Biomedical subjects
Publications and source records attributed to C Schmidt.
The effects of N-methyl-formimino-methylester were studied in albino mice. Very short exposure (0.5 and 1 s) to the concentrated vapour led to an increase of the neural olfactory threshold to geraniol by a factor of 10(5)-10(7). There was a slow recovery of the olfactory sensitivity and after about 40 days the threshold values returned to normal.
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Vascular acrosyndromes are mainly subjective clinical phenomena that are difficult to classify, are related to the patient's background, and require a particularly strict protocol for the evaluation of their therapy. An essential criterion is the homogeneity of groups treated, the Raynaud's phenomenon having to be separated into idiopathic Raynaud's disease, digital arteritis and scleroderma. Functional subjective disturbances have to be rated by the patients themselves, while taking into account the conditions of daily life and of climate. Clinical trials must be double-blind against placebo after a pre-inclusion study. They must be conducted entirely during cold spells for Raynaud's phenomena. Static measurements are of limited value amongst functional exploratory techniques, dynamic tests (vascular reactivity to cold) providing more valid data on the action of medication.
Detection and localization of peripheral arterial disease was evaluated by an intravenous injection of 201Tl at peak exercise in 18 subjects and at rest in 6 patients. Images of the skull (S), thighs (T), knees (K), calves (C) and feet (F) were obtained at rest or after exercise and stored in a computer. Intraleg (T/K, T/C, T/F), and left to right interleg (TL/TR,...) count ratios were calculated. In addition, all patients were submitted to routine functional tests (walk perimeter, serial local arterial blood pressure measurement, Strandness test, venous occlusion plethysmography). Correlations between functional tests and the intra and interleg ratios were calculated. After exercise, there is a medium correlation between the tissular blood flow under hyperemia at the calf level and the T/C and C/K ratios. At the calf level a good correlation is obtained for CL/CR and the flux under hyperemia (r = 0.81, P 0.001). A ratio between the counting rates of limb segments after exercise and those of skull was established. The ratios T/S and C/S compared with the systolic pressure index of the most affected limb after a Strandness test give a correlation of 0.72 (P 0.02) for the thigh and of 0.86 (P 0.001) for the calf. For hyperemic flux, the correlation are 0.58 (P 0.005) with T/S and 0.75 (P 0.001) with C/S. In order to find the best quantitative scintigraphic index of the arterial illness, we compared the different ratio values with the distance walked. For T/S we found a relationship very close to a linear one and for C/S a less significant exponential one. Thus, quantitative scintigraphy using 201Tl appears as an accurate method to measure local muscular perfusion deficit in the cases of lower limb arterial disease.
The part played by blood rheological factors in any vasomotor phenomenon is still difficult to define, in relation to its onset, maintenance and possible worsening. A high viscosity may contribute towards a difficulty in flow and viscosity is known to vary in an inverse manner with temperature. Many studies have been published reporting results of rheological investigations in Raynaud's syndromes, but whereas the majority describe both blood and plasma hyperviscosity, others report negative results or those that are interpretable with difficulty. A recent study in 49 patients with Raynaud's syndromes confirmed the presence of elevated blood and plasma viscosity values, particularly in Raynaud's syndromes secondary to other disorders and in digital arteritis. Elevated viscosity levels in "essential" Raynaud's syndromes were significant at low speeds only, suggesting the association of a disorder of erythrocyte aggregation with the properly termed vasomotor disturbance.
The authors study the vascular reactivity to cold exposure in 48 normal subjects and 37 Raynaud's phenomenon (20 Raynaud's diseases, 9 digital arteritis, and 8 acrocyanosis). The haemodynamic profile of primary Raynaud's diseases is quite different: important drop in digital systolic pressure after cold (-27%), suppression of the postischemic hyperaemia (-47%). Digital arteritis has a lower digital pressure at rest (-24 mm Hg), a higher pressure gradient between the arm and the finger (30 mm Hg) and a reduced digital blood flow. The acrocyanotic hands are the coldest, the recovery time is long and the blood flow low.
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Circulatory effects of intravenous injection of sodium nitroprusside are appreciated in 6 patients by monitoring systemic pressure, heart rate, digital systolic pressure, pulse plethysmography and nail-fold capillaroscopy. Low doses of nitroprusside (1.5 microg./kg/mn) enhance digital blood flow (+ 78.9%) and maximum height of the plethysmographic curve (+ 71.6%), without any significant modification of the systemic blood pressure (- 0.6%), heart rate (+ 6.3%) and digital pressure (- 1.15%). The peripheral resistances are strongly reduced. Nail fold capillaroscopy is unchanged. Higher doses, even with an adequate vascular filling, are potentially harmful for microcirculation.
Vascular reactivity to cold has been studied on 22 patients by means of digital dynamic thermography. Using an interface the thermographic images are digitized in real time and stocked in the computer. After the cooling (two minutes in water at 10 degrees C) the warming-up is followed by sequential thermographic images. Profiles of thermic evolution are represented for 12 regions of interest (at the level of each finger and two for the back of the hands). Four types of thermic profiles are observed: Type 0: all fingers and back of hands have the same basal temperature. After cooling the warming-up is immediate, synchronic for all fingers and goes on more or less rapidly. Type I: at the basal state all fingers have identical temperature. After cooling, the warming-up starts after a latency period of several minutes, which is identical for all fingers. After it the warming-up is fast and synchronic with a thermic "overshot" phenomenon at the end of the examination. Only the thumbs are warmed-up without a latency period. Type II: a latency period similar that of type I is observed but the following warming-up takes place with variable speeds for each considered finger. Type III: at the basal state the fingers are colder than the back of the hand. Spontaneously, some fingers are warmed only by the influence of the hand vertical position. After cooling, the warming-up takes place with variable speeds and after variable latency periods which are a characteristic of each finger.(ABSTRACT TRUNCATED AT 250 WORDS)
Cisplatin (20 mg/m2 on five successive days, together with hydration and osmotic diuresis) was administered in two treatment cycles to 32 patients with locally advanced tumours (T2-4, N1-3, M0) of the head and neck region. Cisplatin-free interval was at least four weeks. At the same time there was radiotherapy with photons or electrons, daily fractions of 2 Gy four to five times weekly to a final volume dose of 60-70 Gy. Tumour resection was undertaken if there was no tumour involution of at least 50% after 40 Gy and one cisplatin cycle. Total remission rate (complete and partial) was 91%. Complete remission occurred in 22 patients (69%). Biopsies in 14 patients after 40 Gy and one cisplatin cycle indicated that in seven there was no histological evidence of tumour. There was no clinically serious rise in local toxicity. However, erythema and oedema in the radiation fields were more frequent and earlier than with radiotherapy alone. The results indicate that combined cisplatin administration and radiotherapy give the same or even better results than aggressive chemotherapy followed by radiotherapy.
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The sequence of intron 1 in the cob gene in mtDNA (bI1) of the yeast strain 777-3A has been determined. Furthermore, we have performed a systematic search for complementary sequence stretches within this intron RNA, and within the RNA of intron 5 gamma of the oxi3 gene (aI5 gamma) which shares distinctive sequences with bI1. Possible secondary structure models derived from this analysis show nearly identical core structures for bI1 and aI5 gamma RNA with conserved sequence stretches in prominent positions. These core structures are similar to those previously reported for RNAs of introns having very limited sequence homology with bI1 and aI5 gamma. In two mutants which are defective in bI1 excision from cob pre-mRNA, nucleotide sequence alterations in bI1 have been determined. One mutation (G5049) apparently affects the stability of a hybrid stretch in the proposed secondary structure of bI1 RNA whereas the other one (M1301), a deletion of one A in a run of five As, affects a sequence which is conserved in bI1 and aI5 gamma and is involved in the formation of a distinct secondary structure. Out of seven revertants of M1301, three were found to have restored the wild-type bI1 sequence AAAAA, three others had the related sequence AAAAG which is functionally indistinguishable from wild-type, whereas one revertant had a nuclear mutation which suppresses the splicing defect exerted by the mitochondrial mutation M1301. This nuclear suppressor (SUP-101) is allele specific and dominant. The possible role of the sequence affected by M1301 in terms of a recognition site for a nuclear gene product will be discussed.
A measurable result of nearly all influences which affect the primary processes of photosynthesis is a change of the fluorescence emission of a plant. This change of the fluorescence emission due to substances which affect or block photosynthesis is well known since the work of Kautsky (1943). The fluorescence test used here, due to the optical characteristics of the photosynthetic pigments (chlorophyll fluorescence greater than 660 nm), allows the measurement of the fluorescence of algae (Scenedesmus sp./Chlorella sp.). The measurement process is demonstrated. The results show the principal function of the bioassay and its sensitivity. Effects of the algae can be demonstrated at a very low pollutant concentration. The time from the dosage of a toxicant to a clear reaction of the algae is very short (5 min). The aim of the actual research is the determination of the sensitivity of the bioassay to a representative number of chemicals and possible interactions with physical parameters. A connection to a data system, e.g., computer registration of the fluorescence curve and an automated process control, will be the next step.
The results of 35 patients who got whole brain irradiation for metastatic disease are analysed in terms of relief of symptoms, quality of remission and survival time. Patients are distinguished in a group with known and in a group with unknown primary tumor. The results of the first group are indicated in brackets. The mean survival time for patients with unknown primary tumor is 7,5(4,2) and the median survival time is 3(2,2) months. 12 months after radiotherapy, 25% (9%) of the patients are still alive. More than 75% (55%) show considerable relief of symptoms. The proportion of failures is approximately 20% for both groups. These results indicate that radiotherapy of brain metastases gives good palliation even for patients with unknown primary tumor.
Nail-fold capillaroscopy is performed on 135 patients with primary Raynaud's disease. There is no significant difference between patients with long clinical story and new ones. The capillaroscopy is highly correlated with severity of vasomotor troubles. Parameters of bad prognosis are a high frequency of morphological abnormalities, venodilation, sludge phenomenon and hemorrhagies.
Simultaneous application of 5-fluorouracil and radiotherapy is generally accepted in the treatment of gastrointestinal tumours. However, in 10 patients with metastatic gastrointestinal tumours we observed intolerable toxicity during this combined treatment regimen. Because of gastrointestinal and haematological toxicity the combined modality was interrupted in all patients. Given sequentially, this regimen was tolerated. Our experience indicates that an intolerable high rate of toxicity has to be taken into consideration in case of the simultaneous combination of 5-fluorouracil and radiotherapy.
Four mitochondrial mutations are known to block excision of intron I1 of the cob gene in S.cerevisiae. The nucleotide sequence alteration of one of them, M4873, has been determined. It is a deletion of 1 bp in a run of five G's at a distance of 30 to 34 bp upstream to the 3' splice point. Reversion is found to occur by restoration of the run of five G's either by insertion of 1 G (wild type reversion) or by transition A leads to G next to this run of G's (pseudo-wild type reversion). The effect of mutation and reversion on RNA splicing indicates that the run of five G's is of critical importance for intron I1 excision, possibly in participating in the formation of a splice signal with a helical structure. This presumption is confirmed by the observation that this sequence is part of a larger sequence of some 80 bp next to the 3' splice point which is conserved to some extend in the four mitochondrial introns (bI1, aI1, aI2, aI5) that survive after excision as circular RNAs. Most striking is the conservation of this sequence at the level of secondary structure.
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