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Biomedical subjects

M Bak

Publications and source records attributed to M Bak.

At least 19 recordsLinked to original sources
PubMed2001

(13)C chemical shift and (13)C-(14)N dipolar coupling tensors determined by (13)C rotary resonance solid-state NMR.

This work explores the utility of simple rotary resonance experiments for the determination of the magnitude and orientation of (13)C chemical shift tensors relative to one or more (13)C--(14)N internuclear axes from (13)C magic-angle-spinning NMR experiments. The experiment relies on simultaneous recoupling of the anisotropic (13)C chemical shift and (13)C--(14)N dipole--dipole coupling interactions using 2D rotary resonance NMR with RF irradiation on the (13)C spins only. The method is demonstrated by experiments and numerical simulations for the (13)C(alpha) spins in powder samples of L-alanine and glycine with (13)C in natural abundance. To investigate the potential of the experiment for determination of relative/absolute tensor orientations and backbone dihedral angles in peptides, the influence from long-range dipolar coupling to sequential (14)N spins in a peptide chain ((14)N(i)--(13)C(alpha)(i)--(14)N(i+1) and (14)N(i+1)--(13)C'(i)--(14)N(i) three-spin systems) as well as residual quadrupolar-dipolar coupling cross-terms is analyzed numerically.

Journal Article↗
PubMed2001

Primary IgA nephropathy in children: association of clinical and pathological findings with prognosis.

Primary IgA nephropathy is a disease characterized by recurrent macroscopic or microscopic hematuria and diffuse mesangial IgA deposition. Although IgA nephropathy had previously been suggested to have a benign prognosis, long term follow-up of the patients revealed that it might lead to chronic renal failure. In this study, the association of the initial clinical and laboratory findings with the renal histological changes was evaluated in 14 cases with primary IgA nephropathy who were at follow-up with a mean duration of 43.07 +/- 16.88 months. Finally the correlation between the clinicopathological findings and prognosis was investigated. In 92.8% of the patients, macroscopic hematuria was the presenting complaint. Proteinuria was detected in 42.9% of the cases mild proteinuria in 14.3% and moderate in 28.6%. Renal biopsy specimens, evaluated according to Churg-Sobin's classification, showed grade 1 changes in 35.7% cases, grade 2 in 35.7%, grade 3 in 14.3% and grade 4 in 14.3%. Both the patients with grade 4 histology had moderate proteinuria, and developed chronic renal failure requiring hemodialysis. Prognosis was found to be associated with the degree of proteinuria and the severity of the histopathological findings.

Female↗
PubMed2001

Conformation of alamethicin in oriented phospholipid bilayers determined by (15)N solid-state nuclear magnetic resonance.

The conformation of the 20-residue antibiotic ionophore alamethicin in macroscopically oriented phospholipid bilayers has been studied using (15)N solid-state nuclear magnetic resonance (NMR) spectroscopy in combination with molecular modeling and molecular dynamics simulations. Differently (15)N-labeled variants of alamethicin and an analog with three of the alpha-amino-isobutyric acid residues replaced by alanines have been investigated to establish experimental structural constraints and determine the orientation of alamethicin in hydrated phospholipid (dimyristoylphosphatidylcholine) bilayers and to investigate the potential for a major kink in the region of the central Pro(14) residue. From the anisotropic (15)N chemical shifts and (1)H-(15)N dipolar couplings determined for alamethicin with (15)N-labeling on the Ala(6), Val(9), and Val(15) residues and incorporated into phospholipid bilayer with a peptide:lipid molar ratio of 1:8, we deduce that alamethicin has a largely linear alpha-helical structure spanning the membrane with the molecular axis tilted by 10-20 degrees relative to the bilayer normal. In particular, we find compatibility with a straight alpha-helix tilted by 17 degrees and a slightly kinked molecular dynamics structure tilted by 11 degrees relative to the bilayer normal. In contrast, the structural constraints derived by solid-state NMR appear not to be compatible with any of several model structures crossing the membrane with vanishing tilt angle or the earlier reported x-ray diffraction structure (Fox and Richards, Nature. 300:325-330, 1982). The solid-state NMR-compatible structures may support the formation of a left-handed and parallel multimeric ion channel.

Alamethicin↗
PubMed2001

Maastricht Assessment of Coping Strategies (MACS-I): a brief instrument to assess coping with psychotic symptoms.

OBJECTIVE: To examine the reliability of a brief instrument to assess coping with symptoms by patients with psychotic illness. METHOD: A semi-structured interview (MACS) was developed to assess the amounts of distress, control and coping in relation to psychotic symptoms. Two raters interviewed 23 symptomatic but stable patients with a diagnosis of chronic schizophrenia on two separate occasions. Case managers were also interviewed. RESULTS: Both the number of coping strategies used for different groups of symptoms, and the amount of coping used in different domains of coping strategies could be assessed reliably between interviewers (intraclass correlation coefficients range: 0.90-0.97) and between interview sessions (ICCs range: 0.75-0.80). Reliability with case managers, however, was low. CONCLUSION: The MACS may be a reliable and useful instrument to assess coping in relation to subjective experience of distress by and control over psychotic symptoms.

Adaptation, Psychological↗
PubMed2001

MACS-II: does coping enhance subjective control over psychotic symptoms?

OBJECTIVE: Associations between subjective experience of control and the use of self-initiated coping strategies were examined in patients with psychotic symptoms. METHOD: Twenty-three patients were interviewed to assess (i) the subjective experience of distress with and control over symptoms and (ii) the coping strategies used. RESULTS: There was a positive association between coping type and control (OR = 1.07, 95% CI: 1.03-1.12). Active coping strategies had the strongest association with experience of control (active problem-solving: OR = 1.41 95% CI: 1.18-1.68; active problem-avoiding: OR = 1.45 95% CI: 1.18-1.68). Symptomatic coping was negatively associated with control (OR = 0.40, 95% CI: 0.30-0.55), but was the most frequently used strategy. Depressive symptoms were associated with the highest number of coping strategies. CONCLUSION: Coping strategies differ in the degree and direction of associated subjective control, and symptoms differ in the degree with which coping is mobilized. Assessment of coping strategies may be useful as a prelude to psychological therapy.

Adaptation, Psychological↗
PubMed2001

Delayed neutropenic enterocolitis in a 12-year-old girl treated with total colectomy and J-pouch reservoir.

Neutropenic enterocolitis (NE) is a clinicopathologic condition characterized by bowel wall inflammation, which can proceed to necrosis and perforation. It is mostly seen in neutropenic patients with leukemia who undergo induction treatment with chemotherapy. Most often the cecum is involved. The authors present a 12-year-old girl with acute lymphocytic leukemia who, under maintenance therapy, experienced NE. The disease was localized to the left side of colon, and even the rectum was involved, which is an unusual localization of the disease. An ileoanal anastomosis with a J-pouch was done in a second operation with a good outcome.

Antineoplastic Agents↗
PubMed2001

Screening for human papillomavirus infection in asymptomatic women in Hungary.

BACKGROUND: A multicentre epidemiological survey was carried out in order to determine the prevalence of, and risk factors for, persistent cervical human papillomavirus (HPV) infection in women in Hungary. METHODS AND RESULTS: A total of 728 women were examined for the prevalence of HPV. The estimated overall rate of HPV infection was 17%. In univariate analysis the strongest predictors were young age (< or =24 years), unmarried family status, smoking, a pathological Papanicolaou (Pap) smear, having a condyloma and previous gynaecological cancer in the family (age and marital status being the most important predictors). In multiple regression analysis, young age (< or =24 years)(odds ratio = 1.86, 95% confidence interval = 1.19-2.90, P < 0.01), smoking (1.78, 1.17-2.71, P < 0.05), an abnormal Pap smear (6.92, 2.68-17.84, P < 0.001), having a condyloma (4.22, 1.42-12.58, P < 0.01) and living in a region where the unemployment rate is relatively high (1.56, 1.24-2.82, P < 0.01) were associated risk factors for HPV infection. CONCLUSIONS: The prevalence of HPV infection in young women in Hungary is high. Screening for HPV is suggested only in women with an unfavourable gynaecological history who are < or =24 years old.

Adult↗
PubMed2001

Effects of the somatostatin analogue octreotide on renal function in conscious diabetic rats.

BACKGROUND: Studies performed during the last decade have indicated that growth hormone (GH) and insulin-like growth factors (IGFs) may mediate the early renal changes in diabetes mellitus, i.e. hypertrophy and hyperfiltration. This and other observations have led to the suggestion that GH/IGF inhibitors, such as long-acting somatostatin analogue (e.g. octreotide and lanreotide), may be useful in order to inhibit or prevent development of long-term diabetic complications. METHODS: The present study examined the acute and chronic effects of octreotide on renal function following induction of streptozotocin (STZ)-diabetes in rats. The studies were carried out in conscious, non-fasted diabetic animals. RESULTS: Chronic administration of octreotide for 7 days, from onset of diabetes, prevented the decrease of effective renal vascular resistance (ERVR), and the increases in filtration fraction (FF), glomerular filtration rate (GFR), and absolute proximal tubular fluid reabsorption (APR) induced by diabetes. The renal hypertrophy was only partially prevented. In the acute study, similar changes were observed in effective renal plasma flow (ERPF) and ERVR but FF increased and GFR remained unaltered. CONCLUSIONS: Chronic but not acute treatment with octreotide prevented the renal hyperfiltration caused by diabetes. This effect is most likely due to an increase in afferent arteriolar resistance.

Animals↗
PubMed2001

Three-year results of the first educational and early detection program for testicular cancer in Hungary.

OBJECTIVE: To determine whether a testicular self-examination-based early-detection program may help in the early diagnosis of testicular cancer. METHODS: Advertisements were placed in the media describing the early signs of testicular cancer, the risk factors, the correct method of self-examination and the importance of early detection. Between April 1995 and April 1998, 5,056 men underwent physical and ultrasound examination of the testicles, and in case of suspicious findings tumor markers were checked. RESULTS: Testicular tumors were found in 1.28% of the men with symptoms. No tumors were found in men without symptoms or in men with pain, sensitivity to palpation, or complaints unrelated to the testicle. Of those with a palpable lump or swollen testicle, 4.5 and 3.9% were found to have a tumor. In total, 28 testicular cancers (15 seminomas and 13 nonseminomas) in 26 volunteers and 4 benign tumors were detected. The occurrence of cancer was most frequent in the age group of 15--40 years (1.6%). CONCLUSION: The rate of cancer detection and the detected seminoma rate in the program are not sufficient to justify a widespread early detection program for testicular cancer (examination of men who reveal testicular abnormalities by self-examination) despite the increased tumor incidence. Early diagnosis should be based on an educational program for the population at risk, the training of staff engaged in the health care of the young, and the use of early ultrasound examination in men with palpable lumps and swollen testicles, especially in young men.

Adolescent↗
PubMed2001

The human hedgehog-interacting protein gene: structure and chromosome mapping to 4q31.21-->q31.3.

Hedgehog-interacting protein (Hhip) is a novel regulatory component in the vertebrate hedgehog-signalling pathway. The murine Hhip encodes a type I TM protein that attenuates hedgehog signalling by binding all three mammalian hedgehog proteins. Here we describe the cloning and characterisation of the homologous human hedgehog-interacting protein gene (HHIP). HHIP comprises 13 exons and spans >91kb encoding a protein of 700 aa which shares 94% sequence iden- tity with mouse Hhip. HHIP maps to chromosome 4q31.21--> q31.3. Additionally, we have mapped murine Hhip to chromosome 8.

Animals↗
PubMed2001

Transforming growth factor-beta2 antibody attenuates fibrosis in the experimental diabetic rat kidney.

Diabetic nephropathy is characterised by an increase in glomerular and tubular fibrosis that compromises kidney function. The transforming growth factor-betas (TGF-betas) have been shown to play a major role in fibrosis and we have shown that TGF-beta2, in particular, increases co-ordinately with fibrogenesis in the diabetic kidney. The aim of this study was to investigate the changes in expression of extracellular matrix molecules in the diabetic kidney, with and without systemic administration of a recombinant human monoclonal antibody to TGF-beta2. Streptozotocin-induced diabetic rats were split into two groups. The first were treated with 5 mg/kg irrelevant control IgG4 (placebo) and the second treated with 5 mg/kg isoform-specific recombinant monoclonal anti-TGF-beta2 IgG4 (termed CAT-152) systemically every second day for 14 days. A further group of six non-diabetic rats was also used as a control. Various biological parameters were measured daily throughout the experimental period, and on termination of the experiment at 14 days Western blotting was performed on kidney cortices for procollagen-I C-propeptide, which is an indicator of the rate of collagen-I synthesis within the kidney. In the placebo-treated diabetic rats, blood glucose, food consumption, urinary albumin excretion (UAE) and kidney weights were all significantly higher than in the non-diabetic group (P<0.05, n=24, by ANOVA). In the anti-TGF-beta2-treated diabetic rats, kidney weights and UAE levels were decreased when compared with those in placebo-treated diabetics. Western blotting for the procollagen-I C-propeptide in kidney cortices showed a significant increase in levels in placebo-treated diabetic rats compared with non-diabetic controls over the 14 day diabetic period, indicating initiation of fibrogenesis. By contrast, in anti-TGF-beta2-treated diabetic rats, levels of the propeptide remained at non-diabetic levels. In summary, a significant suppression of kidney fibrosis was seen in anti-TGF-beta2-treated diabetic rats, compared with placebo-treated diabetic rats. We conclude that systemic delivery of CAT-152, a neutralising anti-TGF-beta2 antibody, during the acute stages of diabetic nephropathy reduces the rate of pathogenic fibrosis in the kidney.

Albuminuria↗
PubMed2001

Colloidal calcium phosphates in casein micelles studied by slow-speed-spinning 31P magic angle spinning solid-state nuclear magnetic resonance.

The composition of bovine casein micelles was analyzed by 31P magic angle spinning solid-state nuclear magnetic resonance spectroscopy. By looking at isotropic and anisotropic 31P chemical shift parameters, resonance line shapes, the combination of single-pulse and 1H to 31P cross-polarization spectra, and comparison with spectra for various model compounds combined with multiple-component simulation and iterative fitting procedures, we were able to identify and quantify a variety of inorganic and organic phosphates in the micelles. These include phosphates from mobile and immobile inorganic hydroxyapatite-type phosphates as well as phosphates from kappa-casein and the Ca2+-binding phosphoserines from alphas1-, alphas2-, and beta-casein. This information is discussed in relation to previous knowledge and various models for the colloid formation.

Animals↗
PubMed2001

[Retrospective evaluation of surgically treated cases of non-palpable breast tumor].

Between 10.01.1997 and 09.30.1999 authors performed operations on 78 patients who had nonpalpable breast tumors. If mammography was considered abnormal during breast screening program patients were recalled. Besides clinical investigation complimentary mammograms were performed. After sonogram, and if needed, aspiration biopsy cytology (ABC) if necessary core biopsy (CB) was the next investigation. 79 operations were performed on 78 patients (one was patient had synchronous breast tumor). The mean age of the patients was 56.3 years. If the radiological investigations (R4-R5) and/or the ABC (C4-C5) or CB suggested malignancy operation was performed. Mammography suggested malignancy in 60.75% of the patients, it was suggested by ABC in 30.18%, and by CB in 55.5%. The nonpalpable tumor, suspected to be malignant was marked with a wire loop and was excised under anesthesia along with the affected breast sector. The excision and tissue-border around the tumor was checked by specimen mammography performed during the narcosis. No cryohistology was performed. After the specimen mammography, the wound was closed. The final histology of the operations showed malignancy in 40.5%. In their retrospective study the authors evaluated the complete sensitivity and the positive predictive value (PPV) of the preoperative investigations regarding the final histology. They analyse the value of preoperative mammogram, the ABC and CB in malignant and in benign cases. Early diagnosis and surgical treatment is expected to improve significantly the survival of patients with breast cancer. Reduction in the number of unnecessary operations can be expected from increasing the accuracy of radiological and cytological investigations and the adequate usage of core biopsy.

Biopsy, Needle↗
PubMed2000

SIMPSON: a general simulation program for solid-state NMR spectroscopy.

A computer program for fast and accurate numerical simulation of solid-state NMR experiments is described. The program is designed to emulate a NMR spectrometer by letting the user specify high-level NMR concepts such as spin systems, nuclear spin interactions, RF irradiation, free precession, phase cycling, coherence-order filtering, and implicit/explicit acquisition. These elements are implemented using the Tcl scripting language to ensure a minimum of programming overhead and direct interpretation without the need for compilation, while maintaining the flexibility of a full-featured programming language. Basically, there are no intrinsic limitations to the number of spins, types of interactions, sample conditions (static or spinning, powders, uniaxially oriented molecules, single crystals, or solutions), and the complexity or number of spectral dimensions for the pulse sequence. The applicability ranges from simple 1D experiments to advanced multiple-pulse and multiple-dimensional experiments, series of simulations, parameter scans, complex data manipulation/visualization, and iterative fitting of simulated to experimental spectra. A major effort has been devoted to optimizing the computation speed using state-of-the-art algorithms for the time-consuming parts of the calculations implemented in the core of the program using the C programming language. Modification and maintenance of the program are facilitated by releasing the program as open source software (General Public License) currently at http://nmr.imsb.au.dk. The general features of the program are demonstrated by numerical simulations of various aspects for REDOR, rotational resonance, DRAMA, DRAWS, HORROR, C7, TEDOR, POST-C7, CW decoupling, TPPM, F-SLG, SLF, SEMA-CP, PISEMA, RFDR, QCPMG-MAS, and MQ-MAS experiments.

Algorithms↗
PubMed2000

The structure of the membrane-binding 38 C-terminal residues from bovine PP3 determined by liquid- and solid-state NMR spectroscopy.

The secondary structure and membrane-associated conformation of a synthetic peptide corresponding to the putative membrane-binding C-terminal 38 residues of the bovine milk component PP3 was determined using 1H NMR in methanol, CD in methanol and SDS micelles, and 15N solid-state NMR in planar phospholipid bilayers. The solution NMR and CD spectra reveal that the PP3 peptide in methanol and SDS predominantly adopts an alpha-helical conformation extending over its entire length with a potential bend around residue 19. 15N solid-state NMR of two PP3 peptides 15N-labelled at the Gly7 and Ala32 positions, respectively, and dissolved in dimyristoylphosphatidylcholine/dimyristoylphosphatidylglycerol phospholipid bilayers shows that the peptide is associated to the membrane surface with the amphipathic helix axis oriented parallel to the bilayer surface.

Amino Acid Sequence↗
PubMed2000

Vascular grading of angiogenesis: prognostic significance in breast cancer.

The study aimed to evaluate the prognostic value of angiogenesis by vascular grading of primary breast tumours, and to evaluate the prognostic impact of adding the vascular grade to the Nottingham Prognostic Index (NPI). The investigation included 836 patients. The median follow-up time was 11 years and 4 months. The microvessels were immunohistochemically stained by antibodies against CD34. Angiogenesis was graded semiquantitatively by subjective scoring into three groups according to the expected number of microvessels in the most vascular tumour area. The vascular grading between observers was moderately reproduced (kappa = 0.59). Vascular grade was significantly associated with axillary node involvement, tumour size, malignancy grade, oestrogen receptor status and histological type. In univariate analyses vascular grade significantly predicted recurrence free survival and overall survival for all patients (P < 0.0001), node-negative patients (P < 0.0001) and node-positive patients (P < 0.0001). Cox multivariate regression analysis showed that vascular grading contributed with independent prognostic value in all patients (P < 0.0001). A prognostic index including the vascular grade had clinical impact for 24% of the patients, who had a shift in prognostic group, as compared to NPI, and implied a better prognostic dissemination. We concluded that the angiogenesis determined by vascular grading has independent prognostic value of clinical relevance for patients with breast cancer.

Adult↗
PubMed2000

Sentinel node localization in breast cancer patients using intradermal dye injection.

In a series of 161 consecutive breast cancer operations, intradermal injection of Patent Blue was used to localize the sentinel node (SN). The surgical localization rate was 60%. Including the blue lymph nodes found by the pathologist, localization rate was 70%. After the first 103 operations, the surgical procedure was changed, resulting in a localization rate of 83%. Ten surgeons participated, but only one had previous experience with SN dissection. The others experienced a steep learning curve. Metastasis was found in 42 of 97 SNs (43%). In 15 cases (36%) metastasis was recognized only after step-sectioning and immunohistochemical staining for cytokeratin. In one case a benign epithelial inclusion was found. The sentinel node was false negative in 9.1% of cases. The consensus from the literature is that the best results are achieved using a combination of dye and isotopic techniques.

Adult↗