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Biomedical subjects

J Lin

Publications and source records attributed to J Lin.

At least 685 records · Page 38Linked to original sources
PubMed1991

[Glycosaminoglycans associate with corneal transparency].

Keratoplasty specimens form 12 patients with macular corneal dystrophy, 1 patient with systemic glycosaminoglycan stored disease and 12 cases of normal cornea were studied by electron-histochemistry. The results showed that the normal cornea contains chondroitin sulfate in the basement membrane and bowman's membrane, Keratan sulfate and chondroitin sulfate between the collagen fibrils of strome, heparan sulfate on the cell membranes of various cells, and hyaluronic acid on the surface of endothelial cell. The chondroitin sulfate of the stroma of macular corneal dystrophy increases, but the keratan sulfate is absent. The keratocytes and endothelial cells of macular corneal dystrophy synthesize fibrillogranular material and abnormal glycosaminoglycan. The heparan sulfate is stored in the cytoplasm of corneal epithelial cell and keratocyte of systemic glycosaminoglycan stored disease and absent on the membrane of involved cells. The authors suggest that glycosaminoglycan play important role in maintaining corneal transparency and the changes of distribution, character and quantity of glycosaminoglycan in the cornea cause corneal opaqueness.

Cornea↗
PubMed1991

Ribose facilitates thallium-201 redistribution in patients with coronary artery disease.

To investigate whether i.v. infusion of ribose, an adenine nucleotide precursor, postischemia facilitates thallium-201 (201Tl) redistribution and improves identification of ischemic myocardium in patients with coronary artery disease (CAD), 17 patients underwent two exercise 201Tl stress tests, performed 1-2 wk apart. After immediate postexercise planar imaging, patients received either i.v. ribose (3.3 mg/kg/min x 30 min) or saline as a control. Additional imaging was performed 1 and 4 hr postexercise. Reversible defects were identified by count-profile analysis. Significantly more (nearly twice as many) reversible 201Tl defects were identified on the post-ribose images compared to the post-saline (control) images at both 1 and 4 hr postexercise (p less than 0.001). Quantitative analyses of the coronary arteriogram was available in 13 patients and confirmed that the additional reversible defects were in myocardial regions supplied by stenosed arteries. We conclude that ribose appears to facilitate 201Tl redistribution in patients with CAD and enhances identification of ischemic myocardium.

Aged↗
PubMed1990

Effects of acrylamide and N,N'-methylene-bis-acrylamide on creatine kinase activity.

In vitro, both acrylamide and N,N'-methylene-bis-acrylamide inhibited creatine kinase (CK) activity from brain or sciatic nerve with almost the same potency. In vivo, only acrylamide (50 mg/kg b. wt./day, 8 days) caused paralysis of hind limbs and suppressed CK activity in cerebrum, cerebellum, spinal cord and muscle in rats. Bis-acrylamide (50 mg or 100 mg/kg b. wt./day, 8 days) caused no paralysis nor inhibition of CK activity in any tissue examined. Definite inhibition of CK was not found in sciatic nerve from rats given either chemical. The inhibition of CK may play a role in the genesis of toxicity of acrylamide especially in the central nervous system.

Acrylamide↗
PubMed1990

Insulin- and thyroid hormone-independent adaptation of myofibrillar proteolysis to glucocorticoids.

Myofibrillar protein breakdown in skeletal muscle progresses through two distinct phases in response to chronic glucocorticoid administration in the rat, i.e., an early phase lasting 4-5 days, during which proteolysis increases followed by a later phase during which proteolysis decreases. The possible involvement of insulin and the iodothyronines in this phenomenon has now been examined. Diabetic, thyroidectomized, and normal rats were treated with corticosteroid for 10-11 days, and at timed intervals muscle proteolysis was evaluated by measuring the release of 3-methyl-L-histidine (3-MH) and tyrosine from the perfused hindquarter as well as the excretion of 3-MH in the urine. Corticosterone (CTC) administration to normal rats increased plasma insulin, whereas plasma 3,5,3'-triiodothyronine responded with an early rise followed by a fall after 4-5 days. However, the biphasic response of myofibrillar proteolysis to chronic glucocorticoid treatment was not abolished in CTC-treated diabetic or thyroidectomized rats. CTC treatment increased release of tyrosine by perfused muscle of diabetic rats but, unlike 3-MH release, did not diminish later. Thus the adaptation of myofibrillar proteolysis to chronic glucocorticoid treatment appears to be independent of insulin and thyroid hormones. However, insulin may play a role in curtailing glucocorticoid-induced breakdown of nonmyofibrillar proteins.

Animals↗
PubMed1990

Acanthamoeba keratitis successfully treated with prolonged propamidine isethionate and neomycin-polymyxin-gramicidin.

We report a case of Acanthamoeba castellanii keratitis that was successfully treated with intense propamidine isethionate and neomycin-polymyxin-gramicidin over 11 and nine days, respectively. The frequency with which the medications were applied, once every 30 minutes with each medication, has been surpassed only once before in reported cases. Additional medical treatment included topical miconazole 1% drops for five days and clotrimazole 1% drops for one day; the latter was discontinued due to corneal epithelial toxicity. Intense treatment of Acanthamoeba keratitis with these medications has not been reported before for as long as 11 days. Our aggressive approach was successful, and no clinically detectable significant side effects were observed. There has been no recurrence to date.

Acanthamoeba Keratitis↗
PubMed1990

[Effects of endotoxin on the cochlear electrophysiology and Na(+)-K(+)-ATPase activity].

Hemophilus influenzae (type B) endotoxin 10 micrograms was put in the niche of the round window in guinea pigs. The CAP thresholds and N1 latencies were measured before and 12, 24 and 72 hours after experiments. The 10 kHz and 8 kHz CAP thresholds after experiments were significantly higher (P less than 0.01), the N1 latencies were prolonged (P less than 0.05). There were minute changes in 4kHz CAP thresholds and N1 latencies (P greater than 0.05). In all time groups, the Na(+)-K(+)-ATPase activity was outstandingly weakened. It suggested that: (1) endotoxin put in the niche of the round window is responsible for the cochlear function disturbances in high frequencies, and (2) the decrease of the Na(+)-K(+)-ATPase activity is an important factor for the electrophysiological disturbances in the inner ear.

Animals↗
PubMed1990

In vitro influence of enkephalins on the proliferative response of mouse and rat splenic lymphocytes to phytohemagglutinin.

The opioid peptides leucine enkephalin (LENK) and methionine enkephalin (MENK) were investigated for their effect on the proliferative response of activated BALB/C mouse and Sprague-Dawley rat splenic lymphocytes in vitro. The results showed that LENK and MENK (1 x 10(-3) mg/ml to 1 x 10(-13) mg/ml) significantly suppressed the proliferative response of mouse lymphocytes to phytohemagglutinin (PHA) and enhanced the proliferation of rat lymphocytes at peptide concentrations similar to those effective in mice. It is proposed that endogenous ENKs play a neuroendocrine role between the central nervous system and the immune system.

Animals↗
PubMed1990

[Effects of the enkephalins on natural killer cytotoxicity].

Spleen mononuclear cells of BALB/C mice and YAC-1 cells were used in this experiment. Leucine enkephalin or methionine enkephalin at time 0 was added to cell cultures and the amount of the enzyme lactate dehydrogenase released from lysed target cells was determined 22 hours after incubation. There were on average 41% (5% to 60.7%) and 63% (46.8% to 78%) enhancements of natural killer activity in the presence of leucine enkephalin (1 x 10(-11)-1 x 10(-3) mg/ml) and methionine enkephalin (1 x 10(-15)-1 x 10(-3) mg/ml) respectively. The results showed that opioid peptides can modify NK cell function.

Animals↗
PubMed1990

[Studies on serum angiotensin-I-converting enzyme activity of experimental silicosis in rats].

The level of serum angiotensin-I-converting enzyme (SACE) activity on experimental silicosis in rats at different stages and under treatment with PVNO is reported. The results showed that levels of SACE in each dust groups begun to rise significantly higher than control groups as from the fifth day until 180th day (P less than 0.05). The levels of SACE of treatment groups with PVNO were significantly lower than the dust groups and similar to normal groups of the same age. It is suggested that SACE activity might be used as a reference index of silicosis.

Animals↗
PubMed1990

[Anti-cancer effects of sanjie pellets].

In the present paper, the authors applied Sanjie pellet in the anti-cancer study on the animals. The results indicated that in the extracorporeal experiment, stomach perfusion with Sanjie pellet 12.5g/kg daily for 10 successive days, the inhibitory rate for the substantive liver cancer was 84%. For ascites liver carcinoma, it could raise the average rate of prolonging life span to 76%. Lethal dose (LD50) was 25 g/kg. The pathological observations indicated that Sanjie pellet acted directly on the cell membrane and organelle of the liver cancer cells and causing lysis of the cell membrane, dilation of rough surface endoplasmic reticulum, the swelling of mitochondria and disintegration of the liver cancer cells body. The authors concluded that these were the main pharmacological efficacies of Sanjie pellet.

Animals↗
PubMed1990

[F3, a fractionated extract of Astragalus membranaceus, potentiates lymphokine-activated killer cell cytotoxicity generated by low-dose recombinant interleukin-2].

Success with rIL-2 immunotherapy of human cancer appears to depend on the administration of high doses which are frequently associated with excessive toxicity. Future use of rIL-2 will require certain modifications based on the use of lower doses of rIL-2 without significant loss of antitumor efficacy. The authors tested in vitro the possibility of potentiating the activity of rIL-2 in terms of LAK cell generation. The authors hypothesized that co-incubation of LAK cell precursors with a Chinese herbal extract (F3) of Astragalus membranaceus (an immune modulator currently under study in the authors' laboratory), along with a low concentration of rIL-2 would generate levels of LAK cell activity equivalent to those generated by high concentrations of rIL-2 alone. The authors found: (1) a 10-fold potentiation of rIL-2 activity manifested by tumor cell killing activity of 80% resulting from LAK cell generation with F3 plus 100 u/ml of rIL-2 versus 76% generated by 1000 u/ml of rIL-2 alone; (2) a significant reduction in the number of effector LAK cells required for equicytotoxic reaction following LAK cell generation with F3 plus rIL-2 compared to rIL-2 alone. The authors conclude that potentiation of antitumor activity mediated by rIL-2 in low concentrations is possible by the concomitant use of another immune modulator such as Astragalus membranaceus.

Astragalus propinquus↗
PubMed1990

[Ecological studies on the cercariae of Echinochasmus japonicus].

Results of ecological observation on the cercariae of Echinochasmus japonicus showed that their development in and emergence from Parafossarulus striatulus as well as their activity in infecting the fish host in water were closely related to temperature and light. The number of cercariae emerged varied with the temperature of water. When the infected snails were reared at water temperature of 27-32 degrees C, the germinal cells and germ balls in the daughter radiae multiplied continually into cercariae a majority of which emerged. At water temperature below 24 degrees C, multiplication was hindered and, emergence of cercariae obviously decreased. Cercaria shedding stopped at water temperature of 14 degrees C. The reason why the rate and degree of infection with meta-cercariae of Echinochasmus japonicus in the small-sized species of fresh water fishes were higher than in the large-sized species was that the cercariae were tactic to light and so active in shallow water where they were constantly in contact with smaller fishes. Since the natural infection rate of Parafossa-rulus striatulus was found to be higher (32.2%; 37.3%) during the months of July-October than during the other months, investigations on the first intermediate host should be carried out in early autumn.

Animals↗
PubMed1990

Gossypol-induced alterations of aminophospholipid composition in human sperm.

Gossypol-induced alterations of aminophospholipid composition in human sperm were observed and the effects of some factors on these alterations were investigated. The alterations of aminophospholipid composition of human sperm induced by gossypol included a progressive decrease in the levels of phosphatidylethanolamine (PE) and phosphatidylserine (PS) when gossypol concentrations ranged from 5-500 mumol/L, and a progressive increase in the level of (LPE) at lower gossypol concentrations (5-50 mumol/L). The conversion of PE into lysophosphatidylethanolamine (LPE) was strongly enhanced by Ca2+ and inhibited by 0.5 mmol/L EDTA, while PMSF, NEM, iodoacetamide and Zn2+ had no effect. This conversion was weaker in sperm with stripped surface proteins than in normal sperm. In addition, three surface proteins (MW 80, 60 and 40 kD) were fixed on the plasma membrane by gossypol treatment. The significance of gossypol action and the possibility that sperm PLA2, PE and some surface proteins might play an important role in the physiological acrosome reaction of human sperm, as well as in oocyte penetration, are discussed.

Gossypol↗
PubMed1989

Determination of the roles of active sites in F1-ATPase by controlled affinity labeling.

The affinity reagents 3'-O-(5-fluoro-2,4-dinitrophenyl) [alpha-32P]ATP (FDNP-[alpha-32P]ATP) and 3'-O-(5-fluoro-2,4-dinitrophenyl) [8-14C]ATP (FDNP-[14C]ATP) were synthesized and used to characterize the structure and function of the three active sites in F1-ATPase. FDNP-[alpha-32P]ATP was found to bind covalently to F1 up to two DNP-[alpha-32P]ATP labels per F1 in the absence of Mg2+ without decreasing the ATPase activity. However, when MgCl2 was subsequently added to the reaction mixture, the enzyme could be further labeled with concomitant decrease in ATPase activity that is consistent with the complete inactivation of one enzyme molecule by an affinity label at the third ATP-binding site. Partial hydrolysis of the FDNP-[14C]ATP-labeled enzyme and sequencing of the isolated peptide indicated that the affinity label was attached to Lys-beta 301 at all three active sites. Samples of F1 with covalent affinity label on Lys-beta 301 were also used to reconstitute F1-deficient submitochondrial particles. The reconstituted particles were assayed for ATPase and oxidative phosphorylation activities. These results show that the catalytic hydrolysis of ATP either by F1 in solution or by F0F1 complex attached to inner mitochondrial membrane takes place essentially at only one active site, but is promoted by the binding of ATP at the other two active sites, and that ATP synthesis during oxidative phosphorylation takes place at all three active sites [corrected].

Adenosine Triphosphatases↗
PubMed1989

8-Azido-2'-O-dansyl-ATP. A fluorescent photoaffinity reagent for ATP-binding proteins and its application to adenylate kinase.

The photoaffinity reagent 8-azido-2'-O-[14C]dansyl-ATP (AD-ATP) has been synthesized for labeling and monitoring the active sites of ATPases and kinases. In its first application, the reagent is used to explore the active site of adenylate kinase from rabbit muscle. In the dark, AD-ATP inhibits adenylate kinase reversibly and competitively with KI = 0.25 +/- 0.01 microM. Under weak UV illumination, AD-ATP labels adenylate kinase irreversibly. The photoinactivation data also show KI = 0.25 +/- 0.02 microM. The ratio (r) of the specific activity of AD-ATP-labeled adenylate kinase to that of the unlabeled enzyme has been determined as a function of the number (n) of label/enzyme. The linear plot of r versus n with slope equal to -1 shows that the labeling is very specific, i.e. each label completely inactivates an enzyme molecule. After the labeled enzyme was partially hydrolyzed and the radioactive peptides analyzed and sequenced, it was found that Leu-115, Cys-25, and probably His-36 were labeled, in agreement with previous conclusions on the structure of the active site of this enzyme based on amino acid sequence, x-ray diffraction, and NMR studies. The environment-sensitive fluorescent dansyl group of AD-ATP can function as an in situ probe for monitoring ligand or conformation changes at the active site. The fluorescence of AD-ATP-labeled enzyme with n = 0.9 is not affected by ATP but increases with the concentration of AMP in solution. This observation is also in agreement with the previous conclusion that ATP does not bind to the AMP site of adenylate kinase. The observed enhancement of fluorescence indicates that binding of AMP by this enzyme causes environmental change at its ATP site. The possible usefulness of AD-ATP as an effective biological inhibitor or as a molecular probe for studying the structure and regulation of ATP-binding proteins is discussed.

Adenosine Triphosphate↗