Biomedical subjects

S Kan

Publications and source records attributed to S Kan.

At least 55 records · Page 3Linked to original sources

PubMed1999

Possible paracrine mechanism of insulin-like growth factor-2 in the development of liver metastases from colorectal carcinoma.

BACKGROUND: Insulin-like growth factor-2 (IGF-2) is considered one of the autocrine growth factors in colorectal carcinoma. In addition, it is well known that IGF-2 is produced in the liver. However, the role of IGF-2 in liver metastasis is not yet understood clearly. METHODS: Immunohistochemical staining of IGF-2 and IGF-1 receptor (IGF-1R) was performed on tissue samples of liver metastases from 30 colorectal carcinoma patients. In situ hybridization of IGF-2 also was conducted on the same tissue samples. Furthermore, proliferating cell nuclear antigen (PCNA) was immunohistochemically stained for use as an indicator of the proliferative activity of cancer cells. RESULTS: Invasive margins of liver metastases were stained highly by both IGF-2 (70%) and IGF-1R (83%). Overexpression of IGF-2 protein and mRNA was observed in the normal liver adjacent to the tumor. The PCNA labeling indices (LIs) of the IGF-2 positive groups were significantly higher than those of the IGF-2 negative group (P < 0.0001). In addition, the PCNA LIs for the IGF-1R positive groups also were significantly higher than those for the IGF-1R negative group (P=0.0002). CONCLUSIONS: These findings suggest that hepatocyte-derived IGF-2 stimulates tumor cell proliferation by a paracrine mechanism and plays an important role in tumor progression in colorectal carcinoma patients with liver metastases.

Aged↗

PubMed1999

Clinical application of a blood pressure autoregulation system during hypotensive anesthesia.

A blood pressure autoregulation system based on the state-predictive control method was developed to minimize intraoperative blood loss and hence avoid blood transfusion. In this report, the system is further improved by incorporating fuzzy logic with a fail-safe function and an individual parameter-identifying function. The safety and stability of this system had been confirmed by preclinical experiments with dogs. Thereafter clinical application with 17 patients was conducted to maintain their mean arterial pressure at around 60 mmHg during major surgery. The use of this system resulted in decreased blood loss and more speedy and accurate surgery due to a clearer surgical field. Unwanted effects of hypotension were not observed clinically or in laboratory tests. This system is therefore safe, stable, and effective in reducing the blood loss during major surgery that otherwise might cause substantial blood loss.

Anesthesia↗

PubMed1999

Gd-DTPA enhancement of cranial nerves on MR imaging. Neoplastic lesions.

This study describes a radiological finding - enhancement of cranial nerves and correlates patients' clinical findings and outcome. Seven patients with enhancement of cranial nerves on postcontrast MR were retrospectively reviewed. Cranial nerves having contrast enhancement were optic, oculomotor, trigeminal, facial, acoustic, glossopharyngeal, vagus and accessory nerves. The patients' underlying diseases were malignant lymphoma (3), leukemia (1 patient) and metastatic tumor (2 lung, 1 rectum cancer). Most of the cases (4 out of 7) developed parenchymatous lesion later. Seven patients had CSF cytology study, positive in 3 cases, negative in 4 cases at first spinal tap. In 1 case (case 5) of negative cytology, elevated CEA (carcinogen antibody) was noted. In 2 cases, initial symptoms were sudden hearing loss. Autopsy was done for 1 case of metastatic tumor involving cranial nerves. Contrast MR is a useful examination for depicting cranial nerve involvement with neoplastic change.

Adult↗

PubMed1999

Correlation of tensile strength with bursting pressure in the evaluation of intestinal anastomosis.

BACKGROUND: Although bursting pressure and tensile strength have long been measured to evaluate anastomotic techniques, it has yet to be clarified whether or not they are correlated, what implications they have, and which should be used as a gold standard. MATERIAL AND METHODS: Using an experimental model to estimate pressure and tension in the same colonic anastomosis, the following variables were measured in 48 rats between days 0 and 14: bursting pressure (BP); minimal tensile strength (MITS) necessary to break a part of the anastomosis, and maximal tensile strength (MATS) needed to disrupt the whole anastomosis. Also, circulatory wall tension (CWT) was derived from BP and the anastomotic circumference (AC), and longitudinal wall tension (LWT) from MITS and AC. These variables were compared using correlation and regression analysis. RESULTS: During the lag phase (days < or = 4) there was poor correlation between pressure-related and tension-related variables whereas highly significant correlations were noted in the subsequent fibroplastic phase (day > or = 5). It was shown by regression lines that positive MITS and MATS were expected when BP was zero. CONCLUSION: Contrary to the previous assumption, no correlation was found between BP and tensile strength in the critical postoperative period. Based on our present and previous studies, measurement of MITS is recommended to evaluate the healing of colonic anastomosis.

Anastomosis, Surgical↗

PubMed1999

Lumbar spinal subdural hematoma following craniotomy--case report.

A 52-year-old female complained of lumbago and weakness in the lower extremities 6 days after craniotomy for clipping an aneurysm. Neurological examination revealed symptoms consistent with lumbosacral cauda equina compression. The symptoms affecting the lower extremities spontaneously disappeared within 3 days. Magnetic resonance (MR) imaging 10 days after the operation demonstrated a lumbar spinal subdural hematoma (SSH). She had no risk factor for bleeding at this site, the symptoms appeared after she began to walk, and MR imaging suggested the SSH was subacute. Therefore, the SSH was probably due to downward movement of blood from the cranial subdural space under the influence of gravity. SSH as a complication of cranial surgery is rare, but should be considered if a patient develops symptoms consistent with a lumbar SSH after craniotomy.

Brain↗

PubMed1999

Bow hunter's stroke associated with an aberrant course of the vertebral artery--case report.

A 53-year-old male presented with repeated vertebrobasilar insufficiency on turning the head to the left. Angiography revealed severe stenosis of the dominant right vertebral artery at the atlantoaxial level in this position. Decompression surgery for the affected vertebral artery at the transverse foramen of the atlas was planned. However, surgery revealed an aberrant course of the artery, turning at the orifice of the transverse foramen of the atlas and perforating the dura at the occipitoatlantal level after passing through the bony canal of the atlas. Therefore, decompression was performed at the bony canal, which was the contributing site, and the symptoms improved. Bow hunter's stroke may be caused by atlantoaxial arterial anomalies, so accurate preoperative evaluation of the region is necessary to avoid anatomical confusion at surgery.

Atlanto-Axial Joint↗

PubMed1999

[CT findings of nasal non-Hodgkin's lymphomas associated with prognosis].

X-ray CT images of the head obtained from thirteen patients (9 men and 4 women) among 33 patients (19 men and 14 women) with nasal non-Hodgkin's lymphoma (NHL) who had been seen at Kitasato University Hospital during the period from April 1975 to March 1995 were retrospectively reviewed to search for useful prognostic image factors for nasal NHL. Extracavitary subcutaneous tumor extension into the nasal wing or cheek, and tumor penetration through the nasal septum revealed on X-ray CT images seemed to be likely indicators of a poor prognosis for patients with nasal NHL.

Female↗

PubMed1998

The value of long-term clinical follow-up for cases of spontaneous carotid cavernous fistula.

To clarify the value of clinical long-term follow-up with radiological examination, ranging from 12 to 63 months (average: 35 months), 18 consecutive patients suffering from spontaneous carotid cavernous fistula (CCF), were studied prospectively. Five aged patients without aggressive symptoms were treated conservatively, and the other 13 underwent transarterial embolization. The radiological follow-up was primarily by magnetic resonance angiography (MRA), performed from 2 to 6 times (average: 4.1 times) during the follow-up period. In three cases, CCFs persisted, but the other fifteen (83%) demonstrated complete cure as defined by long-term follow-up MRA. The three patients with persistent CCFs were comparatively young, less than 60 years old, had no atherosclerotic factors and demonstrated multiple venous drainage routes with cortical venous drainage on angiography. In two of them, the symptoms completely disappeared, and the other had only mild chemosis. However, surprisingly, in two, MRA revealed residual CCF with drainage into only cortical veins through the sphenoparietal sinus, this radiological finding being well known to signify danger. During the follow-up period, central retinal vein thrombosis occurred in two cases. The common point in these cases was that the superior ophthalmic vein was the only venous drainage route. This is also a point requiring care. We therefore emphasize the importance of careful long-term radiological follow-up for spontaneous CCF patients even when their symptoms improve or disappear. MRA is particularly suitable for this purpose and applicable in the out-patient clinic because of its non-invasive nature.

Adult↗

PubMed1998

Efficacy of the stump pressure ratio as a guide to the safety of permanent occlusion of the internal carotid artery.

To determine whether the absolute value for the stump pressure might be a useful index of symmetrical cerebral blood flow (CBF), and to examine correlations with the stump pressure ratio (initial mean stump pressure/preocclusion mean arterial pressure), fifty candidates for ICA injury or permanent occlusion were evaluated preoperatively. Each was continuously monitored for mean stump pressure and arterial pressure before, during (for a total of 20 min), and after balloon test occlusion. During the occlusion, CBF was measured by 99 m Tc-hexamethyl-propyleneamine oxime (99 m Tc-HMPAO) single photon emission computed tomography (SPECT). The stump pressure and the stump pressure ratio were then compared with the results of 99 m Tc-HMPAO SPECT. Patients who failed to tolerate even brief periods of carotid occlusion and showed asymmetric decreases in CBF on SPECT were divided into high and moderate risk groups. Those with no significant changes in CBF on the occluded site formed the minimum risk group. Mean stump pressure was over 50 mmHg in 10 of a total of 25 patients in the high and moderate risk groups, and below 50 mmHg in 5 of the 25 patients in the minimum risk group. The stump pressure ratio did not exceed 56% in any but two patients in the high and moderate risk groups, and values were at least 60% in all patients of the minimum risk group. Decrease of CBF in two moderate risk group cases was localized in the posterior circulation. Difference in symmetrical CBF between the stump pressure ratio vs. the absolute value of mean stump pressure were statistically significant (p < 0.01, Fisher's Exact Test). Maintenance of a stump pressure ratio of 60% or more during test occlusion may be a more useful index for a good collateral circulation than any absolute value for mean stump pressure.

Blood Pressure↗

PubMed1998

Effects of antineoplastics, antibiotics and antidiabetics on acetaldehyde metabolism after alcohol ingestion.

The main purpose of this study was to evaluate the inhibitory effects of 5-fluorouracil antineoplastics, cephem antibiotics containing the methyltetrazolylthiol (MTT) group and antidiabetics on aldehyde dehydrogenase (ALDH) activity in vivo and in vitro. In in vivo experiments, rats were given a 100 mg/kg dose of drugs (10 mg/kg for glibenclamide) orally or intraperitoneally. When each drug was administered singly immediately after an oral administration of 1.5 g/kg ethanol, only carmofur, an antineoplastic, produced marked increases in blood acetaldehyde concentrations. This action was also noted when ethanol was ingested 15 h after administration. The remaining drugs did not increase blood acetaldehyde concentrations. When rats were treated with carmofur at 12 h intervals for 3 consecutive days and were given 1.5 g/kg ethanol after the final treatment, blood acetaldehyde concentrations were elevated more significantly than with a single administration of carmofur. Furthermore, daily administration of cephem antibiotics containing the MTT group, latamoxef, cefamandole, cefoperazone and cefbuperazone, significantly increased blood acetaldehyde concentrations. Daily administration of sulfonylurea antidiabetics, chlorpropamide and acetohexamide, slightly increased blood acetaldehyde concentrations. Drugs causing increases in blood acetaldehyde concentrations when administration was combined with ethanol ingestion also inhibited ALDH activity in vitro. The results of the in vitro experiments roughly correlated with those of the in vivo experiments. The inhibitory effects of drugs on ALDH activity were in the following order: carmofur >> cephem antibiotics containing the MTT group > sulfonylurea antidiabetics.

Acetaldehyde↗

PubMed1997

Synthesis of Uniform Ferric Oxide Particles from Deionized Colloids

A modified method was employed to prepare monodispersed colloidal particles of ferric (hydrous) oxide. The method contains three steps: (i) preparation of uniform nuclei of ferric hydrous oxide via a so-called instantaneous nucleation method; (ii) purification of the nuclei suspension via dialysis; (iii) aging of the purified nuclei suspension in a reflux reactor at certain pH. Cubic and pseudocubic alpha-Fe2O3 monodisperse particles which are much smaller than the cubic alpha-Fe2O3 particles obtained from the same reactant through a usual method were produced by aging needle like nuclei at a lower pH. A close-packed three-dimensional QDs (quantum dots) superlattice structure 40 nm in edge length with cubic geometry was formed by self-aggregation between spherical amorphous ferric hydrous oxide nuclei 3-5 nm in diameter. The growth processes of the two kind particles were also illustrated. This study showed an approach to prepare smaller particles from aqueous metal salt solutions in relatively higher concentration, and ordered QDs superlattice structure by controlled self-aggregation of QDs in hydrosol.

Journal Article↗

PubMed1997

Multi-turn split-conductor transmission-line resonators.

Multi-turn split-conductor transmission-line resonators (MSTR) can be designed to operate over a wide range of NMR operating frequencies without lumped tuning capacitors. This architecture constitutes an alternative solution to recent designs proposed for high-Q, thin-film, high-temperature superconducting NMR probes. An advantage is that the resonant frequency can be calculated in a relatively simple manner in terms of coil turns or total coil length, coil width, substrate thickness, and dielectric constant. Analytical calculation of the resonant frequency is provided. Also, a series of MSTRs was constructed on a double copper-clad substrate, and their resonant frequencies are noted. The results obtained were in good agreement with the predicted values.

Electric Conductivity↗

PubMed1997

Non-compartmental analysis of pharmacokinetic data after multiple intravenous and oral administration.

Non-compartmental analysis is routinely used to determine the pharmacokinetic parameters such as area under the curve (AUC), area under the first moment curve (AUMC), clearance (CL), mean residence time (MRT), terminal half life (t1/2) and volume of distribution (Vd). These parameters are important to define the fate of a drug after administration by a particular route. It is well known that the AUC after a single dose is equivalent to that after multiple dose at steady state during one dosing interval. However, this relationship is not true for AUMC. Hence, it is not possible to calculate MRT as the ratio of AUMC and AUC from multiple dose data. It was the purpose of this presentation to evaluate the calculation of MRT for single and multiple dosing after intravenous and oral administration and compare two different approaches to determine MRT from multiple dose data. The results show that after multiple dosing MRT is most reliably determined by continuous sampling after the end of the last dosing interval until no more drug can be detected.

Administration, Oral↗

PubMed1997

[A case of dural sinus thrombosis during the medication of medroxyprogesterone acetate].

It is reported that medroxyprogesterone acetate (MPA) causes venous thrombosis as one of the side effects. A 49-year-old woman suffering from metastatic lung carcinoma from breast carcinoma was administered MPA 1200 mg/day for about four months. Thereafter she complained of dizziness about two weeks but the general practitioners could detect no abnormality on physical examinations and on brain CT X-ray findings. Six days later, she died suddenly at her home. Forensic autopsy findings revealed the marked superior sagital sinus thrombosis and the malignant lymphadenomatosis caused by metastatic lung carcinoma. As the patient had not disease or trauma causing dural sinus thrombosis except for the administration of MPA, we concluded that superior sagital sinus thrombosis was due to the medication of MPA. This case illustrates that forensic pathologist should consider the major side effect of some drugs like our case.

Antineoplastic Agents, Hormonal↗

PubMed1996

Preferential deimination of keratin K1 and filaggrin during the terminal differentiation of human epidermis.

The upper layers of mammalian epidermis contain citrulline-containing proteins formed by enzymatic deimination of arginine residues. To study the role of protein deimination in epidermal differentiation, we identified deiminated proteins extracted from human epidermis. Major deiminated proteins were identified as partially degraded keratin K1, while those from keratin K10 and a highly heterogeneous mixture of deiminated filaggrin isomers were detected as minor components. Deiminated keratins were recovered in a fraction enriched with keratins from the cornified layers. The subsequent immunohistochemical study showed that deiminated proteins were localized mainly in the lowermost cornified layer, but not in the granular layer. These data suggested that partially degraded/disulfide-cross-linked keratin K1 was preferentially deiminated during the terminal stages of epidermal differentiation. We therefore speculated that the protein deimination might influence the interaction of basic K1 with its acidic partner K10, pre-existent K5/K14 networks or keratin-associated protein filaggrin.

Adult↗

PubMed1996

A source of haemorrhage in adult patients with moyamoya disease: the significance of tributaries from the choroidal artery.

This study concerns 19 patients over 16 years of age with Moyamoya disease. Ten cases of intracranial haemorrhage, as the initial haemorrhagic event in patients aged from 21 to 55 (haemorrhagic group) and 9 cases of ischaemic events in 18- to 53-year-old patients (ischaemic group) were included. All haemorrhages were associated with intraventricular haemorrhages (IVH); and all but one case of thalamic haemorrhage were thought to be primary IVH (2 cases of small paraventricular haemorrhage; 2 of small haemorrhages in the splenium; 5 with no intracerebral haematoma). In the 9 patients of the ischaemic group, there were 2 cases of transient ischaemic attacks and 7 of cerebral infarction. Angiographic evaluations demonstrated that the abnormal basal vessel formation and the collateral supplies from the external carotid arteries were poorly developed in both groups. In contrast, the collateral circulation via the choroidal and posterior pericallosal arteries was well demonstrated. Furthermore, marked enlargement of the choroidal arteries and the medullary arteries derived from them was seen more frequently in the haemorrhagic group. These findings suggested that the haemodynamic load in the vessels supplying the walls of the posterior parts of the ventricles and the periventricular region was increased, especially in the haemorrhagic group. Those vessels were considered to be important sites of IVH in adult patients with Moyamoya disease.

Adult↗

PubMed1996

Stump pressure as a guide to the safety of permanent occlusion of the internal carotid artery.

Does the absolute value of the stump pressure (post-occlusion back pressure) become a useful index of a good collateral circulation? The authors continuously monitored the mean arterial pressure before, during and after 20-minute balloon test occlusion in 24 patients. The stump pressure was then compared with the results of 99mTc-hexa-methyl propyleneamine (99mTc-HMPAO) single photon emission computed tomography (SPECT) performed after 20 minutes of test occlusion. Patients who failed to tolerate even brief periods of carotid occlusion and showed asymmetric decreases in cerebral blood flow (CBF) on SPECT were divided into high and moderate risk groups. Those with no significant change in CBF on the occluded side formed the minimum risk group. Mean stump pressure was over 50 mmHg in three of a total of 13 patients in the high and moderate risk groups, and below 50 mmHg in two of the 11 patients in the minimum risk group. The ratios of the initial mean stump pressure to the pre-occlusion mean arterial pressure (%) and of the final mean stump pressure at the end of occlusion to the post-opening mean arterial pressure (%) did not exceed 58% in any patient in the high and moderate risk groups, and were at least 60% in all patients of the minimum risk group. Maintenance of a mean stump pressure of 60% or more of the mean systemic pressure during test occlusion may be a more useful index of a good collateral circulation than the absolute value of mean stump pressure.

Adult↗

PubMed1996

Involvement of protein kinase C in gamma-aminobutyric acid release from Xenopus oocytes injected with rat brain mRNA.

Involvement of protein kinase C (PKC) in the release of gamma-aminobutyric acid (GABA) was examined in Xenopus laevis oocytes injected with mRNA from rat cerebellum, as compared with findings in slices of rat cerebellum. The mRNA-injected oocytes preloaded with [3H]GABA showed spontaneous release of [3H]GABA, approximately 0.5% of GABA content per 1 min. Stimulation with either Ca2+ ionophore (A23187) or a high K+ concentration increased the release of [3H]GABA from slices of rat deep cerebellar nucleus and mRNA-injected oocytes but not from noninjected and water-injected oocytes. 12-O-Tetradecanoylphorbol 13-acetate (10-300 nM) but not 4alpha-phorbol 12,13-didecanoate (300 nM) potentiated the A23187-stimulated release of [3H]GABA from slices and from mRNA-injected oocytes, in a concentration-dependent manner. Thus, machinery associated with release processes of GABA can be expressed in oocytes by injecting rat cerebellar mRNA, and PKC participates in GABA release from the functionally expressed GABAergic nerve terminals.

Animals↗