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Biomedical subjects

R S Liu

Publications and source records attributed to R S Liu.

At least 127 records · Page 7Linked to original sources
PubMed1992

Cognition and 99Tcm-HMPAO SPECT in Parkinson's disease.

99Tcm-hexamethylpropyleneamine oxime (HMPAO) single photon emission computed tomography (SPECT) of brain was performed in 43 unselected patients with Parkinson's disease to evaluate whether low cerebral perfusion on SPECT correlated with cognitive impairment in the patients. All patients received neurological, Mini-Mental State Examination and a neuropsychological assessment. Eighteen (41.9%) of the 43 patients were demented. Thirty patients (69.8%) had abnormal SPECT: 17 had perfusion defects in cortical regions, eight in basal ganglia and five in both regions. Of the 22 patients with abnormal cortical perfusion, 15 (68.2%) were demented; only three (14.3%) of the 21 patients without cortical defect were demented (P < 0.01). Twelve of the 15 demented patients had low perfusion in the parietal region alone or in parietal and occipital regions. The cortical perfusion defects, present in 22 (51.2%) Parkinson's patients, are highly correlated with cognitive impairment. The pattern of SPECT abnormality in most demented patients with Parkinson's disease is similar to that seen in Alzheimer's disease, suggesting that the underlying pathophysiology for dementia in patients with Parkinson's disease may be similar to that in Alzheimer's disease.

Adult↗
PubMed1992

Liver disease in patients with liver dysfunction prior to bone marrow transplantation.

Twenty-two patients with previous hepatic compromise who underwent allogeneic bone marrow transplant (BMT) for treatment of hematologic malignancy or other hematologic disease between 1984 and 1990 were chosen for the present study. After transplant, 19 (86.4%) of the patients developed hepatitis, including six cases (27.3%) of acute hepatitis, 12 (54.6%) of chronic hepatitis and one uncharacterized hepatitis. Nine chronic hepatitis patients were followed-up for 7-56.5 months (medium 35.5 months) with biochemistry studies and ultrasonography. Throughout the observation period, liver cirrhosis or hepatoma were not detected and no patients developed veno-occlusive disease. Furthermore patients who developed hepatitis after transplant had worse prognoses. Based on serial serological survey of the various hepatitis B virus (HBV) antigens and antibodies, we have found that most of the recurrent viral hepatitis in transplant patients could be attributed to the reactivation of the virus. In addition, the use of immunosuppressive drugs, persisting infection by HCV and the development of graft-versus-host disease may also play a role in modulating the course of viral hepatitis in BMT patients.

Adolescent↗
PubMed1991

NMR studies of fluorinated visual pigment analogs.

The 19F-nmr chemical shift data of isomeric pigments (11-cis and 9-cis) of four vinyl fluororhodopsins and two trifluororhodopsins have been recorded. When compared with model protonated Schiff bases, a set of F-nmr opsin shift parameter (FOS) was obtained. The data revealed regiospecific protein perturbations on the F-resonances. They can be interpreted in terms of specific protein interactions such as the postulated second point charge and other polar interactions as well as the common hydrophobic protein perturbation.

Fluorine↗
PubMed1991

Spectroscopic study of the batho-to-lumi transition during the photobleaching of rhodopsin using ring-modified retinal analogues.

Photochemical and subsequent thermal reactions of rhodopsin containing 9-cis-retinal [Rh(9)] or one of four analogues with 9-cis geometries formed from ring-modified retinals, alpha-retinal [alpha Rh(9)], acyclic retinal [AcRh(9)], acyclic alpha-retinal [Ac alpha Rh(9)], and 5-isopropyl-alpha-retinal [P alpha Rh(9)] were investigated by low-temperature spectrophotometry and nanosecond laser photolysis. Irradiation of each pigment at -180 degrees C produced a photosteady-state mixture containing the original 9-cis pigment, its 11-cis pigment, and a photoproduct, indicating that the primary process of each pigment is a photoisomerization of its chromophore. The photoproduct produced by the irradiation of AcRh(9) had an absorption spectrum red shifted from the original AcRh(9) and was identified as the batho intermediate of AcRh(9). It was converted to the lumi intermediate through a metastable species, the BL intermediate, which has never been detected in Rh(9) at low temperature and whose absorption maximum was at shorter wavelengths than that of the batho intermediate. In contrast, the absorption maxima of the photoproducts produced from the other analogue pigments were at shorter wavelengths than those of the original pigments. They were identified as BL intermediates on the basis of their absorption maxima and thermal stabilities. The formation time constant of the lumi intermediate at room temperature was found to be dependent on the extent of modification of the ring portion of the chromophore, decreasing with the complete truncation of the cyclohexenyl ring [Ac alpha Rh(9)] and increasing with the attachment of the isopropyl group to the ring [P alpha Rh(9)].(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Butyl conformational reorganization as a possible explanation for the longitudinal flexibility of the binding site of bacteriorhodopsin. The azulene and C-22 retinoid analogs.

The UV-VIS absorption data of four bacteriorhodopsin (BR) analogs formed from azulene-retinals of varying polyene chain length show that the one-bond-shortened to one-bond-lengthened analogs possess comparable opsin shift values to that of BR. A two-bond-shortened analog exhibited a much smaller opsin shift. These data, combined with those reported for the C-22 retinal analog (Tokunaga et al., 1977, Biophys. J. 19, 191-198) were analyzed by molecular modelling and computer graphics in terms of a model where conformational flexibility of the appended butyl is the controlling factor in determining ease of pigment formation and protein/substrate interaction.

Azulenes↗
PubMed1991

[CA125 in non-Hodgkin's lymphoma].

CA125 is an antigenic determinant recognized by monoclonal antibody CA125 raised against a serous ovarian cancer cell line. Elevation of this antigen has been reported in over 80% of women with epithelial ovarian cancer and many other diseases including both malignant and non-malignant ones. However, in non-Hodgkin's lymphoma (NHL) only a few reports have focused on this topic thus interesting us. In order to exploit its possible role in this field, a total of 61 eligible patients with a diagnosis of NHL were studied. Serum CA125 was measured by radioimmunoassay (RIA) prior to any operative procedures or chemotherapy. Serum CA125 above 35 U/ml was seen in 47.7% of nodal NHL (n = 44) and 70.6% of extranodal NHL (n = 17) with an overall positive rate at 54.1%. The elevation of serum CA125 correlates well with the presence of peritoneal involvement and therefore, with disease extent to some degree. No correlation between it and the histological type or with the B symptom was the rule. Avidin-biotin peroxidase stain by anti-CA125 MoAb was applied to identify the tissue content of this antigen in 15 cases of whom 11 had CA125 well above 35 U/ml. None of the 15 cases examined showed positive result. In conclusion, serum CA125 is probably no more than an indicator of peritoneal stimulation released by tumor invasion rather than a tumor product. The possible role in disease follow-up remains to be elucidated.

Adult↗
PubMed1991

Lung deposits of lipiodol in normal and cirrhotic rats.

The distribution of Lipiodol in the liver and lungs following arterial or portal injection was studied in normal (n = 55) and cirrhotic rats (n = 20). Using magnified xeroradiography and radioisotope labeled tracers, it was found that Lipiodol was deposited mainly in the liver and lung after either arterial or portal administration. In control rats after arterial injection, deposits in the lung peaked after 2 hours and gradually declined over 48 hours; whereas after portal injection, the deposit steadily increased for 48 hours. Twenty-five percent of cirrhotic rats demonstrated a Lipiodol-induced military pattern in the lung. An increased number of portosystemic shunts in cirrhotic rats was also noted. These results suggest that cirrhosis of the liver may be a potential risk factor for developing pulmonary complications after Lipiodol administration.

Animals↗
PubMed1991

Radionuclide imaging clinical study. Corporeal 133Xe washout for detecting venous leakage in impotence.

A quantitative test, corporeal 133Xe washout, was developed to detect venogenic impotence. Data were acquired in frame mode after intracorporeal injection of 0.1 ml (1-2 mCi or 37-74 MBq) of 133Xe in saline on one side of the midline just behind the glans in the flaccid state for 20 min. A time-activity curve (TAC) was generated from the region of interest (ROI) at the site of injection and a computer routine was then used to calculate clearance half-time (T1/2) in minutes and flow rate (Q) in ml/100 g tissue/min from corporeal 133Xe clearance. The data from 12 controls and 21 patients with venous leakage were analysed. In patients with venogenic impotence, T1/2 (mean +/- S.D.) was greatly increased (24.4 +/- 10.7 min vs 10.7 +/- 4.6 min in controls, P less than 0.005) whereas Q markedly decreased (2.4 +/- 1.3 ml/100 g tissue/min vs 5.4 +/- 2.3 ml/100 g tissue/min in controls, P less than 0.005). The sensitivity and specificity for detecting venous leakage at the optimal threshold of T1/2 equal to 13 min and Q equal to 3.7 ml/100 g tissue/min were 95 and 75%, respectively. The corporeal 133Xe clearance half-time and flow rate are two simple and clinically useful indices for detecting venous leakage.

Adult↗
PubMed1990

Structure of the retinal chromophore in 7,9-dicis-rhodopsin.

Bovine rhodopsin was bleached and regenerated with 7,9-dicis-retinal to form 7,9-dicis-rhodopsin, which was purified on a concanavalin A affinity column. The absorption maximum of the 7,9-dicis pigment is 453 nm, giving an opsin shift of 1600 cm-1 compared to 2500 cm-1 for 11-cis-rhodopsin and 2400 cm-1 for 9-cis-rhodopsin. Rapid-flow resonance Raman spectra have been obtained of 7,9-dicis-rhodopsin in H2O and D2O at room temperature. The shift of the 1654-cm-1 C = N stretch to 1627 cm-1 in D2O demonstrates that the Schiff base nitrogen is protonated. The absence of any shift in the 1201-cm-1 mode, which is assigned as the C14-C15 stretch, or of any other C-C stretching modes in D2O indicates that the Schiff base C = N configuration is trans (anti). Assuming that the cyclohexenyl ring binds with the same orientation in 7,9-dicis-, 9-cis-, and 11-cis-rhodopsins, the presence of two cis bonds requires that the N-H bond of the 7,9-dicis chromophore points in the opposite direction from that in the 9-cis or 11-cis pigment. However, the Schiff base C = NH+ stretching frequency and its D2O shift in 7,9-dicis-rhodopsin are very similar to those in 11-cis- and 9-cis-rhodopsin, indicating that the Schiff base electrostatic/hydrogen-bonding environments are effectively the same. The C = N trans (anti) Schiff base geometry of 7,9-dicis-rhodopsin and the insensitivity of its Schiff base vibrational properties to orientation are rationalized by examining the binding site specificity with molecular modeling.

Animals↗
PubMed1990

14-Fluorobacteriorhodopsin and other fluorinated and 14-substituted analogues. An extra, unusually red-shifted pigment formed during dark adaptation.

Five vinyl-substituted fluororetinal analogues (8-F, 10-F, 12-F, 14-F, and 13,14-F2) were found to give bacteriorhodopsin analogues with properties similar to those of the parent system. Of these, only 14-fluororetinal was found to give an extra red-shifted BR analogue (lambda max less than or equal to 680 nm) in equilibrium with the normal 587-nm pigment. The 680-nm pigment was enriched upon irradiation. It rearranged to the 587-nm pigment at room temperature (delta E [symbol: see text] = 20.8 kcal/mol). Chromophore extraction experiments revealed the all-trans geometry for the 680-nm pigment. 14-Chlororetinal gave a similarly red-shifted pigment while 14-methylretinal did not. A scheme for dark adaptation of the 14-halogenated bacteriorhodopsins has been proposed in which the new red-shifted pigment was assigned the all-trans, 15-syn geometry.

Bacteriorhodopsins↗
PubMed1990

Comparative study on the chromophore binding sites of rod and red-sensitive cone visual pigments by use of synthetic retinal isomers and analogues.

A comparative study on the chromophore (retinal) binding sites of the opsin (R-photopsin) from chicken red-sensitive cone visual pigment (iodopsin) and that scotopsin) from bovine rod pigment (rhodopsin) was made by the aid of geometric isomers of retinal (all-trans, 13-cis, 11-cis, 9-cis, and 7-cis) and retinal analogues including fluorinated (14-F, 12-F, 10-F, and 8-F) and methylated (12-methyl) 11-cis-retinals. The stereoselectivity of R-photopsin for the retinal isomers and analogues was almost identical with that of scotopsin, indicating that the shapes of the chromophore binding sites of both opsins are similar, although the former appears to be somewhat more restricted than the latter. The rates of pigment formation from R-photopsin were considerably greater than those from scotopsin. In addition, all the iodopsin isomers and analogues were more susceptible to hydroxylamine than were the rhodopsin ones. These observations suggest that the retinal binding site of iodopsin is located near the protein surface. On the basis of the spectral properties of fluorinated analogues, a polar group in the chromophore binding site of iodopsin as well as rhodopsin was estimated to be located near the hydrogen atom at the C10 position of the retinylidene chromophore. A large difference in wavelength between the absorption maxima of iodopsin and rhodopsin was significantly reduced in the 9-cis and 7-cis pigments. On the assumption that the retinylidene chromophore is anchored rigidly at the alpha-carbon of the lysine residue and loosely at the cyclohexenyl ring, each of the two isomers would have the Schiff-base nitrogen at a position altered from that of the 11-cis pigments.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Complications of bone marrow transplantation in Chinese.

Forty-three patients with hematopoietic disease were treated with intensive chemotherapy and radiotherapy, followed by allogeneic bone marrow transplantation (BMT) from 28 HLA-identical and 10 one to two antigen haploidentical sibling donors and autologous BMT (5 cases). Of these cases, there were 21 with acute nonlymphocytic leukemia (ANLL), 5 with acute lymphocytic leukemia (ALL), 6 with chronic myelocytic leukemia (CML), 2 with Hodgkin's disease (HD), 8 with severe-form aplastic anemia (SAA) and 1 with thalassemia. Complications of BMT were evaluated including acute graft-versus-host disease (GVHD), interstitial pneumonia (IP), veno-occlusive liver disease (VOD), abnormalities of liver function (LF), and alteration of hepatitis B virus (HBV) markers. In thirty-three patients who were followed up for more than 3 months, we found that the incidence of moderate to severe acute GVHD (9.1%) and IP (two cases, 4.7%) were low. No VOD occurred in our series. During the follow-up period, 27 out of 35 patients (77%) had high alanine aminotransferase (ALT)/aspartate aminotransferase (AST) levels, even up to 1000 U/liter; however, only one patient succumbed to a hepatitis-related complication. Previous hepatic damage from HBV infection before BMT does not appear to increase the risk of posttransplant morbidity and mortality.

Adolescent↗
PubMed1990

Salivary scintigraphy with vitamin C stimulation: an aid in differentiating unilateral parotitis from Warthin's tumor.

Of the nine patients included in this study, five with proven unilateral parotitis initially had diffuse high uptake of 99mTc-pertechnetate in the affected glands with adequate washout following vitamin C stimulation. Of four patients with proven Warthin's tumor, two had focal high uptake in the parotid masses and two had diffuse high uptake on baseline images. All tumors were clearly delineated after stimulation. 99mTc-pertechnetate salivary scintigraphy with vitamin C stimulation may provide a useful tool in differentiating unilateral parotitis from Warthin's tumor.

Adenolymphoma↗
PubMed1990

Morphologic studies of intrapulmonary airway mucosa-associated lymphoid tissues in swine.

Morphologic structures of the lymphoid tissues associated with the mucosa of the respiratory tract in swine aged 11 to 13 weeks were studied by dissecting, light, and transmission electron microscopy. Tissues along the respiratory tract were collected for further examination. Light microscopic examination showed that the lymphoid tissues were associated with bronchi (8.38%), bronchioles (81.63%), and respiratory bronchioles (9.98%). The lymphoid tissues were identified at different levels of the airways and were designated intrapulmonary airway mucosa-associated lymphoid tissues. Anatomically, the lymphoid tissues were found mostly in the bronchiolar bifurcations, with an arteriole frequently nearby. Histologically, the lymphoid tissues contained a single dome-shaped lymphoid follicle, which bulged out from the mucosal surface into the airway, where it was covered along the mucosal side by a layer of specialized epithelium. Ultrastructurally, the mucosal surface of the specialized epithelial cells was equipped with microfolds or cytoplasmic projections instead of cilia. The cytoplasm was elongated, and therefore much thinner than that of ordinary epithelial cells. Many lymphocytes were found scattered in the mucosal epithelium between or beneath the specialized epithelial cells. This structure was similar to that seen in the Peyer's patches of the small intestine in swine and other animals.

Animals↗
PubMed1990

Changing of hepatitis B virus markers in patients with bone marrow transplantation.

The hepatitis B virus (HBV) infection and its resulting hepatic abnormalities are very high in prevalence among the Taiwan population. They also seem to compose a major problem to patients subjected to bone marrow transplantation (BMT) due to intensive chemoradiotherapy. In this study, the sera of 42 patients were investigated before and after BMT to detect the presence of HBV markers and to test their liver function (LF). Being followed-up for 3-12 months after BMT, 12 out of 27 were found to have altered HBV markers according to the classification of the following: seroconversion of HBsAg, clearance of HBsAb, appearance of HBeAg, clearance of HBeAb, and acute hepatitis. Thirty-seven out of 42 patients (88.1%) were found in routine LF test to develop one or more abnormality; however, 90% of them turned normal within one year after BMT. Only one patient died of complications associated with fulminant hepatitis. In conclusion, the previous hepatic damage from HBV infection appears unlikely to increase the risk of posttransplant morbidity and mortality.

Adolescent↗