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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
PubMed1990

The cluster diathesis.

We present further evidence for a sympathetic defect of vasomotor control of the anterior cerebral artery (ACA) on the side of the headache during cluster periods. In 119 cluster headache patients, utilizing transcranial Doppler, we measured CO2 reactivity of the major intracranial vessels, in and out of cluster. Reactivity was significantly lower during the cluster period, but only in the ACA on the side of the headache. Nineteen patients followed sequentially for a full cycle (ie/both in and out of a cluster period) showed the same changes. In 3 out of 6 patients in an active cluster period, we describe a lesion on Gallium single-photon emission computerized tomography (SPECT) in the region of the cavernous sinus which fades as the patient moves out of cluster. It is felt that this lesion may represent the cavernous sinus plexus lesion postulated as the central lesion in cluster. Changes in the sympathetic outflow at this point could explain the changes we have described in ACA CO2 reactivity during cluster.

Adult↗
PubMed1990

Comparative analyses among interfaces of some ceramic materials and bone in sheep.

Aim of this work is the evaluation of "in situ" implants in an animal model to study the interfaces that some ceramic materials for dental bone defects develop with bone and to check which material is more osteoconductive. In a sheep's jaw, eight holes were drilled and filled with six ceramic materials in granular shape. Two bilateral holes were left empty as reference. The ceramic materials were: porous tricalcium phosphate (TCP), porous hydroxylapatite (HA) and four bioactive glasses. The glasses differ for doping agents that affect the velocity of biodegradation in the living body. Monthly radiographs were taken and the X-ray pictures analyzed by means of a Video Display Computer in order to quantify the optical density changes occurred in the holes. After 4 months implantation, the segments of the jaw containing the materials were fixed in paraformaldehyde, embedded in methylmethacrylate and sectioned. The results obtained under the microradiograph, the SEM and the X-ray microprobe showed a good bone repair only with TCP granules. A great degradation was seen in HA granules and particularly in glasses. The degradation modified the structure and the composition of the glass granules, but it was not followed by a consequent bone deposition.

Animals↗
PubMed1989

Reversal of cluster headache side following treatment of arteriovenous malformation.

We describe the case of a forty-four year old man who had typical right sided cluster headaches and an arteriovenous malformation supplied mainly by the right anterior cerebral artery. Following endovascular embolisation of this artery the AVM was supplied mainly by the left anterior cerebral artery. Subsequent headaches have always been on the left. Transcranial Doppler studies now suggested an increase of middle cerebral artery flow velocity. We suggest that the change in haemodynamics was responsible for the change in headache side.

Adult↗
PubMed1988

Mineralization and calcium fixation within a porous apatitic ceramic material after implantation in the femur of rabbits.

Cylinders (0.8 cm long, 1.0 cm of diameter and with an axial hole), constituted, after firing, of a ceramic mixture of hydroxylapatite (HA) and beta-tricalciumphosphate (beta-TCP) in a 10:1 ratio, were implanted into mid-diaphyseal defects of one femur of 20 rabbits and stabilized with intramedullary rods. The implantation sites were checked radiographically every month, and after 3 months (3 animals) and 6 months (17 animals) the rabbits were sacrificed and the implants with the surrounding tissue were embedded in methylmethacrylate, cut to thick sections and analyzed by scanning electron microscopy (SEM). Porosimetric and x-rays diffraction analyses were carried out before and after implantation of the cylinders, and the state of mineralization at the bone-implant interface was determined by EDAX microprobe analysis. Bony callus formation started at 1 month at the osteotomy sites, as judged by radiography, but after 3 months a not-mineralized zone had still been demonstrated between bone and the implants. At 6 months, 13 implants showed themselves firmly fixed in their implantations beds, while 4 implants were only incorporated at their proximal ends. In bone contact zones, an enrichment of Ca2+ was displayed by microanalytical techniques in the outer zone of the implanted samples which may be explained by an apparent additional phase transformation of HA into TCP, thanks to the change of the Ca/P ratio, that takes place in vivo.

Animals↗
PubMed1988

Interpretation of difficulties in the initial adhesion of bio-active glasses to bone.

The authors propose a model to explain the initial difficulties in achieving adhesion between bio-active glasses and bone. It is explained that in vitro tests involve biophysical situations which are different, and in many cases very different, from those which take place in in vivo implantation. The model suggests procedures which could be applied to bio-active glasses after the manufacturing process in order to improve their initial adhesion to bone.

Animals↗
PubMed1988

Structural modifications and biological compatibility of doped bio-active glasses.

The Raman laser and infrared spectra of doped bio-active glasses of the 45S5 type are presented and discussed. The spectroscopic results show that the doping agents cause the destruction of the basic glass structure and the consequent formation of SiO4(4-) units in the glass network. When the doped glasses have been immersed in a physiological solution (199 medium), a film of calcite forms on the glass surface and this modification is related to the type of doping agent used, decisive for close linking between metal supports and the glass. The presence of doping agents does not prevent the normal growth of the bone onto the surface of doped bioactive glasses. Histological tests show that tissue response to very fine powders of doped glasses increases up to 15 days more or less according to the structural modifications revealed by spectroscopic measurements.

Animals↗
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↗