficient basis for the elucidation of the structure of one major DDH isoenzyme form; partial sequence data for this protein are reported.

Alcohol Oxidoreductases↗
PubMed1990

Clinical course and pharmacokinetics following a massive overdose of amphotericin B in a neonate.

Amphotericin is the drug of choice for the treatment of fungal infections in infants and children. When used in the recommended doses, amphotericin therapy is associated with high rates of adverse effects, including nephrotoxicity, hepatotoxicity, decrease in white blood cells, platelets and hemoglobin, chills, fever and even death (1). We report a case involving a neonate who was exposed to a 50 fold overdose of Amphotericin over a three day period.

Amphotericin B↗
PubMed1990

[Laparoscopic cholecystectomy--initial experiences and results].

In a prospective pilot study on 100 consecutive patients with symptomatic cholelithiasis the laparoscopic cholecystectomy shows to be a safe technic without mortality and a low complication rate (3%). The time of operation is influenced by a learning curve of the operation-team and depends on the technical equipment. The postoperative hospital stay is 3 days in median. Postoperatively the pain-intensity is low and decreased very fast. These increased the patients perioperative comfort.

Adult↗
PubMed1990

Malignant external otitis and mastoiditis associated with an IgG4 subclass deficiency in a child.

We have presented the first child in Delaware with malignant external otitis associated with IgG4 deficiency. Our patient needed three courses of intravenous antibiotics and twice required mastoidectomy, but has recovered completely following the restoration of the natural barrier between the internal and external ear, using a fascial graft from the large temporalis muscle. Some hearing deficit remains.

Child, Preschool↗
PubMed1990

Dapsone is an effective therapy for the skin lesions of subacute cutaneous lupus erythematosus and urticarial vasculitis in a patient with C2 deficiency.

The deficiency of second component of complement (C2d) is the most common hereditary complement deficiency. Patients with C2 deficiency are frequently associated with an auto-immune disease process, in particular, systemic lupus erythematosus (LE)-like syndrome and/or vasculitic syndrome or bacterial infections. C2d has been associated with the LE subset of subacute cutaneous LE (SCLE), the presence of anti-Ro (SSA) antibodies, and the human leukocyte antigen (HLA) types A10, B18, DR2. We describe the clinical, serologic and immunogenetic data in a patient with manifestations of Sjögren's syndrome who developed urticarial vasculitis and photosensitive annular SCLE which were effectively treated with oral dapsone. Our case illustrates the dynamic nature of LE.

Administration, Oral↗
PubMed1990

Methodological issues in studying the effect of the new oral chelator 1,2-dimethyl-3-hydroxypyrid-4-one (L1) on absorption of iron.

Although deferoxamine is currently the drug of choice for iron chelation, there is more and more evidence of its toxicity. As a replacement for deferoxamine, 1,2-dimethyl-3-hydroxypyrid-4-one (L1), a new oral iron chelator, is undergoing clinical studies in thalassemic patients. Iron handling in experimental acute iron intoxication is being studied in a multiphase study. Preliminary results suggest that the L1-iron complex is not absorbed from the gastrointestinal tract. Methodological issues in studying iron chelation in the context of acute iron intoxication are presented.

Administration, Oral↗
PubMed1990

[The effect of scattered radiation and tube focal size on the background density of x-ray pictures using an x-ray exposure system].

By experimental variation of scattered radiation (various field sizes with and without grid) it is shown, that even under defined experimental conditions there is little or negligible influence of scattered radiation on the photographic density of films. The variation is less than 5% for tube voltages between 55 and 120 kV (Exposure control system Robotron type 20041). Variations of film density connected with changes of focal spot size are explained by changes of kVp (insufficient tube load compensation) and by differences of energy sensitivity of ionization chambers and screen-film combinations as well as differences in exposure time for different focal sizes. Short exposure times below 200 ms and constant tube voltages result in equal film exposure, if different focal sizes are used.

Quality Control↗