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Biomedical subjects

N Frank

Publications and source records attributed to N Frank.

At least 37 records · Page 2Linked to original sources
PubMed1998

Listeria monocytogenes and Escherichia coli septicemia and meningoencephalitis in a 7-day-old llama.

Listeria monocytogenes and Escherichia coli were isolated from blood collected on presentation and tissues samples taken postmortem. Listeria monocytogenes was isolated from cerebrospinal fluid collected antemortem. The importance of passive transfer of immunity, the subtlety of neurologic signs in early meningitis, and considering blood-CSF penetration in antimicrobial selection are discussed.

Animals↗
PubMed1997

Child temperament, parenting discipline style, and daytime behavior in childhood sleep disorders.

Fifty-two children without significant sleep disturbance seen at a primary care clinic for well-child care were compared on measures of temperament, parenting style, daytime behavior, and overall sleep disturbance to three diagnostic subgroups identified in a pediatric sleep clinic: children with obstructive sleep apnea (n = 33), parasomnias (night terrors, sleepwalking, etc.) (n = 16), and behavioral sleep disorders (limit-setting disorder, etc.) (n = 31). The mean age of the entire sample was 5.7 years. Temperamental emotionality in the behavioral sleep disorders group was associated with a higher level of sleep disturbance (p < .001); parenting laxness was associated with sleep disturbance in the general pediatric population (p < .01); and intense and negative temperament characteristics seemed to be associated with clinically significant behavioral sleep disturbances. Ineffective parenting styles and daytime disruptive behaviors were more likely to be associated with the milder sleep disturbances found in children in a primary care setting.

Analysis of Variance↗
PubMed1997

Recombinant plasmid mobilization between E. coli strains in seven sterile microcosms.

Transfer by mobilization of a pBR derivative recombinant plasmid lacking transfer functions (oriT+, tra-, mob-) from one E. coli K12 strain to another was investigated in seven sterile microcosms corresponding to different environments. These microcosms were chosen as representative of environments that genetically engineered microorganisms (GEMOs) encounter after accidental release, namely attached biomass in aquatic environments (biofilm), soil, seawater, freshwater, wastewater, mouse gut, and mussel gut, GEMOs survived in the same way as the host strains in all microcosms. Recombinant DNA mobilization occurred in the mouse gut, in sterile soil, and in biofilm. The plasmid transfer rates principally reflected the environmental conditions encountered in each microcosm.

Animals↗
PubMed1996

Intravenous iron supplementation for the treatment of the anemia of moderate to severe chronic renal failure patients not receiving dialysis.

Iron deficiency may develop in hemodialysis patients, especially when erythropoietin is given. The role of iron deficiency in the anemia of predialysis chronic renal failure (CRF), however, is much less clear. We have intravenously (IV) administered iron as ferric saccharate in a total dose of 200 mg elemental iron monthly for 5 months to 33 CRF patients who remained anemic despite oral iron supplementation and who had no laboratory signs of iron overload. None was receiving erythropoietin therapy. In 22 of the patients there was an increase in the hematocrit values by the end of the study. These patients were considered responders to intravenous iron (IV Fe) therapy. In 11 patients the iron administration was not associated with improvement of the anemia (nonresponders). Before onset of the IV Fe therapy there were no differences between the responders and nonresponders with regard to degree of anemia, serum ferritin, iron saturation, renal function, or blood pressure. One additional patient was excluded from the study because of a mild reaction during an IV test dose before the study. No worsening of kidney function and no other side effects were noted. In four patients (three responders and one nonresponder) the control of blood pressure necessitated antihypertensive drug therapy adjustment. In conclusion, IV Fe supplementation in two thirds of anemic CRF patients not receiving dialysis resulted in a significant improvement of the anemia, thus avoiding the necessity of erythropoietin or blood administration. This could be achieved by increasing the plasma ferritin levels to 200 to 400 microns/L and/or increasing the iron saturation to 25% to 35%. Intravenous ferric saccharate appears to be a safe and effective method of administering iron for the correction of anemia in CRF patients not receiving dialysis.

Administration, Oral↗
PubMed1996

[Mini-probe ultrasound of the upper gastrointestinal tract--1995 state of the art and perspectives. Workshop on Mini-Probe Ultrasound in Gastroenterology, Münster, 28 October 1995].

Endoscopic ultrasound (EUS) allows for intraluminal sonographic imaging of the oesophagus, stomach, pancreatobiliary duct system, the papilla of Vater, as well as the colon and rectum. EUS has proved valuable for diagnosis and staging of tumours of the upper intestinal tract. EUS can also provide valuable additional information concerning lesions that cannot be immediately classified. As doing this involves, first, removal of the conventional endoscope and, second, insertion of the echo endoscope, EUS is not suitable for routine examinations. Therefore EUS has remained an independent endoscopic diagnostic modality. Moreover, due to their diameter conventional echoendoscopes cannot be inserted into the pancreatobiliary duct system. Fine calibre high frequency ultrasound probes promise a resolution of less than 2 mm in diameter. The following report is a summary of a one-day workshop which took place in Muenster, Germany on Oct. 28, 1995. Its goal was to define the current state of the art of miniaturised endoscopic ultrasound probes in the field of gastroenterology. During this workshop, possible clinical applications for diagnosis, therapy, as well as follow-up were described and discussed. The potential of miniaturised endoscopic ultrasound probes was explored in terms of possible future technical developments.

Endoscopy, Gastrointestinal↗
PubMed1996

Blocking the endogenous formation of N-nitroso compounds and related carcinogens.

Humans are exposed to a wide range of nitrogen-containing compounds and nitrosating agents, such as nitrite, nitrate and nitrogen oxides (NOx), that can react in vivo to form potentially carcinogenic N-nitroso compounds (NOCs), as well as several carcinogenic C-nitro(so) or reactive diazo compounds. Nitrosating agents can also be synthesized endogenously by bacteria and activated macrophages via the nitric oxide (NO) synthase pathway. Endogenous nitrosation can thus occur at many locations in the body, including sites of chronic infection or inflammation. Ascorbic acid, alpha-tocopherol, phenolic compounds, and fruit, vegetable and plant extracts inhibit NOC formation by destroying nitrosating agents. Fresh fruits and vegetables (sources of nitrosation inhibitors) exert a protective effect against various epithelial cancers. In addition to giving rise to nitrosating agents, overproduction of NO in chronic inflammatory conditions leads to the generation of peroxynitrite (a source of oxidative DNA damage and lipid peroxidation) and aldehydes and epoxides derived from lipid peroxidation that yield miscoding exocyclic DNA adducts. Inhibition of the inducible NO synthase and strengthening of the cellular defence system against oxidative stress should block NO-associated DNA damage. This chapter summarizes mechanistic, experimental and human studies that address the inhibition of endogenous formation of NOCs and related carcinogens as a method of chemoprevention.

Anticarcinogenic Agents↗
PubMed1995

Comparative studies on the pharmacokinetics of hydrophilic prolinedithiocarbamate, sarcosinedithiocarbamate and the less hydrophilic diethyldithiocarbamate.

The pharmacokinetics of the antitoxic and anticarcinogenic compounds diethyldithiocarbamate, prolinedithiocarbamate and sarcosinedithiocarbamate were compared in rats. The bioavailability, the distribution in the organism, the oxidation to thiuramdisulfides, the cleavage to CS2 and the excretion in urine and bile were investigated. The results showed different behaviour of the three compounds. The more toxic diethyldithiocarbamate had a short in vivo half-life, was oxidized to tetraethylthiuramdisulfide in blood, and was metabolized to high yields of CS2 in 24 h. In contrast, prolinedithiocarbamate was more stable in vivo, was found predominantly in the urinary tract and was excreted in urine. The differences could not be explained by the presence of the carboxy group in the latter dithiocarbamate, since sarcosinedithiocarbamate, which also contains a carboxy group, behaved like diethyldithiocarbamate.

Animals↗
PubMed1995

Effects of nicotine on perceptual speed.

Two experiments investigating the effects of nicotine on performance in the inspection time (IT) procedure are reported. Experiment 1 compared ITs in smoking (0.8 mg nicotine cigarette), sham-smoking, and no-smoking conditions. IT was significantly shorter in the smoking condition as compared to both the no-smoking or sham-smoking conditions, suggesting that nicotine enhances early information processing. This result is of particular interest because of the correlation between IT and IQ reported in previous experiments. The nicotine related decrease in IT raises the possibility that nicotine enhances at least a subset of the physiological processes underlying intellectual performance. Experiment 2 examined the persistence of this nicotine related enhancement in IT, and investigated the effects of nicotine across 480 IT trials. Results suggested that ITs derived from the last third of the 480 trials were significantly shorter in the 0.8 mg cigarette condition than in no-smoking condition. The results from these two experiments, taken together with recent work examining the effects of nicotine on the string length measure of AEP waveform complexity and Hick decision time (DT), and studies investigating cognitive functioning and cholinergic system dysfunction in dementia, suggest a role of the cholinergic system in intellectual performance.

Adolescent↗
PubMed1995

Inhibitory effects of mixed disulfides from disulfiram on the metabolism and genotoxicity of N-nitrosodiethylamine.

Disulfiram (CAS 97-77-8, DSF), a potent anticarcinogenic compound, is known to form mixed disulfides with sulfhydryl group containing amino acids or proteins in vivo. In the present study the stabilities of two mixed disulfides which may arise in the metabolism of disulfiram, i.e. S-(N,N-diethyldithiocarbamoyl)-N-acetyl-L-cysteine (AC-DDTC) and S-(N,N-diethyldithiocarbamoyl)-L-glutathione (GS-DDTC) in phosphate buffer (pH 7.2) and in rat liver subcellular fractions were investigated as well as their influences on the glutathione (GSH)-related detoxifying system, on the metabolism of [14C] N-nitrosodiethylamine (NDEA) and on the genotoxic activity of NDEA in rats. Both substances were stable in buffer and in microsomes but were degraded in cytosol showing a half life of 4.7 h (AC-DDTC) and 3.2 h (GS-DDTC). Addition of GSH to the incubation media accelerated the degradation of mixed disulfides in cytosol. In vivo administration of AC-DDTC and GS-DDTC (1.7 mmol/kg i.p.) led to an increase in hepatic GSH content and to an inhibition of the activity of NDEA deethylase. Both mixed disulfides inhibited the metabolism of NDEA. After a 28 mg/kg i.p. dose of [14C] NDEA only 0.4% was excreted unchanged in the urine. Pretreatment with AC-DDTC and GS-DDTC caused a 10 to 20 fold increase in the amount of NDEA excreted in the urine. The occurrence of DNA single strand breaks in rat liver cells induced by NDEA was completely neutralized by the pretreatment with AC-DDTC.

Animals↗
PubMed1994

Sugar-linked dithiocarbamates as modulators of metabolic and genotoxic properties of N-nitroso compounds.

A series of putative anticarcinogenic and antimutagenic compounds was synthesized on the basis of tetraethylthiuram disulfide (disulfiram) and its metabolite, diethyldithiocarbamate (DDTC). Diallyldithiocarbamate was synthesized in order to combine the anticarcinogenic properties of diallyl sulfide, a known inhibitor of chemical carcinogenesis from Allium species, and those of DDTC. Several sugar-linked dithiocarbamates (SDTCs) were prepared using glucose, cellobiose, and lactose as glycosyl donors and DDTC and diallyldithiocarbamate as acceptors. All the S--glycoside bonds of SDTCs were very stable under physiological conditions in vitro. At low nitrosamine concentrations, glucose-DDTC inhibited microsomal nitrosamine dealkylases in vitro. In vivo these enzymes were also inhibited 4 h after i.p. administration of glucose-DDTC or lactose-DDTC to rats (1.7 mmol/kg); after 24 h, the values had returned to control levels. Glucose-DDTC induced the activity of glutathione-related enzymes. Concomitant treatment of rats with glucose-DDTC and N-nitrosodiethylamine (NDEA) led to a depression of the oxidative metabolism of [14C]NDEA to 14CO2 but increased the elimination of unchanged [14C]NDEA in the urine. Furthermore, glucose-DDTC totally inhibited the formation of DNA single-strand breaks induced by NDEA. All these effects may contribute to possible antimutagenic and anticarcinogenic actions of the dithiocarbamates investigated.

Animals↗
PubMed1994

A new miniature ultrasonic probe for gastrointestinal scanning: feasibility and preliminary results.

A prototype of a new miniature ultrasonic probe (Aloka) was clinically evaluated in 37 patients with a variety of gastrointestinal lesions. The probe's diameter of 2.0 mm allowed passage through the working channel of conventional endoscopes; the ultrasonic frequencies used were 15 and 20 MHz. Fourteen patients with benign and malignant gastrointestinal tumors, and thirteen patients with a variety of benign conditions, were examined, 12 of whom also underwent conventional endoscopic ultrasonography with side-viewing echoendoscopes. The image quality of the two systems was well comparable, but the ultrasonic penetration depth of the miniprobes was inferior to that of conventional endoscopic ultrasonography (EUS). All but three lesions were adequately visualized by the ultrasonic probe, whereas conventional EUS failed to completely visualize four cases. Of the two ultrasonic frequencies used, we found 15 MHz to be superior, since it provided good image quality and adequate penetration depth. In conclusion, we feel that the probe can be used for EUS indications in the gastrointestinal tract, whereas further technical improvements, such as increasing the penetration depth, are necessary before pancreatobiliary EUS can be carried out.

Adult↗