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Biomedical subjects

C Kramer

Publications and source records attributed to C Kramer.

At least 19 recordsLinked to original sources
PubMed2001

Reactive and proactive aggression: attachment and social competence predictors.

In this study, 107 boys and girls aged 3 to 8 years were rated by their mothers on 6 factors: Reactive and Proactive Aggression, Secure and Insecure Attachment, and Prosocial Orientation and Social Initiative (i.e., social competence). Both secure attachment and prosocial orientation predicted proactive and reactive aggression, but prosocial orientation mediated the attachment-aggression relation in the case of reactive but not proactive aggression.

Aggression↗
PubMed2000

[Reactions of 4,5-dihydro-4-oxo-1H-pyrido(3,2-b)indol-2-carboxylic acid ester].

The title compounds 5 were saponificated and decarboxylated, N- and O-alkylated; the ester group was reduced to the primary alcohol and than oxidized to the aldehyde. In the same manner the N- and O-methylated products 9 and 10 were derivatized. The tetrazoles 24 and 25 were synthesized from the aldehydes 18 and 19 via the aldoximes and nitriles. The aldehydes 18 and 19 reacted with beta-amino crotonic acid esters in the Hantzsch pyridine synthesis to mixtures, from which the 1,4-dihydropyridines (DHP) 26 and 27 as well as the ylidenes from methyl acetoacetate 31 and 32 and in the case of 18 the oxidation product 30 of a 1,2-DHP could be isolated. The pyridines 28 and 29 were obtained by chemical dehydrogenation of the 1,4-DHP 26 and 27. By anodic oxidation of 26 and 27 by means of difference pulse voltammetry not only an one step two-electronic dehydrogenation yielding the corresponding pyridines took place, but also a two step one-electronic oxidation of the vinylogous hydrazine structure to diiminium salts occurred.

Electrochemistry↗
PubMed2000

[Potential antiallergic agents--synthesis and reactions of 1,4-dihydro-4-oxo-(1)benzofuro(3,2-b)pyridin-2-carboxylic acid esters].

The title compounds 5 were received from the saponification of ethyl 3-aminobenzo[b]furan-2-carboxylate (3) followed by reaction with acetylenedicarboxylic diesters. The esters 5 reacted with alkyl iodides to give mixtures of the 4-alkoxypyridines 8 and the N-alkylpyridones 9. Alkaline hydrolysis of the esters 5, 8 and 9 yielded the carboxylic acids 6, 11 and 12. The carboxylic acid 6 could be decarboxylated to afford the annulated pyridone 7. The tetrazoles 21 and 22 were synthesized starting from the esters 8 and 9. At first, reduction afforded carbinoles, subsequent selective oxidation yielded the aldehydes 15 and 16, which were converted into aldoximes. Dehydration of the aldoximes formed nitriles, which added hydrazoic acid. The carbaldehydes 15 and 16 reacted in the Hantzsch-Synthesis with beta-aminocrotonic acid esters to form the 1,4-dihydropyridines (DHP) 23 and 24, which could be dehydrogenated to obtain the pyridines 25 and 26. The unsymmetrical pyridine compound 27b was isolated as a by-product using 15b in the DHP-synthesis. The DHP 23 and 24 were more stable against oxidation than the reference drug nifedipine.

Alkylation↗
PubMed2000

[Gyrase inhibitors. 3. Synthesis and reactions of 1,4-dihydro-4-oxo-(1)benzothieno(3,2-b)pyridin-3-carboxylic acid esters].

The title compound 4a is synthesized from potassium 3-aminobenzo[b]thiophene-2-carboxylate (1) by Gould-Jacobs reaction. Compound 4a reacts with alkyl halides and sodium hydride in DMF to yield the N-alkylpyridones 5a-c as well as the 4-alkoxypyridines 6a-c; with phosphoryl chloride the 4-chloropyridine 7a is obtained. The carboxylic acids 4b, 5d, 5e, 6d and 7b are received by alkaline saponification of the esters 4a, 5a-c, 6a-c and 7a. The carbinoles 8 and 9, formed by boranate reduction of the esters 6a and 7a, are transformed to the aldehydes 10 and 11 by activated manganese dioxide oxidation. The aldoxime 12 from the carbaldehyde 11 is dehydrated to yield the nitrile 13. The carbaldehyde 11 reacts with methyl beta-aminocrotonate to yield the 1,4-dihydropyridine (DHP) 14, which is dehydrogenated to give the 3,4'-bipyridine 15. The pyridone 4a reacts with tosylisocyanate to yield the 4-tosylaminopyridine 16a. The antibacterial activity of the carboxylic acids 4b, 5d, 5e and 6d is proved. The growth of Escherichia coli and Bacillus megaterium is inhibited by 5d in the same range as nalidixic acid does.

Bacteria↗
PubMed2000

[Potential antiallergics. 3. Synthesis and transformations of 1,4-dihydro-4-oxo-(1)benzothieno(3,2-b)pyridine-2-carboxylic acid esters].

The title compounds 2a, b are obtained by reaction of potassium 3-amino benzo[b]thiophene-2-carboxylate (1) with acetylenedicarboxylic acid esters in acetic acid. The substance 2a gives the carboxylic acid 2c by saponification, reaction with phosphoryl chloride affords the 4-chloropyridine 3. The carbinol 4, received by boranate reduction, was dehydrogenated with activated manganese dioxide to yield the carbaldehyde 5. Compound 2a reacts with methyliodide to give a separable mixture of the O- and N-alkylated products 6a and 7a, while by reaction of 2b with ethyliodide only the 4-ethoxypyridine 6b is formed. The carboxylic acids 6c, 7b are obtained by alkaline hydrolysis of the esters 6a, 7a. The carbinols 8, 9, formed by reduction of the esters 6a, 7a, are oxidized to give the carbaldehydes 10, 11. The 1H-tetrazoles 17, 18 are synthesized from the aldehydes 10, 11 via the aldoximes 13, 14 and the nitriles 15, 16. The aldehydes 10, 11 react with the beta-aminocrotonic acid esters 19 in acetic acid to yield the 1,4-dihydropyridines (DHP) 20, 21, which are dehydrogenated to form the pyridines (Py) 22, 23. The half-wave potentials E1/2 of the redox system DHP/Py is determined by difference pulse voltammetry using nifedipine as reference substance.

Anti-Allergic Agents↗
PubMed2000

[Synthesis and transformations of ethyl 1,4-dihydro-4-oxo(1)benzofuro(3,2-b)pyridine-3-carboxylic acid esters: new antibacterial agents].

The title compound 7 was synthesized from potassium 3-amino-[1]benzofuran-2-carboxylate (1) by Gould-Jacobs-reaction. The pyridone 7 reacted with ethyl iodide by N- and O-alkylation to give 9 and 10, while methyl iodide only yielded the N-methylpyridone 11. The 4-chloropyridine 15 was obtained by heating 7 in phosphoryl chloride. Alkaline saponification of the esters 7, 9-11 and 15 afforded the carboxylic acids 8, 12-14 and 16. The carbaldehydes 19 and 22 were prepared from the ethylesters 10 and 15 by boranate reduction to the carbinoles 17 and 20 followed by dehydrogenation with activated manganese dioxide. The aldehyde 22 reacted with beta-aminocrotonic acid esters to yield the 1,4 dihydropyridines (DHP) 23. The pyridines 24 were formed by chemical or electrochemical dehydrogenation of the DHP 23. The tetrazole 27 was accessible from the aldehyde 22 via the aldoxime 25 and the nitrile 26. The pyridone 7 reacted with tosylisocyanate to yield the 4-tosylaminopyridine 28, which after alkylation to form 29 followed by detosylation to give 30 and subsequent alkaline hydrolysis produced the 4-aminonicotinic acid 31. The investigation The N-ethylpyridone-3-carboxylic acid 12 showed antibacterial activity comparable to the reference substance nalidixic acid against Pseudomonas aeruginosa, Escherichia coli and Bacillus megaterium.

Anti-Bacterial Agents↗
PubMed1999

Interference of H2O2 with stimulus-secretion coupling in mouse pancreatic beta-cells.

1. We have reported previously that in mouse pancreatic beta-cells H2O2 hyperpolarizes the membrane and increases the ATP-sensitive K+ current recorded in the perforated patch configuration of the patch-clamp technique. The present study was undertaken to elucidate the underlying mechanisms. 2. The intracellular ATP concentration measured by chemoluminescence was reduced by H2O2. The ADP concentration increased in parallel during the first 10 min, resulting in a pronounced decrease in the ATP/ADP ratio. 3. Consistent with these results, glucose-stimulated insulin secretion from isolated islets was inhibited by H2O2. 4. Membrane hyperpolarization measured with intracellular microelectrodes in intact islets and inhibition of insulin secretion were counteracted by tolbutamide, indicating that the channels are still responsive to inhibitors and that the ATP concentration is not too low to trigger exocytosis. However, the sensitivity of the beta-cells to tolbutamide was reduced after treatment with H2O2. 5. H2O2 increased the intracellular Ca2+ activity ([Ca2+]i) in a biphasic manner. A first transient rise in [Ca2+]i due to mobilization of Ca2+ from intracellular stores was followed by a sustained increase, which was at least partly dependent on Ca2+ influx. The first phase seems to reflect Ca2+ mobilization from mitochondria. 6. Our results demonstrate that H2O2 interferes with glucose metabolism, which influences the membrane potential and ATP-sensitive K+ current via the intracellular concentration of ATP. These events finally lead to an inhibition of insulin secretion despite an increase in [Ca2+]i.

Adenosine Triphosphate↗
PubMed1999

Analysis of hamster protamines: primary sequence and species distribution.

Basic nuclear proteins were isolated from the sperm of the Syrian hamster Mesocricetus auratus and characterized by gel electrophoresis, amino acid analysis, and sequencing. Analyses of the proteins by gel electrophoresis show that sperm of this species contain both protamines 1 and 2. The two proteins were purified by HPLC and the complete primary sequence of hamster protamine 1 was determined by automated amino acid sequence analysis. The protein sequence was subsequently confirmed by sequencing the PCR-amplified protamine 1 gene. The first forty-two residues of the hamster protamine 2 sequence were obtained by amino acid sequence analysis of the isolated protein, and this sequence was also confirmed and extended by sequencing the gene. Total basic nuclear protein was also isolated from sperm of six other species of hamsters, the protamines were identified by HPLC and amino acid analysis, and the proportion of protamines 1 and 2 in each species was determined. Marked differences in the protamine 2 content of sperm were observed among the different species of hamster. This variation and the high level of sequence similarity between mouse and hamster protamines provide insight into how the two protamines may be organized in sperm chromatin. Mol. Reprod. Dev. 54:273-282, 1999. Published 1999 Wiley-Liss, Inc.

Amino Acid Sequence↗
PubMed1999

Background ionizing radiation plays a minor role in the production of chromosome translocations in a control population.

PURPOSE: To obtain a relationship between background chromosome translocation frequency and age with translocation frequency measured to a high statistical precision, and to identify the role of background ionizing radiation in the production of chromosome translocations in a control population. MATERIALS AND METHODS: Lymphocytes from 35 healthy control individuals (15 females and 20 males) were scored, using fluorescence in situ hybridization, for the presence of chromosomal translocations. Translocation frequencies were measured to a high statistical precision (s.d. 25% or less for each individual). These control subjects were of varying ages, ranging from 0 (cord blood) to 98 years. RESULTS: In a total of 521,492 metaphases (203,754 genome equivalent cells) scored, an average of 5,822 genome equivalent cells per individual, 764 translocations were observed in the 35 individuals. The translocation frequencies ranged from 0 (for cord blood) to 0.0167 (for a 98 year old) translocations per cell. The average age and translocation frequency was 50 years and 0.004 translocations per cell, respectively. The best fit of the relationship between translocations and age was: Y=7x10(-4)+6.9x10(-6)A+1.35x10(-6)A2, which does not obey the linear relationship expected from chronic background radiation alone. The curvilinear relationship observed clearly shows that other endogenous and exogenous clastogens or clastogenic events, in addition to radiation, serve to generate chromosome translocations in control populations. CONCLUSION: The background translocation frequency in control individuals follows a curvilinear relationship with age. No significant variation was observed between individuals of the same age. Clastogenic processes of normal aging and physiological factors in additional to ionizing radiation play a major role in the production of chromosome translocations in a control population. Background radiation, however, appears to play a minor role in chromosome translocation production in control individuals living near sea level.

Adult↗
PubMed1998

Low-molecular-weight heparin and partial thromboplastin time-adjusted unfractionated heparin in thromboprophylaxis after total knee and total hip arthroplasty.

Thromboprophylaxis with heparins after total hip arthroplasty (THA) and total knee arthroplasty (TKA) is well established. The aim of this study was to compare low-molecular-weight heparin (enoxaparin) with partial thromboplastin time (PTT)-adjusted, unfractionated heparin (heparin sodium). In a prospective study of THA and TKA 246 patients, physical examination and compression and duplex ultrasound were performed 1 day before and 7 and 14 days after surgery. One hundred thirty patients received 40 mg enoxaparin subcutaneously once per day. One hundred sixteen patients received 5,000 IU heparin sodium subcutaneously 3 times daily. As the PTT did not reach 40 seconds, the heparin sodium dosage was increased to 7,500 IU 3 times daily. The overall thrombosis rate was 4% (n = 10). In the enoxaparin group, the rate was 2.9% of the 70 THAs and 10% of the 60 TKAs. Thrombosis also occurred in the group that received heparin sodium: 1.8% of the THAs and 1.7% of the TKAs. For TKA, the difference between the 2 heparin groups was statistically significant. In the thromboprophylaxis of TKA, PTT-adjusted unfractionated heparins are superior to fixed doses of low-molecular-weight heparins.

Aged↗
PubMed1998

[Psychosocial predictors for initiating a pension procedure after bypass operation].

From the psychologist's point of view, a routine coronary artery bypass operation is often looked upon by patients as a negative situation. The patient develops the feeling that his or her life has been dramatically altered, thus the patient feels he must somehow make a change in the upcoming pattern of the future. The patient, as well as his employer, is convinced of subjective models of etiology, which cause the attitude that circumstances of living must change rapidly. In this context continued employment is viewed as a significant burden and hindrance, despite an excellent post-operative discharge diagnosis. According to the hypothesis, emotions and attitudes directly concerning the working environment, that lead to an application for early retirement should be identified. Medical and psychological counseling before surgery and post-op rehabilitation, should be carried out to ease the obsession with early retirement and prevent possibly following psychopathological disturbances.

Activities of Daily Living↗
PubMed1998

A fatal overdose of transdermally administered fentanyl.

We present a case of fentanyl overdose via mucous membrane absorption. A 31-year-old man presented to the emergency department in respiratory arrest. At intubation, a Duragesic transdermal patch (75 micrograms/h) was recovered from the buccal cavity. A second fentanyl transdermal patch (75 micrograms/h) was noted on the right lateral aspect of the thigh. Postmortem blood evaluation returned a venous fentanyl level of 17.2 micrograms/L. The therapeutic range for analgesic use is 1 microgram/L to 3 micrograms/L. Drug screens were positive for benzodiazepines and cocaine. Mass spectrophotometry/gas chromatography was used to determine fentanyl levels and to confirm drug screen results. Case history, findings at intubation, and high fentanyl blood concentration suggest the cause of respiratory arrest and death was fentanyl overdose.

Administration, Cutaneous↗
PubMed1997

[Position identification in knee joint endoprosthesis].

In this paper we present a method for measuring the wear of the polyethylene inlay in knee joint endoprostheses from standard X-ray images. Our approach is to estimate the spatial position of the tibial and femoral components of the prostheses from their contours in the X-ray image. When we know the exact shape of these two components, we can calculate the minimal spatial distance between them which approximates the remaining thickness of the inlay. First results show that this approach might provide sufficient accuracy for the given task.

Biometry↗
PubMed1994

Comparison of four commercially available rapid enzyme immunoassays with cytotoxin assay for detection of Clostridium difficile toxin(s) from stool specimens.

Rapid (2.5- to 3.5-h) enzyme immunoassays (EIAs) for the detection of Clostridium difficile toxins have been developed. We report the results of simultaneous testing of 700 fresh stool specimens by the tissue culture cytotoxin assay and four EIAs (Bartels Prima System C. difficile Toxin A EIA, Cambridge Biotech Cytoclone A+B EIA, Meridian Diagnostics Premier C. difficile Toxin A EIA, and TechLab C. difficile Tox-A Test EIA). In cases of disagreement, culturing for toxigenic C. difficile was performed. A total of 61 (8.7%) specimens from 46 patients were positive for C. difficile toxin. The sensitivity of the cytotoxin assay was 87%, and that of culture was 93%. In comparison with the cytotoxin assay results, the sensitivity and specificity of the EIAs were as follows: Bartels, 87 and 96%; Cambridge, 89 and 99%; Meridian, 87 and 98%; and TechLab, 87 and 95%, respectively. In comparison with the cytotoxin assay plus toxigenic culture results, the sensitivity and specificity of the EIAs were as follows: Bartels, 84 and 97%; Cambridge, 85 and 99%; Meridian, 79 and 98%; and TechLab, 80 and 96%, respectively. The EIAs varied in positive predictive values (PPVs). A high PPV was seen with the Cambridge EIA (96%); lower PPVs were seen with the TechLab (64%), Bartels (72%), and Meridian (80%) EIAs because of high false-positive rates. The negative predictive values (98 to 99%) were excellent with all EIAs. Results were indeterminant with 0.3% of the samples by the Meridian EIA and 3% by all the other EIAs. Although the EIAs were less sensitive than the cytotoxin assay, they provide same-day results and may be useful in laboratories without tissue culture facilities.

Bacterial Proteins↗