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Biomedical subjects

R Steffen

Publications and source records attributed to R Steffen.

299 records · Page 17Linked to original sources
PubMedDate not supplied

Prevention of travelers' diarrhea by nonantibiotic drugs.

Travelers have resorted to a variety of drugs for prevention of diarrhea. No beneficial prophylactic effect has been confirmed for halogenated hydroxyquinoline, lactobacilli, antimotility drugs, ethacridine, and various other agents. In contrast, bismuth subsalicylate (BSS) in liquid form reduced the incidence of diarrhea in students from the United States living in Mexico and in tablet form in volunteers challenged by enterotoxigenic Escherichia coli. In tourists visiting various developing countries, a randomized, double-blind study was conducted in which 390 persons received a total of 2.1 or 1.05 g of BSS daily or placebo in tablet form in two doses. BSS reduced the incidence of diarrhea by 41% in the high-dose group and by 35% in the low-dose group without causing important adverse reactions.

Antidiarrheals↗
PubMedDate not supplied

Differential in vitro anti-HIV activity of natural lignans.

Two naturally occurring lignanolides, isolated from the tropical climbing shrub Ipomoea cairica, (-)-arctigenin and (-)-trachelogenin, were found to inhibit strongly replication of human immunodeficiency virus type 1 (HIV-1; strain HTLV-III B) in vitro. At a concentration of 0.5 microM, (-)-arctigenin and (-)-trachelogenin inhibited the expression of HIV-1 proteins p17 and p24 by 80-90% and 60-70%, respectively. The reverse transcriptase activity in the culture fluids was reduced by 80-90% when the cells (HTLV-III B/H9) were cultivated in the presence of 0.5 microM (-)-arctigenin or 1 microM (-)-trachelogenin. At the same concentrations, the formation of syncytia in the HTLV-III B/H9-Jurkat cell system was inhibited by the compounds by more than 80%. A series of other lignan type compounds displayed no anti-HIV activity. Studying the molecular mechanism of action of (-)-arctigenin and (-)-trachelogenin we found that both compounds are efficient inhibitors of the nuclear matrix-associated DNA topoisomerase II activity, particularly of the enzyme from HIV-1-infected cells. Our results suggest that both compounds prevent the increase of topoisomerase II activity, involved in virus replication, after infection of cells with HIV-1.

Animals↗
PubMedDate not supplied

Risks of hepatitis B in travelers as compared to immunization status.

BACKGROUND: Our objective was to determine the risks of infection with hepatitis B among European travelers and to compare this with the immunization status in various risk groups. METHODS: A cross-sectional telephone questionnaire survey of randomly selected subjects, in nine European study populations was used. A total of 9, 008 individuals were involved, with approximately 1,000 interviews conducted in each country in the native languages. Situations with a high risk of hepatitis B infection, such as invasive medical procedures, attending to a bleeding person, and skin perforating cosmetic practices, particularly when performed in countries with medium/high transmission risk, and vaccination status of travelers, were the main outcome measures. RESULTS: Depending upon the destination, 6.6-11.2% of travelers were classified as at high risk of hepatitis B, with 24.4% vaccinated; between 60.8-75.8% of travelers at potential risk, with 19.2% vaccinated; and 33.4% of travelers where no hepatitis B risk was identified. Significantly more travelers who only visited medium/high endemicity regions exposed themselves to a high risk of contracting hepatitis B, (40, 10.5%) compared to travelers who only visited low endemicity regions (225, 6.6%; p <.01). CONCLUSIONS: A significant proportion of travelers surveyed unwittingly exposed themselves to the risk of hepatitis B infection while at medium/high risk destinations. The majority of at-risk travelers had not been vaccinated, regardless of their destination. Improved advice and clear recommendations to avoid transmission are needed.

Adolescent↗
PubMedDate not supplied

Travel health insurance: indicator of serious travel health risks.

BACKGROUND: Travel health risks documented by questionnaire surveys obtained (e.g., during homebound flights) are incomplete since they miss most patients who need to be repatriated. METHODS: All patient claim files were reviewed from 1997 to 1998, of the largest Swiss travel insurance company. RESULTS: Among 242 claims, 69.4% were due to illness, 30.6% due to accidents; infections were the most frequent illnesses, the extremities were the most frequently traumatized part of the body. Although the illness-to-accident ratio was 1:5 in industrialized countries and the Caribbean, it exceeded 3:0 in some developing regions. Accident proneness was noted in the first week abroad. CONCLUSION: Even if no denominator data are available, this analysis offers an insight in travel health risks, allowing comparison of the occurrences of very different, serious, health problems abroad.

Accidents↗
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Travelers' health.

Explore the source record for details and available documents.

Communicable Disease Control↗
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Associated ulcerative colitis, sclerosing cholangitis, and insulin-dependent diabetes mellitus.

We report two young men with clinical and laboratory evidence of macroscopic ulcerative colitis, sclerosing cholangitis, and insulin-dependent diabetes mellitus. The first patient presented at age 15 with vomiting, abdominal pain, weight loss, and abnormal liver function test results. Liver biopsy and endoscopic retrograde cholangiopancreatography (ERCP) demonstrated sclerosing cholangitis. Colonoscopy with biopsy revealed ulcerative colitis which responded to sulfasalazine. Diabetes occurred at age 18 and insulin therapy was begun. The second patient was 19 at presentation with diarrhea, hematochezia, and weight loss. Proctosigmoidoscopy revealed ulcerative colitis, and sulfasalazine led to clinical remission. Three months later he developed diabetes requiring insulin therapy. At age 28, he developed elevated alkaline phosphatase, and ERCP revealed sclerosing cholangitis. At age 37 he expired from adenocarcinoma that metastasized to the liver. Literature review revealed only one possible case report of this association with microscopic asymptomatic ulcerative colitis in that patient. Statistical analysis suggests that this association is real rather than a chance occurrence. An autoimmune process may be involved and a specific histocompatibility locus antigen (HLA) type may exert a regulatory influence.

Adolescent↗
PubMedDate not supplied

Elective mutism: effect of dental treatment with N2/O2-inhalation sedation: review and report of case.

Elective mutism in children is characterized by a marked, emotionally determined selectivity in speaking, such that the child demonstrates his or her language competence in some situations but fails to speak in other situations. An eight-year-old boy with elective mutism had to undergo restorative dental treatment. It was chosen to use relative analgesia to perform this treatment. The sedation with oxygen and nitrous oxide resulted in complete symptom remission as long as the sedation lasted.

Anesthesia, Dental↗
PubMedDate not supplied

[Age-related changes in the activity and post-translational modification of DNA topoisomerase II in the quail oviduct].

In the present work, we show that the activity of DNA topoisomerase II in quail oviduct nuclei significantly increases with age. Posttranslational modifications of the nuclear-matrix-associated enzyme by matrix-bound poly(ADP-ribose) synthetase and protein kinase, whose activities change with age, are demonstrated and offer possible mechanisms by which the age-dependent change in enzyme activity may be caused. It is assumed that the age-correlated enhancement of DNA-topoisomerase-II activity may cause changes in the topological state of DNA, with possible consequences for DNA replication, transcription, and repair with age.

Animals↗
PubMedDate not supplied

Liver transplantation: significance of the periportal collar on MRI.

OBJECTIVE: Liver transplantation is performed with increasing success and frequency all over the world. Experience with MRI of the liver allograft is, however, limited. This study was designed to correlate MRI to clinical-laboratory findings, CT, and biopsy and to evaluate the significance of the periportal collar on MRI. MATERIALS AND METHODS: Fourteen patients who had undergone orthotopic liver transplantation were studied by CT and MRI [T1-weighted imaging: gradient-echo, repetition time/echo time (TR/TE) 306/14 ms, theta 90 degrees; proton density and T2-weighted imaging: spin-echo, TR/TE 1,600/30-120 ms]. Three patients also had follow-up MR examinations 43 days, 89 days, and 5 months after transplantation. RESULTS: Magnetic resonance imaging demonstrated a perivascular collar around central portal venous branches in all 14 patients and around peripheral portal branches in 10 of the 14 patients on the initial MRI study. The perivascular collar showed low signal intensity on T1-weighted imaging and an increase in signal intensity on T2-weighted multiecho imaging. The distribution and prevalence of central and peripheral periportal collars were identical on MR and CT. Peripheral periportal collars were seen in 9 patients who had no clinical-laboratory signs of rejection. In 3 patients with biopsy-proved rejection, the periportal collar was less prominent on MR at the time of rejection when compared with MR performed when the patient had no signs of transplant rejection. CONCLUSION: A perivascular collar in a patient with liver transplantation is likely to be related to impaired lymph drainage after surgical interruption of the draining lymph vessels and lymphedema. In contrast to previous CT reports, however, a perivascular collar around peripheral portal branches does not appear to correlate to rejection, since it is frequently observed in the normal liver allograft.

Adult↗