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Biomedical subjects

J Knap

Publications and source records attributed to J Knap.

At least 19 recordsLinked to original sources
PubMed2003

Effect of indenter-radius size on Au(001) nanoindentation.

We address the question of whether results obtained for small indenters scale to indenter sizes in the experimental range. The quasicontinuum method is used in order to extend the computational cell size to 2x2x1 micro m(3), nominally containing of order 2.5x10(11) atoms, and in order to permit consideration of indenter radii in the range 70-700 A. The dislocation structures for the large indenter are found to be less sharp and to extend over a larger region than for the small indenter. In addition, the large-indenter force-displacement curve differs from that corresponding to the small indenter in one important respect, namely, the absence of force drops during indentation, despite profuse dislocation activity. Based on these observations, we conclude that the indenter force is not a reliable indicator of the onset of dislocation activity and plastic deformation for indenter sizes in the experimental range.

Journal Article↗
PubMed2001

[Prophylactic use of counterpulsation in patients with severe myocardial dysfunction].

During the period between 2/2000 and 11/2000 21 patients with severe ventricular dysfunction were investigated (EF less than 30%) where in a planned manner intraaortic balloon counterpulsation was introduced before cardiac surgery. The low mortality (5%), zero incidence of complications caused by the method and the improvement of the contractility of the heart muscle, evaluated from a rise of the ejection fraction (EF) make so-called prophylactic use of contrapulsation possible as a method of first choice in severe myocardial dysfunction.

Aged↗
PubMed1998

Medium-term results of coronary artery bypass surgery in patients with severe left ventricular dysfunction and preoperatively documented hibernating myocardium.

In patients with multivessel coronary artery disease (CAD), severe left ventricular dysfunction (LVD) and hibernating myocardium (HM) demonstrated on preoperative assessment, coronary artery bypass grafting (CABG) surgery can be performed safely with low operative morbidity and mortality rates. Surgical revascularization of reversibly dysfunctional myocardium improves significantly both patient's clinical status and left ventricular ejection fraction (LVEF). Diagnosis of HM prior to CABG surgery seems to be crucial because it does not leave the patient with multivessel CAD and LVD a candidate only for heart transplantation (HTX). In the presence of HM, more aggressive surgical approach could be recommended to salvage chronically jeopardized but viable myocardium using not only routine CABG procedures in extracorporeal circulation (ECC) but also alternative approach of coronary endarterectomy (EAE) or minimally invasive direct coronary artery bypass grafting (MIDCAB) procedures on beating heart, without any adverse impact on operative mortality.

Coronary Artery Bypass↗
PubMed1997

[The hibernating myocardium--its use in clinical practice].

Hibernated myocardium is a term used to describe a state of myocardial hypocontractility which is due to chronic hypoperfusion of the heart muscle. The myocardium remains, however, viable and therefore revascularization can significantly improve the reduced mechanical function of the left ventricle. Differentiation between hibernated myocardium and a myocardium which was irreversibly damaged and replaced by scar tissue is particularly important in patients with ischemic dysfunction of the left ventricle. Information on the viability of dysfunctional areas of the myocardium helps in reflections on the indication and strategy of the revascularization operation.

Coronary Circulation↗
PubMed1997

Hemothorax--a complication of subclavian vein cannulation.

Massive bleeding into pleural cavity after subclavian vein cannulation is a rather rare but very serious complication. Usually laceration of the venous wall is the cause. In patients where conservative treatment, i.e. pleural drainage, maintaining the circulatory volume, treatment of possible coagulopathy, etc. is ineffective, surgery has to be performed. Bleeding can be surgically managed either from posterolateral thoracotomy or direct subclavian vessel revision is possible after partial resection of the clavicle. Brachiocephalic vein bleeding can be approached and managed through median sternotomy. We present a case report of 22-year old man with hemothorax after subclavian vein cannulation. In our patient only complex surgical procedure enabled proper management of bleeding complication.

Adult↗
PubMed1997

[Coronary revascularization in diffuse atherosclerosis of the anterior descending coronary artery].

The authors present surgical possibilities of treatment of diffuse atherosclerotic changes of the left anterior descending coronary artery. In such serious disease they choose the procedure of endarterectomy performed from long arteriotomy under direct eye control followed by reconstruction by long bypass anastomosis. Endarterectomy of the left anterior descending artery was performed in 32 patients during the period between 1988-1996. This represents 1.38% of patients operated for ischemic heart disease during that period (32/2324). Two patients died in consequence with the operation (6.25%), also there was one myocardial infarction as a perioperative complication (3.1%). Endarterectomy of the diffusely diseased left anterior descending coronary artery can, when carefully indicated and using proper technique, contribute to complete revascularization in patients with end-stage coronary artery disease.

Adult↗
PubMed1997

[Legionnaires' pneumonia. Remarks related to a case].

A case of 21-years old soldier diagnosed with Legionnaires' disease was presented. Serologic dynamics of antibodies to the organism confirmed the diagnoses (anti-Legionella pneumophila). In this case serologic tests were used in Poland for the first time.

Adult↗
PubMed1996

Hibernating myocardium--mechanisms and clinical implications.

Hibernating myocardium is defined as persistently impaired myocardial and left ventricular function at rest resulting from reduced myocardial blood flow. It is postulated that despite the reduced coronary blood flow, metabolic activity is sufficient to prevent tissue necrosis. Recovery of the hibernating myocardium has clearly been shown to occur with the establishment of successful revascularization either by coronary bypass surgery or by percutaneous transluminal coronary angioplasty. The differentiation of viable, hibernating myocardium from non-viable myocardium in patients with coronary artery disease and left ventricular dysfunction is a key issue in the current era of myocardial revascularization.

Humans↗
PubMed1996

Contribution to technique of endarterectomy of the right coronary artery.

We present our technique of performing endarterectomy of coronary arteries by means of injecting cardioplegic solution into the plane of dissection of the endarterium. This simple and gentle technique in combination with manual endarterectomy helps in separation of the core far into the periphery of the diseased vessel and thus helps to perform revascularization in patients with diffuse atherosclerotic changes. During the last 6 years (1991-1996) endarterectomy in coronary revascularization was used in 116 cases (it was 5.7 % (116/2031) of all myocardial revascularization procedures). On right coronary artery endarterectomy was used in 82 patients. Mortality rate in our group of patients was 4.88 % (4/82) and perioperative myocardial infarction developed in 4.88 % (4/82). According to our own experience with this technique of endarterectomy on right coronary artery we are convinced that in desperate patients with diffuse coronary artery disease our method can bring better and wider application of surgical treatment.

Adult↗
PubMed1995

[Infection in the dialysis unit as a contributing factor to the problem of hospital acquired infections].

Hospital acquired infections are especially dangerous for patients with chronic renal insufficiency. An epidemic of hospital acquired infection of dramatic course in described in 13 patients (8 being on haemodialysis (HD) and 5 treated conservatively), with 15 episodes of septic syndrome (12 cases) or septic shock (3 cases). Initial cultures of blood, urine and pharyngeal swabs were positive only in 5 patients treated conservatively. Initial cultures of dialysing fluid from all 12 monitors of HD in our Dialysis Unit revealed the presence of Gram-negative bacteria (Achromobacter) in blood of 3 patients as well as in the dialysing fluid compartments from 2 monitors of Gambro AK 10/100. The possible role of Gram-negative, apparently benign water rods, in the pathogenesis of hospital acquired opportunistic infections in Dialysis Unit were discussed.

Alcaligenes↗
PubMed1991

[Respiratory rehabilitation of patients with chronic obstructive lung diseases in the subjective and objective evaluation].

An intensive 14 day respiratory rehabilitation program was carried out in 24 COPD patients of mean age 66.0 +/- 10.0 yrs (FVC 1.56 +/- 0.52 L, FEV1 0.94 +/- 0.4 L/s). A statistically objective improvement was seen measured by the 100 meter tread mill test (p = 0.001) which was not seen in spirometric analysis. Seventeen patients reported a subjective improvement in their clinical state. The authors have demonstrated usefulness of the 100 meter walk test in analysis of rehabilitation processes.

Administration, Inhalation↗
PubMed1990

[Interleukin-2 in the treatment of malignant melanoma. A case report].

Interleukin-2 is a lymphokine with documented antineoplastic influence, with not completely understood mechanism of action. The case of 46-years old patient with relapsed metastatic malignant melanoma treated with constant-infusion of rIL-2 is described. 9-month remission was achieved. During the course of treatment a lot of side effects including flu-like symptoms, hypotonia, anemia and thrombocytopenia, and also many biochemical disturbances were observed.

Humans↗
PubMed1989

[A case of diphtheria in a young man].

A case of pharyngeal diphtheria with mild course was observed in a man aged 21 years who had had received four vaccinations. This was the first case of this disease in Poland since 1983, and the possibility is discussed of diphtheria spread in a country with widespread Di-Per-Te vaccinations, as pointed out in the present literature.

Adult↗