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Biomedical subjects

M Weber

Publications and source records attributed to M Weber.

At least 541 records · Page 30Linked to original sources
PubMed1991

[Detection of acute graft rejection with Fourier transformation of the surface ECG in long-term follow-up of heart transplantation].

Up to now, diagnosis of acute rejection after heart transplantation (HTx) has been based on endomyocardial biopsy (EMB), but there is the need for reliable noninvasive parameters. Spectral analysis of the surface ECG with fast Fourier transformation (FFT) has been shown to be useful for rejection monitoring in the immediate postoperative phase. We tested the method in the chronic phase after HTx: the QRS complex (2 bipolar leads, position tattooed with Indian ink) was repeatedly analyzed with FFT (segment size 120 ms, 512 points. Blackman-Harris window) in 38 patients for 4-36 months after HTx. In mean intervals of 3 months, 254 checkups with FFT and EMB were performed on the same day. EMB revealed 28 acute rejection episodes in 21 patients, and ongoing rejection was diagnosed in 17 EMB. During rejection the frequency content of the QRS complex between 70 and 110 Hz increased in 25/28 rejection episodes (89%) and in 15/17 ongoing rejection cases, whereas in the time domain no specific changes could be seen. The QRS-amplitudes did not reliably indicate rejection, but decreased slowly during follow-up. After therapy the spectral changes disappeared within weeks. No signs of acute rejection were evident in 209 EMB: in 156/209 frequency analyses (77%) the spectra were constant, in 45/209 cases the frequency content increased, and eight analyses could not be evaluated. As the number of rejection crises decreased in the first postoperative months, there was an increasing number of false positive FFT analyses (positive predictive value 35%). Thus, a change of frequency content requires control by biopsy.(ABSTRACT TRUNCATED AT 250 WORDS)

Biopsy↗
PubMed1991

Documentation: short, simple, and meaningful.

Nursing diagnosis has been incorporated into the documentation in our neonatal units because it gives nurses credit for their unique functioning, provides for consistency in communication, facilitates continuity of care, and is therefore likely to improve the quality of nursing care. The documentation system utilizes flow sheets to document physiological functioning. The nursing progress note/individualized patient care plan provides for a narrative note and continuous update of the patient care plan, keeping it current and meaningful. Previous care plans have involved massive writing about nursing actions. By providing reference tools that list the actual nursing actions, this system allows the nurse's written documentation to describe what the focus of the nurse's work has always been: the patient and the patient's responses to nursing care.

Forms and Records Control↗
PubMed1991

[Bacterio-expert: an integrated system for assisting in the validation of antibiotic sensitivity tests. Retrospective application in 4053 Staphylococcus].

Bacterio-expert is a simple expert system for assisting in the validation of antibiotic sensitivity testing. This system is incorporated in a data acquisition and editing program for bacteriologic test (Bacterio program written in Turbo-Pascal for personal computer users by the same authors). The principles of this system are explained and results with 4,053 antibiotic sensitivity tests on Staphylococcus aureus isolates are reported. Approximately 10% of tests required corrections.

Anti-Bacterial Agents↗
PubMed1990

Aromatic L-amino acid decarboxylase-immunohistochemistry in the cat lower brainstem and midbrain.

By indirect immunohistochemistry, the present study examined the distribution of neuronal structures in the cat medulla oblongata, pons, and midbrain, showing immunoreactivity to aromatic L-amino acid decarboxylase (AADC), which catalyzes the conversion of L-3, 4-dihydroxyphenylalanine (L-DOPA) to dopamine, and 5-hydroxytryptophan to serotonin (5HT). With simultaneous and serial double immunostaining techniques, immunoreactivity to this enzyme was demonstrated in most of the catecholaminergic and serotonergic neurons. We could also demonstrate AADC-IR cell bodies that do not contain tyrosine hydroxylase (TH-) or 5HT-immunoreactivity (called "D-type cells") outside such monoaminergic cell systems. At the medullo-spinal junction, very small D-type cells were found within and beneath the ependymal layer of the 10th area of Rexed surrounding the central canal. D-type cells were localized in the caudal reticular formation, nucleus of the solitary tract, a dorsal aspect of the lateral parabrachial nucleus, and pretectal areas as have been reported in the rat. Furthermore, the present study describes, in the cat brainstem, new additional D-type cell groups that have not been reported in the rat. Dense or loose clusters of D-type cells were localized in the external edge of the laminar trigeminal nucleus, dorsal motor nucleus of the vagus, external cuneate nucleus, nucleus praepositus hypoglossi, central, pontine, and periaqueductal gray, superficial layer of the superior colliculus, and area medial to the retroflexus. D-type cells were loosely clustered in the lateral part of the central tegmental field dorsal to the substantia nigra, extending dorsally in the medial division of the posterior complex of the thalamus and medial side of the brachium of the inferior colliculus. They extended farther rostrodorsally along the medial side of the nucleus limitans and joined with the pretectal cell group. Almost all these cells were very small and ovoid to round with 1-2 short processes with the exception of dorsal motor vagal cells. AADC-IR axons were clearly identified in the vagal efferent nerves, longitudinal medullary pathway, dorsal tegmental bundle rostral to the locus coeruleus. Serotonergic axons were identified not only in the central tegmentum field and lateral side of the central superior nucleus, but also in the ventral surface of the medulla oblongata. We describe principal densely stained fiber plexuses in the cat brainstem. The findings of the present study provide a morphological basis for neurons that decarboxylate endogenous and exogenous L-DOPA, 5HTP, and other aromatic L-amino acids.

Animals↗
PubMed1990

Bleeding times in rats treated with heparin, heparin fragments of high and low anticoagulant activity and chemically modified heparin fragments of low anticoagulant activity.

A template bleeding time study in the rat was undertaken to see if it is possible to correlate bleeding times with the molecular weight, anticoagulant activity or chemical composition of heparin or heparin-derived compounds. Heparin from porcine intestinal mucosa (PM-heparin) and from bovine lung (BL-heparin) as well as heparin fragments from these sources were compared. Heparin fragments of low anticoagulant activity were prepared by affinity chromatography on immobilized antithrombin as well as by chemical modification. A heparin fragment of high affinity for antithrombin (HA-fragment) caused a marked and dose-dependent increase in bleeding time while the corresponding heparin fragment with low affinity for antithrombin (LA-fragment) had a marginal and non-dose dependent effect on the bleeding time. Similar results were also obtained with PM-heparin with high and low affinity for antithrombin. A high anti-FXa activity was not always correlated with a marked bleeding tendency. Provided that a fragment was devoid of activated partial thromboplastin time (APTT) activity, it was not possible to provoke a bleeding time of 20 min or longer, although the compound was administered at a dose of 1,088 U/kg (anti-FXa activity). On the other hand, a N-acetylated chemically oversulphated heparin fragment, with a very low anti-FXa activity (1 U/mg) and with an APTT activity of 34 U/mg, caused a bleeding time of 20 min or longer in 70% of the animals after injection of the same number of APTT units, 1,088 U/kg. These data indicate that the APTT activity is a better and more sensitive indicator of the bleeding than is the anti-FXa activity.

Acetylation↗
PubMed1990

An assessment of diltiazem and hydrochlorothiazide in hypertension. Application of factorial trial design to a multicenter clinical trial of combination therapy.

This multicenter, factorial-design trial assessed the safety and additive antihypertensive efficacy of a slow-release (SR) formulation of diltiazem hydrochloride given alone or in combination with hydrochlorothiazide for treatment of mild to moderate hypertension. After a 4- to 6-week placebo run-in period, 297 qualifying patients were randomized to receive placebo, 1 of 4 doses of diltiazem SR monotherapy, 1 of 3 doses of hydrochlorothiazide monotherapy, or 1 of 12 possible combinations of diltiazem SR and hydrochlorothiazide for 6 weeks. A dose-related reduction in blood pressure was demonstrated for each drug as monotherapy and for the two drugs in combination. Absolute blood pressures of patients who received combination therapy were lower by an overall mean of 3.0 mm Hg diastolic and 8.0 mm Hg systolic vs diltiazem SR used alone and 3.5 mm Hg diastolic and 4.0 mm Hg systolic vs hydrochlorothiazide used alone. At the largest doses used, 50% of patients achieved goal blood pressure while taking hydrochlorothiazide, 57% while taking diltiazem SR, and 75% while taking combination therapy. Combination therapy was well tolerated. This trial clearly demonstrates that diltiazem SR and hydrochlorothiazide have additive antihypertensive effects.

Adult↗
PubMed1990

[Epilepsy in elderly patients].

Epilepsy starting in patients aged over 60 years is classically said to be rare, but it is in fact remarkably frequent with an incidence rate higher than 100 in 100,000. Although these figures include isolated seizures, the recurrent seizure rate is still very high. In elderly people epilepsy is more often partial than generalized, and it must be distinguished from cerebral accidents of ischaemic origin and in particular from syncopes consecutive to postural hypotension or heart disease. Late onset epilepsy is often of vascular origin, but it may also be tumoral in some cases or, less frequently, post-traumatic, alcoholic or atrophic. Idiopathic generalized epilepsy is no longer observed. Cases of undetermined cause are less common than in younger subjects.

Adolescent↗
PubMed1990

Additive effects of calcium antagonists on cyclosporin A-induced inhibition of T-cell proliferation.

The purpose of this study was to investigate possible additive effects of calcium antagonists on the cyclosporin A (CsA)-induced inhibition of cellular immunity. Human T-cells were isolated using standard methods and stimulated with phytohaemagglutinin (PHA, n = 8), the monoclonal antibody OKT3 (n = 6), or mixed lymphocyte reaction (MLR, n = 5). Verapamil, nifedipine, nimodipine or diltiazem were added (5 x 10(-7) - 5 x 10(-5) M) to the cultures, either alone, or in combination with CsA (62.5, 125, and 250 ng/ml). 3H-thymidine uptake was measured to estimate the proliferative responses and dose response curves were constructed for the Ca antagonists and their combinations with CsA. A 50% inhibition of T-cell proliferation in the different stimulation assays was achieved with 3.2 x 10(-5) - 5.3 x 10(-5) M verapamil, 2.5 x 10(-5) -4.3 x 10(-5) M nifedipine, 3.7 x 10(-6) - 5 x 10(-6) M nimodipine, and greater than 5 x 10(-5) M diltiazem. In combination with CsA a dose-dependent additive inhibitory effect of the Ca antagonists on T-cell proliferation was observed. This effect was less pronounced in the OKT3 assay, intermediate after PHA stimulation and most pronounced in MLR. Even in low concentrations, which correspond to therapeutic serum concentrations, Ca antagonists have an additive inhibitory effect in MLR. We conclude that Ca antagonists exert a dose-dependent inhibitory effect on T-cell proliferation. A combination of CsA with verapamil, nifedipine, nimodipine, or diltiazem is more effective than each drug given alone. This additive effect of Ca antagonists and CsA may possibly contribute to a better graft survival in clinical transplantation.

Adult↗
PubMed1990

Distribution of Goodpasture antigens within various human basement membranes.

Collagenase-digested basement-membrane preparations from human kidney glomeruli, kidney tubules, lung, choroid plexus, aorta, intestine, and placenta were analysed according to their reactivity to anti-glomerular basement membrane (anti-GBM) antibody-positive Goodpasture sera. Sodium dodecylsulphate polyacryl gel electrophoresis (SDS-PAGE), and immunoblotting were performed after antigen enrichment by passage of the collagenase digests through an anion-exchange column. Reactivity of anti-GBM antibodies with one to three monomers (24, 26 and 28 kD) and two dimers (44 and 50 kD) were demonstrated in basement membrane preparations of kidney glomeruli, kidney tubules, lung, placenta, and aorta. In basement membranes of choroid plexus reactivity with only the 28 kD monomer and the 50 kD dimer were identified. In intestinal basement membrane, reactivity was restricted to the 50 kD dimer. Analysis of the amounts of Goodpasture antigen by inhibition ELISA demonstrated that the highest concentration were in glomerular basement membrane, while the lowest were found in aortic basement membrane. The results indicate that Goodpasture antigens are common to all the basement membranes investigated. The differences in antigen concentration and in reactivity on immunoblotting may indicate different antigen amounts, a heterogeneity of collagen IV within the various basement membranes, or differences in antigen accessibility within the membranes. We conclude that the primary clinical restriction of the anti-GBM disease to lungs and kidneys is not explained by a preservation of the antigen to this basement membrane. Rather, the clinical pattern may be influenced by differences in the molecular composition of the basement membranes as well as by non-immunological mechanisms.

Anti-Glomerular Basement Membrane Disease↗
PubMed1990

Urinary secretory immunoglobulin A in acute renal allograft rejection.

Periodical determinations of the urinary secretory immunoglobulin A (S-IgA) excretion rate were performed in 12 cadaveric graft recipients. In five patients with primary functioning grafts the S-IgA excretion on the first postoperative day was 4.2 +/- 2.6 mg/g creatinine, decreasing to 1.8 +/- 1.2 mg/g creatinine (P less than 0.05) at the day of discharge. Acute tubular necrosis developed in the seven remaining patients. In this group the initial S-IgA excretion was 12.6 +/- 7.5 mg/g creatinine (P less than 0.05 compared to the former group), decreasing to 2.0 +/- 0.9 mg/g creatinine (P less than 0.05) at discharge. An acute rejection episode was observed in six patients. The S-IgA excretion increased from 3.0 +/- 1.5 mg/g creatinine 3-4 days before rejection to 6.4 +/- 3.1 mg/g creatinine (P less than 0.05) 1-2 days before rejection, and peaked at 14.0 +/- 8.6 mg/g creatinine (P less than 0.05) when the diagnosis of rejection was established and anti-rejection treatment was started. In three patients the initial steroid pulse therapy was not successful and S-IgA excretion further increased to 29.0 +/- 15.6 mg/g creatinine. After successful anti-rejection treatment, using steroids and OKT3, the S-IgA excretion decreased to 3.4 +/- 2.6 mg/g creatinine. In acute graft rejection, the elevated globulin synthesis by infiltrating plasma cells. In the early phase of rejection, dimeric IgA is the only immunoglobulin able to penetrate into the urine by transepithelial transport after binding to secretory component expressed on tubular epithelial cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Evaluation of posttraumatic cerebral blood flow velocities by transcranial Doppler ultrasonography.

Thirty-five patients were admitted to the hospital with Glasgow coma scale scores of 4 to 7 after severe, blunt head injury. Blood flow velocities of the middle cerebral artery (MCA) and the ipsilateral internal carotid artery (ICA), high in the neck, were recorded noninvasively by Doppler ultrasonography. Serial examinations were begun within 48 hours of trauma and continued until the patient either died or was discharged. Spasm of the MCA was assumed if the ratio of the velocity of blood flow in the MCA (VMCA) to the velocity of blood flow in the ICA (VICA) exceeded 3 (normal value, 1.7 +/- 0.4). In cases of severe MCA spasm, this ratio is higher because of increased flow velocity in the MCA and reduced flow in the ICA due to increased cerebrovascular resistance. Higher MCA velocities with VMCA/VICA above 3, consistent with MCA spasm, were found in 14 of the 35 patients (40%). The increase began as early as 48 hours after injury, reached a maximum between Days 5 and 7, and lasted until 2 weeks after injury. There was a significant correlation between the occurrence of vasospasm and the quantity of cisternal or intracerebral blood seen on a computed tomographic scan. No correlation was found with the age of the patients, the Glasgow coma scale score at admission, the intracranial pressure, or the functional outcome 6 months after injury. The occurrence of a secondary infarction in a patient with severe MCA spasm suggests that, at least in some cases, spasm may influence the prognosis.

Adolescent↗