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Biomedical subjects

P Pietsch

Publications and source records attributed to P Pietsch.

At least 19 recordsLinked to original sources
PubMed1991

Tectectomy in the cyclopean salamander.

In an Ambystoma larva with both natural eyes removed and one eye grafted atop the head (Cyclops preparation), vision-dependent behavior usually recovers from the enucleation inherent in the operation, but the optically activated skin blanching reaction reappears in a very small number of instances. In the present studies, while the latter trend continued for the conventional Cyclops preparation, tectectomy concurrent with the ectopic eye transplantation resulted in a several-fold increase in the recovery of blanching competency. Some 60 percent of the tectectomized Cyclops animals exhibited the same Hogben-Slome pigmentation indices as larvae with one natural eye intact (controls). As measured planimetrically with an image analyzer, the pigment spots (melanosome containing portions of dermal melanocytes) contracted to the same extent in the blanch-competent Cyclops animals as in controls with a single natural eye.

Ambystoma↗
PubMed1991

Measures of phototaxis and movement detection in the larval salamander.

In this investigation, we describe two precise tests of visual function that integrate quasinatural situations with time-lapse video recording and infrared computerized monitoring of activity to assess movement detection and phototaxic tendencies, respectively. Four groups of larvae from A. punctatum, A. tigrinum, A. mexicanum, and a mutant albino axolotl were tested in an alley containing light and dark halves and lined with infrared sensors to monitor their phototaxic response. A. punctatum showed no phototaxic tendency, while the other three groups displayed a strong negative phototaxic response. Enucleation of the eyes in mutant albinos eliminated the negative phototaxis. Visual detection of motion was tested by videorecording the behavior of A. punctatum, A. mexicanum, and the mutant albino axolotl larvae while they explored a large bowl with 6 small vials on the perimeter, one of which contained white worms. A. punctatum rapidly approached the worm vial and engaged in intense predatory behavior. A. mexicanum responded to the presence of worms very slowly and rapidly lost interest. Albino axolotls displayed no visual recognition of the worms. The results indicate that visual function can be precisely determined in larval salamanders utilizing behavioral measures consistent with the animal's natural tendencies.

Ambystoma↗
PubMed1991

Effects of retinoic acid on the muscle patterns produced during forelimb regeneration in larval salamanders (Ambystoma).

After systemic treatment with retinoic acid (RA), Ambystoma opacum and A. punctatum larvae regenerated forelimbs with a wide variety of skeletal and gross anatomical abnormalities. Yet the musculatures within the RA-treated limb regenerates were normal even in instances where the cartilages were deformed beyond recognition as components of the limb skeleton. RA is known to induce reduplication of limb structures, sometimes entire segments. When the latter condition occurred in the present study, the corresponding replicates exhibited limb musculatures which were perfect down to minute details, yet of opposite bilateral symmetry. The results attest, firstly, to the independence of myogenesis and chondrogenesis during limb regeneration. Secondly, RA treatment unmasked an otherwise hidden potential within postembryonic salamander limb tissue for the morphogenesis of the contralateral musculature.

Abnormalities, Drug-Induced↗
PubMed1990

Two-eyed versus one-eyed salamanders: does binocularity enhance the optically evoked skin blanching reactions of Ambystoma larvae?

A wide variety of visual functions show increases attributable to binocularity, and the question pursued here was whether a second eye enhances the visually stimulated skin blanching reaction of the larval salamander. Dermal melanin spots (produced by the aggregations of melanosomes within dermal melanophores and which contract or expand to lighten or darken the skin) were measured in eyeless (controls), one-eyed and two-eyed Ambystoma punctatum larvae after chronic adaptation of the subjects to a white background (i.e., stimulus conditions for maximum blanching). The eyeless subjects showed no blanching (thus remained dark) in white cups, and they exhibited melanin spots 7 or 8 times the size of those of the other two groups. All one-eyed or two-eyed subjects exhibited blanching reactions; planometric comparison revealed a significantly larger melanin spot area for one-eyed than for two-eyed animals; i.e., the binocular condition permitted greater contraction of the pigment spots than did the monocular condition. Analytical data compared favorably with independently ascertained pigmentation indices. The results indicate that a second eye quantitatively elevates the blanching maximum of a larval salamander.

Ambystoma↗
PubMed1990

Anterior decerebration blocks visual habituation in the larval salamander (Ambystoma punctatum).

Amputation of the rostral half of the cerebrum induces a compulsion-like reaction in larval Ambystoma punctatum towards Enchytraeus protected within glass vials. Normal and craniotomized larvae are visually attracted to worm-containing vials, as revealed by time-lapse video taping but, after several unsuccessful attempts to get the prey, habituate and depart. The video tapes revealed that anteriorly decerebrated animals spent as much as 100 of 120 minutes at the worm-containing vial, repeatedly but futilely attacking the glass. The data indicate that the telencephalon plays an active negative role in the salamander larva's visually guided behavior.

Ambystoma↗
PubMed1989

Immunological alterations inducible by mercury compounds. II. HgCl2 and gold sodium thiomalate enhance serum IgE and IgG concentrations in susceptible mouse strains.

We determined the levels of total IgE, IgG and IgM in the sera of HgCl2 and gold sodium thiomalate (GST) treated A.SW, C57Bl/6, and DBA/2 mice. In HgCl2 treated A.SW mice, IgE and IgG levels increased up to 30 times above normal. In C57Bl/6 mice HgCl2 induced a slight IgE increase, but no change in IgG. Strain DBA/2, by contrast, did not show significant increases in either IgE or IgG. A.SW mice also proved susceptible to the immunostimulatory effects of GST in that they responded by significant increases in IgE, IgG, and IgM. C57Bl/6 mice responded to GST by an increase in IgM alone, and DBA/2 mice again, were resistant. The same strain-specific responses have been reported with respect to the autoimmunizing effects inducible by HgCl2 and GST.

Adjuvants, Immunologic↗
PubMed1987

Respiratory phase detection and delay determination for breath-by-breath analysis.

The delay between air flow and gas concentration signals is generally assumed to be constant within a breath as well as from breath to breath, but it was not possible to examine the constancy of the delay with the delay determination techniques so far available. Thus we developed new methods for respiratory phase detection and delay determination. The presented algorithm for the detection of the start of inspiration and expiration (phase detection) replaces the generally used valve assembly with two pneumotachographs. Now, the pneumotachograph is used in a bidirectional mode, but with a volume criterion for phase detection replacing the less reliable threshold criterion. To measure the delay between flow and gas concentration signals, a test gas is periodically injected as a marker. This test gas contains less N2 than ambient air. Therefore, the delay is determined as time between the moment of injection and the drop of N2. These two methods rendered it possible to examine delay variations and their consequences. The investigation of various breathing patterns demonstrated that the usually assumed errors caused by delay uncertainty are underestimated. We suggest reliance on a breath-by-breath delay determination to account for delay variations.

Capillaries↗
PubMed1986

A pulsed diagonal-beam ultrasonic airflow meter.

The construction and specific function of a new ultrasonic flowmeter are described. The mean velocity of the respiratory airflow is calculated by measuring the transit times of short ultrasonic pulse trains, simultaneously transmitted upstream and downstream at a 500-Hz rate. The flowmeter system consists of a control unit and a separate flow head. The former includes the power supplies, a controlling microprocessor, most of the signal-processing circuitry, and three analog outputs for flow, volume, and temperature. The flow head contains the respiratory tube with a constant circular cross section (length 90 mm, diam 20 mm, dead space 35 ml), a fast temperature sensor, two electronic circuits for processing of flow and temperature data, and a sound transmission channel with two capacitive ultrasonic wide-band transducers. This respiratory airflow meter, suitable for spirometric maneuvers (vital capacity, forced vital capacity) as well as for long-term breath-by-breath respiratory analysis, is extremely fast (response time 1-2 ms) and accurate (volume accuracy with room air +/- 0.7%), with low noise (below 9 ml/s), a wide flow range (bidirectional from 0 to 9 l/s), and a flat frequency response up to 70 Hz.

Biomedical Engineering↗
PubMed1986

[Hepatitis B screening in pregnant patients and their children--a Greifswald perinatal-pediatric study].

During a period of one year with systematic screening performed in 1,401 pregnant women 8 cases positive for HBs-antigen could be detected. For the investigation we used a counter electrophoresis method. In 500 serial specimens an additional examination was performed by aid of a RIA as well. With an incidence of 0.57% the number of HBs antigen positive pregnancies in the territory of Greifswald was found to be significantly higher than reported previously from other regions of the GDR. Our results claim for a mass screening for hepatitis B during pregnancy. Because of the possibility of virus excretion with human milk, HBs positive mothers should not be used as milk donors. Other results related to our investigations give evidence for the significance of obtaining specific hygienic regulations when medical care is given to asymptomatic HBsAg carriers. They also underline the necessity of interdisciplinary cooperation for teaching medical staff in health care centers and giving correct advice to those detected as hepatitis B carriers.

Breast Feeding↗
PubMed1985

[Falithrom and pregnancy].

A case of uncontrolled, overdosed therapy with a coumarin in unknown pregnancy is reported on. Informations are discussed from the literature about the use of coumarin-derivates during pregnancy.

4-Hydroxycoumarins↗
PubMed1978

Phleomycin and bleomycin: molecular model building studies.

Molecular model building studies were conducted to simulate phleomycin-bleomycin (PB) antibiotics and thus assess a hypothetical polyphleomycin-DNA complex proposed earlier. While the latter model was not conclusively proved it was found to be quite consistent with the structure of PB compounds.

Anti-Bacterial Agents↗
PubMed1977

Electron microscopic detection of phleomycin during different waves of replication in regenerating skeletal muscle of mice following staining with mercuric chloride.

Phleomycin has devastating effects on regeneration of skeletal muscle when applied during an early wave of replication in the pre-myotube (new fibre) period of the reaction. The effect cannot be explained from the contribution of dividing cells to myotubes. Phleomycin's effects on regeneration are much less severe when the challenge coincides with a later wave of pre-myotube proliferation, effects that can be explained from the contribution of such cells to new muscle. An attempt has been made, by means of electron microscopy, to explain how phleomycin distributes early versus late wave cells, using a mercury substitution stain to detect the antibiotic. Cells of the two periods showed conspicuous differences in the staining characteristics of their chromatin. Positive staining reactions outside the nucleus were confined mainly to ribosomes. Exceptions included materials in transit across nuclear and cytoplasmic membranes.

Animals↗
PubMed1975

[Individual selection for operation in the surgery of ulcer].

In 918 operations of gastroduodenal ulcer the operation was individually chosen. The critically indicated selective oral vagotomy with or without drainage operation yielded comparatively good results, it is a valuable supplementation of the previously only performed resection treatment. Ulcus duodenum and ulcus pepticum jejuni post-operativum are the domain of vagotomy, whereas in ulcus ventriculi in most cases is resected according to Billroth I. In old patients or severe concomitant diseases vagotomies--even in hypochlorhydria--yield as satisfying results as excision of ulcer and segment resections. Bleeding or perforated parapyloric ulcers were in selected cases also treated by vagotomies. On account of good early and late results the 2/3 resektion after Billroth I or II is never defective and it is more favourable for the patient than a wrongly indicated and technically insufficiency performed vagotomy. Operative techniques should be used which are mastered methodically. The vagotomy demands a critical indication and cautions technique, in the hand of an experienced operator it anticipates the removal of peptic ulcer. A final judgment is allowed only after an interval of 1 to 2 decenniums.

Anemia↗
PubMed1975

[Transformation surgery in dumping syndrome after Billroth II stomach resection].

After ineffective conservative therapy of the dumping-syndrome the transformation of Billroth's second operation into Billroth's first operation or the interposition of a jejunum segment between reamins of the stomach and duodenum are indicated. The increased risk of operation demands a careful selection of the patients. By means of these interventions an essential improvement of the complaints may be achieved.

Adult↗
PubMed1975

[Prenatal brain damage in maternal, untreated phenylketonuria].

Several reports in literature exist about mentally retarded non-phenylketonuric offspring from untreated phenylketonuric mothers with normal intelligence. One additional case is added who was detected after screening of about 1600 pregnant women. Biochemical investigations of the mother identified her as "classical phenylketonuria". Column chromatographic analysis of amino acids in amniotic fluid revealed a very high pheylalanine level and the diminution of the other, especially essential amino acids. The estimated amino acids in fetal brain also revealed a very high phenylalanine level. Routine screening for phenylketonuria by means of the Guthrie's test is recommended for all pregnant women at the first visit of the counseling.

Amino Acids↗