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Biomedical subjects

J Fischer

Publications and source records attributed to J Fischer.

At least 559 records · Page 31Linked to original sources
PubMed1977

New practical treadmill protocol for clinical use.

A new continuous treadmill protocol (USAFSAM) has been designed using a constant treadmill speed (3.3 miles/hour) and regular equal increments in treadmill grade (5%/3min). The constant treadmill speed requires only initial adaptation in patient stride, reduces technician adjustments and produces less electrocardiographic motion artifact than do protocols using multiple or higher treadmill speeds, or both. The regular equal increments in treadmill grade are easy to implement and provide a larger number of work loads than do protocols that are discontinuous or require larger changes in work load. The USAFSAM protocol was compared with the older Balke-Ware protocol in 26 healthy men (aged 30 to 59 years). Each fasting subject completed two maximal treadmill tests from each protocol. Measurements included minute heart rate from the electrocardiogram, auscultatory blood pressures and oxygen consumption obtained with standard techniques. Similarities in between-protocol measurements for submaximal and maximal treadmill efforts were impressive; differences were small and unimportant. Further, both protocols showed equal reproducibility for the measurements noted. Importantly, time to maximal effort was reduced by 24% with the USAFSAM protocol. The USAFSAM treadmill protocol has since been used in more than 500 clinical and screening examinations, thus confirming its advantages and practicality for routine clinical stress testing. Normal reference values previously established for the Balke-Ware protocol are shown to apply to the new USAFSAM protocol as well.

Adult↗
PubMed1977

Spreading depression elicited by thermal effects of ultrasonic irradiation of cerebral cortex in rats.

Cortical spreading depression (CSD) was elicited by focused ultrasonic irradiation (800 kHz) of exposed cerebral cortex in anesthetized rats. With the acoustic output of 0.64 W at the probe-tissue contact (3 mm in diameter), CSD was elicited after 28-sec irradiation in normothermic rats. Reduction of cortical temperature to 31 degrees C increased the threshold irradiation time to 82 sec on the average. Ten- to thirty-sec heating of cerebral cortex with a thermode elicited CSD when surface temperature exceeded 47 degrees C. Histological examination of the cortical areas exposed to threshold irradiation revealed a central coagulation lesion surrounded by edema. It is concluded that the ultrasonic irradiation elicits CSD by dissipated heat. Differences in threshold duration of irradiation in hypothermic and normothermic rats were used to compute the threshold temperature which had to be exceeded in the critical volume of cortex in order to start CSD.

Animals↗
PubMed1977

Optical studies on the molecular-sterical mechanism of metachromasia.

We have investigated how the stereochemical situation of the dye binding negative side groups on polysaccharides influences metachromatic staining effects. We found that selective binding of toluidine blue (pH = 1.0) in the places of substituted (acidified) vicinal OH groups C2 and C3 resulted in the clearest metachromasia with the strongest anisotropy effects and with a bright clear green polarization color. On the other hand, selective toluidine blue binding in the places of C6 of the carbohydrate rings of the polysaccharide chains resulted in orthochromatic basophilia and lack of birefringence. After transformation of all OH side groups into negatively charged groups, metachromatic staining was found mixed with an orthochromatic hue and a birefringence effect weaker than in the case of staining on the vicinal OH groups only. The need of poststaining stabilization of the labile metachromatic staining reactions is emphasized.

Animals↗
PubMed1977

Central venous cannulation: A radiological determination of catheter positions and immediate intrathoracic complications.

The incidence of immediate complications on inserting central venous catheters into 475 patients is reported. The catheter positions were verified by X-rays. Six different insertion routes were used. Central venous cannulation via the right internal jugular vein is recommended because of the high incidence of satisfactory catheter positions and the small number of puncture complications with this route.

Catheterization↗
PubMed1977

Comparison of the antidiuretic effects of single intravenous and intranasal doses of DDAVP in diabetes insipidus.

In 13 patients with hypothalamic diabetes insipidus after daily single intravenous (0.04-24 mug) and single intranasal (5-320 mug) doses of 1-deamino-8-D-arginine vasopressin (DDAVP) the relationships between the log doses and antidiuretic responses (log osmolalities of 24-hour urine samples) were compared. On the basis of such comparisons the ratio of nasal per venous daily single dose requirement was determined and found to be 26:1. Similarly, the relative potency of venous DDAVP was investigated in two subgroups of patients classified according to their response to peroral drugs. Seven times more DDAVP was required for patients treated previously with high doses of peroral antidiuretics. It was concluded that in groups of patients with divergent peroral dose requirements different DDAVP single-dose treatment schedules should be planned.

Administration, Intranasal↗
PubMed1977

The response of healthy men to treadmill exercise.

Heart rates, blood pressures, and functional responses to submaximal, maximal and postexertional treadmill testing are presented for a group of 704 healthy, asymptomatic aircrewmen referred to the USAF School of Aerospace Medicine. The indicated measurements are individually described by the use of percentiles. These data provide the practicing clinician with an accurate and complete description of the response of healthy men to treadmill exercise.

Adult↗
PubMed1977

Stimulation of the thalamus and its effect on electrographic manifestations of the brain in unrestrained rats.

The thalamus was electrically stimulated in unrestrained rats with implanted cortical and subcortical electrodes. Single pulses often triggered rhythmic cortical activity identical with the 8--9/sec spike episodes which occur spontaneously in rats in the walking state. In rhythmic stimulation of the thalamus, self-sustained 3/sec spike-wave paroxysmal activity, with partial clonic jerks, was observed. Specific and non-specific thalamic nuclei participated in the production of these activities.

Animals↗
PubMed1977

Optical polarization reveals different ultrastructural molecular arrangement of polysaccharides in the yeast cell walls.

The topo-optical aldehyde bisulfite-toluidine blue (ABT) reaction of vicinal OH and amino-OH groups offers new ways to study the ultrastructure of polysaccharides in different biological substrates. Through oriented dye binding on the reacting groups, the ABT reaction induces strong birefringence on the linearly ordered polysaccharides, which is negative with respect to their chain length. Using this method, two types of molecular order of the polysaccharides could be distinguished in the cell walls and capsules of yeasts. (1) The optically negative spherulitic character of the yeasts after the ABT reaction indicated that the toluidine blue molecules were bound tangentially (in a surface-parallel pattern) while the polysaccharide chains of the cell walls and capsules were oriented mainly radially. This structural pattern may be explained as resulting from a helicoid conformation of the polysaccharide component. (2) Acid or alkali hydrolysis removed the radially oriented polysaccharide component of the cell wall. The remaining, resistant polysaccharides showed up in the form of optically positive spherulites indicating radially oriented dye molecules on a circularly ordered, micellar polysaccharide texture.

Candida albicans↗
PubMed1977

[Immobilization of proteins on macroporous glasses involving maleinimide as the anchoring group].

Macroporous glasses with pore sizes from 400-1000 A appropriate for protein binding were produced and characterized by a thermal demixing procedure and alkaline after treatment. To achieve a covalent binding capacity relative to proteins, the gamma-aminopropyl derivative was allowed to react with 4-maleinimido benzoylic chloride to give preparations containing, in addition to maleinimide residues, acid chloride structures for the protein binding. A preparation of 400 A pore size was tested for its protein binding capacity relative to bovine serum albumin and trypsin. Furthermore, the capacity of binding glucoamylase from Endomycopsis bispora in active form was studied.

Animals↗
PubMed1977

[Vascular reconstructive procedures in patients with chronic occlusive arterial diseases and diabetes mellitus (author's transl)].

97 diabetic patients of 734 patients with a chronic occlusive arterial disease were observed in the years from 1968 to 1974. It was established the operability of arterial occlusions are influenced by heaviness, duration and setting in the diabetes mellitus only a little. The indication to operate is determined by the three-points-regulation at the diabetic patients, too. Vascular reconstructive procedures were only possible at each of a second or third patient independent of diabetes mellitus. 28 vascular reconstructive procedures in the femoro-popliteal reach were made at 22 diabetic patients. The results were successful in more about than 80 per cent by explorations from 1 to 5 years after operations.

Adult↗
PubMed1977

Photometric determination of total protein in lipemic sera.

We compared various procedures and biuret reagents suggested for determination of protein in lipemic sera. A modified procedure, consisting of the precipitation of serum protein with acetone and dissolution of the precipitate in a biuret reagent, has been developed. The sample (0.02 ml) is mixed with 0.1 ml of distilled water and 2 ml of acetone. The mixture is shaken, centrifuged, and the precipitate dissolved in 1.5 ml of ethylenediaminete-traacetate-chelated biuret reagent. This method is suitable for both clear and lipemic sera. Values obtained with the procedure proposed are in good agreement with values by the Kjeldahl method.

Biuret↗
PubMed1977

Histone phosphorylation and synthesis of DNA and RNA during phases of proliferation and differentiation induced in mouse epidermis by the tumor promoter 12-O-tetradecanoyl-phorbol-13-acetate.

The tumor promoter 12-O-tetradecanoyl-phorbol-13-acetate (TPA) induces discrete waves of proliferation and differentiation when applied to mouse epidermis. The aim of this study was to elucidate the temporal relationship between histone phosphorylation and synthesis of DNA and RNA in mouse epidermis during the process of tumor promotion. This investigation as facilitated by choosing a low but nevertheless strongly tumor-promoting dose of TPA (0.002 micronmole/mouse), which induced the epidermal cells to go through only one round of DNA synthesis and cell division. Histones were isolated from mouse epidermis, and the rates of phosphorylation of the individual histone species were determined at different times after treatment with TPA. The results demonstrated that the phosphorylation of H1 histone was initiated at about the same time as the synthesis of DNA but continued past the S phase and reached a maximum simultaneously with the maximum in the epidermal mitotic rate. The only other histone that phosphorylated to any significant extent was Histone H2A. From the results obtained, it was concluded that histone phosphorylation in the epidermis is related to the processes of DNA replication and mitosis after stimulation with TPA. Positive evidence for the activation of specific genes, which has been proposed by other authors to be important in the promotion of epidermal tumors, was not found in this investigation.

Animals↗
PubMed1977

The influence of pentobarbital upon a cortical epileptogenic focus in rats.

Three subsequent doses of pentobarbital (5, 15, and 40 mg/kg) were applied intraperitoneally in acute experiments in rats with a cortical epileptogenic focus. Histograms of intervals between individual focal discharges were shifted towards longer intervals even after the smallest dose of pentobarbital; the prolongation of intervals was clearly visible after the third dose also in the EEG recording. Shape of primary as well as projected cortical focal discharges after pentobarbital resembled that seen after local application of GABA. Barbiturate spindles which were present after the first and second dose of pentobarbital were regularly triggered by focal discharges. The mechanism of this triggering was probably a thalamocortical one, because marked projected discharges were recorded from various thalamic nuclei from the very beginning of focal activity.

Animals↗