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Biomedical subjects

P Stark

Publications and source records attributed to P Stark.

At least 199 records · Page 11Linked to original sources
PubMed1979

The effect of local anaesthetic agents on afferent and motor nerve impulses in the frog.

In the frog nerve-muscle preparation an attempt was made to determine the sites of local anaesthetic activity. The drugs were applied not only to the nerve fiber, but also to other structures of the nerve. Different blocking concentrations proved that the drugs effected different sites. It was shown that small concentrations of the agents effected the sensory endings of afferent nerves and the muscle spindles. The muscle spindle needed the smallest minimal concentration (Cm) to be blocked. The sensory endings of the C fibers needed a higher one and the motor terminal a still higher one. However, all these concentrations belonged to a similar range (3 X, 4 X and 5 X 10(-5) g/ml bupivacaine or etidocaine). To block the nerve trunk a much higher Cm was mandatory (4 X 10(-4) for C fibers and greater than 5 X 10(-4) g/ml for A alpha fibers). This means that the effect of the local anaesthetic drugs on the nervous system is not single but multiple.

Action Potentials↗
PubMed1979

[The dose-effect-ratio of isobaric bupivacaine in spinal analgesia (author's transl)].

Isobaric bupivacaine 0.5% with adrenaline 1:200,000 was used for spinal anaesthesia. The influence of dose (mg) and volume (ml) on segmental spread and duration of spinal block was investigated. Bupivacaine 10 or 15 mg was injected in 2 or 3 ml of solution. The segmental spread and duration of analgesic block was tested at certain time intervals. The results showed that: 1. an increase in dose is not followed by a larger segmental spread or longer duration of analgesic block, 2. the increase of the volume injected is followed by an increase in segmental spread of analgesic block. This is independent of the concentration of the local anaesthetic, 3. the segmental regression of analgesic block starts in the cephalad segments. Therefore, higher spread of analgesic block provides prolonged analgesia in the lower segments. The results of this investigation are controversal in relation to the reports in the literature of the last two decades. The increase in dosage of the local anaesthetic did not increase the segmental spread and duration of analgesia. Only the volume injected is responsible for an increase in segmental spread of analgesia. Of course the concentration of the local anaesthetic injected has to be at least the minimal concentration necessary to result in a sensory nerve block.

Anesthesia, Spinal↗
PubMed1978

The retrorectal space.

Ninety-nine adults with an enlarged retrorectal space on barium enema examination have been evaluated. Measurements were based on previously described methods using the lateral view of the barium filled rectum. In 38.4% of the cases there was no lesion (normal variations). The rest were classified as inflammatory conditions, tumours, and miscellaneous lesions. It is concluded that an increased width of the presacral space per se does not necessarily connote a lesion. Pathological widening of the space is usually associated with changes of the contour of the rectum, abnormalities of the sacrum, or other alterations of the presacral soft tissues.

Barium Sulfate↗
PubMed1978

Intrathoracic lymph node metastases from extrathoracic neoplasms.

The clinical records of 1,071 cases of extrathoracic malignant neoplasms seen over a 2 year period sere reviewed: 163 had abnormal chest films, and 25 of these showed evidence of mediastinal and/or hilar lymph node metastases. The primary malignancies which metastasized to intrathoracic lymph nodes included eight tumors of the head and neck, 12 genitourinary malignancies, three carcinomas of the breast, and two malignant melanomas. The chest films were analyzed to determine the distribution of lymph node groups involved. Unilateral lymph node enlargement occurred in eight. The most frequently detected lymph node group was the right paratracheal chain (60%), while the subcarinal and posterior mediastinal groups were rarely affected. Of the 25 cases, 10 had radiographic evidence of hematogenous or lymphangitic metastases in addition in the lungs. Metastatic disease from extrathoracic neoplasms should always be considered in the differential diagnosis of hilar and mediastinal adenopathy.

Adolescent↗
PubMed1978

[pH of the cerebro spinal fluid during subdural block (author's transl)].

This study was initiated by other authors who found that bupivacaine precipitated together with spinal fluid in vitro and who assumed that during spinal anaesthesia complications might be possible. Under the influence of several local anaesthetic agents the pH of the spinal fluid and in 160 cases the precipitation was examined. There was no precipitation. The experimental conditions were nearly in vivo conditions. The results differed clearly from those in vitro. While in vitro bupivacaine precipitated from a pH higher than 7.37 in concentrations higher than 0.8 mg/ml [2], the pH of the spinal fluid in vivo was lower than 7.35 continually and the concentration of bupivacaine not higher than 0.3 mg/ml. This means that the border of bupivacaine precipitation is by far not reached in vivo and that complications therefore are not possible.

Anesthesia, Spinal↗
PubMed1978

[The use of nerve stimulators for nerve blocks (author's transl)].

The clinical experience using peripheral nerve stimulators for nerve blocks is described. This method has the advantage that the patient cooperation is not required. In addition injections of local anaesthetic agents can be placed more accurately and therefore the total dose may be lowered. Thus successful injection is more probable and the possibility of an inadequate block, a Wedensky block, is diminished. 301 therapeutic blocks and 195 blocks for clinical anaesthesia are described.

Anesthetics, Local↗
PubMed1977

Pneumothorax.

Explore the source record for details and available documents.

Adult↗
PubMed1977

Cannabinoids. 1. 1-Amino- and 1-mercapto-7,8,9,10-tetrahydro-6H-dibenzo [b,d]pyrans.

A series of 1-amino- and 1-mercapto-7,8,9,10-tetrahydro-6H-dibenzo[b,d]pyrans was synthesized and subsequently evaluated in three rodent test systems for CNS activity. The structure-activity data generated indicate that, in general, a change of the 1-hydroxy group to an amine results in a retention of pharmacological activity but that a change to sulfur results in loss of pharmacological activity. Derivatization of the 1-amino group with various functions decreased the activity of the parent compound. For optimum potency, in all series, the 3-position alkyl side chain should be either 1,1- or 1,2-dimethylheptyl. With either the 1-hydroxy- or 1-amino-7,8,9,10-tetrahydro-3-(1,1-dimethylheptyl)-6,6,9-trimethyl-6H-dibenzo[b,d]pyran (4c or 10c), preparation of the optically active antipodes did not lead to any great degree of spearation of activity. Both of the antipodes possess pharmacological activity as measured in these rodent test systems.

Animals↗
PubMed1977

Cannabinoids. 2. Synthesis and central nervous system activities of some B-ring homocannabinoid derivatives and related lactones.

The syntheses of some novel B-ring homocannabinoid derivatives 1,2, and 4 and related lactones 3 and 5 are described. Compounds 1-5 are 6,7,8,9,10,11-hexahydrodibenz[b,d]oxepins. CNS structure-activity correlations were determined using three rodent models. The potency and activity profile of these seven-membered ring compounds were compared with the corresponding six-membered ring homologues 6 and 7. A possible seperation of CNS activities was noted with compound 1. Unexpected pharmacological activity was discovered with lactone 3, which was about equipotent to 1-delta9-tetrahydrocannabinol. It was found that dimethylation at the 7 postition decreased CNS activity when the 6 position was either a carbonyl or methylene group.

Animals↗
PubMed1977

[The pH-changes of the spinal fluid following bupivacaine (author's transl)].

The ph-changes of cerebral spinal fluid were measured following subarachnoid injection of bupivacaine 0.5% with and without adrenaline (1:200,000) during the three hours after the start of anaesthesia. At the same time drug precipitation was not detected. The ph-changes however, were pronounced but not enough to cause disturbances of the homoeostatic milieu. Especially no significant differences related to adrenaline were be found. The authors recommend bupivacaine 0.5% with and without adrenaline for spinal anaesthesia.

Aged↗
PubMed1977

[On spinal anaesthesia with isobaric bupivacaine 0,5% (author's transl)].

Clinical experiences of 5001 subarachnoid blocks using isobaric bupivacaine 0.5%, with and without adrenaline, for surgery are reported. The clinical results are satisfactory and no neurological sequelae are known to the authors. In vivo studies of C.S.F. after subarachnoid injection of bupivacaine 0.5% in an isobaric solution showed no changes in pH or precipitation. According to these results the authors see no contraindication in the use of bupivacine 0,5% for subarachnoid injection. The use of higher concentrations (e.g. 1%), however, can not be recommended.

Anesthesia, Spinal↗
PubMed1976

Control of plasma aldosterone in infancy and childhood. A study of plasma renin activity, plasma cortisol and plasma aldosterone.

In order to elucidate the main factors controlling plasma aldosterone in infancy and childhood, plasma renin activity (PRA), plasma cortisol (PC, as a parameter of ACTH activity), plasma aldosterone (PA) and serum sodium and potassium were measured simultaneously in 84 healthy children (62 recumbent, 22 upright) ranging in age from 6 days to 16 years. 10 healthy male students served as adult controls. As compared to the controls, PRA levels were significantly higher in the children up to the age of 12 years. PA was also elevated in most children; the highest values for PA and for PRA were observed during the first 4 years of life. A significant positive correlation between PRA and PA (n = 84, r = 0,62, p less than 0.001) was found. There were no significant differences in serum sodium or potassium or in PC. All PC values were - with one exception - within the range found in healthy adults. Our results indicate that high PA values are freuqently observed in healthy children. They are mainly caused by elevated PRA. The physiological significance of increased activation of the renin-angiotensin-aldosterone system in infancy is not yet clear.

Adolescent↗
PubMed1974

Poly(ADP-ribose): release of template restriction in HeLa cells.

Evidence is presented to show that ADP-ribosylation of nuclear proteins by poly(ADP-ribose) polymerase enhances template-primer activity of HeLa cell nuclear DNA. We used Escherichia coli DNA polymerase I (EC 2.7.7.7; DNA nucleotidyltransferase) as an exogenous probe of nuclear DNA status. Neither NAD nor free poly(ADP-ribose) acts directly on the bacterial enzyme. The stimulation is specific for formation of ADP-ribosylated proteins and is not a generalized polyanion or nucleotide effect on chromatin. The release of template restriction is proportional to the capacity of a given cell line to synthesize poly(ADP-ribose); both the stimulation and poly(ADP-ribose) formation are coordinately proportional to NAD concentration. Binding studies with DNA polymerase indicate exposure or generation of additional 3'-OH primer sites due to ADP-ribosylation in intact nuclei. With intact cells, there appears a correlation among growth, physiological template restriction, and the above effects of ADP-ribosylation.

Adenosine Diphosphate↗