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Biomedical subjects

A Krajewski

Publications and source records attributed to A Krajewski.

At least 37 records · Page 2Linked to original sources
PubMed1988

Basilar artery blood flow in subclavian steal.

Subclavian "steal", when blood siphons from one vertebral artery to the other, has been suggested as a cause of brain stem ischaemia and stroke. We investigated 33 patients using transcranial Doppler to determine the direction and velocity of basilar blood flow. All patients had severe subclavian stenosis with reversed vertebral blood flow in the ipsilateral artery previously demonstrated by extracranial Doppler. Basilar flow was normal in direction in all cases, but its velocity was significantly increased (p less than 0.0008) compared to age- and sex-matched controls. These findings, in conjunction with previous observations using extracranial Doppler techniques, suggest that subclavian steal is little more than a harmless haemodynamic phenomenon.

Aged↗
PubMed1988

Identification of human herpesvirus 6-specific DNA sequences in two patients with non-Hodgkin's lymphoma.

Human herpesvirus 6 (HHV-6) is a recently discovered virus which has not been causally linked to any particular disease. In order to investigate the possible role of this virus in the pathogenesis of lymphoid malignancies, we examined tissue samples from 117 patients for the presence of HHV-6-specific DNA sequences. Two cases of non-Hodgkin's lymphoma were found to be positive. One patient had a T cell lymphoma and a preceding history of angioimmunoblastic lymphadenopathy; the other had a B cell lymphoma occurring in the context of Sjögren's syndrome. HHV-6 has been isolated previously from a patient with angioimmunoblastic lymphadenopathy, and viral sequences have been identified in another patient with Sjögren's syndrome and B cell lymphoma. The relationship between HHV-6 and these conditions therefore warrants further investigation.

Aged↗
PubMed1987

Primary lymphoma of the breast.

Fifteen patients with primary lymphoma of breast are reported from a 30-year review. Eight of the patients were diagnosed in the last 5 years of this review, suggesting either an increase in the incidence or an increasing awareness of this condition. The age range was from 17 to 77 years. All patients presented with a breast mass and nine had histologically proven axillary node involvement. One patient had Hodgkin's disease and the remainder were non-Hodgkin's lymphoma. Treatment was by a combination of surgery, radiotherapy and chemotherapy. During follow-up which varied from 4 to 20 years (median 8 years) three patients developed metachronous involvement of the opposite breast and three died from their disease. Prognosis was related to tumour histology and stage of disease. The three who died all had high grade centroblastic lymphoma, the three largest tumours and nodal involvement. Five and ten-year survivals were 85 per cent and 73 per cent respectively, better than the survival of patients for either other non-disseminated extranodal lymphomas or breast cancer.

Adolescent↗
PubMed1987

A vector based approach to age-related changes of Doppler velocity waveforms in the brachial artery.

The shape of blood flow velocity wave has been correlated with age. The continuous wave Doppler ultrasound technique was used to obtain the blood flow velocity from the brachial arteries in 40 subjects of different age. The blood flow velocity was analysed by means of the Fourier method. The changes of relative values of harmonics were observed according to age. The second harmonic was maximum for the young and the first one for the old. To quantify these changes the vector formed from the first eight moduli was introduced. The angle between the vector so defined and a certain reference vector was accepted as a measure of the Fourier transform. Continuous alteration of wave shape described by angle has been observed according to age. The correlation between angle and age was r = 0.79 (p less than 0.001).

Adult↗
PubMed1987

Histochemical studies of human breast cancer using a monoclonal antibody against an oestrogen receptor-related antigen.

The presence or absence of an oestrogen receptor-related antigen in breast tumours has been examined histochemically using a monoclonal antibody ('Ds' - Coffer & King, 1981). In frozen sections, fixed either by the method of Tamura et al. (1980) or in methanol, staining was apparent in 14/24 (58%) and 22/26 (85%) of the breast cancers respectively. In paraffin sections fixed in ethanol, staining was present in 25/33 breast cancers (76%). In either type of section, staining was predominantly in the cytoplasm of the epithelial cells. When staining was scored by independent observers (2 or 3) and related to the tumour oestrogen receptor activity, determined by a standard biochemical technique, antigen was present in both receptor-positive and receptor-negative tumours. No significant association was found between the presence of antigen and receptors in the frozen sections, but for the series of paraffin sections, there was a weak association (r = +0.48) between the presence of the two proteins. Histochemical processing of paraffin sections from 9 tumours under conditions of higher sensitivity increased the staining significantly in 2/9 tumours, but did not alter the relationship between staining and receptor status. Six tissues were stained after exposure to 'receptor-translocating' conditions (25 degrees C/2 nM oestradiol/both for 1 h): this did not consistently change the subcellular staining pattern, though all tissues tended to stain more after exposure to 25 degrees C. Staining was not blocked by absorption of the D5 antiserum with a variety of pure proteins or human serum but at higher concentrations (approx. 2-15 mg protein ml-1), extracts from human uterus, an oestrogen-receptor-positive breast cancer and an oestrogen-receptor-negative breast cancer all effectively abolished staining in sections from another breast cancer. These results are consistent with other reports suggesting that the D5 antibody detects an antigen which is not the oestrogen receptor, but which may be associated with the receptor in its tissue distribution.

Antibodies, Monoclonal↗
PubMed1984

The behaviour of apatite-based ceramics in relation to the critical 1150 degrees-1250 degrees C temperature range.

Characterization of synthetic calcium phosphates is reported and compared with previous studies. Barium hydroxyapatite was also synthesized. Shrinkage on sintering, water absorption, tensile strength, porosity and X-ray diffraction patterns were studied. Hydroxyapatite and beta-tricalcium phosphate show compositional and mechanical property variation dependent on sintering temperatures. The property change on introduction of barium removes the practical value. X-ray diffraction analysis is considered essential before clinical use due to sensitivity of composition to sintering conditions.

Barium Compounds↗
PubMed1981

A physico-chemical study of crystal growth of hydroxyapatite bioceramic.

Synthetic hydroxyapatite powders were pressed and fired at different temperatures for varying time intervals. Fired samples were fractured and the surface produced was examined by SEM. Four kinds of crystal growth has been seen, grains (principally) lamellae, dendritic interlacings and efflorescences and large hexagonal crystals. Evaluation of trends in activation energy permitted a determination of the temperatures at which phase transformation occurred and discussion of the competing processes involved. The studies confirmed that the optimum firing temperature is between 1100 degrees and 1150 degrees C.

Biocompatible Materials↗
PubMed1980

Characterization of synthetic apatites for bioceramic implants.

Hydroxyapatite has been studied as a substance suitable for surgical substitution of bones and teeth with emphasis on its biocompatibility. The present work tries to identify the characteristics of this material either from the chemico-physical-structural point of view, or from the technological one, evaluating the best performance. By X-ray, i.r., thermal, chemical and SEM analyses, the relationship of different phenomena involved in the sintering was evaluated. Technological tests demonstrated the stability and the workability characteristics. In particular, the influence of CO2 was studied, in connection with the most suitable technique for hydroxyapatite (HAP) sintering, considering the eventual aims and requirements for industrial production.

Ceramics↗
PubMed1975

Eosinophil chemotaxis of supernatants from cultured Hodgkin's lymph node cells.

Cultured lymph node cell supernatants from five out of six cases of Hodgkin's disease were relatively more chemotactic for peripheral blood eosinophils than neutrophils. In contrast, supernatants from two cases of lymphocytic lymphoma and four nodes showing reactive hyperplasia were chemotactic for neutrophils but had little eosinophil chemotactic activity. In most instances the dgree of eosinophil infiltration observed histologically in the Hodgkin's lymph node correlated with elaboration of eosinophil chemotactic activity from the cultured cells. Following gel-filtration of three of the Hodgkin's lymphnode supernatants, four peaks of eosinophil chemotactic activity were demonstrated in each case. One of these corresponded in molecular size to th previously described eosinophil chemotactic factor of anaphylaxis (ECF-A). It is suggested that the eosinophil chemotactic activity of cultured lymph node cell supernatants may be on value in the diagnosis and classification of Hodgkin's disease.

Anaphylaxis↗
PubMedDate not supplied

Albumin adhesion on ceramics and correlation with their Z-potential.

An investigation into albumin adhesion on ceramics was carried out, providing useful information on the relationship between the Z-potential of ceramic materials and the amount of closely adhered albumin. The chemical nature of the substance constituting the ceramic is mainly responsible for the adhesion, but additional influencing factors are also considered. A differentiation in the amount of adhesion (which is a consequence of the forces of attraction between the ceramic surface and the molecules of albumin) is found and concerns the biological quality of the materials, particularly the bioactive and bioinert ceramics.

Adsorption↗