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I Pak

Publications and source records attributed to I Pak.

At least 19 recordsLinked to original sources
PubMed2004

The potential energy surface of the Ar-CO complex obtained using high-resolution data.

A potential energy surface is retrieved for the Ar-CO complex by carrying out a global analysis of its high-resolution spectroscopic data. The data set consists of already published microwave and infrared data and of new microwave transitions which are presented in the paper. The theoretical approach used to reproduce the spectrum is based on a model Hamiltonian which accounts simultaneously for the two large amplitude van der Waals modes and for the overall rotation of the complex. Only the vCO = 0 state is considered. The root-mean-square deviation of the analysis is 18 MHz for the microwave data and 1.4 x 10(-3) cm(-1) for the infrared energy difference data. Fifteen parameters corresponding to the potential energy function are determined in addition to two kinetic energy parameters and two distortion-type parameters. The potential energy surface derived is in good agreement with the one obtained by Shin, Shin, and Tao [J. Chem. Phys. 104, 183 (1996)].

Journal Article↗
PubMed2003

Gastroduodenal metastases in a clear cell sarcoma patient.

Clear cell sarcoma is a rare tumor with an unpredictable clinical course and usually poor prognosis. Almost all of the patients will have pulmonary metastases during the clinical course. Other more common metastatic sites are bones, lymph nodes, liver and spleen. Treatment of clear cell sarcoma is primarily surgical aiming to achieve uninvolved margins. Role of chemotherapy, radiotherapy and immunotherapy is controversial and remission of metastases has been reported rarely. In this study we report a case of clear cell sarcoma, with gastroduodenal and pulmonary metastases and remission of these metastases in response to chemotherapy.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed2002

High resolution TDL spectroscopy of the Ar-CH4 complex.

The spectrum of the weakly bound complex Ar-CH4 in the 7 microm region was discovered, analysed, and compared with a spectrum, predicted from ab initio calculations. The measurements were made by probing a supersonic gas expansion with a tunable diode laser (TDL). Several bands of Ar-CH4 associated with different ro-vibrational transitions of the v4 vibration of CH4 were recorded and analysed in a spectral region from 1295 to 1330 cm(-1). In particular the following transitions were studied: j = 1 <-- 0 (at 1311 cm(-1)) reported in Pak et al. [Z. Naturforsch. 53 (1998) 725], j = 0 <-- 1 (at 1301 cm(-1)), j = 2 <-- 1 (at 1316 cm(-1)), and j = 3 <-- 2 transitions (at 1322 cm(-1)). Here, j denotes the angular momentum of the methane unit inside the complex. Analysis of the recently recorded j = 1 <-- 1 transitions at about 1306 cm(-1) in the region of methane Q(1) is in progress. The experimental results are compared with ab initio calculations. The close agreement between observed and ab initio spectra is convincingly demonstrated with respect to the gross spectral features, including many details of the spectra.

Argon↗
PubMed2001

Doppler-free two-photon millimeter wave transitions in OCS and CHF3.

Doppler-free two-photon rotational transitions J = 13<--<--11 and J = 12<--<--10 of OCS and J = 8<--<--6 and J = 7<--<--5 of CHF (3) were detected in the frequency range 134-156 GHz, using a novel, highly sensitive intracavity-jet technique. The sub-Doppler narrowing of the observed peaks (down to 40 kHz full width at half maximum as compared to 300 kHz of the Doppler width) demonstrates the potential of this new technique for high precision millimeter wave spectroscopy. The possibilities of the further reduction of the two-photon absorption line widths are considered.

Journal Article↗
PubMed2000

Diagnosis of pyogenic pelvic inflammatory diseases by 99mTc-HMPAO leucocyte scintigraphy.

Pelvic inflammatory disease (PID) is one of the major health problems of women of child-bearing age. Among the most serious complications of PID is the formation of a tubo-ovarian abscess (TOA). Early diagnosis of this condition may prevent serious surgical complications such as peritonitis and sepsis, which may be fatal. The purpose of this study was to investigate the efficacy of technetium-99m hexamethylpropylene amine oxime (HMPAO) leucocyte scintigraphy in the diagnosis of TOA. Twenty women with high clinical suspicion of TOA underwent 99mTc-HMPAO leucocyte scintigraphy. The labelling of leucocytes with 99mTc-HMPAO was performed according to a standard protocol. Scans were obtained at 1, 3 and 24 h following the injection of the labelled leucocytes. In eight cases the early and/or late scan was positive, in 11 cases it was negative, and in one case of ovarian cyst torsion, confirmed by laparoscopy, it showed slight uptake in the capsule of the cyst (false-positive). The sensitivity of 99mTc-HMPAO leucocyte scintigraphy was 100%, specificity 91.6%, positive predictive value 89%, negative predictive value 100% and overall accuracy 95%. It is concluded that leucocyte scintigraphy is a non-invasive, safe, physiological and accurate procedure for the diagnosis of TOA. The 24-h scan is crucial, since in some cases the abscess was not clearly visualized on the early scan. Leucocyte scintigraphy may reduce the need for CT, diagnostic laparoscopy and unnecessary invasive surgical procedures.

Adult↗
PubMed2000

Lymphatic mapping and sentinel lymphadenectomy in early stage breast carcinoma.

The rate of axillary lymph node metastases is low in early stage breast carcinoma and axillary lymph node dissection is controversial in the treatment of these patients. Intraoperative lymphatic mapping technique is suggested for the identification of metastatic lymph nodes. Intraoperative lymphatic mapping was performed on 60 clinical stage I and II patients who were treated at Ankara Oncology Hospital between 1996-1998. Patent blue dye was injected in all cases, as the tumor was totally excised before mastectomy, into the surrounding breast tissue at four different quadrants. Presence of metastases were examined on stained lymph nodes (sentinel lymph node: SLN) by frozen-section. Modified radical mastectomy was performed including level I, II, III lymph node dissection. Metastases were evaluated on the remnants of frozen-section tissues and unstained lymph nodes (nonsentinel lymph node: nSLN) in axilla on hematoxyline-eosin stained slides and by immunohistochemistry. Forty-nine (81.6%) SLNs were identified among 60 cases. In 18 (36.7%) of these 49 patients, metastases were detected in SLNs by frozen section. In one case micrometastasis was detected in the remnants of frozen-section by immunohistochemistry though it was negative with hematoxyline-eosin. There were no metastases in nSLNs of 27 cases whose SLNs's frozen-sections were tumor free. In 3 cases SLNs were negative but metastases were detected in nSLNs (false negative: 6.1%). There were no local or systemic complications due to injections of dye. Selective lymph node dissections can be performed on early stage breast cancer patients by means of lymphatic mapping. This minimally invasive technique identifies metastatic axillary lymph nodes with a high degree of accuracy, so we can suggest that, non-metastatic patients can be treated without axillary dissection.

Adenocarcinoma, Mucinous↗
PubMed1999

Submillimeter Detection of the van der Waals Stretching Vibration of the Ar-CO Complex.

With the Cologne submillimeter-wave supersonic jet spectrometer, we extended molecular jet spectroscopy with backward wave oscillators up to frequencies of about 600 GHz. For the first time, the van der Waals stretching vibration of the Ar-CO molecular complex was detected in direct absorption. We measured 13 ro-vibrational transitions (Kvstretch = 1 <-- 0, Ka = 0 <-- 0) in the frequency range from 528 to 600 GHz and additionally the two R(3) K doublet (Ka = 4 <-- 3) pure rotational transitions at 447 GHz with an accuracy of about 200 kHz. The ro-vibrational transitions were assigned and fitted within experimental accuracy to a simple Hamiltonian taking into account the Coriolis interaction between the stretching and bending states, i.e., between vstretch = 1, Ka = 0, and vbend = 1, Ka = 1. The intensity of the transitions in the van der Waals stretching mode was estimated to be a factor of 5-10 less than that in the bending mode of Ar-CO. Copyright 1999 Academic Press.

Journal Article↗
PubMed1999

Cumulation of TP53 mutations and p16INK4A/p15INK4B homozygous deletions in human papilloma virus type 16 positive scrotal cancer.

Scrotal cancer is the first described occupational cancer. The frequency of occupation-related scrotal cancer is very rare because of better hygiene and protective clothing. Human papilloma viruses (oncogenic types 16 and 18) were reported as the causative agents in the pathogenesis of scrotal cancers. E5, E6, and E7 proteins, expressed by human papilloma virus type 16, affect the cell cycle at the G1 checkpoint. TP53, p16INK4A, and p15INK4B were reported as the transcription factors that regulate the cell cycle on the same pathway. Here, the mutation pattern of TP53, p16INK4A, and p15INK4B genes and the homo/hemizygous deletion patterns of p16INK4A/p15INK4B genes are presented in four scrotal carcinoma cases. The results were correlated with the findings of oncogenic human papilloma viruses (types 16 and 18) in this panel. In two of four case, human papilloma virus type 16 was observed. Homozygous deletion in p16INK4A/p15INK4B genes and a codon 259 missense point mutation (GAC-->TAC; Asp-->Tyr) in the TP53 gene were observed in one human papilloma positive scrotal carcinoma case. The homozygous deletion in p16INK4A/p15INK4B genes was observed in another human papilloma positive scrotal carcinoma case. The cumulation of TP53 mutations and p16INK4A/p15INK4B homozygous deletions in human papilloma virus type 16 positive scrotal carcinoma cases indicate that the alterations of TP53, p16INK4A, and p15INK4B genes have an important role in the progression of scrotal cancers, as well as other factors. The survival rate for the two human papilloma virus type 16 positive patients who had a TP53 mutation or p16INK4A/p15INK4B homozygous deletion or both was lower than that for the human papilloma virus type 16 negative cases who had no TP53, p16INK4A, and p15INK4B mutation. The molecular alteration of TP53, p16INK4A, and p15INK4B genes may be useful as a prognostic marker in scrotal cancer.

Carcinoma, Squamous Cell↗
PubMed1999

Secretory breast carcinoma in a boy.

Secretory breast carcinoma is a very rare condition in boys. An 11-year-old boy with secretory breast carcinoma is presented here. Modified radical mastectomy was performed by irradiation and chemotherapy because of axillary metastasis. There was no local recurrence or distant metastases in the follow-up period of 14 months.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1998

High-Resolution Jet-Cooled Spectroscopy of SF6: The nu2 + nu6 Combination Band of 32SF6 and the nu3 Band of the Rare Isotopomers.

The Fourier transform infrared spectrum of SF6 was recorded in a supersonic expansion jet of an SF6/argon mixture. The SF6:Ar seeding ratio was 2:3. The instrumental bandwidth was 0.005 cm-1. A globar source and an MCT detector were used. A rotational temperature of approximately 30 K was achieved. The nu2 + nu6 combination band of 32SF6 was analyzed using a modified version of the spherical top data system (STDS) programs developed in Dijon. A very good fit was obtained for this band with an rms of 0.0036 cm-1. The effective Hamiltonian was developed up to fourth order for the nu2 + nu6 part, to second order for the nu2 and ground state parts, and to first order for the nu6 part. Five hundred twenty-one transitions were assigned, 40 of them reaching the F2u forbidden sublevel. The positions of the two F1u and F2u sublevels are found to be 991.276 and 989.487 cm-1, respectively. The nu3 band of the 33SF6 and 34SF6 isotopomers were also analyzed. Parameters and simulations are presented. A first detection of the nu3 Q branch of 36SF6 (0.02% natural abundance) is reported. Copyright 1998 Academic Press.

Journal Article↗
PubMed1997

Submillimeter-Wave Absorption Spectroscopy of the Ar-CO Complex: Detection of the van der Waals Bending Vibration

Van der Waals bending rovibrational transitions of the Ar-CO complex were observed between 308 and 383 GHz using submillimeter-wave absorption spectroscopy in a pulsed supersonic jet. The submillimeter radiation was generated by a phase-stabilized backward wave oscillator source. Fourteen transitions of the P and R branch of the bending vibration were measured with an accuracy of about 100 kHz. The frequencies were fitted using effective molecular parameters including the band origin and the rotational constants for the ground state and for the excited bending vibrational state.

Journal Article↗
PubMed1997

The fate of intraperitoneally retained gallstones with different morphologic and microbiologic characteristics: an experimental study.

Management of intraperitoneally retained gallstones after laparoscopic cholecystectomy (LC) is controversial, as their natural course is not known. This study was undertaken to assess the probable effects of stone morphology and clinically obvious infection on the outcome of retained gallstones in a mouse model. Forty albino mice were divided into four groups. Group I served as the control group (simple laparotomy, n = 10). Groups II, III, and IV (n = 10 in each group) were study groups. "Intact-sterile-cholesterol" (group II), "crushed-sterile-cholesterol" (group III), and "intact" (n = 5) [group IVa] and "crushed" (n = 5) [group IVb] "infected-cholesterol" gallstones aseptically retrieved from three different human patients were implanted to the peritoneal cavity of the animals. Group IV animals were implanted with stones retrieved from an acutely inflamed gallbladder with proven infection. Animals were sacrificed 6 and 12 weeks after the operations. Cultures and tissue samples were obtained. No animal was lost, no microscopic or macroscopic abnormality was observed in groups I and II, and cultures remained negative. In group III, adhesions surrounding the fragmented stones were evident at the 12th week, and no mortality was encountered. The histopathology revealed a fibroblastic reaction, and cultures remained negative in group III. In group IV, three animals from group IVb and one animal from group IVa died because of intra-abdominal sepsis before their sacrifice. All remaining mice showed severe adhesions with localized abscesses at the 12th week. In conclusion, intraperitoneally retained cholesterol gallstones remain inert and do not cause serious peritoneal reaction unless they are crushed into fragments or are from an acutely inflamed gallbladder. It is for this group of patients that laparotomy for total stone clearance is probably not justifiable. Better stone retrieval techniques or even laparotomy may be worthwhile considering in patients with crushed and particularly infected retained stones.

Animals↗
PubMed1996

The effects of chemotherapy on breast cancer tissue in locally advanced breast cancer.

It is well known that chemotherapy induces cytomorphological changes in neoplastic and non-neoplastic tissue. Thirty-one stage III breast-carcinoma patients, treated with both pre-operative chemotherapy and mastectomy, were evaluated to define the effects of systemic chemotherapeutic agents in tumours, non-neoplastic breast tissue, and lymph nodes. Histological changes were compared with those observed in patients who had been treated by surgery alone. Cytoplasmic vacuolization was the most striking change in the tumour cells (59%). Chemotherapy was especially effective in the terminal duct lobular unit in non-neoplastic breast tissue. Lobular atrophy was observed in 20 (65%) cases, and lobular cellular atypia was seen in 16 (52%). The rate of ductal cellular atypia (42%) was not different from the control group. The most important changes seen in the non-neoplastic stromal component were fibrosis and hyalinization. These were found in 31 out of 727 evaluated lymph nodes. In serial sections, metastatic deposits were seen in or around these fibrotic or hyalinized areas. Chemotherapy is widely used in the treatment of early and locally advanced breast carcinomas. Familiarity with chemotherapy induced changes in breast tissue and lymph nodes have considerable importance in the accurate interpretation of these specimens.

Adult↗
PubMed1994

Expression of hepatitis A virus precursor protein P3 in vivo and in vitro: polyprotein processing of the 3CD cleavage site.

Hepatitis A virus (HAV) cDNAs encoding the P3 region proteins were expressed in vivo and in vitro to characterize the HAV 3D protein and to identify the cleavage site between 3C and 3D. Protein coding sequences were placed under control of a T7 promoter and an EMCV translational initiation signal. T7 RNA polymerase was provided by simultaneous infection of transfected BS-C-1 cells with a recombinant vaccinia virus vTF7-3 (T. R. Fuerst et al., Proc. Natl. Acad. Sci. USA 83, 8122-8126, 1986). Efficient synthesis and processing of P3 proteins occurred to yield 3CD (78 kDa), 3D (54 kDa), 3ABC (33 kDa), 3BC (25 kDa), and 3C (23 kDa). Similar products were produced by translation of T7 transcripts in a rabbit reticulocyte lysate in vitro. The 3C/D cleavage site was mapped by comparing the mobility of 3D in SDS-PAGE with 3D proteins engineered to begin at each of the two proposed cleavage sites; in addition, direct N-terminal sequencing of radiolabeled 3D protein from translation in vitro was performed. The results showed that 3D was formed by cleavage at the glutamine-arginine (Q/R) pair at position 1738 and 1739 of the HAV polyprotein. HAV 3D protein produced by autocatalytic cleavage of P3 precursor proteins in BS-C-1 cells is virtually completely insoluble and sediments after low-speed centrifugation. This is in contrast to the poliovirus 3D protein, produced from a similar construct, a significant portion of which remains soluble. Extracts containing the poliovirus 3D protein manifested high levels of RNA-dependent RNA polymerase activity, whereas those containing the HAV 3D protein showed no detectable activity by the same assay.

3C Viral Proteases↗
PubMed1993

Gastric cancer and Helicobacter pylori infection.

Gastric adenocarcinoma can be divided into two histopathological types: intestinal and diffuse. In addition to the role of environmental factors, an association between gastric cancer and Helicobacter pylori has been suggested. A retrospective study was therefore carried out among 46 patients who had gastric cancer. As a control group, 40 patients with non-malignant disorders were selected (11 patients with peptic ulcer, 12 with chronic superficial gastritis, 17 with chronic atrophic gastritis). Twenty-six cancers were classified as intestinal type and 20 as diffuse type. H. pylori was found in 23 (88 per cent) of the intestinal type and 11 (55 per cent) of the diffuse type (P < 0.05). Patients with the intestinal-type gastric cancer had a higher prevalence of H. pylori infection than those with gastric ulcer (55 per cent) and chronic superficial gastritis (50 per cent) (P < 0.05). These findings suggest that there is a possible association between the intestinal type of gastric cancer and H. pylori infection.

Adenocarcinoma↗
PubMed1989

Spinal extradural metastasis from a medulloblastoma.

Medulloblastoma metastasising extraxially is a rare entity. The mechanisms that cause such spread are not fully understood. We present a patient who developed a low thoracic metastasis three years after surgical removal of a posterior fossa medulloblastoma. A spinal metastasis penetrated the dura, thus becoming extradural and from this tumour a completely extradural lumbal metastasis developed. Simultaneous local recurrences of systemic metastases were not noted.

Adolescent↗