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Biomedical subjects

M Lukes

Publications and source records attributed to M Lukes.

16 recordsLinked to original sources
PubMed2001

Prostate-specific antigen: current status.

PSA is the most important of all tumor markers because it has significant applications in all aspects of the management of men with prostatic disease. Certainly, the most important utilization of PSA is for early detection of this most ubiquitous of all human neoplasms. In this article the authors describe the molecular forms of PSA and their characteristics, the factors influencing values of serum concentration of PSA, the problems of screening, and particularly the possibility to use PSA for detection of prostate carcinoma. A big problem in prostate carcinoma detection is the low specificity of PSA at the concentrations between 4-10 ng/ml, the so-called diagnostic gray zone, where the incidence of prostate carcinoma is only 25%. The authors evaluate the methods which make it possible to increase the sensitivity and/or specificity of PSA detection, such as PSA density, PSA density of the transition zone, PSA velocity, PSA doubling time, age-specific PSA, free PSA and, prospectively, the use of the RT-PCR technique.

Biomarkers, Tumor↗
PubMed2000

[Lower urinary tract function and its disorders].

The lower urinary tract provides two modes of operation--storage and elimination of urine. The normal function results in the coordination of contraction and relaxation of muscles of the urinary bladder and urethral sphincters. Disorders of these activities or their interaction lead to the development of lower urinary tract dysfunctions. The nervous system plays an essential role in the regulation of the functions. The control of micturition is coordinated by several regious of the central nervous system. Afferents and efferents of the peripheral nervous system carry signals from and to the lower urinary tract. The reflex circuitry controlling micturition consists of five components: spinal efferent neurons, peripheral efferent neurons, primary afferent neurons, spinal interneurons and neurons in the brain. Preganglionic neurons located in the sacral parasympathetic nucleus and lumbar sympathetic nucleus excite the peripheral efferent neurons innervating smooth muscles of the urinary bladder and urethra. Motoneurons of sacral Onuf's nucleus excite the striated muscle of the external urethral sphincter. Myelinated and unmyelinated afferent axons transmit information from the lower urinary tract to the lumbosacral spinal cord. Three receptor types of the lower urinary tract are present: tension receptors, volume receptors and "silent receptors", which become nociceptors following the sensitization. Afferent pathways terminate on spinal interneurons. Spinal interneurons relay information to the brain or to other regions of the spinal cord. Because micturition reflexes are mediated by disynaptic or polysynaptic pathways, interneuronal mechanisms are of crucial importance in the regulation of lower urinary tract. Central pathways involved in micturition reflexes are located in spinal and supraspinal areas. Micturition reflexes can be modulated at the level of the spinal cord by viscero--bladder and somato--bladder reflexes. Supraspinal areas have a more complicated organization: critical component of the micturition reflex is the pontine micturition center and the periaqueductal gray. Inhibitory and excitatory areas in the pontomedullary and hypothalamic systems and the brain play an important role in the regulation of micturition reflexes.

Humans↗
PubMed1999

Extracellular matrix degradation by metalloproteinases and central nervous system diseases.

Matrix metalloproteinases (MMPs) are a gene family of neutral proteases involved in normal and pathological processes in the central nervous system (CNS). Normally released into the extracellular space, MMPs break down the extracellular matrix (ECM) to allow cell growth and to facilitate remodeling. Proteolysis becomes pathological when the normal balance between the proteases and their inhibitors, tissue inhibitors to metalloproteinases (TIMPs), is lost. Cancer cells secrete neutral proteases to facilitate spread through the ECM. MMPs increase capillary permeability, and they have been implicated in demyelination. Neurological diseases, such as brain tumors, multiple sclerosis, Guillain-Barré, ischemia, Alzheimer's disease, and infections, lead to an increase in the matrix-degrading proteases. Two classes of neutral proteases have been extensively studied, namely the MMPs and the plasminogen activators (PAs), which act in concert to attack the ECM. After proteolytic injury occurs, the process of ECM remodeling begins, which can lead to fibrosis of blood vessels and gliosis. TIMPs are increased after the acute injury and may add to the fibrotic buildup of ECM components. Thus, an imbalance in proteolytic activity either during the acute injury or in recovery may aggravate the underlying disease process. Agents that affect the proteolytic process at any of the regulating sites are potentially useful in therapy.

Animals↗
PubMed1999

[Personal experience with administration of Smektit (hydrated magnesium aluminum silicate) in the treatment of diarrhea of non-infectious origin and diarrhea after resection of the large intestine].

Smektit was used for treatment of 24 patients, incl. 10 hospitalized with diarrhoea of a non-infectious etiology (postoperative period, non-adherence to the dietetic regime). Microbiological examination involved only examination of the common flora of the large bowel. In the 10 hospitalized patients the complaints receded very rapidly, after a maximum of three days. In the remaining 14 patients who had resections on account of colorectal carcinoma the diarrhoea was in the majority due to reduction of the large bowel and thus reduction of the resorption area. The condition of ten patients became stabilized and the frequency of bowel movements decreased. In the group of four patients after subtotal colectomy only one patient improved. In three patients smektit administration had no effect. In these patients the cause of frequent bowel movements was the extensive reduction of the large bowel.

Adult↗
PubMed1997

Rat mesangial cells and matrix metalloproteinase inhibitor: inhibition of 72-kD type IV collagenase (MMP-2) and of cell proliferation.

The synthetic inhibitor of matrix metalloproteinases (MMP) Ro 31-9790, a hydroxamic-acid derivative, was investigated for its effect on rat mesangial cells (MC) in culture. For these studies, proliferating MC with a high degree of constitutive expression of a MMP, the 72-kD Type IV collagenase (gelatinase A, MMP-2), were chosen, because they reflect aspects of an inflammatory phenotype that may occur during certain forms of glomerular inflammatory diseases. Ro 31-9790 inhibited activity of the rat MC MMP-2 in a concentration-dependent and competitive fashion, as analyzed by quantitative densitometry and by a continuously recording fluorescent assay. Furthermore, Ro 31-9790 inhibited the proliferation rate of cultured rat MC in a concentration-dependent and at least partially reversible manner without affecting cell viability. It was concluded that the application of synthetic MMP inhibitors may offer a new perspective for the therapy of mesangial cell-derived forms of glomerulonephritis.

Actins↗
PubMed1996

Endotoxin-induced acute renal failure in the rat: effects of urodilatin and diltiazem on renal function.

Acute renal failure (ARF) due to endotoxins is a common problem in clinical medicine. Endotoxins are released from the outer membrane of the gram-negative bacterial envelope and are composed of lipopolysaccharides (LPS). Although systemic hypotension often is present, LPS-induced ARF is characterized by marked intrarenal vasoconstriction. Both calcium channel blockers and natriuretic peptides are able to antagonize vasoconstricting signals and have been reported to exert beneficial effects in toxic and ischemic ARF: We investigated the effects of diltiazem (Dil, 300 micrograms/kg) or urodilatin (Uro, 40 micrograms/kg) or a combination of both (same doses) on renal function in early LPS-induced ARF: One hour after induction of ARF by i.v. injection of LPS glomerular filtration rate (GFR, clearance of fluorescence-marked inulin) was distinctly reduced to about 54% of basal values. In the following infusion period (60 min) a significant increase of GFR was observed with diltiazem (1.54 +/- 0.11 ml/min), urodilatin (1.60 +/- 0.10 ml/min) and the combination of both drugs (1.66 +/- 0.04 ml/min) compared to controls (1.17 +/- 0.08 ml/min). Combined administration did not cause additive effects. Also 60 and 120 minutes after stopping of drug infusion elevated GFR could be maintained in all experimental groups. Due to their vasorelaxing activity both Uro and Dil induced a decrease of mean arterial blood pressure in comparison with controls and revealed remarkable diuretic and natriuretic activity. In conclusion our results underline that marked intrarenal vasoconstriction in LPS-induced ARF can be antagonized by the well known relaxing potency of Uro and Dil towards vascular smooth muscle and mesangial cells. Both Uro and Dil were capable of improving suppressed renal function in the early phase of LPS-induced ARF in the rat as long as severe systemic hypotension is absent.

Acute Kidney Injury↗
PubMed1993

[The solitary kidney in patients after nephrectomy in Wilm's tumor].

A single kidney in patients with agenesis or after nephrectomy is regarded as a risk factor. Primarily, the role of glomerular hyperfiltration and later possible glomerular sclerosis are emphasised. Complex treatment of Wilms tumour patients includes previous chemotherapy and radiotherapy. The aim of our study was to investigate late sequelae of this aggressive treatment on the morphology and function of a single kidney and to compare these results with a group of single kidney patients, where the diagnosis of Wilms tumour was excluded.

Adolescent↗
PubMed1981

Conventional versus computer-aided interpretation of long-term ECG recordings--aspects of precision and economy.

In a sample of 60 12-h long-term ECG recordings we compared a computer-aided analysis method to a conventional scanning technique for diagnostic precision and time consumption. As regards diagnostic precision no significant difference between the methods could be found. Both were considered efficient in detecting episodes of arrhythmia. Using the computer-aided method a physician spent an average of 16 min on analyzing a recording and writing the diagnostic report. The conventional method required 69 min from an ECG technician and 9 min from a physician for each recording. From these figures we conclude that about 750 12-h recordings/year are required to outweigh the extra annual cost for the computer, if it is used only for long-term ECG analysis. If the computer can also be used for other purposes the system for long-term ECG analysis is profitable with a smaller annual number of recordings.

Adult↗