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Biomedical subjects

M Haider

Publications and source records attributed to M Haider.

At least 19 recordsLinked to original sources
PubMed2003

Magnetic resonance imaging in the radiation treatment planning of localized prostate cancer using intra-prostatic fiducial markers for computed tomography co-registration.

PURPOSE: To assess the feasibility, and potential implications, of using intra-prostatic fiducial markers, rather than bony landmarks, for the co-registration of computed tomography (CT) and magnetic resonance (MR) images in the radiation treatment planning of localized prostate cancer. METHODS: All men treated with conformal therapy for localized prostate cancer underwent routine pre-treatment insertion of prostatic fiducial markers to assist with gross target volume (GTV) delineation and to identify prostate positioning during therapy. Six of these men were selected for investigation. Phantom MRI measurements were obtained to quantify image distortion, to determine the most suitable gold alloy marker composition, and to identify the spin-echo sequences that optimized both marker identification and the contrast between the prostate and the surrounding tissues. The GTV for each patient was contoured independently by three radiation oncologists on axial planning CT slices, and on axial MRI slices fused to the CT slices by matching the implanted fiducial markers. From each set of contours the scan common volume (SCV), and the scan encompassing volume (SEV), were obtained. The ratio SEV/SCV for a given scan is a measure of inter-observer variation in contouring. For each of the 18 patient-observer combinations the observer common volume (OCV) and the observer encompassing volume (OEV) was obtained. The ratio OEV/OCV for a given patient-observer combination is a measure of the inter-modality variation in contouring. The distance from the treatment planning isocenter to the prostate contours was measured and the discrepancy between the CT- and the MR-defined contour recorded. The discrepancies between the CT- and MR-defined contours of the posterior prostate were recorded in the sagittal plane at 1-cm intervals above and below the isocenter. RESULTS: Phantom measurements demonstrated trivial image distortion within the required field of view, and an 18K Au/Cu alloy to be the marker composition most suitable for CT-MRI image fusion purposes. Inter-observer variation in prostate contouring was significantly less for MR compared to CT. The mean SEV/SCV ratio was 1.58 (confidence interval (CI): 1.47-1.69) for CT scans and 1.37 (CI: 1.33-1.41) for MR scans (paired t-test; P=0.036). The overall magnitude of contoured GTV was similar for MR and CT; however, there were spatial discrepancies in contouring between the two modalities. The greatest systematic discrepancy was at the posterior apical prostate border, which was defined 3.6 mm (SD 3.5 mm) more posterior on MR- than CT-defined contouring. CONCLUSIONS: Prostate contouring on MR is associated with less inter-observer variation than on CT. In addition, we have demonstrated the feasibility of using intra-prostatic fiducial markers, rather than bony landmarks, for the co-registration of CT and MR images in the radiation treatment planning of localized prostate cancer. This technique, together with on-line correction of treatment set-up according to the fiducial marker position on electronic portal imaging, may enable a reduction in the planning target volume (PTV) margin needed to account for inter-observer error in target delineation, and for prostate motion.

Biomarkers↗
PubMed2002

Laser therapy of freckles and lentigines with quasi-continuous, frequency-doubled, Nd:YAG (532 nm) laser in Fitzpatrick skin type IV: a 24-month follow-up.

BACKGROUND: Newly developed lasers produce excellent results with minimal complications compared with traditional treatments for freckles and lentigines. OBJECTIVES: To assess the efficacy and safety of the frequency-doubled Nd:YAG (532 nm) laser in the treatment of freckles and lentigines in type IV skin. PATIENTS AND METHODS: Twenty adult patients (14 with freckles and six with lentigines) were subjected to a variable number of treatments with a minimum 4-week interval until no additional improvement occurred or > 75% improvement was obvious. Patients manifesting > 50% improvement were followed up once every 3 months for 24 months. The rest were regarded as treatment failures and not followed up. RESULTS: Sixteen (80%) of 20. patients (freckles, n = 10; lentigines, n = 6) manifested more than 50% improvement. They were treat- irradiated between three and eight times with a 4-12-week interval. Complications included hypopigmentation (25%), mild textural changes (15%) and hyperpigmentation (10%). All these were mild and resolved within 2-6 months. Of 10 patients with freckles followed up for 24 months, four (40%) patients showed partial recurrence. However, all the patients maintained > 50% improvement. None of the patients with lentigines showed recurrence. CONCLUSION: The quasi-continuous, frequency-doubled Nd:Y AG (532 nm) laser safely and effectively treats freckles and lentigines in Fitzpatrick skin type IV.

Adult↗
PubMed2001

The inclusion of capillary distribution in the adiabatic tissue homogeneity model of blood flow.

We have developed a non-invasive imaging tracer kinetic model for blood flow which takes into account the distribution of capillaries in tissue. Each individual capillary is assumed to follow the adiabatic tissue homogeneity model. The main strength of our new model is in its ability to quantify the functional distribution of capillaries by the standard deviation in the time taken by blood to pass through the tissue. We have applied our model to the human prostate and have tested two different types of distribution functions. Both distribution functions yielded very similar predictions for the various model parameters, and in particular for the standard deviation in transit time. Our motivation for developing this model is the fact that the capillary distribution in cancerous tissue is drastically different from in normal tissue. We believe that there is great potential for our model to be used as a prognostic tool in cancer treatment. For example, an accurate knowledge of the distribution in transit times might result in an accurate estimate of the degree of tumour hypoxia, which is crucial to the success of radiation therapy.

Capillaries↗
PubMed2000

Upper limits for the residual aberrations of a high-resolution aberration-corrected STEM

The development of correctors for electron optical systems has already brought the improvement of resolution for a low-voltage scanning electron microscope and a commercially available transmission electron microscope and is anticipated in the near future for a dedicated scanning transmission electron microscope (STEM). The resolution attainable especially of a probe-forming system at 200 kV cannot only be estimated from calculations ignoring all non-rotationally symmetric axial aberrations in an electron optical system. For a certain resolution, one would like to attain, the influence of the deviations from the ideal, aberration-free system has to be investigated. Therefore, in the following we have carried out the evaluation of the required accuracy for the compensation of the various residual aberrations in order to achieve a resolution in the sub-Angstrom regime with a probe-forming system.

Journal Article↗
PubMed2000

Flow-cytometry-enhanced fine-needle aspiration biopsy of the spleen.

OBJECTIVE: Flow cytometry is proving useful in the evaluation of lymphoproliferative disorders. In a case series, the authors investigated the safety of cross-sectional fine-needle aspiration biopsy of the spleen under sonographic guidance, and the usefulness of flow cytometry in analysis of biopsy samples. METHODS: Five patients underwent fine-needle biopsy with freehand sonographic guidance. Samples were analyzed on a flow cytometer. RESULTS: Through cytologic examination enhanced by flow cytometry, 2 cases of lymphoma, 1 case of metastatic transitional cell carcinoma, and 1 case of focal splenic hemangioma were diagnosed. Normal lymphocytes were demonstrated in 1 case, in which long-term follow-up of splenomegaly showed that this was related to cirrhosis and portal hypertension in a patient with a history of treated non-Hodgkin's lymphoma. CONCLUSION: Flow-cytometry-enhanced fine-needle aspiration of the spleen is a safe and useful tool for the interventional radiologist. In our institution, it evolved as the result of effective teamwork between diagnostic radiologists and pathologists. Flow cytometry promises to be increasingly useful in the diagnosis and management of lymphoproliferative diseases.

Aged↗
PubMed1999

Heterologous expression, purification, and kinetic comparison of the cytoplasmic and mitochondrial glyoxalase II enzymes, Glo2p and Glo4p, from Saccharomyces cerevisiae.

The aims of the present study are (i) to purify a mitochondrial glyoxalase II to homogeneity for the first time from any organism and (ii) to compare its kinetic properties with those of the cytoplasmic enzyme. Both the cytoplasmic and the mitochondrial glyoxalases II from Saccharomyces cerevisiae, which are the products of two distinct genes, GLO2 and GLO4, were purified from yeast and in recombinant form from Escherichia coli. To obtain a higher protein yield (compared to wild-type expression) in yeast, the genes were placed under the control of the strong GAL1 promoter on a multicopy plasmid. Amino-terminal sequencing and molecular mass determination by MALDI-TOF mass spectrometry of the mitochondrial Glo4 protein revealed Met-11 of the primary translation product of the gene as the N-terminal amino acid. Judged by enzyme kinetic properties the recombinant and natural proteins were equivalent. The cytoplasmic and the mitochondrial enzyme differed in the pH dependence of the kinetic parameters for the main substrate, S-d-lactoylglutathione. Whereas the cytoplasmic protein showed a pronounced peak of enzyme activity between pH 7-8 and a continuous up to fivefold increase of the K(M) value with increasing pH (from 5. 5-9.0), the mitochondrial protein had a nearly constant K(M) value and an activity maximum over a broad pH range (6.5-9.0). The kinetic parameters (at pH 7.5) of both the cytoplasmic and the mitochondrial enzyme for S-D-lactoylglutathione were of the same order of magnitude as reported recently for the human and Arabidopsis thaliana enzymes which are presumably of cytoplasmic origin. However, both yeast enzymes showed a severalfold lower preference for the more hydrophobic substrate, S-d-mandeloylglutathione.

Cytoplasm↗
PubMed1998

Antibacterial activity of Camellia sinensis extracts against dental caries.

Different bacteria were separated from saliva and teeth of cariogenic patients and identified by a variety of morphological and biochemical tests. Extracts of green tea strongly inhibited Escherichia coli, Streptococcus salivarius and Streptococcus mutans. The antibacterial effect of green and black tea extracts were compared with those of amoxicillin, cephradine and eugenol.

Adolescent↗
PubMed1998

Gestational breast cancer.

OBJECTIVE: To study the problems of breast imaging in gestational breast cancer. PATIENTS AND METHOD: Retrospective review of the charts of 19 patients with breast cancer detected during pregnancy or lactation or within 1 year of delivery, who were referred to a tertiary centre for adjuvant therapy between 1986 and 1996. For 10 patients who underwent breast imaging, mammograms and breast ultrasonograms or reports were requested from outside facilities. RESULTS: The patients ranged in age from 23 to 41 years (mean 31 years). All 19 patients presented with palpable tumours; in 7 patients, the tumours were stage T2 or higher; in 11 patients, the tumours were at an advanced stage with positive axillary nodes. In 11 of the patients there was a delay in diagnosis, which ranged from 2 to 16 months. Of the 8 mammograms that could be reviewed, 5 showed infiltrating ductal carcinomas with typical features, which were detected as a mass (in 1 case), a mass with microcalcifications (in 1 case), microcalcifications (in 2 cases) and asymmetry (in 1 case). Three mammograms were negative, including 1 obtained from a patient with extensive comedocarcinoma. Breast ultrasonograms obtained from 4 patients (2 of whom also had mammograms) showed solid hypoechoic masses; in 2 of the ultrasonograms, the masses simulated a benign lesion. CONCLUSIONS: Although breast cancer during pregnancy and lactation is rare, this study suggests that radiologists should include it in the differential diagnosis of a solid breast mass seen during pregnancy or lactation. Clinicians appear to be reluctant to use breast imaging in these patients; however, this can lead to a delay in diagnosis. Ultrasonography is the modality of choice for initial analysis of such a mass in this age group. Mammography with shielding of the abdomen is recommended if there is suspicion of cancer. Clinical, mammographic and sonographic findings should be integrated for optimum interpretation.

Adult↗
PubMed1997

Identification and phenotypic analysis of two glyoxalase II encoding genes from Saccharomyces cerevisiae, GLO2 and GLO4, and intracellular localization of the corresponding proteins.

We have isolated and characterized two genes coding for the glyoxalase II enzyme from Saccharomyces cerevisiae. The coding region of the GLO2 gene corresponds to a protein with 274 amino acids and a molecular mass of 31,306 daltons. The open reading frame of the GLO4 gene could be translated into a protein with 285 amino acids and a molecular mass of 32,325 daltons. The amino acid sequences of the deduced proteins are 59.1% identical and show high similarities to the sequence of the human glyoxalase II. When grown on either glucose or glycerol as a carbon source, a glo2 glo4 double deletion strain contains no glyoxalase II activity at all and shows no obvious phenotype during vegetative growth. However, this strain showed a similar high sensitivity against exogenous methylglyoxal as compared with a glyoxalase I-deficient strain. Whereas the GLO2 gene is expressed on both glucose and glycerol, the GLO4 gene is only active on glycerol. The active Glo2p protein is localized in the cytoplasm and the active Glo4p in the mitochondrial matrix. Heterologous expression of the full-length GLO2 coding region in Escherichia coli resulted in an active protein. However, to get an active Glo4p protein in E. coli, the putative mitochondrial transit peptide at the N-terminal end had to be removed by shortening the 5' end of the GLO4 open reading frame.

Amino Acid Sequence↗
PubMed1994

Clastogenic effects of radiofrequency radiations on chromosomes of Tradescantia.

The clastogenicity of electromagnetic fields (EMF) has so far been studied only under laboratory conditions. We used the Tradescantia-micronucleus (Trad-MCN) bioassay in an in situ experiment to find out whether short-wave electromagnetic fields used for broadcasting (10-21 MHz) may show genotoxic effects. Plant cuttings bearing young flower buds were exposed (30 h) on both sides of a slewable curtain antenna (300/500 kW, 40-170 V/m) and 15 m (90 V/m) and 30 m (70 V/m) distant from a vertical cage antenna (100 kW) as well as at the neighbors living near the broadcasting station (200 m, 1-3 V/m). The exposure at both sides of the slewable curtain antenna was performed simultaneously within cages, one of the Faraday type shielding the field and one non-shielding mesh cage. Laboratory controls were maintained for comparison. Higher MCN frequencies than in laboratory controls were found for all exposure sites in the immediate vicinity of the antennae, where the exposure standards of the electric field strength of the International Radiation Protection Association (IRPA) were exceeded. The results at all exposure sites except one were statistically significant. Since the parallel exposure in a non-shielding and a shielding cage also revealed significant differences in MCN frequencies (the latter showing no significant differences from laboratory controls), the clastogenic effects are clearly attributable to the short-wave radiation from the antennae.

Chromosome Aberrations↗
PubMed1994

Different patterns of light exposure in relation to melatonin and cortisol rhythms and sleep of night workers.

There is strong evidence to suggest that circadian psychophysiological adaptation processes are modified by light, depending on its intensity and timing. To characterize such modifications and determine whether they are associated with an alteration in the day/night pattern of melatonin excretion, measurements were obtained around the clock in 14 permanent night workers, each studied over a 48 hr period in the field. The light exposure behavior of these workers was studied with a newly developed light dosimetry by measuring light intensity at eye level. Physical activity was continuously registered and sleep indices were obtained by sleep logs and activity markings. Circadian rhythms of melatonin and cortisol were analysed from salivary samples collected for 24 hr at 2 hr intervals. The interindividual variation of melatonin acrophase determined by cosinor analysis was greater than 180 degrees (from around midnight to noon) and that of cortisol was about 135 degrees (from early morning to afternoon). Hormonal phase positions coincided significantly with light exposure: the more bright light pulses in the morning (maximum lux between 0600 and 0900), the less were the melatonin and cortisol acrophases shifted into the day. There was also a negative correlation between melatonin acrophase shift and duration of the overall light exposure above 1500 lux. Morning light maximum and sleep onset correlated highly significantly. Night workers were divided into those with less than ('non-shifters', n = 9) and more than 6 hr deviation from midnight ('shifters', n = 5) of the melatonin acrophase. The group comparison revealed a marked difference of the mean melatonin concentrations at night, and at 0700.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Concentration evaluation of chromatin in unstained resin-embedded sections by means of low-dose ratio-contrast imaging in STEM.

Quantitative STEM with the imaging mode of ratio-contrast was investigated in order to evaluate the local concentration of DNA in situ for different kinds of DNA plasms in terms of intracellular packing densities (p.d.). The ability of ratio imaging to suppress thickness variations provided the basis to use unstained sections from cryofixed and freeze-substituted material. The DNA p.d. within the nucleoid of E. coli was determined to be about 100 mg ml-1. Quantitative data concerning the p.d. of DNA in condensed eukaryotic chromatin assuming equal amounts of DNA and protein were evaluated for the first time: approximately 400 mg ml-1 chromatin which corresponds to 200 mg ml-1 DNA. The p.d. of DNA in chromosomes from the dinoflagellate Amphidinium carterae, a eukaryote devoid of histones and with only small relative amounts of histone-like protein, was also found to be of the order of 200 mg ml-1. The highest p.d. of DNA was measured for the head of the bacteriophage T4 with more than 800 mg ml-1, in fair agreement with previous calculations. The results provide further support for a condensation mode of low protein chromatins that involves a liquid-crystalline organization of the DNA filaments.

Animals↗
PubMed1993

Personal light dosimetry in permanent night and day workers.

Light exposure was measured in six day and six night watches (working 12-hour shifts five days in a row) during 48 h on work days and 48 h on days off using a photocell with a sensitivity corresponding to photopic vision. The photocell was mounted on a frame of spectacles, thus measuring in viewing direction. Light exposure was low both in night and day watches; however, in night watches exposures were significantly lower: On work days, night watches spent a mean of 13 min above 1,500 lx, day watches 52 min; on days off, night watches spent 3 min above 1,500 lx but day watches 89 min. Unexpectedly, night watches had no higher exposure during days off. We suspect that this is due to a light avoidance tendency in permanent night workers. High negative correlations between the acrophases of subjective state (e.g., alertness and mood) and light exposure in night watches indicate that bright light would probably increase desynchronization between subjective state, sleep, and activity.

Adult↗
PubMed1993

[Connection between air quality and room climate and estimation of dwellings by health-impaired inhabitants].

The investigation was performed in winter 1990 and 1991 when measurements were taken in 16 dwellings of patients, recruited from a pulmologic outpatient centre. Patients suffered from repeated respiratory irritations which they attributed to dwelling conditions. Inhabitants reported by means of questionnaires and standardized scales the dwelling situation and their dwelling behaviour, subjective ratings of indoor environmental quality as well as ratings of wellbeing. The load of indoor pollutants (CO2, CO, NO2, HCHO), biological agents (fungal spores, house dust mites) as well as indoor climate factors were assessed. The measurements revealed an evident load at least in one parameter; in the majority of dwellings combined loads of air pollutants and biological agents were apparent. Homes supplied with gas as main energy source had significantly higher concentrations of CO2, CO and NO2. At noon, exposure limits of CO2 and NO2 were frequently exceeded. Inhabitants of homes being supplied with electricity instead of gas gave significantly better air quality ratings. The correlations between the average score concerning the rated health quality of their homes and the rate of excess of exposure limits are significant: The health quality ratings are significantly related to the concentrations of "air quality indicators", which induce the feeling of stale air (CO2) and mucosa irritations (NO2). Ratings of wellbeing are significantly connected to objective parameters, i.e. NO2 baseline load, fungal spores in the air and the difference between wall-air temperature. Our study suggests that people suspecting a connection between their health impairment and dwelling conditions should be taken serious. The measurement program proved to be a suitable screening procedure to assess adverse environmental influences in homes. More homes should be investigated to further support our findings.

Air Pollution, Indoor↗
PubMed1992

[The rectus abdominis syndrome].

Three athletes (one female, two males), aged 18-21 years, developed acute abdominal pain, two of them immediately after exercise including abdominal muscle training. The female patient had a pulmonary infection of uncertain cause at the time. The second patient obviously suffered from an allergic or parasitic disease (eosinophilia of 26%). The third patient, a swimmer, had the symptoms in the course of a flu-like infection after drinking about 100 g alcohol. Serum creatinine kinase activity was 7,800-17,500 U/l, making acute muscle damage likely, probably rhabdomyolysis. Ultrasound examination revealed echo-dense areas of the rectus abdominis muscle in two of the patients, in one of them associated with marked muscle swelling. In the third patient ultrasound was unremarkable during a symptom-free interval 8 days after the onset of symptoms. These observations indicate that even during banal infections sport exercise involving special strain on the abdominal musculature should not be undertaken because of the risk of rhabdomyolysis.

Abdominal Muscles↗