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Biomedical subjects

B Hartmann

Publications and source records attributed to B Hartmann.

At least 19 recordsLinked to original sources
PubMed1992

The fine structure of two DNA dodecamers containing the cAMP responsive element sequence and its inverse. Nuclear magnetic resonance and molecular simulation studies.

1H and 31P n.m.r. (nuclear magnetic resonance) spectroscopy have been used in conjunction with molecular simulation to determine the structure of two DNA dodecamers. The first of these, CATGACGTCATG, contains the octameric sequence CRE (cAMP responsive element), while the second is the reversed sequence, GTACTGCAGTAC. Structure determination was based on both NOESY (nuclear Overhauser spectroscopy) derived distances and COSY (correlated spectroscopy) dihedral angle data. Access to the 31P spectra also allowed the epsilon backbone angles to be determined. Considerable care was taken in deriving structural parameters from the n.m.r. data and an excellent level of agreement is obtained with the simulated conformations. Both dodecamers are found to belong to the B-DNA family; however, there is a striking difference between the CRE sequence and its inverse, the former conformation alone showing a strong structural heterogeneity.

Base Sequence↗
PubMed1992

Conformational sub-states in B-DNA.

Theoretical studies of the sequence-dependent conformation of B-DNA have been carried out using Jumna, a helicoidal co-ordinate minimization algorithm. The results obtained for a series of six oligomers with repetitive sequences show that, with the exception of the homopolymers (dA)n.(dT)n and (dG)n.(dC)n, all sequences can adopt a variety of conformations characterized by considerable changes in helicoidal parameters and also in sugar puckers which adopt C(2')-endo (falling into 2 classes) or, in the case of pyrimidine nucleotides, O(1')-endo forms. These studies lead to an improved understanding of the role of base sequence on DNA conformation and point to a number of interesting correlations between the various structural parameters describing the double helix.

Algorithms↗
PubMed1992

[Colposcopy in gynecologic cancers. Retrospective study of 192 examinations].

One hundred and ninety two colposcopic examinations carried out on 183 patients of whom 140 had carcinoma of the cervix, 26 carcinoma of the endometrium and 17 carcinoma of the ovaries were analysed in order to assess the value of colposcopy in patients with gynaecological cancer. The mean distance from the edge of the anus that was looked at was 45 cms--the range being from--130. Out of all the systematic examinations that were carried out before any treatment was started, 103 were for cervical cancer and among these invasion of the rectal mucosa was found in two cases (1.9%). Twelve cases of external pressure on the rectum and 9 cases of recto-colic polyadenomata (8.7%) of which one was malignant. Out of the 14 colposcopies that were carried out for carcinoma of the endometrium one case of rectal invasion was found and one case of external compression. In the 12 cases of cancer of the ovary 2 were found to have recto-colic spread, 1 external compression and 1 malignant polyadenoma. All these cases of spread to the rectum and colon were diagnosed in advanced cases (stage III or IV). In the 63 examinations carried out on follow-up the most common warning sign was a rectal discharge and the most commonly found lesion in the rectum was actinomycotic inflammation of the rectum. The 5 cases of recurrence in the rectum expressed themselves most often by the rectal syndrome.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

[Bioequivalence and bioavailability after single administration of effervescent ranitidine tablets].

An open two-way cross-over study in 12 healthy male volunteers was performed in order to determine the relative bioavailability of a 150 mg ranitidine (Zantic, CAS 66357-35-5) effervescent tablet sweetened with saccharine in comparison to the 150 mg standard ranitidine dispersible tablet (Trinkette). On two occasions separated by a wash-out period of 1 week volunteers received a single oral dose of both formulations. On each administration day blood samples were collected at predetermined time points in order to investigate the pharmacokinetic parameters. Single oral doses of ranitidine were very well tolerated by healthy male volunteers. The non-parametric 95% confidence intervals for AUC and Cmax were 87 to 116% and 84 to 107%, respectively. The relative bioavailability of the ranitidine effervescent tablet was 99% compared to the dispersible tablet. The mean of the Cmax ratio was 95%. The ranitidine effervescent tablet could thus be claimed to be bioequivalent to the dispersible tablet.

Adult↗
PubMed1991

[CO2-induced acral blood flow and the oxygen partial pressure in arterial occlusive disease].

The effect of CO2-containing water on foot skin blood flow (laser-Doppler flux) and transcutaneous oxygen partial pressure (tcpO2) was measured in 16 patients (15 men and 1 woman; mean age 58 [49-71] years) with peripheral arterial occlusive disease (stage II of Fontaine: bilateral occlusions of the superficial femoral arteries). After 30 minutes lying down and 10 minutes sitting up, one lower leg was immersed in fresh water, the other in CO2-containing water (1400 mg CO2/kg H2O), both at 34 degrees C for 20 minutes. On the next day the measurements were repeated changing sides. Skin blood flow of the dorsum of the foot and rhythmic flow oscillations (flux motion) increased threefold in the CO2 water-bath, after a latency period averaging 2 minutes, within 3 minutes from 1.1 to 3.9 relative units (P less than 0.005). Average tcpO2 increased during the bath in CO2 water by 9 mm Hg (P less than 0.005). There was no change in fresh water. The increase in cutaneous blood flow and oxygen partial pressure, which persisted throughout the period in CO2 water, is interpreted as an increase in microcirculation and can explain part of the effectiveness of this largely empirical treatment.

Aged↗
PubMed1991

[Increase in skin blood circulation and transcutaneous oxygen partial pressure of the top of the foot in lower leg immersion in water containing carbon dioxide in patients with arterial occlusive disease. Results of a controlled study compared with fresh water].

Semi-quantitative Doppler laser flowmetry and measurement of transcutaneous oxygen partial pressure (TCPO2 in mmHg) are reliable, non-invasive methods of continuous measurement suitable for underwater use. We measured the effect of aqueous CO2 (succinate + sodium bicarbonate = Kao Bub; 1400 mg CO2 per kg water) compared with fresh water (both at 34 degrees C, depth of leg immersion 35 cm, immersion time 20 min) on circulation and TCPO2 in the feet of 15 patients with bilateral stage-II occlusion of the Aa. fem. superf. intraindividually in a randomised, crossover trial. Measurements were made at the same time of day on two consecutive days. No change in either cutaneous microcirculation or TCPO2 was observed during immersion in fresh water. During immersion in a CO2 bath both culaneous blood flow (as expressed by Doppler laser flux) and the amplitude of the Doppler laser vasomotion flux increased more than threefold (p less than 0.001, Wilcoxon), while sitting TCPO2 increased by over 10% (from 63 to 71 mmHg; p less than 0.001). The observed changes in oxygen dissociation and cutaneous microcirculation may help to provide an explanation for the well-known therapeutic effect of CO2 baths in all stages of occlusive arterial disease.

Adult↗
PubMed1991

[Stress on adolescents due to forced positions in various postural loads].

To assess the strain imposed by defined static loads, eleven young males were studied in four different postures at three different loads held. In addition to the usual cardiovascular parameters of heart rate and arterial blood pressure, the long-term variability of the cardiac cycle (sinus arrhythmia) and the subjective exertion assessment according to Borg were used as strain criteria. Despite a high interindividual variability, HR arrhythmia data reflect in very good terms the strain imposed by predominantly central activation at static loads and forced postures. Such a strain assessment does not replace other modes of assessment such as biomechanical model considerations. Still, it may add to an assessment made on the basis of heart rate and blood pressure.

Adolescent↗
PubMed1990

Expression of 38-kD cell-surface glycoprotein in transformed human keratinocyte cell lines, basal cell carcinomas, and epithelial germs.

In this study, we attempted to identify and characterize transformation-induced cell-surface glycoproteins of human keratinocytes. Therefore, we first searched for glycoproteins which are significantly elevated in human keratinocytes after transformation and immortalization by SV40 virus and which are also found at high levels in keratinocytic cell lines derived from squamous cell carcinomas of the skin. Out of at least 80 different cell-surface antigenic systems of human tumor cells, only three glycoproteins showed elevated expression in transformed keratinocytes. Among these, a 38-kD glycoprotein (gp 38) was highly increased in all transformed keratinocyte cell lines tested, but was not elevated in transformed fibroblasts. The expression of gp 38 was further characterized in normal epidermis and in its benign and malignant hyperproliferative disorders: gp 38 was generally not expressed in normal epidermis and in benign hyperproliferative disorders. In contrast, strong and homogeneous reactivity was found in solid and fibrosing basal cell carcinomas whereas no or low reactivity was detected in squamous cell carcinomas and in those parts of BCC revealing keratotic differentiation. Interestingly, high expression of gp 38 was also found in primary epithelial germs of fetal skin, secondary germ cells of the telogenic hair follicle and secretory tubules of sweat glands. The immunohistologic data suggest that gp 38 is preferentially expressed by epidermal cells which lack squamous and pilosebaceous differentiation.

Basal Cell Carcinoma↗
PubMed1990

[Results of audiometry screening in adolescent workers].

Results of screening audiometry of male youths aged 16 to 25 (n = 3969) in occupations from metallurgy, machine-building industry and traffic are demonstrated. Part of persons they have hearing loss between 5 to 10 percent increases from 2.8% of pupils before starting vocational training to 4.5% or 7.1% of apprentices and 9.7% of skilled workers. The incidence of persons with respective without middle ear inflammation in anamnesis only differ in stages about 20 percent hearing loss. It shows sensitivity of screening audiometry nevertheless there are possibilities of mistakes. Adolescents already may show measurable hearing loss in connection with professional and nonprofessional expositions as well as individual dispositions.

Adolescent↗