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Biomedical subjects

B Schmidt

Publications and source records attributed to B Schmidt.

At least 415 records · Page 23Linked to original sources
PubMed1989

Activation of mononuclear cells by aqueous extracts from hollow-fibre haemodialysers.

Monocytes from patients treated by long-term haemodialysis with cellulosic membranes can show functional signs of activation depending on the dialyser module. To elucidate the mechanism of this phenomenon, aqueous extracts of various hollow-fibre dialysers were tested for their ability to induce in-vitro interleukin-1 generation in peripheral blood mononuclear cells from healthy donors. Extracts were prepared by passing 0.5 litres of sterile endotoxin-free water from the dialysate to the blood compartment of the dialyser. Different dialysers containing cellulosic membranes, i.e. cuprophan, and hemophan, were studied. Extracts were dried by lyophilisation and resuspended in cell culture medium before incubation with peripheral blood mononuclear cells for 18 hours at 37 degrees C in a 5% CO2 atmosphere. Interleukin-1 was assayed by biological or radioimmunological methods. Extracts from steam-autoclaved, dry-stored, or gamma-sterilised, wet-stored cuprophan and hemophan modules resulted in interleukin-1 activity that did not differ from negative controls. By contrast, extracts from cuprophan caused significant interleukin-1 production when prepared from ethylene oxide-sterilised, dry-stored dialysers. This monokine-inducing activity could not be neutralised by the addition of polymyxin B and was heat unstable, indicating that the cell-activating stimulus was not endotoxin. Extensive rinsing of the module with water before extract preparation totally mitigated the in-vitro production of interleukin-1. Our results suggest that the extract-induced activation of peripheral blood mononuclear cells found with some dialysers containing membranes of cellulosic origin cannot be exclusively related to the membrane polymer, but depends on a number of other parameters such as sterilisation and storage mode of a given membrane.

Adjuvants, Immunologic↗
PubMed1989

[Current observations on the morphology and biomechanics of the human flexor tendon sheath].

Authors give a short description, based on own experimental work and literary data, of the tendon sheat biomechanics of the long fingers. The importance of the integrity of the tendon sheat--subcutis--skin unit is presented. Starting from this, a new possibility of exposing the flexor tendons, a laterobasal exposure is shown. The experimental character of their work is stressed, it is however underlined that clinical importance is attached to their aspect.

Biomechanical Phenomena↗
PubMed1989

CT of primary retroperitoneal soft tissue masses.

CT scans of 54 patients with primary peritoneal soft tissue masses were studied retrospectively. All lesions were untreated at the time of the CT examinations and the nature of the lesions was subsequently proven histologically. Each scan was evaluated initially without knowledge of clinical and pathological information in respect of several criteria including size and number of lesions, delineation of the lesions, border definition, and internal structure of the lesions. The lesions were demonstrated in all patients and displayed with great anatomical detail. The presence of gas and attenuation values below -30 HU were the only singular signs specifically indicative of abscesses or lipomatous tumors, respectively. All other applied criteria were found both in sarcomas and benign masses, and no malignant neoplasm had CT characteristics specific enough to differentiate it from any other one. Considering all criteria, the benign or malignant nature of the lesions could be predicted in 43% of the patients studied based solely on CT morphology. In context with the clinical information provided on the study request form, 54% of the lesions were correctly classified into aetiological sub-groups (i.e. soft tissue sarcoma, abscess).

Abscess↗
PubMed1989

[Decrease of relative amplitude of evoked visual potentials caused by the use of a prism].

In search for an objective method of defining the quality of the binocular vision the author used the visual evoked potentials. The point was before all to estimate the added up records from both eyes checking up whether the amplitude of this record increases in dependence on the fact whether we apply the stimulus to one or to both eyes. A straight dependence between a binocular record from the whole retina and a record from the maculae cannot be discovered. By macular stimulation after placing a prism occurs a lowering of the relative amplitude connected with a disturbance of binocular vision and this enables the differentiation between the presence or lack of the stereoscopic vision in dependence on the fact wheather diplopia occurs or it does not.

Humans↗
PubMed1989

Searching MEDLINE for randomized clinical trials involving care of the newborn.

Randomized clinical trials make up only a small fraction of published articles concerning care of the newborn infant and an even smaller fraction of articles about all human subjects. The busy pediatrician who wants to keep abreast of the medical literature requires strategies to detect such relevant studies promptly and reliably. Computer searching of MEDLINE is an attractive, potentially powerful but not sufficiently validated means of achieving this goal. Therefore, the sensitivity, specificity, and positive predictive value of two MEDLINE search strategies designed to detect randomized clinical trials for prevention and treatment of newborn diseases among all original articles about human subjects appearing in ten pediatric and general medical journals during 1985 were determined. The yield of both MEDLINE searches was compared to that of a manual search. Fifty-three randomized clinical trials of newborn care were identified by hand search among 233 articles concerning care of the newborn and 2,988 original articles about human subjects. The sensitivities of the MEDLINE searches were 53% and 34%, respectively, and the positive predictive values were 82% and 69%, respectively. Specificity of both computer searches was virtually 100%. Twenty-one randomized clinical trials were not identified by either MEDLINE search strategy, 17 of them for failure of the indexer to assign any methodologic terms at all or failure to assign sufficiently stringent methodologic terms. Consequently, sensitivities were higher, 77% and 68% respectively, when no methodologic terms were used during repeat searches. However, positive predictive values decreased concomitantly to 20% or less.(ABSTRACT TRUNCATED AT 250 WORDS)

Clinical Trials as Topic↗
PubMed1989

[History of the human milk collection bank of the Pediatric Department of the Dresden Medical Academy].

The Dresden's milk banking depot was established in 1942. Though there has been a correlation between birth rate and milk quantity collected over the last years, this comparison also points out an unsatisfying willingness of our mothers to nurse their babies. Despite the danger of transferring special infections by raw human milk we will not be able to renounce on this food in special indications in the future.

Academic Medical Centers↗
PubMed1989

[Radiotherapy of esophageal carcinoma: an assessment of patients treated at Tübingen from 1977 to 1982].

We report on the results of therapy of 116 patients with esophagus carcinoma. The patients have been attended to at the Medical Radiation Institute of Tübingen between 1977 and 1982. In 95 cases sole radiation was performed as operation was impossible. The other patients underwent a combined surgical-radiotherapeutical treatment. The joint doses of radiation applied ran from 50 to 70 Gy in five to seven weeks' time. In particular we considered the total survival rate according to tumor stage, the local tumor control and the period until relapse. 22% of the primarily irradiated patients achieved complete remission, 42% reached particular remission and 15% achieved minimal tumor remission (total response rate: 79%). Merely in 8% of the cases the tumor did not respond perceptibly. In the other cases irradiation had to be interrupted because of general worsening, or the patients got lost to post-therapeutical observation. The total survival rates, all stages taken into account, arose as follows: one year: 36.8%, two years: 12.6%, five years: 7.3%. After sole radiotherapy in 67% of the cases which had a radiologically verified relapse more than six months passed by before a local recurrence tumor was stated. The bad prognosis of the esophagus carcinoma, as demonstrated in literature, is entirely confirmed-the negative selection of our patients taken into account. The high rank of radiotherapy in achieving effective palliation is emphasized.

Adenocarcinoma↗
PubMed1988

Heparin clearance and ex vivo recovery in newborn piglets and adult pigs.

The newborn infant requires more heparin per kg body weight than the adult to achieve similar heparin plasma levels. Possible mechanisms include altered heparin pharmacokinetics and/or a decreased expression of anticoagulant activity of heparin in new-born plasma because of low levels of antithrombin III (AT-III). We measured the pharmacokinetics and the anticoagulant activity of heparin in the pig (AT-III level: 100%), in the piglet (levels of AT-III: 50% of adult) and the piglet given exogenous porcine AT-III. All pigs were bolused with 125I-heparin (25 or 100 units/kg) and blood samples collected for the measurement of 125I-radioactivity, and antifactor Xa activity. The half-life of 125I-heparin was dose-dependent and similar in pigs and piglets; however, the volume of distribution was greater in the newborn resulting in an increased total clearance compared to the pig. The anti-factor Xa activity disappeared earlier in the piglet than in the pig. Both the kinetics and the absolute recovery of anti-factor Xa activity were normalized to pig values (after correction for different volumes of distribution) when the piglets were infused with exogenous AT-III. Thus apparent heparin resistance of the newborn is due to both an increased volume of distribution and the low AT-III level which limits the measurement of the anticoagulant activity of heparin in conventional anti-factor Xa assays.

Aging↗
PubMed1988

Antithrombotic properties of heparin in a neonatal piglet model of thrombin-induced thrombosis.

The relative deficiency of antithrombin III (AT III) in neonatal plasma results in lower recovery of heparin in some assay systems. It is uncertain whether low AT III levels also limit the antithrombotic effects of heparin in this age group. We therefore compared the antithrombotic properties of heparin in mature pigs and newborn piglets, whose coagulation and inhibitor system closely resembles that of the human neonate. Animals were pretreated with saline, 10 or 25 U/kg heparin (n greater than or equal to 16 per age group and dose). Following an injection of 100 U/kg thrombin, systemic 125I-fibrinogen consumption and local 125I-fibrinogen incorporation into jugular venous stasis thrombi were measured. Significantly more 125I-fibrinogen was consumed in piglets than in pigs systemically (p less than 0.0001), as well as within the occluded vein segment (p = 0.0112), largely because heparin was less effective in piglets than in pigs. This neonatal resistance to heparin could not be explained by lower heparin levels in the newborn animals. However, pretreatment with AT III concentrate significantly improved the antithrombotic properties of heparin in this age group (p less than 0.0001). We conclude that physiologically low AT III levels reduce the efficacy of heparin in neutralizing thrombin activity in newborn piglets. We speculate that AT III deficiency may also limit the antithrombotic properties of heparin in newborn infants with thrombotic disease.

Animals↗
PubMed1988

Mitochondrial protein import: identification of processing peptidase and of PEP, a processing enhancing protein.

Transport of nuclear-encoded precursor proteins into mitochondria includes proteolytic cleavage of amino-terminal targeting sequences in the mitochondrial matrix. We have isolated the processing activity from Neurospora crassa. The final preparation (enriched ca. 10,000-fold over cell extracts) consists of two proteins, the matrix processing peptidase (MPP, 57 kd) and a processing enhancing protein (PEP, 52 kd). The two components were isolated as monomers. PEP is about 15-fold more abundant in mitochondria than MPP. It is partly associated with the inner membrane, while MPP is soluble in the matrix. MPP alone has a low processing activity whereas PEP alone has no apparent activity. Upon recombining both, full processing activity is restored. Our data indicate that MPP contains the catalytic site and that PEP has an enhancing function. The mitochondrial processing enzyme appears to represent a new type of "signal peptidase," different from the bacterial leader peptidase and the signal peptidase of the endoplasmic reticulum.

Amino Acid Sequence↗
PubMed1988

Human lysosomal acid phosphatase: cloning, expression and chromosomal assignment.

A 2112-bp cDNA clone (lambda CT29) encoding the entire sequence of the human lysosomal acid phosphatase (EC 3.1.3.2) was isolated from a lambda gt11 human placenta cDNA library. The cDNA hybridized with a 2.3-kb mRNA from human liver and HL-60 promyelocytes. The gene for lysosomal acid phosphatase was localized to human chromosome 11. The cDNA includes a 12-bp 5' non-coding region, an open reading frame of 1269 bp and an 831-bp 3' non-coding region with a putative polyadenylation signal 25 bp upstream of a 3' poly(A) tract. The deduced amino acid sequence reveals a putative signal sequence of 30 amino acids followed by a sequence of 393 amino acids that contains eight potential glycosylation sites and a hydrophobic region, which could function as a transmembrane domain. A 60% homology between the known 23 N-terminal amino acid residues of human prostatic acid phosphatase and the N-terminal sequence of lysosomal acid phosphatase suggests an evolutionary link between these two phosphatases. Insertion of the cDNA into the expression vector pSVL yielded a construct that encoded enzymatically active acid phosphatase in transfected monkey COS cells.

Acid Phosphatase↗
PubMed1988

Strengths and limitations of the Apgar score: a critical appraisal.

The Apgar score is widely used for several purposes: to discriminate between infants who require resuscitation at birth and those who do not; to predict outcome; and to evaluate change in the condition of the newly born over the first minutes of life. Using published evidence of its clinical reliability and validity, this article explores whether the Apgar score serves all three measurement purposes equally well. Methodologic guidelines for assessing health indices are applied to examine the structure of the Apgar score as well as its function where performance data are lacking or inadequate. Despite the advent of modern technology, the Apgar score remains the best tool for the identification of newly born infants in need for cardiopulmonary resuscitation. For predicting later death or handicap, the Apgar score is insensitive but fairly specific. The ability of the Apgar score to measure change over time has not been studied systematically; however, available data suggest that serial Apgar ratings in infants with early low scores detect clinically important recovery of lack thereof.

Apgar Score↗
PubMed1988

Evaluation of an outpatient culture device in continuous ambulatory peritoneal dialysis.

From August 1983 through August 1986, we used a dipstick culture device for outpatient dialysate cultures among patients undergoing continuous ambulatory peritoneal dialysis. The device was used in 42% of 531 peritonitis episodes. In 21% of the peritonitis episodes, patients elected to be hospitalized for treatment and, therefore, did not obtain a dialysate culture. The frequency of noncompliance was 18%. All samples were received within four days of mailing. Forty percent of isolates were gram-positive organisms, 30% were gram-negative, 3% were fungal organisms, and 27% of the cultures failed to yield a growth. Aside from a greater incidence of failure to define a bacterial growth responsible for peritonitis, the spectrum of organisms was similar to culture results obtained from the patients who elected, during this same period, to be hospitalized. We believe the dipstick device may be used effectively for outpatient dialysate cultures.

Ambulatory Care↗
PubMed1988

Altered interleukin-1 production in patients undergoing hemodialysis.

The capacity of peripheral blood mononuclear cells (PBMC) to undergo spontaneous and induced interleukin-1 (IL-1) production was examined in 10 healthy controls and in 10 patients undergoing intermittent hemodialysis (HD) using cuprophane membranes. Extracellular and cytoplasmic IL-1 activity was assayed by biologic and radioimmunologic methods. Spontaneous extracellular IL-1 activity was low in the patient and the control groups. However, spontaneous cytoplasmic IL-1 activity was greatly increased in the patients. Both assays gave comparable results. In contrast, the IL-1 response to lipopolysaccharide was significantly decreased in PBMC from the patients compared to controls. From these results we conclude that PBMC from HD patients show functional signs of activation, but an impaired response to exogenous stimuli, such as endotoxin.

Adult↗